Failure Atlas

8/9/2019 Failure Atlas

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fAILURE TLAS FOR

HERZ CoNTAT MAINE LEENTS





© 1999 by he Amerca Socety of Mechaica Engneers hree Park Avenue, New York, NY 10017

Library of Congress Cataogng-nPublication Data

Tallian, T E

Failure atlas for Hertz contact macne elements/ E aian2nd edp cm

Includes bibliographical references and index.ISBN 0-7918-00849 (h)1. Machine partsFailureAtlasesI tleTJ24335 19996218'2dc21 9855099

CIP

All rights reserved Printed in the Uted States of America Except as permtted under the UnitedStates Copyright Act of 1976, no part of ts publication may be reproduced or distrbuted in anyform or by any means, or stored i a database or retrieval system, wthout the prior wrtten

permssion of the pubsher

ASME shall not be responsible for statements or opinions advanced in papers or printed in its publications(B713) Statement from the Bylaws

Authorization to photocopy material for internal or personal use under circumstaces not fallingwithin the far use provisions of the Copyrght Act is granted by ASME to libraes and other usersregistered with Copyright Clearance Center (CCC) ransactional Reporting Service provided thebase fee of $400 per page is paid directly to the CCC, 222 Rosewood Drive, Danvers, MA 0923



CONTENTS

Preface to the First Edition . .... . . .. .. .. .. .. .. .......... .... ... ....... .. ....... ....... .. ... .. .. ..... ..... ........ vn

Preface to the Second Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 1x

PART I GENERAL INFORMATON . Introduction Failure Classification ..

Appearance Classification

PART PATES · 4 Nicks. FC 5 Surface defects from manufacturing. FC - 6 Material and assembly defects. FC 7 Mild wear. FC 8 Galling, skid marking. FC 9 Fretting wear. FC

0 Spalling. FC ; :

Surfae distress. FC Denting. FC Heat imbalance failure. FC 4 Corrosion, electric erosion. FC 5 Bulk cracking, fracture, permanent deformation. FC 6 Guiding component failure. FC 7 ntegral closure failure. FC 8 Lubricant failure. FC 9 Mounting part failure. FC

ENDCES References List of mage Contributors Failure Code List . Failure Mode Index . Text Index Color Images

V

Active and interlinked subheadings and corresponding target headings.



PREFAE TO TE IRST DITION

Tis Atlas is t roduct of fou dcads of hotogaic failu docuntationrlating to Hrt acin nts assbd by nuous woks in th nitdStats Euo and aan T docuntation was contibutd to t Atlas by abouttity nstitutions and individuas T xacting wok of assbing t iags inroducib for and roviding th data quid for tir us was ford slfssy by al contibutors. n addition al contibutors av viwd t Pat atriarard fo thi inuts Most of t contibutions ar idntifid in th Contributorslist at t nd of t book A fw institutions fo businss rasons av ctd notto b xlicitly acknowldgd T authos sinc gratitud is xtndd to t asto al oths

A full viw of t draft anuscit for corctnss in atrials scinc intrrtationwas ford by Mr. Gorg H. Bai an indndnt consultant. Without is xt

advic ors in atrias scinc intrtation ay w av bn unavoidabT contribution of all aticiants notwithstanding sonsibility fo t tchcal

contnt of th Atas as a who rsts of cous wit t authoPubication of t book is ad ossibl by ASME Pss t book ublising a

of t Arican Socity of Mcanical Engins Sincr tanks a du Ms CaryDribatt and t ot ditors of ASME ss wos fxibiity lfulnss andatinc nvr faggd during t rathr laboat ffot of ubising a volu ascox and scialid as this Atas.

ASME and STE t Socity of Triboogists and Lubication Enginrs av botsuortd this wok by tir ndorsnt and wilingnss to ac announcntssking iag soucs in tir jounas.

ow y wif o than I can say for th any ours of ticuous labor sntin fnaiing th anuscit wit its iag atia into a for suitab for ublication

v



PREFAE TO TE EOND DTION

The Second Edition of this Atas has been revised to accommodate information that became avaiable since 1990, when the First Edition went to press. Additons weremade to Chapters 6, 7, 10, , 13 and 8 for the purpose of incuding faiures of vaporphase ubricated roling bearings and Hertzian contact components made of siliconntride ceramics. Additions were aso made to Chapter 8 refecting new informationon galing and skidmarking faiure, based on investigations performed on cam systemsOne failure class (casting defects, FC 00.05) to which new materia was added, isrelocated from Chapter to Chapter 6 which is now its more appropriate pace. Refinements aimed at making text clearer, or reflecting deveopments in the understandingof failure mechansm, have been made in severa other parts of the Atas A few newreferences were added. Some Failure Codes were added to cover newy iustratedfailure modes. The changes ad additions require the updating of all failure code lists,

indexes, cross-references, and many Plate numbers, with the resut that the entireSecond Edition was newly typeset whie reusng a existng image material from theFirst Editon

Image material and text eft unchanged is judged to remain vaid as presented inthe First Edition

I wish to express my sncere appreciation to al contributors of new image materiaand related tecca information, without whom the revisions would not have beenpossible; and to ASME Press who have found the Atlas usefu enough to publish thisSecond Edition. My specia thanks to Mr. John Corrigan and Ms. Tara Colins Smith,ASME Press editors, who have superintended the publishing of the Second Edition.The reception of the First Edition by the triboogica commuity, which ustified aSecond Edition, is most gratifying. My debt of gratitude to my wife, acting as copy

editor, remains the same as ever

x





INTRODUCTON

STRUCTURE OF THE ATLAS

.1

Ts Alas s composed of wo pas Pa I compses e follow capes: Iodco, FaileClassifcao Codes, ad Appeaace Classifcaio Tables Pa II cosss of deailed imae maeiasow fale mopooies ad s aaed i a mbe of Plae capes oized by faiemodes

Moe specifcaly, Pa I. Geea fomao, compses e folow

Chapte ntductin compises a evew of backod o diaosis by fae mopoloy,

eleva lieae, eeal coceps of coac fale cassfcao ad disis feaesof s Aas.Chapte 2 ailue Clacatin descibes e eacica classificaio code ailue cde C offale modes a decmal mbei sysem ad ex desaio of eac faile mode. TeAas mae maea s oazed aod his fale classfcao. Nmec d alpabecdexes of e fale codes ae fod is capeChapte Appeaance Clacatin coais seveal paes op fale modes by appeaaceas ad fd e Plae cape appopae o he obseved faie

Pat Plate is e mai body of e book I s composed of a sees of capes, eac coaioe o moe secos cosis of mae paes, caled Plaes, whic lsae oe mao fae cass.Eac cape s iodced by a descipo of e denitin failue pce appeaance caue ad

eect of e fale mode(s) coveed.

ndexing As saed, e imae maea of e Aas s dexed by faie code. Cindexing offale modes is povded bewee Paes, as explaed ae Cape 1. Text mateial cdall of Pa I ad e deciptin odci eac cape i Pa II ae idexed he sal way bykey wods.

BACKGROUND

.2 Definitions

1. Load-cay mov coacs bewee mace eemes exibi peclia tiblgical failemodes cased by imevaabe sess of e coac sfaces. Cncentated o Hetz cntactae caacezed by e ocofom eomey, i pesses, dsic coac maeiasad lbcaio emes, ad exhibi a weldefed sbse of ese bolocal fale modes.

2. A Hez coac compoe is oe fea load-cay Hez coacs A Hez coacmace eeme s a complee sbassembly of Hez coac compoes ad sppoi (ocoac) compoes wok oee.

3 A faile mode s e pyscal codo of a compoe esl fom a specfc pysicafae pocess.

4. A (iboocal) fae mode daabase fo Hez coac macie eemes s a oazed bodyof fomao o e faie modes of ese elemes ad e eee cases.

. A fale mphl atla s a fale mode daabase cocea o opoapc (vsal)

feaes of e failes, s imaes as a ma daa fom, sppemeed by a classfcao of

3



Failure Atlas for Hertz Contact Machine Elements

4

falures and concse descrptons of faled component, falure mode, and classes of lkely eng

neerng causes of falure. mages lustratng degrees, varants and combntons of falures areused for comparson wth user-observed faures.

.22 Appicaion of Morphology Atlas fo Diagnosis

Trboogcal engneerng of Hertz contact machne elements (and of ther appcatons s amed atthe dual objectves of (a achevng the functon ntended for the machne element; and (b preventng,delayng or reducng any trboogcal falures.

Engneerng for the desred nctn folows dstnct prcples for each of the major casses ofHertz contact machne elements such as gears, rolng bearngs, tracton drves, cams, etc Engneerngforfale cntl s, by contrast, based on much common ground, due to the commonalty of contact

falure modes, even though specfc practces have evolved for each major machne eement cass.Owng to ths commonaty, t s possbe to desgn teccal ads for falure control engneerng thatserve most classes of Hertz contact machne eements

Trboogca faure control s hghly emprca. It begns wth the dentfcaton of operatng condtons, such as geometry, load, speed, temperature, ubrcaton and envroment. Ths s followed bythe selecton of a machne eement desgn class wth a hstory of successful servce under the gvenoperatng condtons. Based on experence, a herarchy of falure rsks by faure mode s thenestabshed whch eads to specfc desgn, manufacturng an appcatons choces for the controof these rsks accordng to ther severty. In many cases, preventon of trbologcal faure throughoutthe desred usefu lfe of the devce canot be assured wth certaty, and choces of acceptablesurvval probabltes are made

After buldng the devce, t s tested ether formaly or through placement n servce, ad anyfaures are observed. They are dagnosed accordng to faure mode and cause, and modfcatonsn machne element desgn, manufacturng process and applcaton specfcatons are made untreabty and ongevty objectves are met.

Trboogcal engneerng for faure control reures precse dagoss of faure modes ad thedentfcaton of ther engeerng causes, as gudes for correctve acton n desgn, manufacturngand appcaton engneerng.

Data concernng trbologca faures can be of many types Examples are statstca data on servcelfe under spalng fatgue, wear rate data, formulas relatng dmensonal nstablty of stee to retanedaustente, etc A dstnct data category s mphlgcal data defned as falure features that are vsble

by eye, by lght mcroscope or by scang electron mcroscope (SEM, or dscerbe by surfacetracng or (mcro geometrc measurement

Hertz contact trbology dagnoss greaty depends on the recogton of the morphoogy of afaure. Such morphoogca dagnoss demands very specfc experence, besdes proper magngand measurement facltes. An atlas of reference mages wth terpretaton, representg, wtnreason, a complete catalog of faure morphooges correlated wth the desgn, manufacturng andapplcaton parameters of the faed machne eement, s a wel recognzed resource for tranng essexperenced dagnostcans and n supportng the experenced dagnostcan when confronted wtha machne element or faure appearance outsde ther experence

A morphoogy atlas dffers from an ustrated textbook on faure dagnoss d suppements t. Atextbk contans nstructons on recovery of the component from the mace, ceang, preservaton,varous examnaton tecques and record keepng method It may offer nformaton on correctveengneerng acton folowng falure dagnoss. Ilustratons n a textbook are lmted to typcal faluresneeded to support the verbal descrptons. A mphlgy atlas on the other hand, provdes a colecton

of falure mages lustratg degrees, varants and combnatons of faures n rch detal, to facltate



Chapter : Introduction

machng he oen unypica an complex observed faiue. I heeby en pecificiy o he iagnoic meho of he exboo An aa oe no cove iagnoic mehooogy

Thi Failue Aa i accoingly an ai in he ienificaion an iagnoi of failue moe anhei caue Tha in n om an inegal pa of faiue conol eign an appicaion engineeingof Hez conac machne elemen

2 Reated Publiatins

Ealy publicaion ecibing iboogical conac failue mophology wee nene fo eviceenginee an pecialize in one of he wo mo common machine elemen cae (oling beaingo gea. Refeence [1 an [2 ae manual fo oing beaing iagnoi fo evice enginee.They ae well iluae an compehenive bu o no inepe failue beyon he nee ofevice iagnoi an o no claiy aie o he eph neceay o eaie coeaion wihaiue caue

Simila bu popieay manua have been pubihe by many majo manuacue of Hezconac machne elemen epecialy of beaing an gea.

Paalel wih pacica iagnoic pupoe inee in failue moe claiicaion by mophologyaoe uing eeach ino machine elemen lie peicion A an example claical oling beaingie heoy [3] i bae on a uy of pal omaion fom ubuace eec. Faiue cono eeachwih exenive ue of mophological cieia wa ae exene o he yemaic caificaion ofconac ailue moe (See eg 4], 5], 6]) Even moe han he peviouy ie manua heepubicaion concenae on he ypica eae o aiue an conain only enough iluaion oocumen he caificaion mae.

The Rolling Bearng Damage Atlas pubihe in 1974 by Talian e a. [7] wa eigne a a pimay

efeence ouce o conac ailue mophology o olling beaing I aempe o cove all ibological aiue moe compehenively in phoogaph incuing macogaph micogaph an SEMimage I conain a inge-ie claificaion of aiue moe bu oy ee ecipion of eachailue an no pecific caue coeaion.

Fo gea he Ameican Gea Manuacue Aociaion publihe a failue nomencaue ana[8] I i a naaive failue ecipion wih iluaion of ypica ailue inene o pimayaiue ienificaion Some caue coelaion ae povie. A hoough pacica exbook o failueiagnoic o gea i by Aban 9] I conain exenive image maeia on faiue wih eaieuoial iagnoic inucion bu no hieachical claiicaion.

Volume 1: "Faiue Analyi an Pevenion of he ASM Handbook [10] conan wie anginginfomaion on meallic maeial ailue claifie pimaiy by geneic failue ype an hei caueSepaae chape on oing beaing faiue an gea ailue ae ao povie Thee chape

conain naaive of aue ecipion wih illuaion o ypical failue.Voume 8: "Ficion Lubicaion an Wea Technoogy of he ASM Handbook [1] conain a

bie uay of olng conac faiue wih a few iluaion.A uoial ex by Wupi 12 cove a wie ange of mechacal aiue in e eail han he

Metals Handbook. Iluaion ae o ypical ailue.An ala o mea uace amage hown in SEM image incung bu no limie o Hez

conac o o ibological failue i Enge e al 13. Thi pubicaion conain high-ualiy imagemaeial an cea cieniic ecipion bu i no yemaize aoun Hez conac.

1Numbers in rackets ct references at th nd of t ok.

5



Filure Atls for Hert Contt Mchine Elements

In chapers dealng wh ndvdual aure modes, reerences peranng o he heory o hesealure modes wl be ced as requred

FEATURES OF THE ATLAS

6

New Features

Ths Aas suppemens oher exsng leraure n severa ways Frs, permis ready comparsonwh observed alures hrough copous lusraon, no ony o he mos ypca alures, bu alsoo he commony occurrng degrees, varaons and combnaons o alures covers he majorclasses o Herz conac machne elemens, permng observaion o common aure characerscs. also ncudes normaon on he alure o upporting (non-conac) componens o he subassembeso elucdae neracons among all aure modes.

Second, a hierarchical aure casscaon s provded or easy searchng durng praccal dagnossThs classcaon s severa ers deep (Exampe spalng n general, surace orgn spals, ocalsurace orgn spalls, deec orgn spals Faure classes are ormazed by numerc failure code, soha alure modes are unambguousy classed Some advanages o such a sysem are:

Users can race a herarchca search pah o a specc morphologcal mach as and wh amnmum o los moon (For nsance, hey can nd an mage showng a spal a suracedsressed conac wh muliple debrs denng

Ready access s provded o ames o aure appearances classed by he specc eaureunder sudy (For exampe, one can nd al mages conang sgns o gallng, wheher behe prncpal or an ncdenal alure mode

Unambguous cross-reerencng o aure modes s avalable across several Pae chapers Many

Plaes show compose alures They are arranged n he Alas by a primary alure mode, andalso lusrae econdary alure modes va cross-reerence abes n he approprae chapers

Common causaon chas operave over enre alure classes are documened2 Falure morphology s correaed wh engneerng alure causes by aachng a shor s o

causes o each aure llusraon The user can accumulae evdence or a gven cause overseveral dagnosc maches As a exampe: I surace dsress and aso overheang o conacsuraces are dagnosed, boh o whch correae wh nadequae lubrcaon, hen hs causeassgnmen gans suppor rom boh correaons

In he Second Edon, new maeral has been ncuded o lusrae he specc appearance oalures in ceramc conac maeras and hose characersc o meallc maerals ubrcaed by meansoher han organc luds Faure mages and descrpons have been updaed hroughou he volume

where new or beer maera became avaable

2 Format of Image Pages

Ths secon descrbes he machne eemen casscaon used n he Aas and he orma o hemage pages Two ypes o mage pages are used n hs Aas: Appearance Casscaon pages andPae pages cassed by alure mode (The aure casscaon sysem s descrbed n Chaper 2.

2 majo tngt of th nmcal cafcaton t appopatn fo lctonc ach, makng t wll utd fo a comptzd

dagnotc ytm, a wll a fo a book



Chapter : Introduction

Machine Element Classifiation. Ts Atas covers rolng bearngs, gears and cas as the praryachne eeents (subassebles) featrng ovng Hertz contacts. Tracton drves are treated under

bearngs, drve chans and spnes under gears. A group other acne eleents s provded tocapture achne eeents not falng these categores Table 1.1 presents the abbrevatons forachne eeents and ther coponents used n the Plate texts (The achne eeent sybol alwaysprecedes the coponent sybol)

Tabl . MACHINE ELEMENT CLASSIFICAION

Symbol Mahin Elmnt Symbol Comonnt

Rg Brg g Brg

B Rollig bearg Cotact components:

BB Bal bearing IR nerrng, shaft washeDGBB Deep groove ball beang OR Otering ousig washeACBB Anga coac bal bearng B BalMCBB Maxmm complemen bal beang R RollerSABB Sef-algg bal beang G Gdng compoetABB Axia (s) bal bearig c Cosre (sea shield)RB Role beag I ntegrated bearing nitTRB Tape roer bearing M Montig paCRB Cyldrcal roller bearigSRB Spherica roller beaigNRB Needle rolle beaingRB aper oer thrs beagSRB Spercal rolle thrst bearngCRB Cyidca oer s beaig

LB Lnea beangBSB Bal screwRSB Rolle screwDB Tracto dve

Grg Grg G Gea Coact compoentsSG Spr gear p PonHG Heica gea w Weel (bl gear)BG Bevel gear 0 WormHYG Hypoid gea R RackWG Wom gea c Dve chaSPG Cha drive s SprocketRPG Rack ad pnio M Montng pa

SLG Spne

c Cam ad oowe Cotact compoents:

CM CamC Cam ollower olerCT appet

u u se Sprag cc S Spag g

s Sprag eemetM Montng pa

0 Or

7



Filure Atls fr Hert Ctt Mhie Elemets

A ppearance Classification (Cha pter 3)Whe dagostas st spet a aed ahe eeet the pay gde to ae ode

detato s the appeaae o the ae. I tooga aes t s ot oo o veydeet aue asses to pode speay sa aue appeaaes Ts s oe o thedtes tooga ae dagoss. To atate the ta dagost oetato the Atasoes a hapte o ages aaged y appeaae ass that s a e oeto o typa aeappeaaes. As a as the sjet pets appeaae asses de shapy o eah othe ae appeaae wheeas appeaaes that ae apt to e osed ae oe ass I ths waythe se a d the ght oetato page wth tte aguty ad a the se the dsttosoeed y the sevea ages o the page o deetato etwee ae asses. Evey eotwas ade to seet statos o sge ae odes (eve thogh dagost pate tpeae odes ae oo. A ages Chapte 3 ae seeted o Pate haptes.

Eah ae ass deted wth a Appeaae Cass s eeeed to a hapte o Patesdevoted to that ass

Nte: Iages ae ot povded the appeaae assato hapte o aues that ae se-assyg y the ate. Fo exape eag sepaato aes ae a oud oe Pate hapte as aeshat aes Theeoe ethe s stated C _ hapte 3 Fo opeteess the ae asses otstated the Appeaae Cassato ae st sted thee y ae.

8

The oat o Appeaae Cassato sed Chapte 3 s desed as oows:

Clss heder. A appearane la s pted osetvey o oe o oe pages. At the head oeah appeaae ass s the la header osstg o:

• Appearane la name The ae o the appeaae ass apta ettes Exape: "POW

ING MA."• Appearane deription A e o text gvg the dstgushg eatues o appeaae o the

ass. Exape: "Depessed e deet o atea eova y powg atio"

Appere illustrtis. A sees o ages wth desptve text detiyg the sevea aeodes that show a appeaae ag wt the appeaae ass. I deta:

Failure ode and mode The e ad text desgato o the stated ae ode aodgto the Fae Code assato desed Chapte 2 Exape: "FC 0002 Fshg ak(ow hatte wheelht)."

• Appearane A e o text gvg the dstgshg eatues ad typa asato o the aeode Exape: "Sath a y jy dg assey o otg"

• Image A e aptoed 'Ahve No ad oe aptoed 'Pate No deed the sae wayas o Pate pages (see Seto 1323) Exapes: "Ave No: 080-01," "Pate No: 5.11."

A age aopaies ost o the Appeaae Istato etes. Whe thee s o statoa expaato s povded. Exape: "Show ude 'geea textue hage. "

late Cha pters (art 11I ts Atas the ae ages wth desptve text assed y ae ode akg p Pat

11 ae desgated as Plate A hapte o Pates states oe o oe primary aue odes eaho whh opes a seto. Seoday ae odes ay aso e peset the Pates ad soae deted the text. Pates a seto de the spe ppa ae ode show (wthithe seto ass the sevety o aue wth a gve ode the aopayg seoday ae



Chapter : ntroduction

mode the presentaton imaging o the alure or the appearance o aiure as it may ary withna gien mode Each chapter and secton s indexed by the Faure Code o the aure cass described

n it.Chapters start wth descrptie text deing each o the aure classes ilustrated in a secton o

that chapter wth derentiaton critera among subordinated aiure modes The descrption giesdenition nomenclature failure process, lkely failure causes and prncipal eects

Next olows a Cross-ndex o Secondary Faure Codes t lists the Plate numbers in any chapterthat eature secondary ailure codes alng wthn the aiure cass o the chapter at hand SuchPates can sere to augment the collecton o aure ilustrations n this chapter

Finaly the body o the chapter s composed o the Pates each o whch contains a alure mageaccompaned by interprete text.

Note: A Pate chapter or secton coers one aiure cass but all machine elements in whch it occurs. Asan example Chapter 0012 Wear o Hertz contact components ncudes bearing rng wear gearwear and cam wear but not shat wear because a shat s not a Hertz contact component Shatwear s ound n Section 22 Shats

la Forma Dscri pionEach Pate consists o three man parts mages Data and Descrptions The images are one

or more reated photographs ilustratng the same ailure mode The data comprise quantitateormation descrbng the ilustrated aure and the imagng process as wel as our aure codesDescriptions are gen or the alure mode the mage appearance and suspected aiure causes. Oneor more Pates may occupy a book page; there is more than one they are separated by a heay ine

Page Header Each Plate page carries a header wth the aiure code o the Pates shown on that

page near the bndng. The chapter ttle n the header is near the outsde page edge. The alurecodes are copied rom the primary code o each Plate on that page as deined below and sere asthe prncipa Plate look-up coding o the Atlas The appearance cassiication n Chapter 3 and theailure code n Chapter 2 both reer to this Pate codng. Each page header aso carres the bookpage number as reerenced n the Table o Contents

Image(s) The image(s are prnted near the top o each Pate. there is more than one the magesare identiied as a b etc.

Data. Plate No ocates the Plate n the boo A Pate number has two parts such as 25. Theirst part is the chapter number the second part s the seria number o the Pate within that chapter.Plate numbers are used or cross-reerencng between Plates See Section 34 or deta.

Archive No. is a two-part number such as 066-00, and identes the mages on the Pate n themaster image arche These numbers are used to gie source credit or image material.

Image type can be

• Vie wblack/ white or color ew o an entre component.• Light macro or clor macro sghty magied or demagned image o part o a component.• Light micro gramback I whte image at substantia magication• Light metallogrammcrogram o a metalograpic section etched or unetched• scaning electron mcrogram. Secondary eectron images are not idented. Backscatter

images are so marked• transmssion electron mcrogram o tn lm or repca as ndcated

9




10

Coor images are located n a separate Appendix, 'Coor Images, where they are identified by Pate

number. In pace of the image on the Plate, a reference appears, stating: ee image in Appendix."If there is more than one image per Pate, each is identified by (a), (b), etc, and each is described.Scalebar . . mm means that the length of the bar drawn on the image equals . mm on the

original object These engths are given either in limeters (mm) or micrometers (�m). If there ismore than one image, a scalebar vaue, identified by (a), (b), etc, is given for each

Image sources do not aways indicate scaes of views and macro images Scales of micrographsare generally (but not aways) availabe. Due to this uncertainty, scales given are informational oy.An error range of + 20% for micros, and +100%, -50% for other images is indicated on al Platesas a precaution These ranges are quite conservative for most Pates

Component is the (coded) designation of the machine element and its parts shown on the image,with indication of material condition (if reevant) and whether the part was in service (run) Themacne element cassification code and the parts code are taken from Tabe 1.1.

Speed, load and lubrication are given for parts that were in service, if this informaion was receivedfrom the image source. This information is useful in pacng the failure n perspective, but not strictynecessa to the diagnosis It must be borne in mind that even where the information is availabe,it may represent typical rather than failure-specific vaues The defiition of these parameters isas folows

Speed is a inear surface speed, where avaiable Speed-related faiures generaly correate withpeak speed in service, but that value is often unavailable

• For roling bearings, the simple measure used is dN [mm·r/min], ie., the bore diameter of theinner ring inm,multiplied by the shaft speed n revolutions per minute (KdN 103 dN, MdN= 06 dN). The measure Nd1 , where the rollng element pitch circle diameter is substiuted forthe bore diameter, is the more modern usage, but this information is not widey enough availabefor e failure ilustrations colected for this Atas, to be used Occasionaly, oly speed of rotationin r Im is avaiabe nd is given

• For gears and cams, linear rolling speed m/sec (at the pitchine for gears) is used.

Load for al contact components is the normal contact pressure GPa No meaningful oad value can be generalized for non-contact components

Lubrication is described by two elements the lubricant type and a ypical operating temperature C0].

• Lubricant type is described generically. Examples mineral oi, synthetic polyester oil, lithiumthickened minera oi base grease, etc Often, however, oly the maor cass is known, suchas grease.

• Temperature is the ypica buk temperature (sustained maximum temperaure) of the componentI faiures where temperature rise is produced, the temperature given is that before onset of failure. Again, typica temperaure is often unknown

Failure code consists of the numerica code and text designation detailed in Chapter 2 Room isprovided for four distinct faiure codes to accommodate composite failures. The four codes areordered generally by their prominence on the image shown (not the order of their importance tothe serviceabiity of the component or their sequence of occurrence) This ordering is somewhatoose, and great weight should not be attached to it in reading the Pates. The sequence, relativeimportance and mutua interaction of failure events is discusse thorougy in the Description partof the Plate text.

See also PLATES is a cross-reference to other Pates in the Atlas, which are related to or hep

iuminate the contents of the present Pate



Chapter Introduction

Descriptions. Te Descptns e ntve sttements explnng te flue lustted. Unfmtemngy f gven flue s ttempted f bengs, ges nd cms Ts my mke tenmenctue ppe unusu t sme edes Cmments egdng fue mde temnlgy en te Intductn f Cpte 2, nd n te Nmencue pgp f te Genel Descptn nec Pte cpte Tee, te temngy used n te Als s celted wt tt custmy fte vus mcne elements

Failure Description Ts s te centl sttement f fue dgnss Te fue mdes e descbedn tems f te pysc fue pcess A sttement s mde but te sevceby f te cmpnentunde fute unng, nd ts kely fnl fue, f expected n te bss f ts bseved cndtn

Image Description. Dgnstc mge feues (tse wc seve t dgnse flue) e pnted

ut nd descbed Te "mp cnventn" s dpted f orientation n te mge Te uppe edgef te mge s Imge Nt (N); cmpss pnts e used s n mp. Left gt, nd up dwn e vded n desgntng dectn n te mge pne In descbng position n te mge,fctns f mge sze e used A pint ne ute f te wy t te gt f te eftnd edges 1 4 E f W mge edge Tese cnventns my ppe cntved, but tey e unmbguus Iftee s me tn ne mge n Pte, ec s efeenced by (), (b), etc, nd ec s descbed

Suspected Causes Ts pgp dentfes engneeng cuses tt my led t te dgnsedflue Exmpes: sevce speed, ld, mnufcung pcess As s we knwn, t mny pssbecuses exst f ny gven flue t pesent n exustve dscussn n ec Pte e actual fuecuse s lsted n te Pte, weeve te suce dt nclude t In ddtn ( wen cu fue

cuses e unknwn), most likely cuses e dentfed Me deted dscussn f fue cuses fn ente flue css s fund n te Gene Descptn n ec Pte cpte If tee s me tnne mge n Plte, ec s dentfed wt lwecse lette nd s descbed

Sg Od f PlsTe de f Ptes wtn ec cpte s s fws:

• Te pmy stng key s Flue Cde 1 (FC 1). Fue cdes e sted stctly n te delsted n te Fue Cde lst t te end f te Ats

• Ptes wt dentc FC 1 e sted by te FC 2, ten FC 3 nd ten FC 4, f ey exst• Ptes f wc l exstng flue cdes e dentcl (f wc nt mny ccu) e sted n

bty de• Once estblsed, te stng de f te Ptes s fxed by e seuent Plte N

Fu Md Gupng

Te deted cssfctn f flues used n ts Als s cntned n te Fue Cde pesentedn Cpte 2 Te csses e bd, s s t encmpss l f te mcine eement ypes cveedn te Ats Of cuse, l flue csses d not ccu n l mcne eement types

An vevew f te ngement f te Ats by fue guping s gven n te st f Ptecpte ttes n Tble 12




ssIndxng f Fu Mds

Becuse ec Ple crries up fur fiure cdes, i cn serve s n ilusrin fr mre nne filure mde Ec Pe is plced in e cper crrespnding e frt (primary) cde I cnbe fund rug ec f is secndry filure cdes by referring crssndex ced fer eGenerl Descripin in e Pe cper fr e fiure css sug. Te crssindex liss l Plescrrying filure cde wiin cpers clss, giving e specific filure cde n e Pe fls in e cpers clss, nd e Ple number

Table LIST OF ATE CHAERS

Chapter ChapterNo. Code Chapter itle (faiure class) Page No.

Contact part failures

4 0001 Nicks 41

5 00004 Sface defects from manfactrng 51

6 000509 Matea and assemby defects

00 Md wear 09

8 00314 Gang skdmarkng 139

9 0015 Fettng wear 163

10 006 Saing 19

1 001 Srface dstress 33

0018 Denting 55

3 0019 Heat mbaance fare 14 000 Corosion eectc eoson 93

5 003 Bk crackng facte ermanent defomaton 313

16 0 Guiding component failure 349

1 0 Integral closure faure 38

18 Lubricant faure 389

19 Mounting part faure 43

1



fAILURE CLASSIFIATION 2

This chapter pesents the forma falure cassfcaton system ('faiure code, abbreviated 'FC) bywch the Atas s structued.

2.1 DFNTON OF FALUR AND NOMNCLATUR USAG

I this Atlas, the wod 'falue s eccay refers to damage occurig n servce The word 'defects used seccay for an off-specfcaton condton o damage pedatng servce The Alas coves bothdefects and faures. Where ths dstincton is rreevant, 'falue (occasonaly, the word 'damage) sused n the boad sense to cove both condtons

The faue code (both numerc and text) descrbng faue classes n this Atlas is appled consstenty acoss the severa Hertz contact machne eement casses Because industy designatons forfaiures of beangs, geas and cams often dffe and nomenclatue vaiants abound even wthn onendustry, general descptons to each Plate chapte list the most common nomencaure altenatvesfo the major falue casses Plate descptons, howeve, adhere for uiformiy to the desgnatonsn the fomal falure cassifcaton code The physca pocess causng each majo falure cass (faurepocess) s used fo the brief deftons in the tabes that folow in ths chapte Addtona dscussonof falue mechansm as wel as dffeentiaton wthn casses s provded n the genea descrptionn the Pate chaptes and on the late pages showng ndvdual falue modes

There ae occasonal dfferences of vew among trboogsts egadng the faure mechsm of

ndvdual falue casses As an exampe, the faure cass desgnated 00.17: Suface distess (sufacefatgue) s consdered n ths Alas to be pecular to rolng contacts and s dentfed as aspeyscae plastc flow brought on by hgh noma stesses and folowed by aspety scae fatigue cackngand micospallng Some authors desgnate t 'fatgue wea This designation s avoded n thsAtlas, because the tem 'wea s eserved for suface matera emova by tactve stresses asngn sding Whee such differences are ecogzed, they wil be commented upon.

2.2 FALUR CLASSFCATON SYSTM

The Falue code cassficaton system of morphoogca defects s an adaptaton of the decmalclassfcation pncpe. It s herarchcal and coded by groups of one or two numeals, wth groups

sepaated by peodsThe cassficaton s amed at morphoogcal faures, e, faures (defects) detectabe by examna

ton of surface topogaphy (afte sutable pepaaton) Othe ypes of defects, such as dimensonaleros, mateial stucture devatons, chemcal devatons or esdua stesses, are covered only inther morphologcal manfestations

The am of ths Atlas s completeness i cassfyng morphologca falues of contact components,gudngcomponents, ntega seals, and ubrcants, but not n cassifyng mountng parts. Accodngly, the detal of coveage for the former group s mted by availabe data ony, wheeas detalof coveage fo mountng parts has been lmted to that beleved necessay in elucdatng fulycoveed falues Of couse, many, f not most, ubrcant faues, especay o falures, are notmorphologca, so that the Atlas faure codng does not appoach completeness n classfyng ubcant faures. Also notabe s the regrettable scarcty of image mateal on ntegra seal falues

13



Failue Atlas fo Hetz Contact Machine lements

Counng cod goups om h o h gh h olowng codng uls appy: Goup 1 dsgnas h componn uncon n laon o h oad cayng Hz conac Goups 2 and hgh

dscb pogssvy mo dad alu classs and au mods appcab o h componnspcd n Goup 1

Th psn chap os dnons o h man au classs and ss ha a usu as ndxso au cod ookup Spccay

1 Goup 1 and (n mos cass) Goup 2 cov h Man Falu Casss Thy a sd n numcalod and dnd n Scon 23 o hs chap Much addona dal s ound n h GnaDscpon n ach Pla chap

2 Compl ss o h classcaon ncudng a goup ods a psnd n Scons 24hough 26 o hs chap Das o dnon o h casscaon ca o hs owod goups can b gland om h au dscpons on ach Pa pag wh hy aady assocad wh h mophology o ach alu mod

Tab 21 numas h Fau Cod ss and ndxs conand n h Alas

Lst Ttl

Failure cass st

Falure code st

Faure cass index

Faure mode ndex

Tabl 2.1 FAILURE CODE INDEXES

Contnt

stng, wth inepeaion of major (1 or code goup) failue casses

stng of a falure modes n numerca code orde

Aphabetc ndex of major (1 or code goup) falure casses

Aphabetc ndex of al aure modes grouped by cass

.3 FALUR CLASS LST

14

mpnn Funn

Gop No.

1

Fal Cod00

01

0

1

Tabl 22 COMPONEN CLASS CODES

Dgts Classfcaton Basis

1 or

LISING OF GROUPS

Componnt FnctonHerz conact component

Gudingcomponent

Inegal closue

Lubrcan

Mountng pa

Component ype

ExampBearng ng bal gea cam

Beaing retane gudering

ntegral seal shied

O gease othe lubrcant

Shat spacer housng ocknut



Chper Filure Clssifiion

Hz n mpnn F

The omponens susanng (roing) Herz ona are ypay (reavey) hard, and highy andyay sressed Norma surfae pressures domnae, h raive sresses dependen on degreeof sdng The surfaes are ypay ground (or finey u as n some gears) and may be superfnshedby poshing or honing These omponens sho severa unque faure modes, h maor assesised in abes 2328

able 2.3 FAILURE CODE GROUP CONTACT COMPONENT MANUFACTURING DEFECT

Gu N Dgts Classfcatn Bass

1 or 2 Maor aiu lass

LISTING OF GROUPS

Falue Cde Maj Faue Class

000 Manuaturing o assmby dt

000 Manufatuing o assmby dfby oaton

0001 Nk

000 nshng mark

0003 o unfnshd aa

0004 oming d

0005 Casting df

0006 nuson

000 Matra stuu df pr o inha tratmnt

0008 Matria strutu damag posthatratmn

0009 Gomry assmby o mountng df

Defntn

Dfs from manufaung assmbly or mountng butprir sece.

Quaifr usd n onjunion wh othr ods oidnify df oaton.

Sua ndntaion rom a shap obt pssdmpatd or movd aross sua pr servce

Unntndd sua mak ausd by nish mahinng

Sua atrng pr service o sua mssd ina fnishng opration

omng (forging prssng) dt whn h maa

Castng modng sining dt whn th maal

Paril of xtranous matral n h marx

Dviatons fom spifd mata strutur nudprior o o durng ha tratmnt (g: hat tratros offspifaton strutur vsib rtandaustnt dftiv am bnd ogng o hatrat stss ogn ak)

Strutura hang nudng raking n nasurfamatra du to dftv hard fnshng

Manufaturng rror of gomtry sorng gangrakng n assmby

15



Failre Atlas for Hertz Contact Machine Elements

abe 2.4 FIURE CODE GROUP 2 CONC COMPONEN SERVCE FILURE

Goup No. Dgits lassifcaton Bass2 1 or 2 Mor fure ss

ISING OF GROUPS

Faiue ode Majo Failure ass

001 -002 Serve fure ontt rt

002

0013

Wer md

Gng (smerng severe mehnwer)

Deniton

Flures rsng in seice, nudng mhne shmentnd storge

"Md mehn wer Adhesve or brsve suemter removl through trtive fores n (sdng)ontt wthout mroso mter trnsfer

"Severe mehn wer Mroso surfe mtertrnsfer through trtve fores in (sdng) ontt

0014 Skd mrkng (mroso severe wer) Mroso severe wer (from hgh eerton of freeelement)

0015 retting wer

006 Slng (ertzn ontt ftgue)

0017 Surfe dstress (sue ftgue)

00.18 Dentng (ndentton)

0019 et imblne fure

0020 Corroson

0021 Eetr eroson

0022 Crking or frture buk

0023 Permnent deformton buk

16

Mterl remov (nd odton) throgh mroslevbrtoy moton

Herz ontt ftgue fure through mroso surferter formton from rks drven by ertz stressfelds etendng to mrosoi subsurfe deths

tgue flure of surfe mteri n serty dmensonsthrough mroso surfe st fow foowed bymros formtion drven by Hez stress fedsetendng to serty dmensons

o st deressons (onts or nes) on onttsues in seice by hrd edges sertes orontmnnts ressed into nd/or roed over thesurfe

Pst fow nd/or hem dmge to omonent by(o) overheting

Pits stns or strutur ttk on sues by ggressivehem envronment

Mro or mrorterng by o metng from eetrurrent ssing through erz ontt

Crk formton wth or wthout r serton from bustresses other thn ertzin nudes buk ftgeresdustress rking therm rking rkng from

hem ttk n seve

Permnent buk hnge from smnuftured dmensonor she by st deformton or stuture hnge



Group No.

1

2

Atas Code

01

011 .

0110

011

012

03

0

05

016

017

012

Chapte Faiue Cassifiation

Gudngmpnn Fu

Table 2.5 FAIURE DE GRUS AND GUIDING-MNENT FAILURE

Dgts Classfcaton Bass

2 Componnt cass

2 Spcfc componnt and major faur cass

LISTING F GRUS

Major Faure Class

Gudingpart faur

Sparator faur

Sparator manufacturng gomtry dfct

Sparator buk dfct

Sparator pastc dformaton

Sparator war

Sparator gang

Sparator corroson

Sparator hat mbaanc falur

Sparator contact spaling

Gudrng falur

Defnton

Manufacturng or srvc faiur of barng) gudingcomponnt

Sparator faur from manufactur or srvc

Sparator gomtry offspcfcaton as manufacturd

ractur cracking wd faiur of mta or pastccomponnt mtng of plastc componnt

Prmannt dformaton of sparator

Mld war of sparator

Svr war galng) of sparator

Chmca surfac attack on sparator

Pastc flow and/or chmca chang in sparator fromloca) ovrhatng

Hrz contact fatgu falur n sparator by macroscopcsuac cratrng

Guidrng matra dfct fractur war gang

Not S Sctons 2 and 26 for dtaild stng of faur mods of gudrings

Group No.

2

Falure Code

02 021

0210

021

022

023

02

025

0219

0022

Ing su Fu

Tabe 26 FALURE DE GRUS AND NTEGRAL LSURE FAILURE

Dgts Classfcaton Bass

2

2

Componnt cass

Spcfc componnt and maor faur cass

ISTING F GRUS

Maor Faure Class

Sa ntgra) faurRubbngsa dfct

Matra or manufacturng dfctn rubbng sal

Rubbng sa war

Torn rubbng sa ip

Rubbng sa countrfac war

Rubbing sa ak

Chmcal attack on rubbng sa

Gomtry or assmby dfct nrubbng sal

Nonrubbng cosur dfct

Defnton

Dfct of ntgra sasDfcts of contact sas as istd bow

Morphoogca dfcts arsng pror to srvc

Md war of sa n src.

Tar of astomr sa p

War on mta) surfac aganst whch sa p slds

ubrcant rtnton or contamnant xcusion dfct

Chmica attack on astomr ps or structura pas

Gomtry dfct from manufactur or suffrd nassmby

nntndd contact n cosur corroson akag

17



Failure Atlas for Hertz Contat Mahine Elements

Lub Fu

Table .7 ATLAS CDE GR 1: LBRICANT FAILRE

Group No Dgts Classficaton Bass

Falure Coe

1

1

12

13

2 brcat type

LISTING F GRS

Component Type

Lbrcat are

O alre

Grease are

Sold composte vapor or gas

brcant are

Defntion

are o ay brican

are o qd orgac brican

are o semsold bricat wth organc base o

Falre o sod lbrcat qd brcant poros or sod ge

matrx vapor phase gas water or cryoid brcant etc

Note: See Sectos 2 and 26 or lstng o are modes o lbrcants

Mug Fu

Table .8 FAILRE CDE GR MNTNG AR FAILRE

Group No Digits Classcaon Bass

1 2 Montng part type

LISTNG F GRS

Falure Coe Maor Faure Class Definon

2

21

22

23

2

25

26

Motng par damage

osng damage

Shat damage

Spacer shoder damage

Montng seeve ntlocwasher damage

Seal exerna) are

Spport bearig damage ogear cam)

Faire o any montng part

are o hosg as montng par eg or bearng)

are o shat ntegra or moted

are o ringshaped spacing elemen (not contact pa)n hosng or on shat

Fare o asenng eement

Falre o sea other than ntegra bearg sea)

Fare o spport bearg n gear or cam assemby

Note See Secions 2 ad 26 or stng o are modes o montng pas

2.4 FAILURE CODE LST

18

The Falue Coe lt at the en of thi boo enumeate a aigne Faiue Coe an thecoeponing text egnaton The t in acenng oe of numeic failue coe an eveto fn the text eignation when the numec coe nown Owing to the hieachica tuctueof the coe, thi it keep falue moe n logcal elatona oe an thu offe a pepectve ofthe coe ytem tuctue Pate n Pat I ae inexe by thei pmay falue coe (Faiue Coe 1)

ome falue coe ae ncue fo competene even though no ilutaton i avalabe fo the

coeponng faiue moe



Chap ail Classicaion

Atoug t txt signtion for c flur mo ttmpts to b sf-contin rfrnc tot irrcicly suprior fiur csss s pful in pcing t flur mo in contxt

25 FAILURE CLASS INDEX

T brf st n ts Sction numrts t mjor fiur clsss in scning pbtic orr oftir txt signton It s usfu ovrviw of xstng mjor fiur csss

abe 2.9 FAURE CLASS INDEX

Failure Desgnation

Contact Part FaureCastng defectCoroson

Cracng o facture bulDening (ndentaonEecrc eroson

Finshng aForng defectFrettng wearGaling (searng severe echanca wear)Geoery asseby or ouning defectHeat ibaance failurencluson

Manufacturng o asseby defect by ocationMateral structure daage osheat reatent

Maera stuctue defect e o n hea teaenNicPeanent deforation bu

Pit or unfnshed areaSdaing (coscoc sevee wearSalng (Hean contact fatgueSuace distress (suace fatgue

Wea d

Guiding-Part Falure

Lubrcant FalreGease faureOl faiure

Sod vaor o gas ubrcant faure

Mountng Part DamageHousng daage

Mountng seeve nut ocwasher daageSea (externa faiureShaft daageSacer shouder daageSuort beang daage (of gear ca

Seal (Integral), Falure

Faiure Code

00050020

002200180021

00020004001500130009

001900060000

0008000700010023

00030014

001600170012

121

13

21225

222326



Failue Atlas fo Hetz Contact Machine Elements

2.6 FALURE MDE NDEX

0

An lbeic inde of fue ode desgnions, w ced nueic filue codes is eend of s book Te inde s lbezed in wo es () bezed edngs for e oflue clsses, nd (b) lbeized enries for ec fue ode in css Ts s e n indeof fiure ode designions s used o look u e ige eil eled o flue ode ofknown designion Fs, one fnds e nuerc code ssgned fo e flue ode in e inde,nd en one ooks u e Pe cer or ndvdu Pes usng e code

A groued is rer n snge-evel lbec nde s rovided becuse looku of flueode by s desgnon roceeds ogicy n wo ses 1) fnd e fure clss, nd (2 find esecfc fure ode eren

Te beized flure ode designions re idenc w ose n e nuerc ls of FiueCodes cied n Secion 24



PPEARANE CLASSIFIATION 3

ngn

hs chaper cassfes faure mages by ppr Ths ders rom he prncpa casscaonof he Aas whch s by aure mode Havng ocaed he appearance cass o he observed aureon a page of hs chaper he user nds aongsde the mage he aure code(s under whch smarappearances can be ound n he Pae chapers

The prncpa dsngushng marks o appearance are he changes hey produce n he asmanufacured surace (or he maera secon produced or examnaon

The ayou o hs chaper s brey as foows (See aso he deaed descrpon of Chaper 3

page formas gven n Chaper 1:

• he chaper consss of Secons each coverng a maor appearance caegory as sed n Tabe 31• Whn each secon are cass headers namng an appearance cass and descrbng s appearance• Under each cass header ndvdua faure modes are usraed wh mages and expaned

n ex

n hs chaper he faed par s no speccay named f s a conac componen. Howevergudng componens seas and moung pars are speccay named

able 3.1 APPEARANCE CATEGORIES

ype of Change ExplanationWde Area Falure

Geneal surace removal Surace uniormly abated (wear or etchng) o deomed(odown)

Genera surace tetre cange Discooration m depost posng nnised surace

Matera cange Sotenng decompostion consstency cange stucte

Matera ocaly removedMatera ocaly deormed

Materia tanserred

Materia separation

Matera deect

Foreign matea

Dimenson ero

Distoon

deect

Pont or Lne Falure

it crater gouge eectrc eroson ase brnnengNck dent ne

Gang skdmakng wedng

Facture cracking seam ap

Castng deect omng deect insing damage

ncluson contamnaton

Geometry Failure

Manuacturng toerance error dmension nstabty

Pastc deomaton resdua stress montng erro

1




3.1 WIDE AREA FAILRE

GEER SURFE DISEMETOriginal surface material displaced

WearFinished toogahy emoved MetallicShow nde Geeal exte Cange.

00 FrettingWo sface wit stcoloed deositShown de Geneal exte Chage

GEER TEXTURE HGEFinishing marks, luster or color changed

Unfinished AreaSface caies te finshing mas of teextto-last oeation.Archive 093-3.14Pae N 5.16

WearPaially o totally elaces oigina finshigmaks wit wea-maked texteArchve 087-036Plae N 8

009 Heat Imbalance FaurePlastic fow sace discooedShow nde Genea exte Change.

FC 00 Pastic DeformationCold lastic flow.Not illstaed



GEERL TEXTURE HGE (contnue)

00 FrettingPoduces a rstcoloed deposit on wonsteel contact o it sface.Archive 027-119Pate No 93

00 Surace Dstress (Gazing)Bnished sface on which oiga fiishigtexte is plasically smootedArchive 027-34Plate No: 113

e 009 Heat maance Faiure

Tempe clor, fiction polyme and/o signso plastic flow on sfaceArchive 01861Plate No: 139(a)

Chapter : Appearance Classification

-

3



Failure Alas or Herz Conac Machine Elemens

GEERL TEXTURE CHGE (coiued)

FC CrrsiRst-colod stins o pis o ny stl scArchive 02-211Pate No 141

MTERIL FILUREComosiio, hysica roeries, srucure chaged

FC Frmig DefectMtlogphc S lt chptNot illsttd

FC Mteril Structure DefectMllogpic S Pl cpt

No illsttd

FC Structurl Dmge,Pst Het TretmetMtlogrphic S t cptNot ilsttd

FC Grese DmgeDiscolotio consistcy cg gttinssArcve 027-11Pae No 1815

24

FC 009 Het mbce FlureMtllogpic S t cptNot llsd

FC 0 Seprtr Mtel DmgeMtllogphic S Plt cp

Not illsttd

FC Oil DmgeS lt chptNot isttd



MTERIL FILURE (continud)

FC or Friction Polymerrom LubricantBown dosit on contact sacArchive 0213Plate N 1812(a

FC hemica Decompositiono Mounting PrtS Plat chat ·

Not ilstatd

32 POINT OR LINE FAILURE

M Ly Rmd

ITDark-bottomd cat (not ractur sufac)

FC Surace PorostyCat on to sac wth tallic nmachindsac (ot fact sac)Archive 093-3.16Plae N: 515

Chaper Appearance Claificaion

.

.

L

.

•

• ••

- .

. ' f - �

25




IT cntned)

e Corroso Ptate open to suface wit cooded suace(ot facte sace)Archive 080-104ate No 147

0 Corrosio Pt (Separator)As above.

SLLFcte-bttmed crte

e Hertz Cotac aigueae left ate suface mateial eovalby fatige cackingMacoscopic (depth 100 m to seveal mm).

Archive 027-133lae No: 1 03

00 Surface DistressBlack poit-maks fom sace ateial emovaly fatigue cackig Micoscopic (depth < 30 m).See also 'Suface Distess (Glazing) de Texte chage.Achve 0 41ate No 1113

26

-

� :_

-

.



LOWIG MRI<

Deressed line defec frm materiaremval b lwing actn

C Fnshing Mark(Furrow Chaer Wheeht)Excessive o iegl ctmkfom cipmkng finisng pocessArchve 080-1 01Plate No 511

C 9 Gouge (Assembly)Sctc mk by njy ding ssemblyo montingArchive 01454Pate No 4.4

C WearSctch mk mde by sding spetyo thid body(see ows on mge)Archive 027-154

Pate No 718

Chapte : Appeaance Classification

27




PLOWING MARK (cotued)

F 00.15: ase Brinnell MarkRunded lcal depressi made y ettigwear in statinary Hez ctact See latechapter fr discriminatinfrm true Brinel mark (C 00.18)Archive 093-15.1Plate No 91

F 002: Elecric Crren ErosionPit (p depressin) r flute (lie depressi)with mte suface made y eecric curretpassage thrugh Hertz cntact.Acve: 01468Plae N 14

F 0113: Searaor WearScratch mar made separar y sldingasperity r tird dy.Archve 08-11Plate No 16.1






DENTMaterial locally (point line) depressed in service

F 00.8: DentDn is a oin defec cased by asically deressnghe surface n svc Nicks are cased in manface.See Pae chaers for differenaion) Den boom is

he finished sface, ih nishing lines usally visible.Dens may be shp from meal aice), n fromsof debris) or m-fgmn from brile debris). ordisincion beeen den yes, see Plae chaerAchve: 0148Plate N 12.1 b)

F 00.8 Rolledin Linene defec in roling direcon on ring rollng-rack inimage), oduced as lasic deression by a conacingedge on rollers n image) See wea mark and guge forsimilar-aearing defecs rom loing acion.Achve 04-9Plate N 7.14

00.18: Debis DentngOriginal surface coveed randomly ih mulle smaldens from loose debrsArchve 0144

Pate N 121 a)

F 00.8 Stippled LineLne in rolling direcon, consising of many denicallyshaed dens from an aseriy or from debris imbeddedin he maing conac suace Image s magniied abo20 .)Achive 005-28Plate N 12.13b)



DENT (continued)

F oo.1a: Brinnell MakPlasic impressn f ne cnacng bdy in he herSee lae chapes fr disincn beeen C 0018)and s C 00.15) brinnelling freing)Achve 08-109Plte No 1216

F 01: Dent {Guding-Component)As fr cnac cmpnen. See Plae chape)N ilsraed.

323 Material Transferred

GALLNGMetal orn from surface and welded

elsewhere on surface

F 0013: GaingLamina f riginal cnac sace emved by earing;maerial remved is elded n cnac srace elsehereResling srfaces are rlled veAchve 093027Pe No 8.7

F 00.14: SkdmarkingMicscpic galling rm emprary slidng beeenhigh-speed cnac sacesAchve 027-178Pe No 818

Chapter 3: Appearance Classification




GALLNG (contnued)

FC 01.14 Gallig (GidigCompoet)As or ona omonen.Archve 093-13.1.12Plate No 16.30

FC 2: Gallig (Motig Part)As fo ona omonen See Plae aer.)No illsraed.

WELDNGUntended jonng of surfaces

FC 00.19: Heat Imbalace with WeldigComonens nnenionaly joined in seizedassembly bearing e.)Achive 093034Plae N 1314



3.24 Matrial Sparato

CRACK, FRACTURESeparaon of matera

FC 00.04 Lap, SeamUidd saran iac in lk marialsally ih srac cnamiain arisng armig rain A p is maral lddvn h srac; a sm is a ld nrma hsuac.Achive 0934.1.1Pae N 5.1

FC oo.o7: Forgg o Hea Trea CrackS l.N illusrad.

FC oooa: Gdg CrackS l

N ilsad

C oo.09 Mouig CackS N illsrad.

FC 00.22: Bulk Cack or Facure Servcecks aa as dark ins n h surac in hmallgrahic scin. cs ar ar sarais.r disincin amng crackig causs s Plachars.Achve 01860Pate N 15.1a

FC 01 Cack or Fracure (Guidig-Compoe)S av.N ilusrad

FC 2 Cack or Fracure (Mouig Par)S avN illsrad

Chapter 3 Appearance Classification




325 Materal Defect

FORMING OR CASTING DEFECT (LOCAL)ocal alterato o materal

FC oo.o4: Formng at Incorrect TemperatreLoca srcra aleraon de o overheaing in orgingMay e visile in ealograhic secion or on ecedsrface as n mage)Achive 00-04cPae No 5.3a)

FC ooo5: Poosity Moldng DefectVoid in conac comonen maeial de o casing defecVisie in meaograic secionNo ilsraed

FC oo.o7: Heat Treatment CrackCrack fored de o excessive heral or residal sressesrom hea reamen of seel).Archve 087108Plate No 618)

OLE



RMING R CASTING DEECT (LCAL) (coninud)

FC oooa: Finishng Damag(Ginding Bun)Aleaion emering rehardening) of near-sraesrre de o absive finishing May e vsible onsurfae afe diagnos ehing.Acve 00136Plate No 623

FC o1 Casing, Molding Poosiy(GudingComponnt)Void in giding-omoen maeria de o asingo modig defe Shon mage as reaired)Arcve 09301

Plate No 6.14

FC 2 Mouning Par Castng Forming DfcVod in mouning ar maeial de o asing or molding dee.See Plae haer.)No illusraed.

Chapter Appearance Classification




326 Foreign Materia

INCUSIONForgn body n matral

C oo.o: InclusionBodies of foreign material inuded in the matrix maerialO gobla elongated or fragmented shape Oasionallyvsible at srfae, otherise in metalogaphi setion ordifferentiation among nlusion types see Pate haptersArchve 07201Pae No 6.7a)

FC 01: Inclusion (GuidingCoponentAs for ontat omponents See Plate hapter.)Not illustrated

FC 1: ContainationSolid pailates or ater oi or grease, or loose in the hamer. See Plate hapter.)Not illstrated.

33 GEOMETRY FAILURE

GEOMERY SSEMBY OR MOUNING ERRORmnson or form out of tolran

FC oo.o9: Geoetry Assebly Mounting ErrorDeviation from design tolerane norret assembly omahine element or iorret monting in mahine.Not illustrated

FC 0: Geoetry Error (Guiding-CoponentDeviation from design toeae, inorre assembly ofmahine elemeNot llustraed

Fe 2: Geoetry Error (Mounting PartDevation from desgn tolerane, inorret assembly ofmahine element or inorre mountig in mahineNot illstrated.



PERMANENT BUK DEFORMATION

Sape dsorted

FC 00.23 Permanent Defrmatin,BulkDsrn shap m asmanfadndn, rng dng srv.N llsrad.

FC 01 Permanent Defrmatin(GuidngCmpnent)As fr na mpnnN srad.

FC 2 Permanent Defrmatin(Munting Part)As fr na mpnn.N llusrad

Chapter 3 Appearance Classification



PART 11

PLATES



NICKS 4Failure Code 00.01

4.1 DefntonNicks (in metals) are pastic depressions (short gashes; multiple, aigned or randomly oriented

marks or rounded depressions). They are caused by impressing (statically or by impact) a h�d,possiby sharp object into a surface of a contact component. Nicks are produced at the time of, orsubsequent to, final fiishing of the surface, after the part has been brought to its final hardness.

Depressions produced prior to final finishing are unnished areas (FC Depressions sufferedin service are dents (FC

A defect of ceramic surfaces corresponding to a nck is a chipped nick in wich a smal voume ofmateria is broken out of the surface. A chipped nck may occur at an edge of the component ifimpacted or indented by another hard, sharp-edged object. It may also occur esewhere on thesurface if impacted or indented by a sharpedged or pointed hard obect

Nicks differ from nishing rrows FC which are ploughing marks made in grinding, hoing,etc. and from score or gouge marks FC made by siding a hard edge over the surface in assembyor mountng

42 NomenatueIndentations formed when the component is not (yet) in service are designated nicks. Indentations

formed in service are designated as dents The Atas dispays nicks (tis chapter) and dents (FC 00.8separately As a generic name for both, it uses indentations The Metas Handbook [10], n its chapteron roling bearing faiures, designates both nicks and dents (see Chapter 8 as indentations. icksare not mentioned in the literature as a sigficant failure mode in gears.

43 Faue PoeA nck is formed by plastic flow of the (meta) component surface material around an indenter.

When it is a short gash or rounded depression, then its mode of formation resembles that caused by an indentation hardness test, ie., the indenter penetrates the surface in an approximate normaldirection, carries surface materia down with it, and usually throws up signficant raised edges,except for ncks created by edgefree roling bodies such as a bal (identical with briel marks,FC 008. An elongated indentation can form by plastic flow beneath a roling indenter (an edgeon the mating roling eement), and may be difficut to distinguish from a wear mark (gouge) arising

from a sliding indenterChipped nicks may be formed in ceramic surfaces or at their edges from heavy impact, for exampe,

the component is dropped onto a hard surface from great height, or as a result of indentation underheavy pressure with an obect as hard or harder than the ceramic. Because of the limited ductility ofceramics, chipped cks are predominanty fractures, although some plastic deformation may occur.

44 Dtntve ppeaaneA ick appears as a depression. I meta surfaces, origna fishing marks generally reman isibe

at the nck bottom Raised edges usualy exist. The mark has a sny surface. By contrast, the surfaceof a score or scratch mark (ploughng mark, FC 00.02 or 0009 is matte (but not oxided) The surfaceof a gouge (FC 0009 contans transferred meta (visibe under the microscope) if formed by galng.

Cipped icks in ceramic surfaces show fracture surfaces where the indentation has caused crackingand separation of surface materia.





Chapter 4: Nicks

may cratch or nck or core, C 0009) the rolg elemet roller bearg a edge o the

roer may nck or core, C 0009) a rg rog urface• Some bearg requre aembly of rolg elemet to eparator by a ap aemby, preg

them pat a retag prog Excee ap caue gahe or core mark, C 0009)

• Cotamato of bearg aemby caue detato or cratch mark, C 0009) o rogurface, whe the aembly rotated for tet or the aemby proce

• Aembly or daemby of compete rolg bearg o haft or houg wth forcetramtted through rolg elemet may caue detato ee brnnel mark, C 008)

• Aemby of part of a eparabe roer) bearg, wth oe rg mouted o a haft ad theother a houg, may caue mpact mark or core, C 0009) betwee rolg eemetad rg

• Ceramc compoet featurng edge are at great rk of cppg at the edge whe mpactgeach other, or other hard part Edge of ceramc compoet ca alo chp other compoet

Th oe reao why ball bearg wth ceramc ba ad metal rg are ued whereerpobe, a ba hae o edge ad ther urface ret cppg by meta compoet

453 Nick Causes Specific to Gears

• he workg urface of gear the tooth urface) are ot greatly expoed to ckg hegear dutry doe ot treat ckg a a como falure mode Howeer, ge ufaorablecrcumtace, harp obect ca mpact o tooth urface to caue ck

• Some medumhard gear wth reately rough urface are more toerat of ckg tha thehard, mooth urface of fuly hardeed bearng or gear

454 Nick Causes Specific to Cams

• Becaue ther workg urface are exteral ad expoed, cam ad cam foower uffer thegeera caue of ckg preouly lted

46 Effet of Nk

• The patc detato proce formg the nck meta urface mpoe hgh oca treeo the urface hee ca tate crack

• The ckng proce ceramc clude crackg• Sharp edge may form at the ck whch, whe roled oer, caue cycc edge tre eadg to

pag falure ear the ck• Spal ted to ntate dowtream of a ck the rollg drecto A arrow upaled rdge

ofte eft betwee the nck ad the pa edge• he ck repreet a ink for the EHD elatohydrodyamc) fm the cotact, whch may

ocay depreurze the fm, reutg oc fm g aroud the nck edge Apertycotact may form, producg loca urface dtre a hy, gazed poby mcropaledhao decoratg the nck) he urface dtre, tur, may tate palng fatgue

• Raed edge aroud a ck a cotact wth gfcat dg may tate galling• Whe oerroled, nck caue clckg oe, whch may repreet a faure of quet runng

compoet• I a aggree eronmet where corroo a rk, ay drupto of the mooth urface

fh, uch a by a nck, may be the ntato pot for corroo pttg meta urface




Cross-Index of Secondary Failure Codes

Failure Cde

00000

000002

000003

000

000

0002

0004

Plate N

44245630

4.3

444.6

47484.10

53

5.9 53545.15

5.16

57632

510

052067

4332

44656

057



Faue Code: .Falue Code: ..

Chapter 4 Ncks

PLATESDATAPlate No 4.1Acve No 087008Imae ype igh macroScaleba 30 mm micros: 0 ohers + 10050)Component CRB; OR & S R, unrnSpeedLoadLubicatonFalue Code 1: 0001 NickFalue Code 2 000001 Defec by ocaion in fi srface

Falue Code 3: Falue Code :

DESCRIPTIONSFalue Descpton merals sarkeched on sidefaceof CRB OR ih an elecric enci fom raised aseries ofmoen meal In recisio alicaions sch as hisaircra bine bearing anguar alignmen s jeoardizedby he oofsqare osiion he sdeface assmesagains a flange due o hese aseriesmae Descpton A arro dark handren nmerals are eevaed above ring sideface This is deeced by lacing he ring ona fla lae ih his face don and measrng sqareness on he oosie face.Suspected Causes The se of eecric encil sakerosion makers is common in seializing hardened as. In some highrecision alicaions he resling molenmeal aseries cause laness oleances o be exceeded and he se of elecric encil

is rohibied

DATAPlate No 4.Acve No 093005mae ype a b: ligh macoScaleba 30 mmmcros 0, ohers + 100 50)Coponent CRB; OR, rnSpeedLoadLucaionFaue Code 1: 00011 Local nickFaue Code 2 0000.01 Defec by locaon in fi srface

Faue Code 3: 00.16.1. Subsurface orgin sal high Herzshear sress)Faue Code : 9 Geomery o assembly defec n hosng

DESCRIPTIONSFaue Descpton A chi raed beeen hosing and OR OD creaed a nick and local conac load concenraon in henderlying roller ah hen overrolled. ague saling olloedmae Descpion The image half shos he OR OD ih a dee nick made by a machining chi near he E imagecenerline, js W of he E ing edge The E image haf shos he oer rack decly nderlying he nick. An exensive sal hasformed in service, sang a he E side of he rack, direcly nderlying he nick on he ODSuspeced Causes A machining chi as raed beeen OR OD and hosing bore roviding he rimary load sor in haarea Ding overolling, his ocal so creaed a load concenraion in he conac hich hen roduced he sall.




DATAPlate No 43

Arche No 087-115mage type lgt microgramScaebar 100 m (micros: ±20 oters +100 50)Component RB OR moutedSpeedoadubrcatonFailure Code 1 00.01.1 Local ickFalure Code 2: 00.01.1.1 Nick wit raised edgesFalure Code 3: 00.0002. efect b locatio i Her coact suraceFalure Code 4: 00.09.1 Scorig from orcible assembl or moutig(o gallig)S s PLATE 4.4

DESCRIPTIONSFaure escripton A series of icks (wit rased edges) was createdi te roller track b impact wit a sarp-poited toolmage escrpton Nicks similar o ose i Plate 44. Te ickscross iisg lies At A fisig lies remai vsible witi ckAlso at A, te earest edge of ick is rased above te srodigsrface e ver brigt appearace of te sou edges of eac ick sde to ligtigSuspected Causes Tese sor rougl parallel icks are prodcedb repeated cotact wit te sarp edge of a ard tool Scrapig aool over te suace b ad pressure ma create sc small icks

DATAPlate No 44

Arche No 01454Image type ligt macroScalebar 100 mm (micros 20 oters 10050)Component TRB OR moutedSpeedLoadLubrcationFalure Code 1: 000 1 Local ickFaure Code 2: 00012 Scratc toomark scuffmarkFailure Code 3 0000.02.1 eect b locatio i ertzcoactsuaceFalure Code 4: 0009 Scorig from forcible assembl

or motig (o gallig)S s PLATE: 43

DESCRIPTIONSFalue escription: Several local icks ad scratces o te roler track o TRB OR

Faue Code 00011

mage escription Tis ligt macro sows a sigtl elarged poio of e roller rack i a RB cp (OR) wit rreglarlsaped depressed icks at A ad irreglar crosstrack scratces at B or a elarged view of assembl icks see late 43Suspected Causes I assembl a pctpe tool (drift} was sed o e arrow face of te cp lt slipped epeatedl ito teroer track we strck wit a ammer makig icks (we impactig oe pot o te track) or scratces (we slidig acoss te track)



Faue Code:

DAA

Plate No 4Archve No 018-201mage type viewScalebar = (micros 20% oters 00% 0%Component NRB OR & R moutedSpeedLoadLubricatonFalure Code 1: 0001.11 Nick wit raised edgesFalure Code 2 00.00.01 efect b locaton in fit sufaceFalure Code 3 00091 Scoring rom orcible assembl or mouing(o gallig)Failure Code 4

DESCRIPTONSFalure Descrpton Several deep cks wit aised edges (at Ocamfer) around te circumferece of OR face due to sarp plasticidentation te tiwalled deepdrawn seetstee cup te indetatiostoves i te seet creatg a buge i te iner suace acing te rolle eds Bearig ma seize if ru

Chapter 4 Nicks

mage Descrpton Several afmoo saped idetatios spaced circumeretial ear te O edge of te face wit raisededges at te O Bottom of icks is sSuspected Causes Use of a ammer ad puc to stall te draw needle roller bearig cp into te ousig as led to plasicindetatio uder te impact of te punc Bendig of te tinwaled cup creates a buge o te rollered facing iner face of tecup and ma distor te etire cup geometr

DATAPate No 46Archive No 093-1.2

mage type ligt iteerece microScaeba 3 �m (micros ±20% oters + 100% 0%Component BB; B uruSpeedLoadLubrcationFaure Code 1: 00.011 Nick wit raised edgesFaure Code 2: 00.00.02.1 eect b location Herz contact suraceFaue Code 3: -

Faue Code 4: -

DESCRIPTIONSFaure Descipton A plastcall ormed ck or gouge" in te ballsrface b identatio wit a sarpedged ard obect under ig

normal pessue Raised edges surroud te ick A bal wt tisdamage runs nosi e damaged suace ma suffer surace distress 00.17 ad suraceorig spalig .00.16 as a resut ofinterrupted H film ad stress cocetration at te nickmage Descipton e image is made b multple beam interferencemicroscop wic creates arrow dark cotour lies spaced 1/2 igtwavelegt (abou 02 �m) apar O a udamaged bal surface teconours are circles (wit smal radom excursios sowig lappig marks) e es sow te depressed ic bottom (abou 04�m deep) ad a raised rim (about 02 �m ig) surrounding itSuspected Causes I ball lappng a too is used to extrac te bals rom betwee te lappig paes If t is metal and develops araised edge t ca mark te bals e mark sown as raised edges indicating tat it must ave bee caused a te end of teiisig operaio Anoter source of icks (less lkel in view of te ick sape sown) s assembl o te bearing




DATA

Plate No 47Arche No 003-012 (a) & (b)mage ye a: ie b ligh micrgamScaebar =a: 10 b 2 mm (micrs: ±20% hers + 100% 0%)Comonent BB B, rSeedLoadLubricatonFalure Code 1 00011 Nick ih raised edgesFalure Code 0000021 eec by lcai: i Hez cac suraceFalure Code 3 00091 Scrig rm rcible assembly r mig( gallig)Faure Code 4:

DESCRIPTONSFaiure Descrton Sraigh ba-shaed lasic ideai i ballsurace, made by a hard sraighedged bec ressed imaced i

he ball. A ball ih his damage is isy ad is ikely sall early asrace deec. aised edge ick may damage rg ballahmage Descrton (a): Vie shs aeaace ick he aded eye.(b): Mcrgrah shs magicai. I bh images brace idicaesick The ba shae shar s ad sraigh edge alg ick ceeridicae deai by shar sragh edge Surface de is shiy sameas deed ball sace. ark cl i image is de ligh reeciSusected Causes ug mig sliierrig bal bearg imache searar/ball cmleme may be dsaced O s ha Imed sha, hs a ball durig rr iseri As aher case Ibal maacure r assembly i beaig balls may dr m smeheigh he shar edge a hard machie cme A dr 2040cm suices case a de as sh.

DATAPae No 48Arche No 014-0mage tye ieScaebar 00 mm(mcrs 20% hers 100% 0%)Comonent TB O (2) urSeedLoadLubrcatonFalure Code 1 00.01.2 Scrach l mark scmarkFalure Code 00.00.021 eec by lcai i Hez cac sraceFalure Code 3 00.091 Scrig rm cible assembly r muig ( galig)Faure Code 4 00.183 brielig

DESCRIPTONS

Failure Code: 000111Failure Code: 0001

a

b

Failure Descrton rcible assembly iled llers i O (cu) cased: (1 series circumereial des aliged aialy(scumarks) (2) aial scemaks ad (3) biel marks. The damage cases a sy bearig ad is likey ead early saliga he des r brell marksmage Descrton ark-aeaig brad zzyedged aal scmarks rler racks (bh Os). I O a image als elared dark briell marks ear bh rac edges ad aially aged seres crcumeeial cs r cs i he N ceer i he rack. The guge marks ad icks are shiy ad may aear ligh r dark agais he backgrud deedig ghicidece agleSusected Causes Wh he O (cu) med a husig ad he I (ce) ad rler assemby he shaf assembly herr he mache sar ih iadequae aligme ca rce cac beee rller (ed) ad O rler ah. Sar eigh r

assembly rces ride he lad ha ca case scuig, icg ad biellig



Fiure Code 00012Fiure Code 00013

Chapter 4 Ncks

DATA

late N 4.Archve N 001-1mage type ight microgramScalebar 500 m (micos: ±0%, ohers ±100%, 50%)Cmpnent ACBB IR runSpeed 1 MdNLad 0.7 GPaLubrcatn syntheic poyeser oil 10°CFaiure Cde 1 0001 Scrach toolmark, scfmarkFaiure Cde 2 006 Shalow enty spall rom suraceline-deectFailure Cde 3 -

Failure Cde 4: -

DESCRIPTIONSFalure Descrptin Severe axia ool mak on land and agroove, followed y spal in groove, extending o edge andchipping nto land Contact apparently extended to edge so that spa coud orm at edge Ring has failedmage Descrptn N 1/3 of mage is land, S /3 is all groove; the wo are sepaated y groove edge Da teardropshapedgouge in land. Eongated scatch stll visie in groove, jst S of land edge, and nea S image edge. Mushroom-shaped spalfomed o gouge (downstream in oling diecton) and roadened near land edge, om edge loading. Near and edge, spallcrossed goge and extended against rollng drectionSuspected Causes Severe nick o goge in rollng suace is case for eary spalling. Boadening of spall oward and edgesggests tha contac mst have overrun he edge so that sustantal edge stresses exsted. This is lkely to cause ealy spallngeven wihot the defect

DATAate N 4.1o

Archve N 093-115mage type lght microgamScaebar 0 m (micos: ±0%, others: + 100%, 50%)Cmpnent BB B, unSpeedLadLubrcatinFaure Cde 1: 00.0.3 Crcular flat nck on allFaure Cde 2: 00.00.01 Defect y location in ez contact sfaceFaure Cde 3: 00.1.3.. Scratch marks kinematc wear marks inrollng saceFaure Cde 4:

DESCRIPTIONS

Faure Descrptn Circua lattened nick (commonly called a la")on all surace maked y arrow A. A slight ulge of displaced mealsurronds the edge of the fla Mltple short small scratches and dentson al surace oth nside and outside the lat de to wear. A flat on aall causes noisy running ut is a serios spal originator only whensevee Scrached and dented surface s lkely to case noisemage Descrptin The al suface is shaded y olique lightng The at is outlined where the light and shadow lend de to itsdiffering orentation. (Unless highlighed y oie ight mpinging at a graing angle, such flas are invisile.) The flat's edge issurronded y a slight ulge Mltiple dens and scraches appear as dak sreaks in he li area and as ight sreaks near the edgeof the unlit area.Suspected Causes las are typical al manuacturing defecs cased y alls impacting aganst each other in a container oagainst a hard a surace De to he small impac area, a a sface is plasically deformed under a drop of as few as 0 cmono a hardened flat suace Bals paced in oxes sufer flats when the ox is dropped om simlar heights.

9





Failure Atla for Hertz Contact Machine Element

wheel ht Siml to wheel ht i mrk left by hnd-held ginder ued to remove lol pllor dent from the ufe.

Tued, Milled, or Hobbed Surface. Tool edge my hip, with the boken-off piee ught gntthe wokpee nd mkng gouge A ter n reut from hipped tool o tool with worn ormpopely fomed edge flng to ut ely

Hrdturned urfe re fuy hdened ufe fihed by ngle-pont rbide or em tooThey how finhng mk of iml orgn do other tuned urfe, but thee re on roughnee omprble to thoe on ground urfe

Chiple Finihed Surface A muttude of urfe mrking n reult from mlfuntion inhiple fiing, depending on the nture of the proe Chrteiztion require pefi infomton oneing the fnhing proe

5.1.4 Dstinctive AppearanceFiihng furow typly re wider nd deepe thn the norm fnhng lne When ued

by dethed pee of grit, they my how one bunt end nd one tiing-off end omet-tl, the gt i ught, dgged, nd expeled o htteed, o eft embedded in the ufe On fineygound o honed urfe, mgnfition requed to identify finihng furow.

Chtte mrk my be een perodi hnge in the luter of the urfe, one proeed oundthe umfeene Often, they beome viible ony fte being highighted by runng Oonly,they e detetble ony wvne, by ufe tring Chtter mkng my produe gndingdmge FC 00.08), whh my ubequenty be obterted by further finhing

Wheel hit or hnd ginder mk my how dreton of grindng ut tht dffer from otheurfe e Uuly, geometry error depreion n be deteted by urfe trng Whee ht

my produe gndng dmge FC 0008), whih my be ubequently obterted by futher finhingShoe mrk e iumfeenti mrk of wer, polihing, o orng, on the ground urfe Shoe

mrk my produe gndng bun ee FC 00.08: Grnding DmgeGouge re deep o iregur too mrk Ter e ptly deformed nd mioked ufe

rregulitieFinng mrk on hiple fhed urfe equie knowedge of the finihing proe for

identfition

5.1.5 CausesCue of fhng mk equire pef formtion on the finihng poe fo their dentf

ton

5.1. Effects of Finishing MarksFinhng mrk my hve iml effet nk FC 00.01) or dent FC 0018). Spefly:

• Mrk repeenting depeion wthout ed edge fiihng fuow nd ome hplefhng mrk If peent on ontt urfe, they imp the E flm, uing urfedte FC 00.17) in uroundng "ho

• Sevee fihng furow repeent urfe defet te onentrtion fo the intiton ofurfeorigin pl FC 00.1).

• Shoe mrk, f glled, re defet tht my ue frther ging FC 00.13) nd pling FC 00.1)

If grinding dmge ext in the mrk, rubbng k FC 00.08), buk k FC 00.22), opl FC 00.) my fom



5.2

Chapter 5 Surface Defects from Manufacturing

• Goues and tears tend to hae raised edes and show microcrackin They act as seere nicksand may cause wear alin spalin or uk fracture

• The effects of finshin marks from chipless finishin require eauation usin the specifics ofthe finishin process.

PI OR UNFINISHED AREA

521 Pit

2. Definition

FAILURE CODE: 0003

Failue Code 00031

A pit is defined as a oid open to the surface caused y a castin or formin defect or chemicalattack on the surface. Al pittin other than y chemical attack predates serice Chemical attackcorrosion pittin may occur at any time after final finishin throuhout the life of the part It is

coered for al cases under FC 0020

2..2 NomenatureIn the iterature the word 'pit has een used to descrie any sharpeded depression in a surface

includin a spall. n this Atlas a pit is distinuished from seera other types of manufacturindefects and from spals.

Pits are distinuished om shg marks, cks dets and unfinished areas y the followin:

• A oid created on the surface y the finishin process is a finishn mark FC 0002)• A oid created y unintended indentation prior to serice is a nick FC 0001. Indentation in

serice is a dent FC 008)•

An unfnished area is a patch of surface where the secondlast inishin operation has not eenreworked y the last operation see section 522)

Pits are distinuished from spals which are fracture craters caused y contact fatiue FC 0016)

2.3 Faiure ProessPits result from either manufacturin process faiure or chemical attack.Maufaturg process faures are exemplified y the followin

• n castin pressin forin rollin or other lank preparation processes internal oids porosity C 0005) may unntentionaly e created. A susequent chipremoal process may cut intothese oids creatin a pit open to the surface.

• Weak interfaces created y the formin operation may separate durin finishin eain a pit.• Inclusions in the material may e intersected in finishin and tear out leain a pit.• Lare carides present in some steels and ceramic rains in onded ceramics may tear out in

finishin leain a pit·

Chemical Attack Any time durin manufacture mountin storae or serice of the machineeement chemical attack corrosion FC 0020) may occur at a surface causin pits.

24 Distintive AppearanePits typicaly appear as sharpeded craters. The surface in the pit does not show the finshin

maks of the surroundin surface distinuishin it from a nick. The pit surface is not a transranularcrack This distinuishes a pit from a spall




Derentaton o a pt rom an ncpent spa may requre mcroscopc or SEM examnaton to

detect the presence or absence o typca spa-bottom surace eatures (FC 006)

21 CausesFor causes o castng or ormng deects, ncusons, or arge grans, each o whch can generate

a pt ntersected n nishng, see FC 0004 through FC 0007 Any chp-ormng shng processcan ntersect one o these deects and eave a pt More severe processes (hgher cuttng orces, argerdepths o cut) are more prone to generatng pts

For causes o corroson pttng see FC 0020

216 ffects of Pits

ts represent depressons wthout rased edges present on contact suraces, they mpar theEHD m, causng surace dstress (FC 0017) n a 'hao surroundng them

t suraces are oten mcrocracked or otherwse weak hey act as surace deects or thetaton o suraceorgn spas (FC 0016)

Sharp-edged pts n a contact surace are deects actng as stress concentrators or suraceorgnspas (FC 006)

Corroson pts promote urther corroson o the surace

Unfnshed Ae

221 Definition

Fue Code

An unnshed area s et on a surace the manuacturng operaton precedng the ast nishngeaves nsuicent stock or the ast operaton to perorm stock remova, or the ast operatonmsses the area

222 NomencatureUnished areas n abrasvey ished (or hardturned) suraces are oten dark due to heat treat

oxdaton and are then reerred to as "back areas Uished areas are aso known as NCU (notceaned-up), unground, or uhoned

223 Failure Process

Castng, orgng, cod ormng, and a chpremova operatons may produce a surace area thats depressed reatve to ts nomna poston he ast ishng operaton may nd the depressondeeper than the stock aowed or nishng, so that, ater competon, the surace condton createdby the precedng operaton eectve n that area s et unchanged Aternatvey, the nshngoperaton may mss an area due to machne or cuttng too mauncton he eect s as prevousydescrbed, except that the surace s now rased rather than depressed

22 Dstinctive AppearanceUshed areas are dentied by the derence n surce nish between that area and the

surroundng surace

n a heat treated part, an area et n the as heat treated condton s usuay back or gray






• A sem is an unweded interfae in a formed part often bearing a aminar inusion of foreign materia

• Defecs in fomed sucue onsist of weak britte or otherwise off-standard voumes of materiaaused by a fauty forming proess suh as wrong forgng temperature

• ipe poosiy, and ccks may be found n formed parts ipe and porosity are overed underFC 00.05; forming raks under FC 0007

32 NomenclureAternative nomenature used in the forging pressing or extruding industries is not overed

he preeding is the usua nomenature for ontat mahine eements

33 Filure Process

• A ap forms if a voume of materia is unntentionay foded over an adaent voume duringthe forming operation and the fod is tighty pressed together here may be partia weding atthe interfae espeiay if the operation is hot forming

• A seam forms if sae or other foreign materia is untentionay forged or roed into themateria where it forms a aminar disontinuity Seams are interfaes extending radiay inwardfrom the surfae

Defets in a (hot)formed struture arise by proesses of oa meting rerystaization segregation et Detais of the proesses depend· on the materia ad speifi forming method used

3 Distinctie AppernceLaps and seams are deteted as neary straight ines on the surfae of the part hey may be

obsured by pastiay fowed surfae materia during finishing operations and reappear afterrunning or when a rak forms at them A metaographi setion shows oxide voids and orirreguar struture surrounding aps and seams n a seam the inuded foreign materia is typiayobservabe Laps extend at a shaow ange to the surfae whereas seams run radiay into the materia

Defetive formed struture is deteted in metas by metaographi examination inuding ething ·n other materias (eramis) speia mirosopi tehniques are required

3 Cusesdentifiation of auses of forming defets requires speifi knowedge of the forming method used

36 ffects of Forming Defects

Foring defets are gross disontinuities whih under stressing typiay ead to

• Buk raking or frature (FC 0022);• Spaing (FC 006).



Chapter Surface Defects m Manufacturing

Cross- of cory Flur Cos

Fr d

P N

57





Failure Code 21 Chapter Surface Defects om Manufacturng

DATAPae No 53

Archie No 093-21.9&11mage tpe SMScalebar a b 50 m (miros±20% ors 100% 50%)Componen BB IR urun Nial tdSpeedoadbicatonFailre Code 0002 rindgoing lappig furowFailre Code 0000.02.1 Dft byloation i Hrtz oat surfaFalre Code 3 Falre Code 4

DESCRPTONS a b

Faie Descrpon (a) 'Comt-talsapd grdng frrow in t ond rolling tra T plowing otat stard at t poitd tail sid of t furrow and dd abrupty a t but ad sid. T frow s oo dp o b rmovd by subst og(b) Dp frrow wit mbddd grdg grit. uows ar a sor of srfa disrss upo rigmage Desciption (a) Fin W rnnig oing lins Mottling fom Nital t Comt-tai (dark srak) a imag W r isgrinding frow Dark or i furrow nr s a dprssion Lig otlis a sarp dgs (b): W onig lis ovbakgroud Frrow ad xtds fom mag dg to poits A B, and C wr dark gridig grit partils ar visibSspected Cases A pal of gridig grit boms dtad from t wl and is draggd along t sa big grod. As

t wl-to-wokpi otat bilds up t git is prssd dpr into workpi asing t widng furow. T grit maysatt o b xplld ad rrow stops abrptly. oing movs isfit matral to rmov t frrow.

DATAPlate No 54

Arche No 093211&2mage tpe SMScaleba a 60 b: 6 m (miros: 20%otrs + 100% 50%)Component DBB; IR unrnSpeedoadbrcationFailre Code 00.02.1 rindg oinglappg furrowFalre Code Failre Code 3 Failre Code 4

DESCRPTONSFaile Descrpon Ilstratios of aid odball groov sufa wit ormal onig lsiludig rossa Sarp utting aton ofong grit is appart from la dgs ad a b

abs of majo tars Not t "fatr dgsin imag (b) w wll plastially dform. Ty may war off rapdly rning ad produ lubriat otamiatio Hoigprods m fi "fa dgs tan dos gindingmage Description (a): At modrat magnifiation sows v fin oig lins runig two rossd dtios (ossat)as at arrows A ad B (b): At ig magnifiation sows dtals of t onig atio (o t sam spimn). At t NW imagorr atr dgs of matrial a sow o t ligt gray flak of a ut SM mags xaggat privd dpt T slops of

t t wals a ot as stp as ty apparSspected Cases T imags sow ormal oig atio

59



Failure Atlas r Hertz Cntact Machine Elements

DATAPlate No 55Ache No 099-35mage tpe light macroScaleba 0 mm mcros0% othrs 00% 50%)Component HG P 4350 stlmd hard runSpeed 60 cm/scoadubricaon oil ? cFaiure Code 0001 Grindnghonig lapping furrowFaure Code 0013.1. Rollingsurac galling dt or nick visiblFalure Code 3 00.6.0. Cotact fatigu cracig

Failure Code 4 00..01.4 Gar tooth crack o factur

DSCRPTONS

Faiure Code 21Failure Code 22

Failue Descption Mutip comt-shapd axial rrows ovrlaid by patchy radal galling straks Loca spaling. Tooth rootbding factur. A ara o th tooth with prssur conctrato was vulabl to galig ad spallg add by th grindigurows Utimatly th tooth brok n bdig atigu in th ovloadd ara.mage Descpon Brokn gar tooth sctiod sctios placd sid-by-sid. N dg of th two larg sctios is th tooth tip Sdg of th imag is th bnding factur surfac.

Furrows ar comt-shapd axal dak lins at A galling straks ru adialy at B;

dark spall cratr at CSuspeced Causes Gomtry rro may hav causd coctratd cotact on a vry long ( m tooth Prsnc of furrows rom

tooth gridig nhacd th isk of galling and spallig Oc sacdamagd bndig atgu cracing fractud th tooth at throot.

DATAPlate No 5.6Archie No 087-005mage tpe: viwScaebar 10 mm micros: 0% oths: 100% 50%)Component CRB; IR unrunSpeedoadubrcationFaure Code 000 WhlhitFailure Code Failure Code 3 Failure Code 4

DSCRPTONS

Failure Descrpion Unintndd ocal gridig whl impactwhlht o rolr path and flang OD. A whlhit on a contactsurfac causs dg loading at th rm of th dprssd hit admay ad to spalling FC 0016). Du to dsruptd contact thwhlht may caus runing nois. In high-spd barings itmay caus rol skw wit rslting failur. Whlhts oftproduc giding burns FC 0008) which lad to ary spallig.mage Description At th arrow is a lightapparing irrgular patch on th rollr path. Blow similar patch o fag OD. If viwdi clos-up th grinding marks i th patchs might ru in dirctios othr than circumfrtialSuspected Causes This whhit was causd by a had-hld smal gridr may b usd to ngrav srial umbrs on rigsidfac Whhits by cotrolld approach of th wh i a spcifd griding opration ar mor commo



Failure Code 22Failure Code 23

DATAPlate No 5 7Arce No 006-0bmage tpe ligt mrogramScalebar 1 mm (mros: 0%otrs: + 100%, 50%)Component TRB IR, rn, spot-grodSpeedLoadubricaon minral oi gras ? cFaure Code 000 WlitFalure Code Failure Code 3 Failure Code -

DESCRIPTIONS

Failure Descrpton oazd spall ratr rpairdby grinding wit a and-ld gridr T rog,rgrod srfa s ovrd wt dp frows Tsa s dprssd bat t workig onta

Chapter Surface Defects o Manufacturing

pat ad ts strssd only at t dgs of t r-grd wr strss ontration ss and ary spallng is ptd Howvr, t stss ontratio is pobably lss an at t dg of a nrpaird spall.mage Description Imag W, to 1 widt, is t original ontat sa wit mltipl dbris dnts mag r ad sows aolow mad by r-grindg. T ligt olord W lins ar t gridig rrows of t last pass. I t dak bakgrod, NSgridig lis from a prvios pass ar faitly visblSuspected Causes As a ost-saving masr, ollig mils ad otr srs of vry larg rollr barigs may, po fiding smallspalls i a rig ontat pat s a igspd and gridr to rmov t spall sa and rat a raivly smootr and bttrblndd ollow to prvnt rapid spall propagaton at spall dgs

DATAPlate No 58Arce No 018-63mage tpe lig maroScalebar 10 mm (miros 0% otrs + 100%, 50%)Component ACBB R (split) rnSpeed: >1 MdNLoadLubrication syntti polystr oil ? cFaiure Code 0003 ridig attrFailure Code Faiure Code 3 -Falure Code

DESCRIPTIONS

Falure Description Svr ig-fry irmrtalwavinss (grinding atr) i ball trak ridig attrprods oisy ad vibratory rning n g spd barigs,kinmati instablity may rslt Svr attr may priptat arly spalg or gallg ailrmage Description Aog ntri of ball trak ligt and dark paralll aial marks, abot 4 mm apa, iglig t ig ad lowpoits i wavss (attr). Ulss svr, atr is visibl oy aftr rnig, wn nvn poising war asd by vibatoryball motio gigts it.Suspected Causes Main vibrations in a ginding opration as osillatory wl prssr ad rslt in a wavy sa on tworkpi



Faiue Atas fo Hetz Contact Macine Eements

DATAPae No 5.9Archie No 031805mage tpe light macoScaebar 20 mm(micros 20%, othes: 100% 50%)Componen CRB; OR runSpeedLoadubricaton gease 1cFalure Code 00023 rinding chatterFaure Code 000002.1Defect by locaio: i Hez contac surfaceFalure Code 3 001602.3 ncipietspalig sigle spallFailure Code 4

DESCRPTONS

Faue Code 23Faiue Code 2

Failue Descption Severe griding chaer in unspaled egion of OR rolle tack. Exesve spalling. ridng damage o materialrom ucontrolled grindng esutig in chatter may cotribute o spallig Bearing vbraio due to chatter may be severe enough

to accelerate spalling eve i the absece of gindng damage The bearing has faiedmage Desciption In he N quadant of the roler path shown periodic light and dark axial lines show grinding chatteElsewhere in the track ae extensive spalling craters There is some idication that spalig is wider where it falls on the darkchatter bands.Suspected Causes rinding chater is due to vbrations o he griding spidle during gridig causig variable grdig pressuread ccumferetia waviess in the workpiece Spalls may be due to normal service with possible corelatio with chatter as aresult of (1) suace roughness changig o wave crests (2) vibatory load compoets caused by chater or (3) possibe grindngdamage (see FC 00.08).

DATAPlae No 5.10Archie No 002-008c&dmage tpe a: light macro b metallogram etchedScaebar a: 4mm b 200 m(micros 20%, others + 100%, 50%)Componen B , hobbed, ruSpeed 91 m/secoad 0.6 PaLubricaon sythetic polyester oil 176°CFaure Code 00024 Maching markFalure Code 000003 Deect by ocation i fee surfaceFalure Code 3 002201 Axial cross section crack i igFailure Code 4 See also PATE 5.27

DESCRPTONSFaiure Descrpion Coarse machnig maks at chamer as sress raisers Crosssection faigue cracking from beding sresses i service, raised by the machigmaks Machining marks are sharpedged and about 20 m deep, producing strongsressraisig effects. Highly sressed gear ings caot toleate machinig as coaseas foud here See Pae 15.27 for fatgue failuemage Descrpon (a): Betwee brackets rough machied chamfe aea wih agedmachiig marks. Crosssectonal crack originated at arrow, from stress cocenratoin hese marks (b): Arrows show roughly evey spaced rectangular cross sections ofmachning marks i the sectoned free surace. The sectioed surace is etched.Suspeced Causes Highly loaded bevel gear ring udergoes high altenating bedigstresses. The machiing marks actig as stress raisers precipitated bendg fatigue.Of-specificaton machiing operaton on the chamfer has poduced the deep marks.



ailre Code 22ailre Code 23

Chapter Surface Defects om Manufacturing

DATAPate No 5.11

Archie No 080101mage tpe ligt macoScaebar 60 mm (mcros +20oters 100 50)Component SG g aess obbesave unuSpeedoadubrcationFalure Code 000242 Gear obbing markFalure Code 2 0003 Pit or unnise aeaFalure Code 3 Falure Code 4 -

DESCRIPTIONSFalure Description Perioic axial marks fromgear obbig wc subsequet savig faile toremove Tese marks are unesirable (may causeoisy runing an poor EHD film coniton) but rarey cause functioal gea aiuremage Desciption Axialy perioc igt a ark appearg patces aog toot flank. Clo epens o ligt incenceSuspected Causes Hobbing of gea teet if ot followe by aequate inising may leave ob marks Tese ae varations isurface rougess an ae usually remove i finisig operatios In te case sow te savig opeation left ucleae obmarks

DATAPlate No 512Archie No 080103mage tpe igt macro

Scalebar 30 mm (micros: ± 20 oters100 50)Component SG ig aress save urunSpeedoadubcationFalure Code 0002.43 Gear saving makFalure Code 2 -Falure Code 3 Falure Code 4

DESCRIPTIONSFalure Descption Pastically isplace materalfom gear savig forms rase "lips at eges

between bot flanks an OD o gear toot Ulessextreme tese lips o ot inteere wt unctionigbut tey o inicate a impeect savig opeationmage Description Te surace at image NE is te gear OD Oe toot fak is visble at SW A igtcolore raise lip appears at

te eges were eac toot lank meets te OD Te raise material at te two eges is similar in magitue.Suspected Causes Te gear saving operatio may wen perome wt a ull cutter plasticaly efom te toot ak materialraisg an ege were te face ntersects te OD Eges at e intesecto of bot flaks wit te OD ten to be smilary rase.





Filur Cod 31Filur Cod 32

Chaper Surface Defecs from Manufacuring

DATAPate No: 515

Archive No 0933.1.6Image type ight mirogramScalebar 150 m (miros: ±20% others + 100%, -50%Component BB; B urunSpeedLoadLubrication:Faiure Code 00.031 Suae orosty or tFaure Code 2 00.0002. Defet by loato: in Het otat surfaeFaure Code 3 00202 Corrosion ittngFaure Code 4

DSCRIPTIONSFailue Descipton Mltie ores in the sufae ot removed in

finishing. A ball oerated with sae deets of this magnitude will failraidly in salling fatigue lt may oy ndentations onto the ontatnga and it may run noisilymage Descrpton Round blak sots o varying sze on a bakgroundof fie sho srathes i the aed surae Near the W edge of theimage where light-inidene is grag the rim of the sots is see tobe deressed below the sherial ball suaeSuspected Causes A likely ase of the its is orrosion of thehardened nfinished bal. The oroso ts wee too dee to beremoved i the hard fishng oeratos.

DATAPlate No 5.16Archive No: 0933.14age type viewScaebar = 20 mm(miros: ±20% others: 100% 50%)Component TRB OR urnSpeedLoad:Lubrcation:Falure Code 00.03.2 Ugrond areaFailure Code 2 00.00.02.1efet by loation: iHertz ontat suaeFailue Code 3 -Faiure Code 4

DSCRIPTIONS

�·

t

•

Faure Description: nfinished surae at edge of RB roller trak Srae s as heat-treated. his area is deressed below the inished otat sufae and does not arry its share of load, eavg the otat area esealy the edge o the ugondath overstressed. If the ugoud aea shold make ontat, its ough suae and oor tegity (sale) will ause it to fail earyi sallig aguemage Descption: he shny finished surfae of the TRB u role ath is interruted at image N by a haf-moon shaed blakarea with feathery borde. n natural lo, the blak area is a dark gray (lor of heat-trea sale.Suspected Causes The TRB u show is a ase hadened thin-waled ring Suh ats may dstort in enhig (xtueqenhing is oten used in large rigs. If sffiet grinding stok s rovided, the grinding oeraton ails to reah the entiresurfae ad ungrond athes reman

5



Failure Atlas for Hertz Contact Machine Eleents

DATAPlate No 17Arcve No 093311mage type light aroScalebar 1 iro ±20% otr 100% -0%)Component: TRB; R urSpeedoadubricatonFalure Code 0003.2 Ugroud araFailure Code 2 0000.021 Dft y loaio i t otat uaFailure Code 3 Failure Code 4

DESCRIPTIONSFaiure Description Nar rolr d fa, th rollg ota a o th

TRB rollr how a aially grod ara a A h gridig oatio kido high oit ut t vally ai a atad oad arrid y thartially groud ara wil oorly diritd o a fw high ot, ladig oarly allig ailumage Description Nar W iag dg, at A a otd dark rt i hartaly goud aa I atral lor, t dark ara i dak gray hat rata).Suspected Causes: TRB roll a otly old add fo wir tok iautoatd hadr. If th to oratio rarig th hadd lug rovdiufiit vol of atrial, a udrill i rodud i t d, lavig aa ar th larg d of th rollr drd. T grdg orao hfa to rov uffii atrial o rovid a la grod a.

DATAPate No: .18Archive No 003009mage type viwScaebar 3 iro ±20% or 100% 0%)Component CRB; IR, uSpeed 60 KdNoad: 1. GPaubrication yht olytr ol, 11 Failure Code 00032 Ugoud araFailure Code 2 002321 Sooth ollig rfa war fiih ark ovd)Failure Code 3 Failure Code 4

DESCRIPTIONSFaure Description Iorly ahid udrut at rolr tak dg trail itorolr trak). Trailig dg ot fiihd Polhg o rollr trak y war whrfiihd), durig ruig. Exiv udrut div ollr of otat ar t d.Edg alig ay rultmage Description Rolr trak ligt lo) i flakd y dark) udru, whi, atarow xtd ito trak darkr tha olid trak).Suspected Causes Iro ahiig of udrt.

Falure Code 32



Filure Code 33Filure Code 1

Capter Surface Defects from Manufacturing

DATAPate No 5.19Arcive No 09321mage type igt microgrmScalebar 1 mm micros ±20%oers + 00% 50%)Component BB IR oned unrunSpeedLoadLubricationFailure Code 0003.3 Unoned eFaiure Code 00.02.1 rnding oninglpping furroFaiure Code 3 Faiure Code 4

DESCRPTONSFailure Description Incomplete oning of grondsufce leving nmeros sgrond furros.Intended EHD film tickness/ogness riodesigned ssumng complete oning is notcieved en deep grinding mrks remn on te suce.mage Description rinding nd oning mrks rn oizontly Oblique ligting illumines te ige slope vleys of emningginding mrs Honing giving oer slopes ppes drk.Suspected Causes Higer tn specified rougness fter grinding or insficent mteri emovl in onng cn cse unonedres o remin on te sce.

DATAPlate No 520

Arcive No 08112mage type ligt mcro ot cid etcedScalebar 4 mm mcros: 20% oters 100% 50%)Component BB; B nrnSpeedLoadLubricatonFaiure Code 00.04.1 Forming lpFalure Code 2 Falure Code 3 Faure Code 4

DESCRPTONSFailure Descripton During forming of te bl lp developedt e equtor encirclng t lest lf te bll. A bll i formngdefec of ts severty is likely to bre in lf pon unnng.mage Description Pebbled gry suce of te bl is due toot cid ecing. Te etc s idened te lp to form te drkopen equtorl seprtion dividng to emisperesSuspected Causes Blls re cold o o eded in dies dividedt te eqtor Normlly fls forms round te equtor ic isremoved in sof fnising Under defcient formng conditions ordefective mteri fod my fom t te fls. Fnising removes te outermost poions but if deep te fold persists s p in

te finised bll

7



Filur Atls for Hrtz Contct Mchin lmnts

DAAPae No .2Archive No 09341mage ype viewScaebar 3 mm (micros 20% others + 100% 0%Coponent TRB; R cold headed iished urunSpeedoadubrcationFalure Code 00.04.2 Formig seamFalure Code 2 Failure Code 3 Failure Code 4

DESCRIPIONS

Failure Coe 2

Faiure Descripton Axial seams at both ends of roller. A seam is a layer of oxde or other ometalic sandwiched ito the metal

durig bar or we mauacture or forging extending ward in roughy radia direction from the surace Seams are sevee formigdefects which tyicaly lead to fracture (FC 00.22 or salling failure (FC 0016 in oeratonmage Descrpton Seams are the dar generaly axial lies at A ad B taering off fom oller ends towad cete. hey showaeciabe width ear both roller eds. Suface is deressed below normal surface at B. The seam extends onto the corner radiusat the of B.Suspected Causes Taered rolles ae ofte made from wire by cold heading In the wre maufacturg rocess seamsoccasoally form Durig cod headg seams are reserved and may oen due to the lastic worig

DAAPae No .22Archive No 00120&21&22mage ype ab: light microgr. c lght metallogr etchedScalebar a 0 b 1 mm c 1 �Jm (micos 20%others + 100% 0%Coponent NRB R runSpeed 2 KdNoad Paubrcation sythetic oyeste oil 60°CFalure Code 00.04.2 Forming seamFailure Code 2 00.16.122 Shallow etry sall from suace lie-defectFailure Code 3 Falure Code 4

DESCRIPIONSFailure Descrpton Forming seam n needle roller extedig viualy itsetre length. xtensive sall originatig rom seam. A seam is a ormingdiscontinuity usually wth non-metallics n the iterface A seam is a severestress raisig defect which whe overroled leads to early salling as i this

roller. Note sal extendg mostly to oe side of the defect (behid i therolig directonmage Descrption (a Sal craters at roller hal. (b: Seam is Wrung white lie. At image W S of seam multle sal crates. Somecaers extend to the seam others eave a narrow band of usaled surfaceSallig is dow-stream from defect ( rolig diectio N to S. (c: etched secto seam is dar taerng strea runng radially nward from thesurace Scale i mage is 24 Jm er numbered dvsion.Suspected Causes I the rolling or drawig of wire stoc for oers seamsoccasoally occu when ometalics ae rolled (drawn to an iteraceruning longitdally ad radially to the wire axis. Salig is reciitated by the severe surface ad subsuace discotuity of the seam.

8

-.

�

:·; ;,_:. -

.•

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Flue Cde 311 Chapter Surface Defects om Manufacturing

DATAPlate No 523

Archve No 002024c&d&emae tye ,b,c lgt mcogrm (,b: ot etch)Scaeba : 6, b 3, c mm (mcos 20, oters 00, 50)Comonent ACBB; B, tool seel, ruSeed 1.7 MdNLoad 4 Lubrication sythetc polyester ol 176CFailue Code 00.043.1.1 Incpet meltg from fogng t excesse

tempertureFaiure Code 2 00.051 McroporostyFaiure Code 3 00042 Formng semFaiure Code 4 00222 Bul tge crckSee als LAES 5.24 nd 15.28

DESCRIPTIONSFalure Descition: Improper forgg hs produced seerl deectsncpent meltng d mcroporosty ( b) formng sem (c) d, uporung blk ftge crck d spll (see lte 528) Formng deects structure my cuse ery spllng. A sem s seere deect Te bllhs fled by spllngmae Descrition () Two lttude bds of deep ech pts (brckets)ndcte leed mterl strctre or mcro-porosty (b) olr crosssecton rogh bl At rrows deep ech pts. (c): At mge N, bllsurfce Drk ftgue crc suce betwee rrows Lghtcoloredsmooth rcures t mge S re mde for exmno.Susected Causes Forgg t excesse tempertre lters mterlstructure by producng corse grs or cpet meltg. I s cse, sem lso formed drg forgg nd ts surce oxdzed t forgg

tempertre. A dl bul ftgue crc propgted dug rnnng fom the dscotuty of the sem

c

a

b

9



Failue Atlas fo Het ontact Machine Elements

DATAPae No 5.24

Archive No 002024&mage type , b: ligt metllogm, Nitepin etcScaebar 100 b 20 m (mcos: ± 20% otes:100% -50%)Compoet ABB B, too steel nSpeed 17 MdNLoad 14 GPLubrcatio stetic poleste oil, 176°alure Code 0004.31 Incpient melg fom fogng texcessie tempetueFalure Code 006024 Icipient splling, mltiple splsFailue Code 3 00.16021.1 Micoplstic defomtion bndso 'bttefliesFaiure Code 4

See aso PLAES 523 d 5.28

DESCRIPTIONSFaiure Descripo Foging of te bl t excesse

tempete s csed incpiet meltig to fom poes in temteil Upo nng, defomton bnds (wite etcinges) fomed toug ftigue dmge ccumltio t tesedefects. Te bll sffeed bulk ftigue ccking d splig(see Plte 1528). See lso Plte 523mage Descriptio () Sectio toug spled e. Dkmotled e t imge S s eced mtx Nmeous blckspots n mtix e poes Wite ieg spots edefomtion bds. Aows lbeled A indicte poosit, oteows ndcte defomtion bnds. (b): Oe poe wit two

defomtion bd "butteflies t ige mgifictioSuspeced Causes Fogig of mteil t excessie tempete ding bll mufcte cses icipient metigwc c est in poosit Te poes e seee sessises tt ted to cse el tige dmge s idicted b

te defomtion bds

70

Falue Code 311

a

b



MATERIAL AND ssEBLY EFECTS 6

6.1

Failure Code 0005-09

General Descripton

hs chapter encompasses a varety of vsualy dentfabe manufacturng defects that are notcovered n Chapter 5 he materal defects covered here are typcally not surface defects However,the assemby defects often are he dvson beween Chapters 5 and 6 s not dctated by a sharpdstncton n subject

MOLDING, CASTING OR SINTERINGDEFECTS

611 Definition

FAILURE CODE: 00.05

Morphoogca defects occurrng n a castng, moldg or snterng process nclude:

orosity (FC 0005): macro or mcrovods n the cast, sntered or powder formed part. Defects of the erami binder n a sntered ceramc

For porosty vsbe at the surface see FC 0003

Underll falure of the cast matera to competely fl the mold ipe: a centra, empty or ncluson-fled thread n a cast ngot or roled product made from

the ngot Cras (FC ) Inlsions (FC Castin strtre deets (FC )

612 NomenclaureAlternatve nomenclatres used n castng, modng or ceramc manufacurng ndustry are not

covered he cted nomencature s usua for contact machne elements

613 Failure ProcessCastng, that s, formng from the qud state, s the nta manufactrng operaton for al (except

powder processed) meta parts astc components are molded or extruded ( roled meta products,castng produces the ngot) Ceramc components are made by compactng, snterng and densfcatonmethods ncudng hot sostatc pressng

he morphologca defects of ascast matera appear n orgna form n components used wthoutsubsequent formng hey are often carred, n modfed form, nto the sem-fnshed (roed, forged,etc.) product

I vew of the wde varety of materas and castng processes used n Hertz contact machneelements, oy the folowg generates can be provded on the faure process

orosity n cast parts may be due to reease of dssoved gases from the soldfyng melt orosity n powder processed parts cudng ceramcs arses from ncomplete densfcaton Deets o the binder n cerc parts arse when the materia used to consolidate he ceramc grans

nto a sod (e bder) fals to provde he requred compete d strong marx around the grans




62

Notes:

7

Forgng porosty may occur from oca remetig of the ascast structure uder excessive forgig

temperaure (FC 0004) Underll occurs whe the mote materia fais to reach a voumes i the mod before soidificatio

Structure defects may arise from a wide variey of chemica ad/ or physica processig errorsspecific to the maufacurig process ad to the materia hey are covered uder FC 0007

nclusons are described uder FC 0006 Cracks (FC 0007) may be due to itera stresses arisig i soidificatio or phase trasformatio

Separatios (weak iterfaces) may be eft where mote materia reaches a cross sectio i themod from two sides ad fais to bod competey

61 Distinctive AppearancePorosiy is visibe as a ope void:

whe it produces surface pits; whe a crack faiure itersects a pore; i a sectio of the compoet, made for examiatio purposes. icusio may be exposed at a surface ad the tor away, eavig a pore

Macroporosity may be show i a castig by Xray or by utrasoud imagigUderfi is visibe as a oca deviatio from iteded shapeFor cracks, see FC 0007; for icusios, see FC 0006.Ceramic bider defects may be visibe i sectios, at fracture surfaces, or whe grai boudary

crackig arises

61 CausesIdetificatio of causes of castig, modig or compactig defects reuires specific iformatio

o the maufacturig process used

616 Effects of Casting, and Molding, Compacting DefectsCastig ad modig defects are gross discotiuities which, uder stressig, typicay ead to

buk crackig or fracture (FC 00.22) or to spaig (FC 00.6)Porosity of some degree is uavoidabe i ceramics; icusios are uavoidabe i wrought stee

Uess porosiy is sufficiety ow ad fie, spaig (FC 0016) ad fracture (FC 0022) of ceramiccompoets wi resut

Bider defects i ceramics ead to graiboudary cracks ad subseuet eary spaig (FC 00 6)

INCLUSONS FAILURE CODE: 00.06

621 DefinitionIcusios are voumes of uiteded foreig materia embedded i the matrix of the compoet

materia I metas produced by a castig process (icudig parts used ascast, pressed, roed,extruded or forged), icusios are mosty onmetaic I powder metas ad ceramics, icusiosmay be either onmetaics or foreig metas

. Hardeabe stees cotai carbides as structura eemets hese are ot icusios, defiedas defects



Chapter 6: Materal and Aembly Deect

2 Some metas ae pecptation hadened he pecpitates ae not incusions, defined as defects

3. Cemets and some ceamcs consist of (had) gains embedded in a binde

ncuson (defect)is a voume of matea othe than the intended gains o binde

622 NomencatureIn metas, ncusions may be efeed to as nonmetaics o sag

Maco-inclusions ae age enough to be visibe wth the unaided eye (0205 mm minimum)

tinges ae stongy eongated maco-incusions Globula inclusions ae oughy spheica maco-incusons

Mico-inclusions ae smia to, but smae than the above, and discenbe by metaogaphy

623 Faiure Processn incuson foms dung met (o powde) pocessing of the matea, when a foegn substance

aggomeates into dstnct voumes and s encosed in the matix mateaIn moten metas, indigenous nonmetacs may be geneated duing the met pocessng (incuding

saggng) o casting Exogenous nonmetaics esut fom extaneous contamination of the met (foexampe, fom the funace inng o ade)

In powde-based mateia (powde-meta, cemets, ceamics), the powde may be extenay contaminated, o contain sag fom its own manufactue

62 istinctive AppearanceMaco-ncusions ae decty vsbe if they extend to a suface o appea n a factue as spots

o (if stinges) as steaks n the othewise unfom suface If incusions do not extend to the suface,they ae obseved in metaogaphc section, on an X-ay o utasound image o as eddy-cuentindicatons Incusons extendng to a fnshed suface ae often coveed in the fnshing opeatonby a thn aye of pastcay fowed meta Duing unnng unde stess, this aye may be emovedand the ncusion eveaed

·

Mco-incusons ae identfied by examination (of sectons) at high magnficatonDepending on matea and ts manufactuing pocess, a mutitude of distnct incuson casses

and appeaances occu hei dffeentiation eues specfc nfomation on matea manufactueand appopate examination methods

62 auses

he mateia of incusons is ognay admixed to o geneated n the met (o powde) duingpocessing of the aw mateia Soidification (o sinteing) foms them into dstinct incuson voumesSubseuent foming steps may signifcanty change the size and shape of the incusons

Identifcation of the pocessng condtons conducve to each type of incusion eues specificinfomaton on the matea and its manufactuing pocess

626 Effects of Inclusionst the incusion/ matix nteface, stess concentations aise oth stong (high utimate stength)

and weak incusons ae detmenta due to these stess concentations Factos affecting the seveityof the stess concentation ae incusion sze, shape, inteface (such as smooth o jagged, bonded ounbonded), eastc moduus dffeence fom the matx, bitteness and paticuas of the maco

stess fed7



Failure Atla fr Hert Cntact Machine Element

6.3

Macoclsos ae macoscopc weak vomes hey may case failre by the folowg pro

cesses Bk crackig ad fractre (FC 0022), if located aywhere i a stressed crosssecto. Spalg (FC 006), if located the Hertz stress vome Gallg (FC 00.3), if extedg to a cotact srface.

Mcoclsios are mcoscopic weak volmes which may case failre throgh:

Sbsrface-orgi spalg (FC 0016), if located i the Hertz stress vome Srface distress (FC 0017) ad sface-og fatge (FC 0016), if located i the cotact sr

face laye. Wear (FC 0012), f extedg to the cotact srface.

ATERIAL STRUCTURE DEFECTS PRIOR TO,

OR IN HEAT TREATENT FAILURE CODE 0007

his sectio s cded fo competeess, to pemit materastrctre related mophologicafares to be traced to ths soce Dagosis of strcte defects reres aboratory methods ofmaterias aalyss, specific fo the material, for ts coditio ad for the defect that s to be diagosed

I metals, the examiato methods ae pmariy hardess testig, fractre examiatio, metalogaphy icldig approprate etchg, ad Xray diffractio. ltasod, magetic o eddy-cetmethods may aso be sed Some of these examiatio methods are also applicable to ocodctve,omagetc materals sch as ceramics

631 DefinitionDefects of materal strcte are those physica defciecies a strctra mateia that impart to

it ess resistace to a mposed stress (mechaica, therma or chemical) tha the specfed strcte possesses

he great maorty of cotact compoets are made of stee heat treated to optma properties forthe specfic appcatio (high hardess sface for most beaigs, hgh o medm hardess srfacefor geas ad cams) his sectio covers strctre defects i these steels

Othe cotact compoet materas, sch as cast iro, osteel metas, ceramics, cermets or pastcshave diffeet strcte eiemets ad defects bt are ot coveed ths tas

632 Nomenclature

teatve omecatre fo strctue defects is ot covered.

High Hardness Steel Components

6331 Definitionhe folowg ae commo strctal defects i hgh hadess (>50 RC) steel cotact compoets

Hardness defect. Most ofte, the pat is softer tha specfied.

Carbn lss ( decarbrizato) at the sface of throghhardeed pats Carbn gradient defet carbized pats Nitrgen gradient defect i trded pats



hapr 6 Maria and Assmb Dfcs

Dcts n rqurd consttunts

• May hardeed stees are martnstc he morphoogy of the martesite eedes may deviatefrom specifcatio Untmprd martnst may be preset from rehardeig.

• Other hardeed stees may be (ower) bantc The specific metaographic morphoogy of thebaite may deviate from specificatio.

Imprmssbl structural consttunts I fuy hardeed stees, these are geeray soft costituetsFerrite ad upper bante are recogzabe soft costituets.Rtand austnt Excessive quatities of austeite retaied i the fiished product.Gran boundary dcts Weakesses i the (prior austeitic) grai size of the materiaCarbd sgrgaton Carbides i the stee are too arge, or segregated ito bads, etworks, etc.Crackng due to excessive processig (castig, formig, heattreatig) stress.

6332 ilure ProcessMateria structure defects i parts of hardeed stee are the resut of defciecies i raw materia

compositio; formig ad or heat treatmet processes which iterfere with the grai size cotro;recrystaizatio i hot formig; deviatios from proper casig (carburizig or itridig, fame oriductio hardeg); errors i austetizig, quechig, temperig or other postquech treatmet.

6333 Distinctive AppernceMateria structure defects are detected by materias aboratory methods.

633 CusesIdetificatio of the processes resutig i materia structure defects i hardeed stee requires

detaied iformatio o castig, hot formig ad heat treatmet methods for the materia.

633 Effects of Defects n Mteri Structurehe materia properties typicay affected by defects i structure are:

• Tnsl strngth or hardnss the imit of pasticity uder tesie stressig or idetatio.• Ductlty or toughnss the abiity to susta pastic deformatio without fracture Fatgu rsstanc Especiay i Hertz cotacts, fatigue resistace (resistace to spaig faiure)

does ot uiquey correate with other macroscopic stregth parameters• Tmpratur rsstanc Impropery heat treated stee may show dimesioa istabiity or softe

at operatig temperatures• Corroson rsstanc I corrosio resistat stees, structure defects detract from corrosio resis

tace.

Medium Hadness Steel Components

Structure defects ad their cosequeces i medium hardess stees are somewhat simar to thosei fuy hardeed stee. However, the structure eemets of ower-hardess stees differ quatitativeyad quaitativey from fuy hardeed stees, as foows:

• The required ad the impermissibe structura costituets may be differet from fuy hardeed stees

Metaographicay idetifiabe carbides may ot be preset.• Retaed austete may ot be preset.

5




6.4

Notes

FINISHING DAMAGE FAILURE CODE: 0008

TO MATERIAL STRUCTURE6 Definition

he as o ea-as fsg pocesses of compoe sufaces may damage he subsuface maeasucue. hs damage s defed as fshg damage o maea sucue. Casses of such damageae gdg damage, coag damage ad cod fomg damage

Ginding Damage Faiue Code: 8

621 DefinitionGdg damage s damage o he ea-suface maea due o aggessve gdg (o ohe

abasve fshg)

622 Nomencaturehe commo desgaos fo ypes of gdg damage ae gdg bus, gdg empe,

ad gdg cacks.

623 Faiure ProcessGdg damage o subsuface maea s he esu of oveheag of he suface ude sog

pessue ad shea foces asmed by he gdg whee, hog o poshg oo. I ypcayaffecs hadeed (maesc, owe baic) see compoes he oveheag esus heeypes of chage hese compoes:

Gdg empe ases whe he maea s ocay heaed above s specfed empeg empeaue ad hus becomes sofe ha he buk maea Sce empeg esus voume chage,some esdua sesses ae se up

2. Gdg bus occu whe he oveheag exceeds he ausezg empeaue of he seead eausezes a voume he ho voume, beg suouded by cod see s apdy cooedad queched bu o empeed eadg o a ehadeed voume, suouded by a empeedshe whch was heaed bu o eauseed Sevee esdua sesses ae se up because heausee maese asfomao upo quechg esus gea voume chage Whegdg bus of subsaa sevey ae ceaed by he ex-o-as fishg opeao, spossbe fo he as opeao o emove he suface evdece of he damage (makg udeecabe by Na echg), bu eave sevee esdua sesses wch ca ead o oca cackg sevce

3 Gdg cacks ae he esu of he esdua sesses descbed above, whe hey exceed he

segh of he maea

62 Distinctive Appearance

Gdg cacks may be dscebe wh he uaded eye o ude ow magifcao. Magecpace, eddy cue o dye-peea speco povde moe sesive deeco

Gdg empe ad bus ae deecabe by Na echg of he suface he tempered voumeeches dak, he rehardened voume eches ghe ha oma. Eddy cue mehods fo gdgdamage deeco ae med use.

1 I some sees, such as secoday-hadeg oo sees, deeco of gdg damage by echgs dffcu



Capter 6 Material and Assembl Deects

2 Gidig bus obscued by efisig ae detectabe oy by a destuctive etcg metodSome success s camed fo eddy cuet detecto

62 Causes

Excessive gdg paametes (g feed); excessve pessue o oig o posg too Iappopate seecto of gdg wee o ote abasve Isuffcet o adequate cooat Sesitive matea stuctue Iadequatey tempeed matea s easiy damaged gdg Hg pessue, hig sidig speed o usutabe matea of sidig suppot eemets (soes)

gdig

626 Effects of Gidig Damage

rackng (ete oca, o buk; (FC 0022), as a esut of esidua stesses• Surfac dstrss (FC 0017) o salln (FC 00 1 6) Damaged matea as ow Hetza fatigue ess

tace

Coatng Damage Falue Code:

63 DefiitioCoatigs commoy used o (metac) cotact sufaces ae

Cemica (oxde, pospate, moybdeum dsufde) coatgs fo dy ubcatio ad ust potec-tio puposes

Eectopatig wit ti o cadmum as a dy ubicat (i a few aeospace appcatios) Speca (speoda) comum patg i highy aggessive evomets Bused-o, sputteed o cemicay deposited sod ubcat coatigs (Fo te faue of

ubicat coatigs n srvc see Capte 18)

e may expemeta o deveopmeta coatigs tat ae apped to cotact sufaces ae otcoveed ths tas

Coatg of ft sufaces by ad comium eectopatg s commo fo te coecto of dmesoaeos i maufactue o te epa of wea

Fuctoay, coatigs may be dvded to ad coatigs aimed at potectg te weake substate;ad soft coatgs wc act sacifciay, as sod ubcats o ui ads, ad addtoay may asobe cooso potectos

Coatig damage is defied as defects te coatg, o deeteous iteacto of te coatig wtte substate

632 Nomeclatueteative desigatios fo coatig damage ae ot coveed

633 Failue PocessDefects coatigs cude

mpope coatg compostio fo a sod ubicat o ust potecto Micocackg mpope stuctue

77



Failue Atlas fo Hetz Contact Macine Elements

78

Icompete sface coveage. Iadeate bodig Off-specificatio hadess Chemca decomposto de to high tempeatue o i teacto with the evionmet. Foeg mateia i the coatg.

Deeteios iteactios of coatig ad sbstate icde:

Hydoge embittemet fom eectopatg. ttack o sface mcogeomety o ga bodaies of the sbstate fom chemcay

fomed coatigs. Resda stesses at the iteface betwee coatg ad sbstate.

63 Dsnve Appearane

Impope composto may be eveaed fctoay by wea o seize of the sbstate o thematg sface It may be vsbe as a dscooatio.

Vsa spectio (wth o withot magificatio) w evea mcocackg ad, by showgisads of coveed sbstate, icompete sface coveage

Impope stucte o foeg matea i the coatig may be dscenbe by metaogaphc examato o by goss appeaace (coo, goss, etc) ad eies specifc ifomatio as to the typeof coatig

adeate bodig o impope hadess may be detectabe by aboatoy scatch tests, bt smoe ofte dagosed fom iadeate wea pefomace.

Hydoge embittemet s diagosed fom the cackg o fakg t cases the sbstate.Resida stesses at the coatig to sbstate iteface ae geeay detectabe oy fom thei effect

o fatge.

Dagoss of chemica attack eues specfc fomatio as to the type of coatig. coatigsthat ca be chemicay stipped withot damage to the sbstate:

Damage to urface microgeomet s diagosed by ceased ogess, pit fomatio o wavessobseved o the stpped sbstate.

Intergranular attac is detected metaogapcay as diffeeta etchig of gai bodaies omcocacks the sbstate.

63 Causesdetfcato of the cases of coatig fae eies specfc fomatio o the coatig pocess

636 Ees o Coang FailureHad coatg defects pomote compoet faie by these pocesses:

Iadeate wea esistace. Iadeate cooso potecto. Sface oig spag, which may tate the coatig o at the teface ad popagate to

the sbstate. Detached akes of coatig case detig of cotact sfaces.

Soft coatg defects maifest themseves as

Iadeate soid bicatg pefomace. Iadeate coosio potecto



Chapter 6 Material and Assembly Defects

Cod Formg Damag Falur Cod: 87

61 DeftoCold forming damage is defined as damage to the subsurface structure due to a cod-forming

fiishing operation.Cold forng as a fiishing operation for contact components is used in the folowing examples:

Dp drwing is the finish-forming method for drawn needle roler bearing cups Sot pning has been used as a second-last or last fiising operation on working surfaces with

the intent of providng work hardeing of the near-surface material Roll burnising or bal burshing has been used to work-harden blend radii subject to heavy

bending stresses

62 NomelatureThere are no other common designations for cod forming damage

63 Falure Proess

Structure damage due to dp drwing of neede bearing cups has not been identified The workhardening effect of cod drawing is generally considered advantageous (Cracks, fods surfacedefects can occur See FC 0002 and FC 00.04)

Sot pning of surfaces in Hertz contact as the last fiisg operation leaves consideraberoughness and waviness. If run in Hertz contact, such surfaces experience high asperity stressesThe work hardenng and compressive stress formation in the nearsurface material acieved byshot peening is beneficial to buk fatigue It is questionabe whether resistance to Hertz contact

fatigue is improved by the work hardeng and compressive residual stress, or impaired bymicroscopic damage to the material The outcome may depend on processing conditions rawmaterial and operatg conditions

Roll or bll burnising of blend radii as used in highly stressed shafts and similar componentsis tended to strengthen the bend radius by smooting the surface (reduce stress concentrations)and work-harden and compressivey prestress the near-surface materia The high Hertziapressures needed to produce the required plastic deformation may cause cracking, leading topremature bending fatigue.

6 Dsttve Appearae

No visible damage to subsurface materia is expected in dp drwing.

The appearance of a sot pnd surface shows the surface rougness. Subsurface materia damageis typicaly not visualy observable and is diagnosed by early contact fatigue Cracks in roll burnisd blend radii may be visibe or can be diagnosed by magnetic partice or

dye-penetrant inspection

6 CausesIdentification of shot peening parameters (shot size impact energy duration of peeing) conducive

to subsurface damage requires specific knowledge of materia and processing conditions

66 Effets of Materal Damage by Cold FshgThe effects of material damage by cod forg are contact fatigue as a resut of shed ntegrity of

the near-surface material and buk fatigue arising from cracks cold finished (ro burished) materia

79



Failure Atlas for Hertz Contct Machine Elements

65

80

GEOMETRY ASSEMBLY OR

MOUNTING FAILURE61 Definition

FAILURE CODE: 00.09

Assembl is defined as the combination of parts into a Hert contact machine element Example:the assemby of components into a bearg

Mounting is defined as the instalation of the Hert contact machine element into the machinein which it wi operate Example: the placement of a gear set in the gearbox

Failres covered in this section encompass geometry errors; and score marks, goges and cracksde to assembly or monting

62 NomencltueAternative designations of these failres (other than geometry defects are 'assemby (montingerror and assembly (monting) damage

Geometry Defect Faiure Code

631 DefinitionA geometry defect is defined as offspecification geometry of the component or the montg,

trogh manfactring error, assemby or monting error, inclding se of wrong parts or omissionof parts

632 NomencltueAlternative designations of this faire are geometry error and dimensiona error.

633 Filue PocessDependng on the machine eement and its assembly or monting method, geometry errors can

arise at any point in manfactre of the components, their assembly into a macine element or inmonting the element into the machine

Specific cases of monting geometry errors are

Monting with off-specification shaft or hosing•

Excessive fastening forces Misaigned monting Monting on a debris-contaminated srface Inadvertent omission of a part, misplacement of a part or se of the wrong part

63 Distinctive Appence

Gross geometry defects are visay detectable by comparison of the machine element or montedassembly with the prodct drawing

Moderately ot-of-tolerance manfactring geometry reqires metrological examination I as-rn components, geometry defects are often detectabe by incorrect wear patterns, sch

as edge contact, improper oad distribtion, etc (See FC 0012)



Chapter 6: Material and Assembly Defects

63 Causes

Cuss of gomtry dfcts rqur spcfc formto o th mufcturg, ssmby or moutg procss for dgoss

636 Eects o Geometry DeectTh rg of possb ffcts from dfctv gomtry compsss vrtuly vry srvc

flur mod Th prcp mchsms through whch gomtry rrors produc flur r

• Mldstrbuto of od mog cotcts or of prssur wth cotct.• Prstc lods from ck of tr oosss• xcssv or suffct ft trfrc to moutg prts• rolg brgs, corrct sprtor clrcs, producg xcssv sprtor lods or u

tdd cotcts.• Lubrcto fur from xcssv surfc roughss.• Gross mlfucto from mssg, mpropr or msssmbd prts

Scoring, Galling or Cracking in

Assembly or Mouning

6 Deinition

Failure Code

• Scorin ssmbly or moutg, rss from ploughg of th surfc by hrd, shrp mpmt, procss of wear FC 00.12)

• Gallin ssmby or moutg occurs from material transfer hgh-prssur sdg cotct

of ffctvy ubrctd surfcs o ch othr S FC 0013)• racks dacture of compots, ssmbly or moutg, rs from xcssv strsss posd

o compot, whch r th rsut of ssmby or moutg gomtry rrors S FC 0022)

62 omencatureNomcltur for ssmby scorg d glg s usttld Scuff mrks, scrtch mrks, d

gougs r usd for thr flur Smr mrks dsgt gg Thr s o ltrtv omctur for crcks or frctur

63 Failure Process

Th flur procsss ths ctgory r dtfd th ftos Mor dtls r gv th Fur Cods std thr


• Scorg s ploughg mrk wth shy bottom d shrp, oft rsd, dgs Th postod ortto of th scor mrk o th compot my srv to dstgush t from fshgfurrow FC 0002) or srvc wr FC 0012) Scor mrks from tool mpct td to b o frsurfcs whch my suffr hmmr blows or scrpg by drft Axl scor mrks th borof brg rrg or gr, or o th O of brg outrrg my rs from moutgo th mtg shft or housg wth trfrc ft or ovr shrp dg. ght scor mrksmy tr oy th surfc sprty tps, rsutg stppd mrk

8



aiure Aa for Her Cona Maine Eemen

8

• alling marks in assembly arise nder similar conditions as score marks bt galg marksshow signs of metal transfer. Differentiation may reqire magnification. aing in assemby isdistingished from in-service galing ( 00.3) in the same way as for scoring.

• racks and fractres are material separations. heir origin in assemby or monting is sallydiagnosed form their location (example: chipping at a flange edge) accompanying impact marksscore or galing marks or geometric distortion.

6 Causeshe cases of scoring galing and cracks differ ony in severity which increases in the order isted.

he principal cases are

• mproper se of assemby or monting tools eading to �lippage of the tool over a componentsrface scratches galing marks impact damage chipping or fractre.

•

Sliding of working or fit srfaces over each other dring assemby or monting when: (a) theinterference fit is excessive (b) there is excessive interface oad (c) srface roghness is excessiveor sharp edges exist (d) monting is attempted nder misaligent (e) brication is inadeqateand/ or (f) solid contaminant is present in the interface.

66 Effects f Scring, Galling r Cracks in Assembly r Munting

• Scoring or galling on t srfaces dring assembly or monting may ead to cracking nder serviceloading ( 00.22).

• Scoring or galling in contact srfaces dring assembly or monting may ead to blk cracking( 00.22), srface distress ( 00.17), srfaceorigin spalling ( 00.16), wear ( 00.12) or inservice galling ( 003).

• Cracks and acture dring assemby or montng represent gross failre making the machineelement nserviceable either immediatey or after frther crack propagation



Chapter 6: Material and Assembly Defects


d

P N

4.3 4.7

48



Faiure Atas for Hertz Cotact Machie Eemets

PTSDATAPlate No 61Achive No: 01 4-007 &009Scaleba a b 1 0 �m (micrs 0%, ters 100% 50%)Image type: SEMComponent ; R test rig rd racture specimen sil icn tideSpeedLoadLubicaton:aue Code 00.05.4 Stuctue defect i ceramicalue Code -ailue Code ailue Code

S s PLTES 10.5 106 10.48 ad 119

DESCRIPONSailue Deciption: Bulk fracture surfaces f lg lived (a) ad sr ived(b) silic itride ceamic tested as n e Plates refereced belw ineequiaxed grais wi rmal bider i lg lived material (a) carse aciculargrains i sr lved materal (b).Image Decpon: (a) Fine fracture suace witut sarply delieated largesapedged grais appears varius sades f gay Smal wite patcesare wel distributed bider. (b): Large grais wit sap straigt edges appeari sades f gray. Small wte patces are wel disributed bderSupected Caue: Tese images ilustrate ceramic structures wc arerespectively g lved (a) and sr lived (b) in rllig ctact fatgue DPardess f material (a) is 18.7 GPa (at 94 N lad) and f material (b) is

1 48 GPa (at 490 N lad) measured uder te gest ideter lad tcausng a crack Te lng lived mateial cracked uder lwer ideter lad.ccrdigly te lg-lived material was arder but wit lwer fracturetugess ta te slived material e mateials may ave ctaineddfferent types ad percentages f bider ad differet silic iride grainsizes

84

Faiure ode: .

a

b



Faiure ode: 000611 Chater Materia ad Assemby Defects

AAPate No 6.2

Achive No 002016Scale ba 1 00 m (mio ± 20% oter: 100% 50%Image ype: ligt metallogram, unetedComponent C O runSpeed 09 MdNoad 08 Pabication yntheti polyeter oi 9Caile Code 00.06.1 .1 Hard mro-inluonaile Code 2 aire Code aire Code S s PLATE: 1532

ESCRIPONS

ale Deciption Multiple iliate miro-inluion in te teel wi arerated a exeeding limit for t appliaton Siliate inluion are ard andrepreent uurae defet of everity dependng on ize and reueny andgeneraly lead to pallin g. In ti ae ulk fatige of a retain ng lug reultedSee Plate 1 532Image Deciption I n u neted gray akground of metallograpi roetion inl ion form dark dae, mot of wi are in a lin e wo areindiated y arow.Spected Cae Sliate are ontituent o lag n teelmaking Oaionally ome of te iiate i ntrapped n te melt toform inluion. uring olling of te a produt, edution of te ro-etion elongate te initially gloular inuon

AAPate No 63Achive No 00201

mage ype (a SEM ( Xray image for auminumScale ba a 5 0 m (mro 20%,oter + 00% 50%Component C O 5200 teel runSpeed 09 MdNoad 0.8 Pabication yntet polyeter oil 19Cale Code 00.06. ard miro-inluionFaile Code 2 Fale Code ale Code S s PATE 1532

ESCRPONS

aile Decpton Cluter of aumina mioinluion in axialradialetion of outerring Aluminum ontent onfirmed y

a b

X-ay analyi Alum ina are ard n on-metalli repreenting ig nifant tre raiing defet. ey typially lead to pallng . I n tiae tey led to antirotation lg ulk aking (See Plate 532 for fatigue faieImage Decipion (a SE M of poied metallograpi ro etion ( ligt ontaini ng a luter of dark inuon , everal ofwi are maked y arrow ( Xray energy di perve image n wi alu min um appear wte. I nuion are outlined yuter of wite dot.Spected Cae Non-metalli are teemakng defet. Aluminum i ued in teelmaking a a deoxidizer. Aluminum oxide(alum ina i removed y lagging ut mi ro-inluion of it are never wholy aent rom melted teel A luter of inlu ion ian unaeptale aident of teelmakin g.

85




DATAPlate No: 6

Archive No: 01-1363Image type: ligt metalogr., a: uetced, b etcedScalebar a: 1 00, b: 1 0 m (micro: 20%,oter 1 00% 50%)Componen T I carbuized tee, ruSpeed:Load:Lubrication:Faure Code 00061 Hard micro-incuioFailure Code 0016022 Contact fatgue crackingFailure Code 006021 1 Microplaticdeformao bad o butterflieFailure Code

DESCRIPTONSFalure Descripton: (a): Nomeallc icluionsrgr extending i te "fibe flow d irection (tedirectio of elongatio drig tube rollng) aiitiated a paig fatigue crack progegupward to te urace (b) atgue damageind cated by te mi croplatc deormation zoe(butteie) formig aroud te iclu ionDeformation zoe idicate ig local tre butnot ecearily te in itiatio of a fatigue crackmage Descrpion: (a) I rectagle at image E,angled lin e of black globue i an icluio triger Te line of ueve wid extending NWfrom ere i a crack Suace A-A (b) Secto

of volume witi te rectagl e of A Etcedmaentic matrx cluion: wavy black le at Nad black patc at center To bot ide o telatter, at abou 20° to uace, wite etcgwing-like buttely.Suspected Causes: Nonmetall ic i cluio particeform durg te teelmakg proce. Du rigrollig tey are ofte trug out i a ie i tefiber flow directio, formig a triger Spaligfatgue cack arie at uc tre conceratingdefect. Deformatio bad are a altered matrixtructure ad may, n ome teel, beaccompanied by letclar carbide formed du ingte deformatio poce.

86

Faiure ode: .

a

b



Faiure ode: 00061Faiure ode: 000613

DAA

lat No: 5Arch No: 09312Imag ty l ght etlogrScalba 1 0 � cros ± 20% others 1 00%, 50%Comonnt: 820 stee rw tel specenSd:oad:ubricationFailur Cod 00.01.2 Sulfde clusonFailur Cod : 00.0.2 Icluso srngerFaiur Cod 00.0.1 .3 Prry cdeFailur Cod -

DESCRPONSFaiur Dscrton: Elonged sulfde c luson stnger fored prllel tothe oll ng drecton of the erl nc luso strngers for su surfcedeects t whch spllg fgue or ulk crckg y nte Se forsze sulf de nclus ons re el eved to e less severe defects thn hrd sl cte cluso s, pesuly ecuse they re soft dsoohsufcedImag Dscrition: rk streks r un g NS on t he unetched l ghtckground re sufde nclusos Note sooth oudres. he lckround spos re prry crdes not defect.Susctd Causs: Sulfu s url contt preset elted steelnd ust e reduced to specfed lts. I ntetolly 'resulfurzed steel srrely used roll ng erngs Resdues of sulfur conton y forgloulr sufde nclusons the ngot whch, du rng terl roll gelongte to strgers

DAAlat No: Archi No: 01 8-309&31 0Imag ty: SEMScalba , : 10 � cros: 20%,others 100%, 50%Comonnt: ACBB B tool steel : unrun unSd: 1 . 125 MdNoad: 22 GPubrication synthetc polyeste ol, 150CFailu Cod 00.0.1 .3 Py crdeFailu Cod : 00.1 7.2 Loclzed surfce

dstress hlo t defecFaiur Cod Faiur Cod

DESCRPONSa

Chater Materia ad Assemby Defects

b

Falur Dscition: Hrd prry crdes of oo steel or stnless steel erngs re exposed t the ll sufce, protudgove u nru n trx surfce On ru su rfce hrd crde s s urouded y suce dstress hlo. Potrud ng crdes ydge the tng surce, cuse toque rregulrty n nstruent ergs d surce dsress n ny erg. The lter yled to preture spllgImag Dscrition: wo roun d protudg crdes re exposed o the lpped surce o n u run l . The sctch rks eo fo ths hgh gfcton SEM ut do pper to cluster oud he crdes he lghtecoored round crde sfltteed r unn ng y wer hl o of dk-colored urn sh rks surroud g t d cte sufce dstess gzngSusctd Causs Hd loy crdes re rnsc o h ghcro hg hlloy too steels nd enstc st nless steels s usedn erospce d nstruent erg s. Fshn g y lpp ng loose sve y reove trx fser th crdes, cusg theo protrude. In operto, the H ertz pressure y defor nd the sld g y wer the protrudng crde The dsrupto of theEH fl roud he crde y prooe surfce dstress

87




DATAlat N: .7Arhiv N: 00303&&014Ima typ SEM c lght croSalbar 25 c 5 (mcros± 20% others + 00% 50%)Cmpnnt: ACBB; (c OR B) tool stee ruSpd: 1 ? MdNLad:Lbriati: sythetc polyester ol ? Failr Cd 00.01 .3 Pry crdeFair Cd 00182.2.2 Stppled lne(s) ord(s) fro rolledn dersFair Cd 001024 Incpet spllgltple spllsFair Cd

DESCRPTONSFair Dript: ool see lls o thserng conted hrd Vndu crdes (1 5 deter) whch creted profselydeted R srfce. Durng rnnng nd ofths dged suce fled le of splsThe erg hs fledIma Dipti () Sufce of OR llph copletely covered wth rolledoverronded dets fro cotct wth sphercl hrdcrdes lls () Bll sfce. At gecter nd 1/2 to NE core specl rdcrdes Elsewhere dents nd scrtches

perhps cospll t (c) OR wth llph etwee whe crcle d sclloped edgeottled y dents. A d of drk splls ncter o ll pthSptd Ca: ool steels y contnhrd prry crdes wh ch re proetdurng ll lppng . Wen rolled gnst rngsufce, crdes crete profuse detseventully pee ng the s rce Plstcty sexhusted d sufce fors splls pofurher rung.

88

Faure ode

a b



Failure ode 0006

DATAPlae N: .8Ahive N: 075-201 &202&204Iage type: : lght cro, SEM, c SEM coposteSale ba : 5 , 200, c 00 cros: 20%,others: 1 00%, 50%Cpnen: CRB R, nruSpeed:Lad:Lubiatn:Falue Cde 000.2 I ncson stngeFalue Cde -Falue Cde Failue Cde

DESCRPTONSFaiue Desiptn: clson strnger totlg 1 0 n lengthor oe, open to the rollng sfce s detered y -ryspectr to e lyered strnger of lrgely l nclusosA strger so locted s to e ope to the s rfce, d of thsgret legth s n et sorce of spl g flure.Iage Desiptin: : O the s-grod sfce grndgl es run N S A 1 0 long nterrupted wvy lck erunng EW s he clson More oetlcs show s feck pons t W ed nd to the N o f the strger. :Inteol fcture og strnge Rollng surfce s N seconedge Prle whte EW lnes e the nclus on c Lyot s . 3 or ore EW yers of lght-clor ncso "peles fcue suceSuspeted Causes: Alu nclusos y e exogenous

etng fo the refrctory used n steelg eqpet,or endogeos fro lunu dded for deoxdzg vewof ts lrge sze ths strnger s eeved to e exogenous. lssues ts elongted shpe prlel to the drecto of erlelongton d rg tue rollng or forgg.

Chater Materia ad Assemy Defects

a

b

8





Faiure ode:

Faiure ode:

DAAPla No:

6.11Ahi No: 09371 2Imag yp: lgt metallogram, Nital etcSala 8 m (micos 20%, oters +100% 50%Componnt: 521 00 bea ring steel raw materialSp:Loa:LationFail Co 000.1 2 Ferriic constitentFai Co : -Fai Co -Fa Co

DESCRPONSFa Diption: Excessive soft ferritc constitent in

ardened 52100 steel Tis strctre as less resistance tofatige spalli ng an properly ardened strctre.Imag Diption: Backgrond is finely disribtedmarensitc atrx wit sall carbdes (dak dots. Streakyconstitent is soft errite, as in circles at and BSpt Ca: Sof constients in a ardened strctremay arise if te asteniting temperatre is nsfcient

DAAPlat No: 612Ah No: 093-1 .4Imag typ lgt eallogra, Nital etc

Sala 8 (micros: 20% oters: + 1 00% 50%)Componn 521 00 stee raw ateriaSp:Loa:Liaon:Fai Co 00.01 .3 Upper baintic constentFa Co : Fal Co Fal Co

DESCRPONSFa Diption: Sof constitent formed by insficientqencing is 'pper bainite believed o be detrimental tofatige resistance t is distnct from 'lower bainite obtained

by a special ig-teperae qenc and sed for iprovedtogness compared to conventonal aenistic qenc.Imag Dption Gray backgrond is martenistic srctreDark areas are pper bainite.Spt Ca If qencing is peromed too slowly or isinterpted before competon, ppe bainite can for

Chater Material ad Assembly efects

·

�




DAAPlate N: 6 . 13Arhve N: 9381 2Iage type lgt metallogam, Ntal etcSaear Jm (micros: 2% oters + % 5%Cpnent: M5 tool steel secimenSpeed:ad:uratin:Faiure Cde 2 Off-secfica on maen site aelet szeFaiure Cde Faure Cde Falure Cde

DESCRPONSFaiure Desrptn: Maensite atelets ormed n ardening may develo

excessive sie f eat treatment conditons ae imroer Tis condit ion istogt to increase brteness and lead to cracking, esecally nder goo stess. l t s not establised weer t e large latelets are t e caseor merely an ndcation of nceased brttleness. Limis are ofen set forermissible marensite latelet size.Image Despn: Marenste laelets aear as steaks or needles n teeced secion. Teir size is oo large (for tis stee to be acceted. eotline at sronds an excessvely long maensite needle Suspeted Causes: Astenitiing at excessve emeratre dring eatreatment cases lage maensite needle sie

DAAPlate N 6 14

Arhve N 8-32&321Iage type a lgt metallogram, eced b SMSaear a b J (micros 2% oters % 5%Cpnent: eat-treated M 5 steel, 1 x 1 mm bi l letSpeed:ad:uratinFaiue Cde 3.1 Carbide segregationFaiure Cde Faure Cde Failure Cde

DESCRPONSFaiure Desrpn: (a: Segregated rmary carbides in g-alloy toolseel. (b Sizeable rimary carbdes in M5 tool stee wo yes(molybdenmric and vanadimric are arayed in steaks. Lagecarbides may mar srace inising Segregation s togt to redceressance to crackng. Reirements exs or limis on carbide segregationin steels sed in bearngs.Image Desrpn (a D ark backgrond s eavily etced marix Wieinear desgn consists of segregated rimary carbdes (b: Gray atternedbackgrond i s etced ardened matrix. At image N s a sting ofmolybdenm-ric cabides sown wite n te SEM. Sigtly N of imagecenter is a keyole-saed, large vanadim-ic carbide sown gray in teSEM.Suspeted Causes: Hig aoy tool seels end o develo cabdesegregation dring ingot rocessing Degree of segegation deends onrocessing metod.

2

aiure ode: .

aiure ode: ..

a



Faiure ode: 0007.3.2

DATA

Plate No: 615Achive No 002-002i&&Image ype: a b c ig metallogram, Nia/Zepira etcScalear a: 1 mm b c 00 m(micro: 20%, ote +100%, 50%)Coponen ACBB B, ool ee, rnSpeed: 0.8 dNoad: 22 GParication ytetic polyeter ol 176CFaile Code 00.0.3.2 amellar carbideFailre Code 2: 00.04.3. 1 Forging at exceve temperatreFailre Code 00.16 Spalig Hea cotact fatigeFailre Code 00.22.01.3 Rollg eement (bal , rolle) crack

a

Chatr Matria ad Assmby fcts

DESCRPTONSFalre Description

Ilad o defectve trctre caracteriedby lamelar carbide de o forging at exceve temperatrewit recrytallizaton . Bl k fatge crack pal g Materialvome wit recrytallied trce are weak vol me awic pall may form prematrely Ti ball alo owincipie meltig. A pall a formed from oe of te materialdefect Blk crackig a reltedIage Descripton: (a): At image NW, materia wi lame arcabide extending o ball race (3 arrow) Sp all ad crackmarked by arrow at E edge. Te wite, keyoleaped makon race i a arifact. (b) At N center recytalized zoe(arrow) etce dark ad ow amelar carbide triatio (c)agged E b ondary o etced ectio b lk crack (label ed).amellar carbide togo t ection (arow)Sspeced Cases: Ti tool teel bal l wa forged at exceivetemperatre wic a caed icipet meting andrecrytaliatio prodcing te lamellar cabide. Spalling adbeq ent cracking occrred i n e weak trctre I cip ietmelting wa alo oberved

c

3




DATA

Plae N: 6 16Achve N: 093-0 .1 .2Image ype: ligh t metallogram, Ntal etchScalea 6 m (mcros: 20% others + 1 00% 50%)Cmpnen: 8620 steel sp ecimeSpeeLa:ucan:Faue Ce 00.07.4 Visi ble retaied asteiteFaue Ce : -Faue Ce Falue Ce

DESCRPTONSFaue Descpn: Micoscopically visible retaed asteite iexcessive amo. epedig o steel aalysis ad heat treatmet,varyig perceages of asteite are etaied after temperig. Asteiteretaied beyod specficatio sited to the applcatio casesdimesoal istability de to gradal trasformao i service. l mayicease wea ad idetatio sestivty.Image Descpn: Dark "eedles i the image are maresite. Whiteaglar patches are retaed asteite. he perceage of retaiedvb astete ca be estimated from sch images bt is sally lesstha the te percetage measrabe by ray difractio.Suspece Causes Astete retetio depeds o seel aalysis admeros heat teatmet varabes (asteitizig ime, temperare,qech coditios, temperig temperatre ad time, special coldtreatmets, etc.)

DATAPae N 6.1Achve N 099-142mage ype: light macoScalea 1 0 mm (micros: 20% others 1 00%50%Cmpnen G; P, med. hard rSpee:La:LucanFaue Ce 00.07.5.02 Heat treat crackFaue Ce -Faue Ce -Faue Ce -

DESCRPTONSFaue Descpn I thogh hadeed gears (geerallyabot 40 HRc hardess), qe chig cracks may occr as areslt of mismatched materal ad heat treatmet procedre,excessive or eve qec hig Qechg cracks are li kely toead to early tooth bedg fatige ad/or spali g

•

Faiure ode:

Faiure ode:

Image Descpn: At the side face of the gear, a crack crosses the tip o he tooth at image E. Three cracs exted to the rootfiet. From the top ad o he tooth a image W wo crosswise-directed cacks exed dow to the tooth flakSuspece Causes Mismached material ad heat treat practice, excessive qech ig, eve qechi g or qe chig i toocoldmedim may precipitate qechig cracks

4

\



Failure ode: 00.075.1

DATAPate No: 6.18Arhive No: 002-007a&cImage type: a: ligt maco, b: fractre specime macroSae bar a: 3, b 1 mm (m icos 20%, oters + 00%,50%Component: ACBB B, tool seel, rSpeed: 1 .7 MNLoad: 1 4 GPaLubriation: sytetic polyester ol 76Cailue Code 00.07 .5.1 Crack wit oxize sraceailure Code : 00.1 6.1 .1 2 Spall from sbsace efectailue Code 00.16.022 Cotact atige crackigailue Code 4 00.12.3.22 Scratc marks kiematic wearmarks i rollig saceS s PATE 1530

DESCRPTONSailue esrpton: (a: Two ajacet cracs wi oxiesraces forme, probably, i eat treatmet o te ball.Ic ipiet spall at oe crack. B l atige crack propagato.Scratc marks some probably rom separaor cotact (b:Oxiize raial eat reat crack extee by oxiie blkfatige crack Hea treat cracs are severe efects tat lea ofractre See also Plate 5.30 illstratig cack propagatio byfatige.Image esription: (a Two cracks are mare wit anarows a a arrows Smal spal at crack (bracket. Twomajorcircle scratc marks fom SW to NE. May sallowerwear marks i N polar egion. (b NW ark crescet

sape oxiie ea trea crac ( Ceral porion of cackextene iwa by fatige (nlettere arows Ts cack faceis oxize (gray "Fres esile frace was mae forexamiaio.Suspeted Causes: Te tortos pat a oxie srface ote nitial crack sggests a ea treat cac Fage spalig ancrackig extee oigial faire i rg Scrac marks aree to servce wear peraps aggravate by spal ebris.

Chater Materia ad Assemby Defects

a

b

95




DATAPlate No: 61 9Ahve No: 087-1 06& 08Image type: a ligt marco, ot acid etcedSalea a 2 mm (micros: 20% oters: + 1 00% 50%Cmpnent: BB; B, rSpeed:oad:aton:Fale Code 00.07.5 .2 Twisted (aseall crackFale Code : 0007.5.02 Heat treat cackFale Code Fale Code

DESCRPTONSFae Despn: Typical eat teat crack i a all designated

as a 'aseall crack ecase te crack ollows the patter of theseam a aseal. Te crack is wideed y ot acd etcigSc cracks reslt from excessive thermal stresses formed ieat treatment de to neven o too-rapid qenc. The cracksmay form afte hardei g, especially i temperg is delayed.mage Despn: Backgod srface is pe led fom hot acidetch sed i examiatio (a Oe oop of te crack is visile asa lack lie ( Te all is tred 90° (S to N to reveal part ofoth oops o te crack.Sspeted Cases: Qeching of trog-hadeed alls willprodce g termal stresses that are redced to acceptalelevel i temperg. Cases sch as improper material andqechat comination, eve qeching, toocold qechant ordelay etwee qec and temper may allow te stresses to

itiate a crack, wic i a al teds to assme tischaracteristc shape.

6

Faiure ode: ..

a



Faiure ode: 0008 Chater 6 Materia ad Assemby Defects

DATA

Pate No 620Achive No: 002-021 dmage ype igt metalogam, Nia-epran etcScalea 40 Jm (micros 20%, oters: 100% 50%)Component: ACBB B, tool steel unSpee: 1 5 MdNoa 0.8 GPauication: synetc polyeste oil, 1 76Calue Coe 00.08 Material structure damage,postea teatmentalue Coe 2

ailue Coe

ailue Coe 4

DESCRPTONSaiue Descption: Ti srface layer of materal sowngetci ng dierece. Assumed o be a sgn of cold plasticworking i fi nis ing Tese bals suffered early wear markingin service, wic is atributed to weakeed suface material.Finis ig of beaing ro lig srfaces for senstive aeospace applications must be free from suc surace damage wic isconducive to suace dstress.Image Descpon: tced section is moted structure in S 3/4 of image Surface is a S-poitig arow. Between 2 arrows, tin(2 m ick) sace layer etces li gte ta bulk material. Cold worked mateial sows tis poperySuspecte Causes: lapping o bearng balls, cosiderabe contact pessure and sldng are appled. f te cung aco of elappng compound is slow and e pressure too ig, e pocess degenerates nto brisig tat s, it costitues predomiantya cod rollig of te suace. e result s a damaged suace maeial laye

DATA

Pate No 6.21Achive No 002-028aIage type: ligt microgram of sectioScaeba 1 mm (micos 20%, oters 100% 50%)Componen CRB RSpee: 2.5 MdNLoa:ubicaon: synteic polyester ol ? ailue Coe 0008 Material structre damage,post-eat treatmentaue Coe 2 00222 Bul k fatige crackaue Coe aue Coe

DESCRPTONSaue Desciption: Heat-damaged srface of oil ole iniiateda atigue crac wic led o bu lk crackig of R uder i gcenrfga stress during rning Ultraig speed bearingin nerrings are a great risk of oop stress failure Oil oes arepotential souces of stress concentraio. Te bearing as faiedmage Desciption Bore of R is at image (i gt-coored area). Ol ole rus W ad connects te bore wit te ndect atroller pa to lange intersectio. (Hal o e oil ole i s visibe in t is factued rig section.) Te srface of te o ole is veryroug ad sows galled or meled metal. At arow is itiation of fatigue crack at led to ulk fractre.Suspecte Causes Oil oles i aircaft engi ne ma nsaft eaing ine rngs ae oten arddril led folowng eat treatmet (Spakeroson maciing is generaly poibited) Hard drilig wit a dl or boken dril may damage, gal and overeat te meta tusleavng residual stresses and gouges as fail ure in tiation points.

97



Faiur Atas for Hrtz Cotact Machi Emts

DATAPlte No: 6.22Achive No: 093-11 1 .5mge type: ight macro Nital etcheScle 7 mm (micros 20%, others 1 00%, 50%)Component: BB B rnSpeedod:uictoniue Code 00.08. Gining temperue Code 00.08.2 Reharee grin ig brnue Code ue Code 4 -

DESCRPTONSilue Descipton: Ginin g temper an reharene grigbrn lines o appe sace o a ball (offman linesReharene Hofma lines lea to early spallig Lies that are notreharene may ece spall ig resstance.mge Descpton: Nmeros ark greatcircle lines on the grayetche bal sace represent giing tempe witho reharenig. th e circe a the l ne ha s a white cener with ak eges Thecene s reharene.

Failure oe 00.08.1Failue oe 00.08.2

Suspected Cuses: I ball apping (an grining bals may be presse agains each othe as they travel throgh he grooves ofthe lapping plate. There s sliig in that contact. I he contact occrs ner sfficien pressre, it locally overheas creating theofma i es. Moeate overheating cases oveemperig hig her overheating cases rehaeni g

DATAPte No: 6.23

Achive No: 018627mge type: light macro hot aci etcheScle 4 mm (micos ± 20%, others + 1 00% 50%Component: ACBB IR tool steel nnSpeed:od:uctionilue Code 00.08.2 Re harene ginng brilue Code : 00.02.2 Wheel hitiue Code iue Code 4

DESCRPTONSlue Desciption: Two confine patches of gining br i the ball

tack with cacks forme ne ho etch. The locale nare of thepatches incates a whee hit. Gring brns severe enogh o crackne hot etch are l kely to case eary spalli g a/or b lk fatig ecracking. A wheel hi t asie from casig stcte amage may asofom a geometic imperection an case vibrato on nig.Imge Descption Mottle akene backgron as a resl o hot acietch I the ball groove (seco NS ban from image E two ajacentrectanglar patches of ense sface crackig shown by etchig asblack line mesh on a arker gray backgro Ths arkenig pon etchig incates he altere strctre at the grining br.Suspected Cuses: Grining bs aise in gining with too-severe parameters of spee fee, impoper wheel or coong, casigoverheang o the material so that it is local y reastenitize an im meiately sel-qech e by co metal. H igh resial esil estresses evelop from the material volme chage. These may lea to crackig rng grinig or i sevice (or pon hot etchingA wheel hit is a nitee severe griing even.

98



Faiure ode: . Chater 6 Materia ad Assemy Defects

DATA

Plae No: 6.24Achive No 001-36Image ype: light macro Nital echedScalea 2 mm (micros 20%, others: + 1 00%50%)Componen: CRB IR rnSpeed: 1 MdNoad: 1 4 GPaLicaion synthetic polyester o 1 20°CFaie Code 0008.2 Rehadened grinding brnFaie Code 0008.3 Grinding cackFaie Code

Faie Code 4

DESCRIPTONSFaie Descipion: Grinding brns containing a rehardenedstrctre and mltip e sace cracks. Gri nding cracks casesfaceinitiated failre or example, spalling or bendingfatige. Rehardened grinding brns containing alteredstcte and high stresses are sorces o early spalling.Image Descipion: At image N the dark zone is he IR roller track (labeed " raceway). T he radial plane s rface S of it is a roll ergide flange Dark radial lines (at arrows) are ginding cacks revealed by the etch. Two oblong light patches wih dark borders aregrinding brns he light area is rehardened, ntempered matensite (abeled rehadening), the da border s oveemperedoiginal matensite.Sspeced Cases Grin din g opeations sing toosevere parameers of speed, feed mproper wheel or coo ing case excessiveheating of the mateial so that it is localy e-astenitied and immedaely selfqenched by the adacen cold metal prodcingnempeed martensite. On he borders of he rehadened area heating is less, and material is overempered b no t rehardened.Stresses de to strctre changes may lead to crackng.

DATAPlae No: 625Achve No 002022Image ype: light macro section Nita etchScalea 5 mm (micros 20%, others: + 1 00% 50%)Componen: ACBB splt IR rnSpeed: 1.7 MdNLoad 14 GPaLicaion synthetic polyester oil, 1 76CFaile Code 00.08.2 Rehardened grinding brnFaile Code 00.1 6.1 2 Srace oigin spallFaile Code Faile Code 4

S s PATE 1049

DESCRPTONSFaie Descipion: Extensive spaling has reslted romrehardened grinding brn n groove A grinding brn containsmodiied stctre and hi gh resdal stresses, possibly cracksand is a sorce of ealy spalli ng fai lre. The i ntiation area o thespall shown is lined p wth the grinding brn This spall is alsoshown in Plate 1 043mage Descipion: Ct innerring pieces. A poion of he ballgoove, with a large spal, is at the image center the land is othe N hereof Matchi ng etched crcmfeential section is placed di recly S o groove. Deep gr indin g damage area nderlying spal lshows ight patches ( brn) measred 200 m deep, sr ronded by dark margins (tempe) between three arows. Spal iniiationaea n groove at , above grinding brn shows deep smooth oval exoliation

Sspeced Cases: Absve grndng cases grinding brns. A brn 200 m deep is o nsa severity. Spallingot ofrehardened grindng brn occrs de to high resdal stresses and weakness of rehardened and overtempered layers




DATAPate No:

626Archve No: 0990Image type: li gt maco of ye-peetrat tete partScaear 0 mm (mcro: 20%, other 00% 0%)Component: SG; G, igh hare rSpeed:Load:Lcation:Faile Code 0008 Griig crackFaile Code 2:

Faile Code -Faile Code 4 -

DESCRPTONSFare Description: Mltiple race crack o te tooth cotactace The crack typically form from a reharee griig brwit hig reia tree. Giig crack cae faceiitiatefalre, ch a pallig or beig atige Reharee griigbr, cotaiig atere tctre a igh tree, ae earlypallig orce.Image Descpton: The bock a ectio of a gear tooth Te

Faure ode: .

arrow N ace te tooth tip la. S of it, te wie rectagle i par o te toot flak e Smot rface wa mae iectio g. The may fokig crack o te tooth a k are h ig li ghte i wite by a peetrat ye.Sspected Cases Giig operatio ig too-evere paameter of pee fee, improper weel or coolig cae exceiveheatig o the materal o that it locally reateite a immeiately e-qeche by the ajacet col metal High reialtree evelop fom te material vome chage reltig rom trctral pae traormatio a tee may ea to crackig.

DATA

Pae No: 627Archive No 099-4Image ype: lght macoScaear mm (micro 20% other 00% 0%)Component: SG; G high hare gro, Speed:Load:Lrcation:Faile Code : 0008 Griig crackFaile Code 2: Failre Code Fare Code 4

DESCRIPTIONSFare Description: Mltiple race crack o the tootflak. The crack orm typically i a rehaee grig brwit hg eia tree Griig cack cae rfaceiitiate ailre, or example, palig or beg atige.Rearee gri ig br, wich cotai altere trctrea gh tee, are early pallig orce.Image Description: Flak (ark gray a tp la (ligt gray o evera teeth i a pr gear O the flak lightcoloe raallie ae crack igligte by a peetrat ye.Sspected Cases: Griig operatio ig too-evere parameter o pee, fee, mproper wheel or coolg cae exceiveheatig of te material o tat it i locally re-ateitize a mmeiately el-eche by the aacet co meta. Hig reialtree evelop om te material volme cage a thee may lea to crackg.



Faiure ode

Faiure ode .

Chater 6 Materia ad Assemy Defects

DATAPlate No: 628Archive No: 08-00Image tye: view

-

!

l

Scaleba 1 0 mm micro 20% othe: + 100% 0%)Comonent: DGBB; IR, 2100 teel nrnSeedLoad:Lubrication:Faiue Code 0008.4 Hydrogen embrittlemen crackng or flakingFaiure Code : -Faiure Code -Faure Code 4 -

DESCRPTONSFalure Descition: Hydrogen embrittlement crackng from improper

electroplating of bore Electroplating of hardened comp onent wthotproper hea treament thereafter diolve hydrogen in the eel, whichcreate reidal ree ffciently high to cae cracking afervarying me peri od Th i gro failre.Image Descrition Two image o ng how extenive and eraticcracking in ball groove and on ide ace. he crack have opened deto remai nin g redal tre Black pen mak at varo poi nt o the rface are not deect

!t·

Susected Causes To repair overize bore or nderie OD, electroplating (motly wih chromim can be ed. Unle poperyheat reated afterward, th method can eave diolved hydrogen in he teel, caing very high eidal tee reting nevere cracking.

DATA

Plate No: 629Achive No: 09-20-1 mage tye: SEMScalebar 4 _m micro 20%oher 1 00% 0%)Comonent: ACBB IR, black oxide coated nrnSeed:LoadLubcation:Falure Code 0008 Chemica attack dringmanfacteFalure Code :

Falure Code Falure Code 4

DESCRPTONSFailue Descrton: Micocopic pefeentialattack by back oxde face treatment on prioratenic grain bondarie Thi degree opreerential attack ihamle Other race treatmen for exampe certain phophate coating may prodce icien grain bondary atack oedce fatige retance of the aceImage Descrton: In thi high ( x 4000) magnificaton SEM, three pior atenitic gain n the hardened tee are otlined bycrving, dark 'canyon: coing N image edge, (2) NS at (3 EW in S image hal. Black oxide coat wa chemicallyemoved, leaving rated-appeaing etched ace nder he coating wih prior atenitc gran bondaie prefeenaly atackedby the oxide coating proce o form canyon.Susected Causes: Black oxide treatmen properly applied i an acceptabe rnningin aid in rolling beaing, eg. or omeaeropace e. l t ao appaenly mitigate the tendency o low EHD fim to cae ace ditre Im proper chem ical rfacetreatment can have erio degradng effect on rface ntegriy, and th contact fatige reance, by creating more evererface atack

11




DATAPate No 6.30

Arcive No 001-28Image type: ligt maroScaear 2 mm (miros 20%, oters + 100% 50%Component: CRB R opper plated nrunSpeed:oad:urcaton:Falure Code 0008.6 Coaing damageFailure Code : 000001 efet by loation in it sraeFalure Code Falure Code 4

DESCRPTONSFalure Decrpton: Copper plating on fi srfae as lfted off

(dring adesion est Uness plate aderes properly intendedanti-frettng efet is not realizedImage Decription: Cut R segment viewed on side fae Atarow peeed opper plating o n ground sde fae of ring Lig/dark radial dividing lne is an artiat.Supected Caue Proessing eror in opper pating.

DATAPlate No: 631Arcve No 08-028Image type: viewScalear 8 mm (miros: 20% oters: + 1 00%, 50%)Component: DGBB assembed unr nSpeed:

oad:urcation:Failue Code 0009 Geometry assembly or mounng defetFaiure Code : -Faiure Code Faiure Code 4

DESCRPTONSFaiure Decrpton: One missing bal omitted n assemby Abearing wit tis defet s (a vibratoy (b of esser loadarrying apaity and ( unbalaned Condition (a may beobjetionable in quiet running appliations (b wll spall n iglyoaded appliations and ( is lkely to suffer separator ailure inig speed appliations.

Image Decrpton: Te ball marked by arrow is missing. Wilete bal l regi ons protrding from separator are visibe i n te oter

Fiue ode 00.08.6Fiue ode 00.09

bals lgt sines past separaor at arrow Baane testing or suitable vibration testing an be sed fo detetion in sealed oselded bearings Manufaurers se speial magneti sensors. Supected Caue: Most ball bearings are atomatially assembed Ba lls are meered in di stribed and te separator is ten ptin pae. A ball may fail to feed and te bearing is assembled wit a missing ba uness a sensor for missing bal detetion ispresent.

2



Faiure ode: 00.09 Chater 6 Materia ad Assemby efects

DATAPlae No: 632

Achive No 031-703Image type ligh macroScalear 30 mm (mcros 20%ohers 1 00% 50%Component: SB O rSpeedLoad:Lrcationalre Code 00.091 Scorig from forcible assemblyor moig (o gall igalre Code : 000002 efec by locaio Hezcoac sraceailre Code 00092 alig from focibe assembly or moigaile Code

DESCRPTONSalre Description: Aial scmaks a roler spacig i he spherical roller pah of a SB O cased by slidig of he rollers derpressre across he O srace o he saioay bearig The marks are asperiy-scae pasic flow wih a sspic io of i cip ie gall ig.mage Descrpton: Score marks are dak aia fzzy-edged li es across boh ro lle racks The marks become m ore visible as hebearig i s The r ig racks show a diffee lser from he ceer bad, becase he bearig was peaed he fzzy faiscorg marks are probaby o gall ed he Wmos mark he N roer pah is sfficiely sharp o sgges ha is gal ed.Microscopi c eamiaio is eeded for dffeeiaioSspected Cases: Spherical roler bearigs ae assembled wih he O placed o of he plae of he ad he separaors opermi oller serio. Havg compleed rolle assembly he O is swiveled io he bearig plae aeive hadlig, lack ofbricaio or sharp roller edges ca case ecessve oller o O coac pesse prodcig he scffmarks. They may o may ocoai gall ig sreaks depedig o coac severiy.

DATA

Pate No: 6.33Archive No 0 8 1 1 3Image type meallogramScalear 40 m (micros 20%ohers + 00%, 50%Component: mealographic secio echedSpeed:Load:rcationaile Code 00.09.1 Scorig fom forcibleassembly or mog (o gal igaire Code : 00.092 al l ig from orcibleassembly o moigare Code 00195 Loca srcre damage

rom fricioal heaigaire Code -S s PLATES: 4. 8 ad 6.3 1

DESCRPTONSaile Descrpon: A ic ipie galli g eve prodced by scfig The scffed srace is goged (probably wih maerial rase. Ashallow laye beeah he scffmark was heaed o aseizig emperare ad selfqeched by he srrod ig cold seel. l echesligh Below is a bad of less heaed empered dark-echig maeral See Paes 4.8 ad 631 for oher views of assembly scorig.Image Descrpton: Meallogr aphic secio i s he S half of he image (he N haf is he pasic mo The black/ligh -gray ieaceli e is he rol ig sace showig depressed ad elevaed elemes i he scfmark de o plasc flow, wear ad possiblegallig The feareless ligh ayer (20 m deep is reaseiized self-qeched maesie The dark echig sbsae bledgio alered maeral below is over-empeed mareseSspected Cases: Scffig a sficie pressre ad speed prodces locaized plasic flow, wear ad probably gall ig , wihoverheaig of maerial leadig o he srcra chages observed. Srcre chage of his magide i s rare a assembymak. A more commo sorce of sch damage is a gridg br (C 00.08

3




DATAPae No: 6.34

Acve No: 02-262Image type viewScalea 5 mm (micros ± 20% ohers + 1 00% 50%)Componen ACBB O rnSpeed:oad:uication:Falue Code 0009.1 Scoing from forcible assembly or mo ig(o gal ig)Failue Code 2: 0012 .1 Fi srace wearFailue Code Failue Code 4 S s PATE 63

DESCRPTONSFaiue Descpton: Aial scoremarks o he O of he oerrig.Marking o he ee show here is de o mild wear ad s geeallyharmless Moe severe scoing may represen gallg (FC 00.3 andmay lead o sbseqe cracking (FC 0022).Image Desciption The scoremaks are hi aial lies wih lserdifere from ha of he d isrbed O s rface They are disribedaod he crcmferece of he ring O Whe eamied dermagficao, he gridg lines are ierped by he marks. Themaks show o maerial rasfer (as dsinc from gall ed scoremarkswhich do).Suspected Causes Assembly ino a hosig, eiher wiho adeqaecore break or wih ecessvely igh fi ad/or rogh srface.Assembly i he presece o solid coamia i he fi.

DATAPlate No: 635Acive No: 002-023dImage type: SEMScalea 1 mm (mcros ± 20%, ohers: + 1 00% 50%)Component ACBB B, oo seel, rSpeed: 1 MdNLoad: 4 PaLucation: syheic poyeser oil 16°CFailue Code 00.09.1 Scoing from foricible assembly ormong (o gall ig)Failue Code 2: 00.1 6.1 22 Shalow ery spall from sacelinedefec

Failue Code Failue Code 4

DESCRPTONSFaiue Desciption: Several goges presmably from bearig

Fure ode 00091

assembly have damaged he ball sface ad iiiaed a spall. The goges are idenaios ad no wear marks, ad have damagedhe maeial o significan deph as show by radia cracks i he spall. The ball has failedImage Descpion Backgrond is ball sface wih varyig gray he de o vewig agle change A remainig ends ofcrossing indeaions made by edges of maing pars. Irreglar spal craer indicaes mliple iniaions from hese icks. Sacecracks eed he spall a N ad W sdes A radal crack face is bewee opposing arrowsSuspeced Causes: Indenaion of ball sace by oicibe assembly, sch as io he pocke of "snaphrogh separaor designor ieferece wih a ring edge, can case saic crackg (especialy i cracksesiive oo seel) i addiion o iaing spallig

4



Faure ode 00092

DAA

Pate No: 6.36rchve No: 093-015&1 6Image ype: a view; b: ligh macoScalear a 25 b 3 mm (micos 20%ohes 100% 50%Componen: CB nSpee:Loa:Lurcationailure Coe 00092 alling fom ocible assembyo moningalure Coe 0009. Scoing fom ocible assembyo moning (no gallngaiure Coe ailure Coe 4

DESCRPONSailure escripon Two aia scoe (wea maksand adacen o one a gall ng seak on I olle pahfom slding o olle ove I dng assembly wihooling nde hgh conac load. A olling pah wih agalled scoe mak fom assembly fals ealy in spallngo om addional gallin g ding opeaon.Image esciption (a olle pah showingccmfeenial nni ng ack acoss he conac widh.One l ong dak saigh scoe (wea mak a imagecene Anohe shoe mak js W of he l ighngchange fom bigh o gay. (b: Cene mak enlagedak nfom line is a scoe (wea mak; dakpiedoblong island wih whie bode in image cene a Eedge of dak mak is maeial ansfeed in gallingSuspecte Causes: Caeess inseon o CB inneingwhich s mo ned on a shaf no O/ole assemblywhich s moned in a hosing especially when ooweigh loads olles. This is a common soce o aialscoemaks wih o wiho gallin g

'

Chater 6 Materia ad Assemby Defects

a

�

. I

l

j

I

j

I

05



Faiure Atas for Hertz Cotact Mahie Eemets

DATA

ae N 6.37Archve N: 02-28Image type clor macro [SEE IMAE IN APPENIX.]Scae bar 20 mm m icos ± 20% ohers + 00% 50%Cmpnent BB assembly, rnSpeed: 180 KdNad: 3 Paubricatn syheic g ease, 60°Caiure Cde 00092 all in g from forcible assembly o mongaiure Cde : 00.131 Fi srace gall ingaiure Cde 001 51 1 eneralized reig, radial fi srfaceaure Cde 4 S s PATE 6.34

DESCRPTONS

Faiure ode 00092Faiure ode: 00093

[ mg App]

aure Descriptin: Aial gall ing sreaks i IR bore rom ocble assembly. Freig corrosion in bore ding nni g a llng inboe may lead o bk crackg of rin g d rig cyclc sressi g de h gh hoo p esile sress from gh neeferece fi. Freing ohe ee shown is no a failreImage Descriptn: Narow brigh aia bads of gall in g mea rasfer beween bearin g b oe and s haf arrows. Brow, sreakyfreing coosio bore highighing waviess 'chaer o shaf or i ingSuspected Causes: al lig sreaks resl from h igh inererece beween R bore and sh a sea comb ned wih r ogh s haf srfaceor a sharp edge a he leadi o he sea, over which he bearig was pressed in assemby reig is o ncommon i IR boresnder roaig load

DATAPlate N: 638Archve N: 01 8-1 0mage type: viewScaeba 20 mm micros 20% ohers + 1 00% 50%Cmpnent: SRB OR&R &R, monedSpeed:ad:ubicatin:Falure Cde 00093 Cracking fracre rom forcible assemblyor monigalure Cde 00091 Scorig from focible assembly or moningo gal ingalure Cde Falure Cde 4

DESCRPTIONSalure Descriptin Chipped side flange o R om hammer blowdrig moning Aal scoemaks in OR roe pah ad on roller

O rom relaive aial moion o saioay bearg ding moingThe bearng is sablemage Descrptin: OR a image N, sanding o I R. Rollers ear Simage edge. ak aial lines on far side o OR roler pah, a rolerspacig are scoremarks Aial scoemaks mosy lgh-colored onroler Os R side flange facing image N severely chipped ear ringcenerlneSuspected Causes: Assembly of bearig sig hamme blows oroher heavy impac especialy i f applied o fage edge, are lk ely ofracre he pa The scoremarks aise from hamm er bowsransmied hrogh rolli g coacs in he saioary beaing

06



Faire ode 00.093 Chater 6 Materia ad Assemby efects

DATAPae N: 639Achive N: 018203mage ype viewScalea 10 mm (micros: 20%ohers + 1 00% 50%Cmpnen NRG OR (drawn cp moed rSpeed:ad:catin:aile Cde 0009.3 Cracking (fracre fromfocible assembly or moigaie Cde : 00.12.3.21 Wear rack ceeredin conacaie Cde -aie Cde 4

DESCRPTONSale Desciptin: Moning damage fromdefecive ool shape cased oe foldedover edflage o break of by circmferenial crackng . (he oher end fage broke in dismoig Rn g racks are visible i hecoac pahs showing he bearing was (brefy rn b is o serviceable owImage Desciptn: Cylidical OR (drawn cp i image ceer. Two broke-of end-flages SW and SE. Separaion of flangesalog circ mferenial crack (smooh o SW flage jagged on SE lage Poished r olle pahs from wo rows of eedle rolle rs incp boeSspected Cases Closed-ed needle ol ler cp ms be mo uned sing a piloed ool wih a backangled flange which bears nearO o end-lange wen pessing he cp ino o sing . The ool sed her e had a forwad angle and pressed agais he borediameer of he ed-flange. Bendig sresses o he flange were ecessive and i cracked aond he O ads.

07



MILD WEAR 7Failure Code 0012

. efnonWear of a contact comonent) s deined as the removal of comonent surface materia in the

form of loose artcles y the alication of hgh tractve forces n aserity dmensons duringservice It s distngushed from:

Surface distress FC 007), defned as surface material astc low and mcroittng y theacation of hgh normal forces in asperity dmensions

Galling severe wear) FC 0013) defned as remova of surface matera n the form of materiatransfer to dstant surface areas y the aicaton of tractive forces in multi-asperity dimensons

Fretting wear FC 005), defned as removal of surface matera, often wth oxidation of ders,as a resut of mcroscoc surfacearael relative movement of surfaces in nominally staticcontact under norma load

. omencatureMild wear is generaly designated n ndustry as just 'wear Often, a distction s made etween

adhesive or twobody) and abrasive or threebody) wear, wth the former taking lace n the asenceof extraneous soid articles n the interface, and the atter caused y such articles

Occasonaly the term wear s used loosely to desgnate all modes of surface materal removal,ncluding the other modes isted in Secton 7 n the Atas, wear always desgnates md wear, utincludes two- or three-ody wear

In some gear faure literature [9, 10], the term adhesive wear s used to denote galling FC 00. 3) n this Atlas, that use s consistently avoded

. Faure rocessSeveral theores exst to descre the mcro-scale mechanism of wear artcle formaton mild

wear For the Atlas, it sufces to defne the macroscoic circumstances causng mld wear If 1) twosold surfaces are n contact under norma load .e., not fuly searated y an ntervening luidflm), 2) slidng takes ace etween the surfaces, and 3) the normal ressure and the sliding veocityn comination are ess severe than the threshod condton for galingthen, under the condtonsand for the materals used n Hert contact machine elements, remova of oose artcles of aseritydmensons may take lace from one or oth surfaces t is assumed that the tractve forces oeratngetween aserties sidng over each other are the cause of the artce removal A wear rate is

associated with the wear rocess; the rate is hgher for more severe stress conditions, and usualyhigher for less wear resstant materals, rougher surfaces, and hgher frcton coeicients The wearrate may e seedndeendent under conditions where temeratre and luricaton arameters donot change with seed

Nonero wear rates vary over many orders of magntude for realistc oeratng contacts For owenough severty of the contact esecialy for low sde roll veocty ratios andI or low tractivestresses) the wear rate may e ero as oserved on a macroscale) throughout the entre ife of thecontact, or may "run in to ero after an ntal erod durng whch the surfaces ecome smootherthrough wear

Boundary lubrication, defined as the rovison, n the interface, of lowshear strength soid fimsncluding some oxides of the surface materia) or adsored luid fms, generaly reduces oth wearand the fricton coecent, ut the two effects are generaly not functionally reated.

09




0

Soid paties on dignad ontaminants or debis prnt in th onat intra ithr roxranou our or a a rut o th war pro it odiy th war pro into h variantdignatd thr-body war

istinctive ppearanceWar ay b idntiid orphoogiay ro h orphoogy o a worn ura or ro h

apparan o oo 'war pari in or nar th onta or n th ubrian. Th apparan owar pari i dribd undr FC 1 and FC 12 (Lubriant Faiur)

In onat oponn a worn ura an hav vra dint apparan dpnding on hondition o th war pro Thy ar dribd bow In dirntia diagnoi o war i iriia o obrv tha th haratriti apparan o th othr atria rova oduraditr (FC 007) gaing (FC 003) or rttng (FC 0015)i not prnt.

Smooth Wear. Whn ooh war i advand thn th worn ura undr ow or no agation appar aur a and nondirtiona. Th harariti inihng ar o a-anuaturd ura hav bn worn away

In h tia tag o ooh war hng ar ar graduay abatd and th at wornura i inrprd wih rnan o th (dpr) inihing ar

Th matte aur ura o a worn oponn ut b diinguihd ro h bunished i.goy aur ura o a 'gazd ura-dird oponnt (FC 007)

Undr th iroop prraby th aning ron iroop a oothy worn urahow a pbby apparan whh undr high agniation rov ino rando-ngth hortrath n h iding dirtion

Sooh war i o oony obrvd in th prn o ne hard ontainant parti(inuding oxid parti ro th ura)

Charariti pii to h ooh war o baring and gar:In beaings igh ooth war aon or in obination wih ight ura gazing (FC 00.17)

produ viib ontat pah whih ditinguih a ura wpt ovr by Hrt ontat roadjan ura outid th ontat Th diintion i on o hangd utr and ay rquirxprinaion wih ighting dirtion to b rvad Contat path hap and poition ar priindiator o oad diribution piay in ba baring

In geas th axiay od rativ poition o hng ura produ vra typ o oothwar (i. war wihout individua viib war rath) whih ay vary ro point to point inth onta

Poishing and smooth tooth wea ar inraing dgr o unior war o th tooh proi horo h vrity hat rndr th garing unrviab

Destutive tooth wea ay b wo-body or hr-body war and in diribution ay b orunom; wavy wih wav rt ruing atray aro th ontat widh; bumpy wih atingaroopi h and vay aro th onta; orowing wih narrow hort radia urrowutrd in axia band roing nihing in

Kiematic Wear Marks Th war pro i pripiad by iding in th ontat Thror anapriy on on ura or an abraiv pari ibddd in on ura trav a prribd inaipath ovr th onaing ura Th pro bgin whn th aprity (pari) nr th onatand nd whn i xi (Earir i th apriy bra o or h parti hatr) Th ra o hapriy on h oppoi ura an otn b n a a rath dignatd a kinemati wea mak.Suh ar hav ditniv gori dpnding on th inai o h ahin n andh oation o th aprity in th onta ara



Chater 7: Mid Wear

In roer aring wih cyindrica neede or tapered rolr

Mar on roing urfac ar circufrnial crach Such ar may ari in h Hrz conacor h conac wn rolr and paraor poc In a Hrz conac a fw dgr angldviaion ay xi if h rolr ha wd Th lngh of h crach i gnrally hor if iari in a Hrzian conac inc h apriy i rold ou of conac (un h rollr idddScrach fro a paraor conac ay run h nir circufrnc of a rolr.

Mar on flang or rolrnd urfac ar picycoidal arc if hy ari in rolr o fangconac On rolrnd urfac concnric circular arc ari rolr o paraor poc conac

In roer aring wih spherica rolr h ar ar iiar o ho in ohr rollr aring uh ngh of crach ariing fro Hrzian conac vari wih poiion A wo axial poiionwhr iding i zro ('Hahco and h crach ngh i nar zro and progrivy incraa h locaion ov away fro h Hahco and

n ba aring

Mar ariing in h Hrzian conac ar paraoic arc for whch h apc raio and orinaondpnd on ocaion raiv o h onary pin po of h all. Th paraoa i concav aviwd fro h pin pol

Mar on al ariing fro a paraor conac ar concnric circular arc

n gears inaic war ar ay produc a yp of unvn war dignad a ridging Thirgory i drind y h inaic of h ooh h nay:

• In spur gar ar folow a gar ooh profil in

In heica gar beve and hypoid gar ar folow h loca liding dircion

Mar on cams wih roing foowers ar iilar o ho in cyindrica ror aring u idingay conidral and accordingly ar ay long Mar on cam and tappet conac inwhich h app pin around i ongiudina axi ar paraolic arc

Ste Wo I Whn war occur in a conac oundd y dg (in conac xnd o hdg and i uanial hn a diconinuiy in h profi ay appar a h conac dg and idignad a step

Pittig Wear Pi can for during war of a urfac if:

Wa arial volu (oly incuion or arg carid ar prn a or nar h urfacAlaion of h urfac y war ay xpo h wa vou o raciv forc and arh ou aving a pi ( alo FC 0003)

Microporoiy xi in h arial ju low h urfac which ay opnd o h urfacy war o for pi

Th war pi diffr fro

Spas FC 00.16), y h urfac characr of h crar which in pi i not a fracur urfac.Th apparanc of a pi i dcrid undr FC 0003

Corrosion pits FC 0020) which how an oxidizd urfac Eectric erosion pits FC 00.2) whch how a oln urfac




2

75 auses

The oon aue of ld wea ae Exeve ldng n he onta Exeve ufae oughe Inuffen boday ubaton nuffen EHD ubaton Inuffen wea etane of ateal due o low hadne, wong tutue o wong ateal

obnaton n he onat In ea o eet bnde defe ontbute to low wea eane

Chealy aggeve envonent (lubant o aophee) Contanaton by od (thee-body wea) The peene of wea atea voue nea the ufae (pttng wea).

Causes of Mid Wear Secic to Roig Bearig Cotact Comoets

In olng ontat

Edge ontat due o geoety eo Exeve ewg of oe Exeve pn of bal Exeve epaato fon Exeve angula aeeaton, epeay at oad zone entane.

In rollerend to nge ontat:

Edge onat due to geoey eo Exeve noa te due o axal load o oe ewng Exeve lding veoy due to geoety eo

In Hertz contct element o seprtor ontat:

Edge onta due to geoey eo Exeve epaao foe n ontat wth uppot eleent Inuffent epaao leaane to ontat eleen.

Causes of Mid Wear Secific to Cams Ca and a followe o tappet uffe the genealaue of ld wea ed above f thee, they ae patulaly vulneable to the followng

Sliding Ca d olng foowe ye undego hgh angula aeleaton one evey ylea he a and followe ae ontat a the tat of the ft phae. Ca and appe yte

opeae wh ontnung elaive pn Edge contct. Rollng a folowe ae dffult o antan n pee algent and edge elef

dffut to povde Tappet wea ay elnae edge eaane. Contmintion Ca ye ae ofen ubated fo genea uang ol yte whh

ay obuton podut (n ntena obuon engne) and wea podut. Rough surfces Cahaft ofen ae age oponen a geoety oplex and ahney

fo a fnhng ay not pe a good a fnih a n ale, pe oponent

Causes of Mid Wear Sec to Gears

Initil er (ung-n) an expeted phenoenon n any gea ye, due to foed ldngof teeth a all oaton away fo the pthlne, and ltaon to ufae finihng poedby he opex ooh hape, epealy n edu-had hobbed gea



Chater 7: Mid Wear

Cntinung wea damages the geometry and fis of the teeth. It is often abrasive, tat is, it

brings on three-body wear by contamination with extraneous hard particles or wear debris. Tw-dy mild wear (not to be confused with the gaing designated as adesive wear in [8, 9])may occur due to te several general wear causes listed earier, such as roug surfaces, insufficientwear resistance of (one or both) gears, inadequate lubrication, and misaigment leading toedge oad.

Note: Gear sets are caracterized by te lateraly locked relationsip between contacting surfaces, leadingto a tendency for wear to become locaied (wavy, bumpy, ridged).

6 ffcs o Md WarMid wear has damaging effects on contact components, if it is not self-imited (run-in). The

damage occurs primariy through the folowing mechasms:Material removal distorts component geometry As a result, surface pressures are often redistrib

uted unfavoraby. In addition, geometric reationsips tat infuence machine accuracy, backlash,quietness and so on, may be impaired.

Surface fish is modified, wich may either improve or destroy as-made surface crogeometry.If materia removal is substantial, buk strengt of components (gears) may be impaired. Finally,components which ave been surface-treated for wear-, fatigue-, galing- or corosion-resistance, orfor solid lubrication, may lose some or all of these ayers.

113





Failure Code Pate No. Faiure Coe Pate No.

001201 8 1 0012322 1 7

2 6 2 1

001 202 7 1 228

7 1 6 6 1

7 1 7 8 1

7 1 9 00 2323 6 0

723 72

725 722

728 731

1 0 733

1 040 734

052 738

1 066 1 3 6 2 3 1 3 8

0 0 1 2 6341 3 3

0 0 1 2 2 5360012324 037

2300 232 9 8 1220

820001233 741

00 23201 2001 233 728

00 23202 0600012332 74

00 23204 7.7 7 7

001 23205 1 047 728

1 3 020

00123206 82 0 6 1

4 3001 2320 7 7 0 0024 78

1 3 7 1 6 2 8 720

00 232 5 8 02

722 0 1 7

87 065

62 36

8 7 44

00 1 2 3 2 63948

1 4 726

166727

162589

9 1 5 0025 1223

1065 00125 10 25 8 1 1 5 6

00 23 2 1 2 8 1 001 252 7.34

00 232 4 3 3 1 0 9

538 022

0012322 4 0 1

6 8 001 253 1 027

7.5 00125 3 737730 8 78 1 0

8 0026 5 5

055 00 27 7 9

4



Faie ode: 001211Faie ode: 00.12.1.2

Chatr 7 Mid War

PSDATAPlate N: 71Arhive N: 093-020Image type: viewSaebar 30 mm (micros 20% ohers + 1 00% 50%)mpnent SRB IR, rnSpeedLad:Lubriatin:Faure de 00.1 21 .1 Fi srface polishi ngFaiure de -Faure de Falure de 4

DESCRIPTONSFalure Desriptin: R bore highly polished by roaion n oose finder roaing load Sch roaion can lead o galling andsbseqen crackng, or o progessve wear. Noise (sqealing) salso possbleImage Desriptin: he I R bore s race is brnished o mirror nish G rindin g l ines are largely oblieaed.Suspeted auses Radial load o roaing diecion wih respec o he innerring ('roaing load) cases relaive roaion o ringand shaf if he fi inererence is nsfficien. Microscopic relaive moon cases freng; more rapid moion prodces polishing orwear n moe severe cases ( highe r load oghe r srface highe r speed and poor l bricaion), i prodces galng

DATAPae N 7.2Arhive N 014-60Image type: a, b: viewSae bar a, b 40 mm (micros: 20%ohers + 1 00% 50%)mpnent: RB, IR assembly, rnSpeed:ad:Lubrian:Faiure de 001 2.1 2 Advanced mild wearof fi sraceFaiure de : Faure de -Faure de 4

DESCRIPTIONS

Faure Desriptin: (a): A groove s worn in helarge sideace of an R (cone). (b) Circmfeenialmarks are worn in he bore of a cone. Progressionof sideface wear leads o ecessive aial loo senessof bearing assembly Progression of bore wearaggravaes spi nni ng of cone on shaf and evenally may lead o gall ng and racre or seize.Image Desrpin: (a) Large sid eface of a TRB IR (cone) wh a cic lar groove worn hogh he leeing. The es of hesiderack s smoohly worn. (b) Several circ mferenial grooves (dark circles) and sm ooh wear in he bore of a coneSuspeed auses When he radia load roaes wih respec o he IR, an inerfeence fi beween bore and sha is reqired opreven epicyclc roaion of he ring on he shaf. The inerference ms be hi ghe r for high er load. If i is insfficien, he rin groaes and wears in he bore . In a TRB, an aial lo ad componen always eiss and cases wea of he large sideface agains hesppor shol der when he IR roaes on he sha.

11





Faiure ode: 002322Faiure ode: 00232Faiure ode: 002323

Plate No 7 continued

Imag ():

Failr Cod 001 232. 1 .2 Wear ack of-ceer coacFailr Cod : 0012.32.0.6 Wear rack for combiedadial/aial load

Failr Dcription: Roll g rack whe ormal magide aialload is combied wih ormal magide radia load roagover he R RBB oad zoes o dffere agles (c 0 ioe rack occr fo combi ed loadImag Dcription: Wear marks (polishig or scaches) i ballpahs away from boh edges. For siglerow gearigs he ORrack is cofied o a oad zoe ragi g rom 1 80° o less ha360° i circmfeece he IR rack eeds hrogh 360° Fordo ble-ow bearigs OR rack may be less ha 1 80° i oe

row

g

Imag (g):Falr Cod 001 232 1 1 Wear rack ceered i coacFailr Cod : 001 232 04 Wea rack for oofrodig

Failr Dcpion: Rolig rack i a o-of-rod OR.Imag Dcription: Wear marks (polishig o scraches i ballpahs away from boh edges The OR rack s cofied o woopposie oad zoes of less ha 1 80° each i c rcmfereceThe R ack eeds over 360° If radial load roaig agaishe ier rig s adde d he oe of he wo load zoes wil bewider.

Chater : Mid Wear

f

Imag f:Failr Cod 001 2.3. 21 .1 Wea ack ceeed i coacFailr Cod : 001 2.3.2 0.3 Wear rack for radia preload

Fail Dcription Rol ig rack for ormal magide radiaload oaig over ierig wih radial preload rom egaveieral looseess wider o he radial load acio sideieded radial preload may case overheaig ad earlyspalg (FC 00.1 9 ad FC 0016Imag Dcription: Wear marks (polish ig o r scraches ballpahs away from boh edges oad zoe o boh rigs isceered o IR is iform arod 360° o OR is > 1 80°wider o he radial load acio side.

Imag ()Far Cod 00.1 232. 1 .3 Wear rack shifs i coacFair Cod : 0012320.7 Wear rack or misaligedierrig

Failr Dcripton: Rollig rack for a misaliged ORImag Dcripon: Wear marks (poishig or scraches i balpahs The OR rack is coied o wo opposie load zoes ofless ha 180° each i circmfeece aially oceer iopposie di recios. Te edge of oe or boh load zoes mayreach he groove edge IR load rack eeds iformly hogh360° ad i s wder ha O R load oes f radial load roaigagais he ie rrig is added he oe of he wo load zoeswill be wide





Failure ode: 00.12.3.21Failure ode: 00.12.3.2.1.1

Chater 7 Mid Wear

DATAPlate No:

Achve No 0931213Image type SEMScaleba 30 m (mcros: 20%, oers +00% 50%Compoet BB I oed rSpeed: 450 KdNoad: 35 Paubicatio: mieral (rbie oil 1 ailue Code 0012.321 Smoo rollig srface wear(fis maks removedaiue Code : 00.1 8.1 .4 M iple ireglar deig from fieoose ard debrisaiue Code 00.12.3.22 Scrac marks kiemaic wear marks rolig sraceaiue Code 4

DESCRPTONSalue Desciptio: Uiform mild wear o rollig sace wimlple very small odirecioal des om fie solidcoamia. Few log scracmarks rom slidig. Al isig marksare obleraed by geeral ablaio of e sface ("sadbasedmic ro-appeaace A ew srface disress mi crospalls (FC 001 7may be prese Miimal wear may permi log life (wi progressively impaired saf sppor accacyIage Desciptio: Te mage backg rod is a eael ess gray srace covered wi very e (2 0 m dia sm oo-boomeddes Some dark-boomed craes probably microspalls from srace disress. Oe log EW wear scrac a A Oers ailyvisible esewere No fiisig lies visible.Suspected Causes Operao i lbrica carryig very e solid coamia cases iform sow wear. I pre rollig, debriscase mliple des Wi e small slidg compoe eisig i BB wear also occrs. Idividal wear eves are odiscerible (ecep few scraces sc as a A Te E ilm was ic k eog o peve geeraized srface disess.

DATAPlate No: 6Achve No: 005-12Image type: lig macroScaleba 5 mm (mcros 20%, oers 1 00% 50%Compoet: C CM (carbized rSpeedoad: 2 Paubicato: iese fel ? aiue Code 00.123.21 Wear rack ceered i coacaiue Code aue Code

aue Code4

-DESCRPTONSalue Descpto Wear marks a ed o e ramp pa of a cam lobe fromsidg bewee cam ad folower. I wea becomes ecessive gallig or spallgaile may follow or cam geo mey is losImage Descpto Secioed cam s viewed from O escedig ramp(bewee arrows s S image al. O ramp circmereial, lig-coloed wearmarks. Wear marks ae deses ear e ei po of e (desc edig ramp.Suspected Causes: Pressre bewee cam ad followe vares sarply by agl arposio, peakig o ascedig ramp ad droppig o zero alog descedigramp. Fricio o pi reards folower. We coac presse o lobe sisfice o provide ecessary drivg force, slip occrs wic may esl

·

-

-

-

.

.

l

l

1

l

.�

i wear.

. .

J

11




DATAPlate No: 7 Achive No: 934mage ype: view wih mirror mageScaleba 3 mm ( micros 2%,ohers 1%, 5%)Compoet: SRB OR, rSpeed:oad:bcatioaie Code .1 23.2. 1 .1 Wear ack cenered in coacaile Code : 1 23.2. 4 Wea ack for o-of-rond ri ngaile Code 21 .6 Hosig deformedaile Code 4

DESCRPTONSaie Descpto: Bearing shows wo diameally opposie loadoes i boh oller racks i ndi caig o-of-rond codiio ohosi ng The codiio cases parasic overloadng ad may ead oearly spallig and ho opeaion

Faiure ode 00.12.3.211

Image Descipo In his image, he W haf of he roler pah is see i direc view and is E hal in a mirror paced behid herig boh haves li gh-colored coac racks show a oad oe in boh rol ler pahs The wo ses of oad oes are 8 aparindcaing o of rondnessSspected Cases: O of rondness s ikely i he hosig (o o rondness of his magni de n he rig proper is a raeoccrrence). The hosig deflecs he oerring elasicaly casing redcio i adial looseess aong one direcion reslig iparasiic radial loading.

DATAPlate No: 78Achive No: 3- 2mage type: viewScale ba 2 mm ( micros 2%ohers 1% 5%)Compoet: SRB R, rSpeed: 25 KdNoad 4 Pabcatio: mea oil 1 2°Cale Code 2.321 .1 Wearrack ceered conacale Code 1 2.4 Wear ofgidng-componen sppo sraceaile Code 8. 12 Sharpidivdal de(s) from meal debris, asperiiesale Code 4 1 1 2 Waer i oil

DESCRPTONSaile Desciptio: Boh oller racks eensivey wor Sod conaminan abrasion probable Separaor sppo srface won insliding conac i he presece of coamian. Some ocal denig of roller rack by coamian paricesImage Desciptio: Boh roller racks show dark, mae slighly pebbled srface from abrasive wear. Ceer flage sppoigseparaor is brnished ad circmferenally scrached by abrasive wear Roller rack in S image hal shows a de near is cener,from a large coamia paicle ark discoloraio of roler pahs ad side langes sggess waer in he oilSspected Cases: hs bearig operaed in a conamiaed and possibly we evironmen. Th e solid coamian precipiaedab rasive wear waer in he oil conribed o he dark discoloraio of rolling srfaces ad side flanges. Oil carboiaion may alsoake place a high emperare.

120



Faiure de: 00.123.2.1.3 Chater 7: Mild Wear

DATAPlat N: 9Ahiv N: 08-036Imag typ vewSaba 20 mm (mcr os ± 20%ohers: +100% 50%Cmpt: BB; I rSpd:ad:ubiat:au Cd 001 232.1 3 Wear rackshfs n coacalu Cd 00090 eomery defecailu Cd ailu Cd 4

DESCRPTONSau Dsipti: Ball rack n he groove o hs weaves aerally. Effecve conac angle vares arond crcmferencecasg cyclc bal orbal speed varao resng n hg h separaor sresses Nosy operaon ad early separaor alre are l kelyImag Dspt: he black ode coaed rg shows a (brgh) wavy wear bad n he groove hal locaed S of he mage ceerSusptd Causs: soon rom relaao of sresses or poor furg drg manacre may case crcmferea wavess he ball groove. I ereme hs may lead o observable conac ange varably as hs case

DATAPat N: .10Ahiv N 014-35Imag typ: lgh macroSalba 20 mm (mcros: 20%ohers + 1 00% 50%

Cmpt: TB O rnSpd:ad:ubiati:ailu Cd 00.1 232 1 .3 Wear rackshfs conacailu Cd 00.12.3.20. Wear rackfor msalgned oerrngaiu Cd 00201 .3 Conac corrosoaiu Cd 4 00202 Corroso pg

DESCRPTIONSalu Dspti Laerally shfg coac paern n msalged oerrng ragg rom o conac a he large roller ed o ocoac a he smal end. Aa sreaks of coac corroso. Msal gn me prodces sero s edge load g a roler ends and maycase early spalg Hgh racve orces ac o he separaor from roler orbal speed varaons and may case fracre ncdenalcorrosonImag Dsipt The conac pah of he rollers on he O appears darker gray han he -conaced rack. The coaccocenraes a he small roller ed (a mage W) ad shs o he large roler end a he mage cener ad E arker aal sreaksn he coac area ndcae coac corroso. 1/4 mage wdh rom W edge are wo clsers of corroson ps.Susptd Causs: The shfng coac pah dcaes a msalgned nerrng de o machne geomey error or msmonng ofrg n ho sn g. Conac corroso may arse from waer n he lbrca (see FC 00201 3

121




DATA

Plate No: 71Achive No: 087-035Image type: viewScaleba 30 mm (micos 20%,ohes + 100% 50%Compoet: BB R nSpeedoad:ubicato:aue Code 001 2321 4 Wea ack a conac edgeaue Code : 00090 eomey deecalue Code ailue Code 4

DESCRPTONS

Faure de: 001314Faure de: 0013.

aiue Descpo: Naow wea bads nea boh edges of he ball pah de o msmach o ball and goove pofle adis andgoove pofile eo The beaing had o appeciable load caying capaciyImage Descptio Black oide coaed ineig shows wo naow whie wea bads nea b no a boh goove edges (inboadof aowsSuspected Causes: Mismach beween goove pofie adis and bal damee (confomiy <50% bal ads eceeded goovepofie adis cased wopoin conac ea goove edges. Since coacs ae no pecisely a he edges goove pofe ms beocicla (wideed a he edges

DATAPate No: 7.12Achive No: 018302mage type: ligh micogam (composieScaleba 400 m (micos ± 20% ohes + 1 00% 50%

Compoet: ACBB IR ool seel nSpeed: 1 .25 MdNoad: 22 Paubcatio: syheic poyese oi l 1 50°Cailue Code 00.1 2.322 Scach maks kinemaic wea maks in olli ng s faceaiue Code : 00.12.0.2 Abasve mild wea

aiue Code 001 7.1 .2 Micospal lig (advaced s ace disessaiue Code 4 00.03.4 Lappig i mpefeco

DESCRIPTONSaue Descipto: Ball ack maked by a dense pae of kinemaic wea maksfom spinig bal wih podig cabdes podces naccepable shoeig offaige lifeImage Desciptio: his composie image of IR ball pah shows swi pae osho kiemaic wea maks ning NE o SW a image N N o S cene, and NWo SE a mage S Back iegla spos may be micospalls of incipien sacedisess Rolling diecon is o W. Unwon goove aeas a N ad S image edgesshow EW ishng maksSuspeced Causes: he bals wee obseved o have had cabdes podig abo1 m above sface pesmably as a esl of difeenial sock emoval n appinghe ool seel maeial. The cabides peeae he (mch he EH i lm andscach he ing sace A fiis hing pocess leavig podig ca bdes isnaccepable.

122



Faiue oe 00.12.32.2 Chapter 7: Mild Wear

DATAPlate No .13Archive No 093-121 .8Image type: SEMScalebar 35 m (micros 20%,ohers 100% 50%Compoet: BB , hoed, operaedSpeed 450 dNoad: 33 Paubricao: syheic polyeser oi 38°Caure Code 00123.2.2 Scrach makskinemaic wear marks rollig sraceailure Code : 001 . 2 Microspa l ing(advaced s race di sressailure Code

ailure Code

DESCRIPTONSalure Descriptio: Mi d wear eves in aspery dimensi onscase shor scrach marks on he coac sace which racehe relaive moion of he conacing sace In a BB whcrved conac ierace all moion has a spin componen amos poins and he kiemaic marks ae fngerail orhorseshoe shaped paraolas Srface disress micros pali g is also presen The damage promoes spaling and (if wearpogresses impairs pecisio.Image Descriptio: Origa ni shing li es n saigh E-W. They are covered wih layers of generally EW oreed crvedfigerail maks conve om aove: he kinemaic wear marks. A rece sharp mak is a , a pay wor-of mark a AMicropalls ie smal dark craers wh fracre sace ooms ad a whie rm ('halo are scaeed o he srface. Eamplea C.Suspected Causes: iemaic wear marks occr in he presence of sli din g (spi in addiio o roll ig nde EH film condii os

isfficien o preven aspery conac. m amos of fie soli d coamna em edded in oe of he coac sraces mayprodce ki emac wea marks y acing as a emporary asperiy. Sace disress is aspeiy scale conac faig e (FC 00 1 )

DATAPate No: . 14Archive No 0149mage ype viewScalebar 20 mm (micros: + 20%,ohers + 00% 50%)Compoet: TB al componens rnSpeed:oadubrcatioailure Code 00.12.32.2 Scrach markskinemaic wear marks i oig saceailure Code : 00.1 8.22 oled-in lie insi de conacailure Code 01 1 3 Separao weaailure Code 1 2.5 Seel coamian i grease

DESCRPTONSaiure Descriptio: Seel conaminaion i he lrican carried y he sepaaor cased circmfereia wear marks i he rollersolle rs ranserred rolledin li nes o he rig roller racks Addiional coamina wore circmferenial l ines o he sepaaor O. Aearing his severely wor has los precisio, is nosy and may soon seze whe he wor sepaaor jams eween rolles and ringIage Descripo Circ mereal scraches o separaor ar O and rol ler O. oll ed i n li nes o he ro ler racks of oh rigsSuspeced Causes See coaminan was fond i he grease, iiaig he wear process. The coaminan m ay arise fomconaminaed assemly conaminaed hosig or he wea of movig pars, oher ha he earing in he same chamer



Failure Atlas for Hert Contact Machine Elements

DATA

Pat No: 715Achv No: 44Imag typ: clor microgram [SEE IMAGE IN APPENDIX]Scaba 2 m (micros ± 2%, others %, 5%)Compot: BB R, tool steel soid tue coatSpd 84 KdNoad:ubicato: GAInWSe urnised film <315°aiu Cod 12322 Scratc marks, kinemac wearmarks n roling suracealu Cod : 1 3 Soi or gas l uricant ailu realu Cod alu Cod 4

DESCRPTONS

Faiure ode .

Faiure ode ....

mg App]

ailu Dsciptio: The all pat n ts too steel earng is solidlurcated wih a urnishedon composite film Durngoperaton the film wears away exposing u ne lying metal Paraolc marks are the tracks of asperities on the a ls , made on tesolid u ricant coating of the ing (knematic wear marks) At maxmum est spee tis earing failed due to retane r wear (notsoli lu ricant depleion on he suace sown)Imag Dsciptio In his micrograp, te surace near the horizontal centeline of te mage relects specuary where metal isexpose (light clor) The luricant coat is dark Near te N and S edges, ligting is ow e orionta dak lines are remnants ofu rnised on l u icant Te paraoli c dark lnes wit apex o te W are knematic wea maksSuspctd Causs: This s natura wea in an expermentally soli luricate ig spee high temperaure earing lt llustatessoid lurcant depletion an kinematic wear marks l is not a faiure image

DATAPlat No: 716Achv No 18131Imag typ viewScaba 6 mm (mcros ± 2%, oters: + 1%5%)Compot SRB; IR & OR, runSpd: 8 KdNoad: 17 GPaubicato: grease 6°au Cod 2323 Step worn in roll i ng su raceor dimension worn offspecau Cod : 22 Arasive mil wearailu Cod 1 24 Wea of guidi ngcomponentsuppor suracealu Cod 4 152 Localized freting, radial itsuface

DESCRPTONSailu Dscpto: Deep weadown of oth OR contact pats, mate wear surace Fute wear of ot IR contact paths Slidingwea of I R center ange from separator conac A few sma ll retting corrosio n spots on OR OD Grease was contaminated yarasive material Arasive wear o this magnit ude severely im pairs s haft support accuracy Separator fail re is lkely B eaing svery noisyImag Dscpto e spherical contac surface of the OR shows a centere and with orgina nisng marks To oth sdeste roller conact pats are worn own to a matte su rface, wit a sharp sep etween them and te cener aea he IR roller patsare worn matte, wit perioic epressions The center lange sows crcumferential wea marks The OR OD shows a few patcesof dak freting corrosion Suspctd Causs Tis earing operate i n a saker screen und er severe vraory load an in arasively contaminated greaseAl wea oserved is aasive te fluted I R wear pattern is related to te viratory lod

24



Faiure ode ..

Faiure ode .

Chapter 7 Mild Wear

DAAPlate No: 7.17Archive N o: 014- &3Image type: viewScaeba = , b: 20 mm (miros ± 20%others: + 100%, 50%)Component: TRB; IR & R se hrd., ruSpeedLoad:Lubrication:Faiure Code 00.12.323 Step wo irollig surfe o dimenso worn offspeFaure Code : 00.12.3.32 Wer, enteredi slidig ontFalure Code 00.12.0.2 Abrsive m d werFalure Code 4 00.16.023 Iipiet splling,

singe spll

DESCRPONSFailure Descption: Hevy brsive wer o IRthrst lnge (rib); IR roller pth roller thrustfe; rolle OD. Mtiple debrs dents o I R

a

rolle pth Wer of his mgn itude hs bremoved most of the rbrized se usngsevere loss of tige resstne Spllng hsbegn of IR Geometry on berig is destroyedmage Descrpon: (): IR (one) with thrust flge (r ib) srfe worn dow to bottom of uderut Rol lng trk wor, showi gip t smll end nd loss of uderut t lrge ed. Mltipe debris dets on rollig trk Spl rter t imge E. (b): Step wor oroller thrst fes where flge otted, with epiyli ki emt wer mrks Roig sre is worn to mtte f ish.Suspeced Causes: Abrsive otmint i lub rint hs proded the hevy wer d debri s dentig S pll g is seodry o

ths dmge.

DAAPlate No: 718Archve No: 027-154Image type: light mroScaebar = 50 mm (miros 20% others: 100% 50%)Componen DGBB; IR, rSpeed 270 KdNLoad:Lubrication: Grese 60°Failue Code 001232.4 Sorig wer (mrosopi gougngwihout glig)Faure Code : 0 0 .1 8 . 1 1 Rod ed de t (from soft otmit)Falure Code 12.502 Severe grese ontmntionFaiure Code 4 12 .5 Soft otmit in grese

DESCRPONSFaure Description: Multple irumferentl soremrks in IRgroove fom sg ont the presee of lrge, hrdontmnt prtiles Roded dets rise from soft otmint, i g The soremrks will use erly srfe distress(C 00.17), glig (C 00.13) or spllig (FC 00.16) The dents my elerte spllng. The slidig shown by the soremrksidites seprtor or bll mlfutio.mage Descrption: O s hiny bkgroud lig htolored horiotl l es (E row) re soremrs. They ould be felt when testedwith srber Center d W rrows pont o lrge, smooth dets Veil light streks re ifts of lightng.Suspected Causes: Contminto my m b ll i th e seprtor, wh ih th e sides o trk d wth otmit, usessoremrks. Offenter seprtor my ont groove d sore it but probbly ner enter ple s here Lrge dets risefrom deformble ontmint trpped in rolig ott where it ndets the steel de to hydrostti pressre odtio prevetig

lterl extrusio.

125



Fiure Ats for Hertz Contct Mchine Eements

DATA

Pat No: 719Acv No: 16Ia t: ligt macrScaa 5 m (micrs ± 2%, ters 1% 5%)Coonnt: 0; caracter typefaceSd: mpact & sl idgoad impactLucaton: ribbn nk 24°Fau Cod .1233 Slding cact wearFalu Cod : .127 I mpact wearFalu Cod .2..2 Abrasive mid wearFalu Cod 4

DESCRPTONSFalu Dscrton: In impact printers lateraly mvig caracter ypeface fmetal strikes a ribb. Slidig under mpact prduces wear marks caracter due t abrasive elements in ink k and ribbn debris trasfer ttypeface Edges f caracter are runded wear acrss surface is sm.Eventualy caracter gemetry s destryed and type must be replaced.

Faie ode

Faile ode

Ima Dscrton: etter "0 typeface eevated abve surrudig metal is brdered by wite metalic edge Dark EW abrasmarks witi te letter face Black frges surrudig letter are ik residue ad ribb debris. Edges are ruded by wear neredge sws apparet cippig at SE ad S wic are actually residua fnising marksSuscd Causs: Im pact ladi g agai nst mvng ribbn causes peratial wear f caracter ypeface req uiring eventuareplacement. Te wear is prima rily abrasive as a result f abrasive imp urities r cmp nets i te ink C emica l effects frm teik may als ccur

DATAPlat No: 72

Achv No: 3-4 & 5Ia t: ligt macrScal a a 1, b 3 mm (micrs: + 2%,ters 1%, 5%)Coonnt: CRB R G runSd: 2.15 MdNLoad: 1.7 GPaLucaton: syntetic plyester il 12°Fau Cod 123 3 .1 Wear at edge f sli di g ctactFau Cod : 1 1 1 2 Separatr fracture crackigFalu Cod 1 . 1 3 . 1 4 Rler separatr pcke bttm wrnFalu Cod 4 .2.4 Wear f guidig-cmpnent supp surfaces

DESCRPTONSFalu Dscrton: In ig-speed cylindrica rller bearigexcetric eavy wear n endface f e rller ig rller/separatrfrces frm skewng separatr ring wear ad separatr barfracture. Tis is grss bearing failureIma Dscrton: (a) Rller W f arrw sws alf-m sapedendface wear Rller W f arrw ad rller E f arrw sw rubbi gmarks n te OD frm separatr cntact. Wear marks Wmstrler endface. Te separatr bar at arrw is miss ing (brke) .Separatr rail wrn at bt sides f arrw ( b) Dark excetric wearband wit epicyclic marks frm flange cntact inbard f crnerradiu s ut er ibard crcumferenial marks frm separatr.Susctd Causs: n ig-speed CRB excessive wbble f rerendface r rler ubalance prduces ig rler/flange frcescreating skewg . Te separatr suffers vey ig rer c nactfrces and wears. Ultimately a separatr bar may break.

26

a



Faiue ode: ....

Faiue ode: ....

DATAa No: 72Achv No 002027mag y: viewScalba 20 mm (mcros: 20%oers: 1 0 0 % 5 0 %)Comonn: CRB IR & G & R, ool steel, runSd 30 MdNoad 1 2 Gaubrcaon syntetic oyeser oil, 204Falu Cod 0012331 Wear at edge of slidingcontactFalu Cod : 0 1 3 . 3 Rol er seaator,diagonal crossar wearFalu Cod 001232.3 Ste worn in rolng surface or dimenson worn offsecFalu Cod 0019 2 Hot lastic fow

DESCRPTONS

Chapter 7: Mild Wear

Faur Dscon: One rolle underwent severe end wear, resulting in sewing, searato wear, lastic ow and fractre. Teroller trned cosswise in te oce and slid along te IR rolli ng at weaing a lat on its OD Te damaged roler , e IR racand te searator ocet all sow overeating. Te earing as failedImag Dscon One roller at image cente is dar discoloed Te N-facing end ace of te rol le s won conical A searatorar is missing E of tis roller Searaor ocet and ar W of is oler are eened wt raised edges Te damaged roler jammedn te ocet efore destroying te ar, a nd woe a at on its OD (see sloi ng wear ma diecton on flat, n dicating sewed ole rosition lt was fond trned 90 n t e ocet.Suscd Causs: In tis extreme seed a cation roller u naance creates arge sew orces, reslting in r oler end wear. Tefriction at te roll er end is self-aggravatin g te roller d estoys te searator ocet and eventally jams overeating in e ocessand wearing a lat on is rollng suface.

DATAla No: 7.22Archv No: 09303Imag y: vewScalbar 30 mm (micros 20% oters 0 0 % 5 0 %)Comonn: CRB; IR & R, run

Sd:oad:ubrcaon: mineal ol ? Falu Cod 001233.2 Wear centered in sliding conacFalu Cod : 001232.3 Ste worn in rolling surface or dimension wornoff-secFalu Cod 001232 Smoo rolling surface wear (finis mars emovedFalu Cod 1 1 3 0 2 Severe oil contamnation

DESCRPTONSFalur Dscon: Te roller end faces sow a ste worn in y ange contactFanges ae worn down to matc Roller OD sows worn grooves Ring rollerrac sows matte won s urface wit fin is ing li nes removed. Severe roller/flange contact wear cases roller sew eavy seaator ocet forces, gfriction Roling suace wear imars contac geomery and earing recisionImag Dscron: On te two rolers a image E end aces sow worn downannla ste of wid eqal o flange eigt Roler laced in IR is too so forfange sacing de o rolle r and flange wear l ange wear visle at image Wunder te roler contact, as ste outoard of underct. OD o oller laced on IRsows cicumferential steas indicave o grooving Surface texture of IR smatte wt no fnis ing l ines.Suscd Causs: Heavy lricant contamination i s most li ely cause of al oserved wea enomen a Flange geomery error

(negative lange ange or incorrect rolle axial looseness leading to sewing or earing misaignment may also cause rolle endwea Wear deri s can ten act as conaminants and cause groovng wea and matte surface i n rolli ng tacs.



Failre Atlas for Hertz Contat Mahine Elements

DATA

Pae No: 723Archive No: 0009 a & mage ype: SEMScaebar a 20 : 10 m (miro ± 20% oter 1 00% 0%)Componen: CRB R, Spee:oaubcaion: oi 0°Failure Coe 0012333 Srat mark i di oatFailure Coe : 001202 Araive mild wearFalure Coe 123 Araive otamiat i reaeFailure Coe 4

DESCRPTONSFaiure Descripon: Mliple atmark (kiemat wear mark) oroller trt ae. Emedded aaive partie ( liate) i ome frow.A poit o te ri t rt flae dere epioid rve o te roll eed, wit a p i i ed at te rol i trak ad a tip adi if it edawa fom te trak Differet epilod ro arave wearae itio, oller kew ad i eparator foe, wi ma rel eat i malae.mage Descrpon: (a): verview o evea kiemati wear mar I NWqadrat te radied tip o a epiloda rat. A mark r from Neter to SW orer, aoter from NW orer to E eter. Ma ratie, pal wor off, i akrod. Dark emedded rt i SW ad E.() : Te E ete part of (a). t E o imae eter i a dark aaiverai at te ed of te at i made. Xra petm owed ilio.Suspece Causes: Cotamatio of l riat (oil) wit araive maerial(ad o ilio aride id rit) ri ai ito te idi/roliroller-ed/flae otat ad prode te arave wear. Te rt emedi oe or te oter rfae ad mark te mati rae. aioall, ai () te ri ae plae etwee fae

DATAPlae No: 724Archve No: 027-180Image ype: li t maroScalebar 1 mm (miro: 20% oter: 1 00% 0%)Componen DGBB, B, rSpee: 30 KdNoa:ubricaon: eae 60C

Failure Coe 00124 Wear o idi -ompoe pport rfaeFaiure Coe : -Faiure Coe -Faiure Coe 4 -

DESCRPTIONSFaiure Descripion: Miorire rat mark o all from eparato

Faie ode ...

Faie ode .

a

b

otat i te preee o otamiatio o arp ede peratio der t odtio ma ae i epaator frto reltii departre of all rotatio rom epili veloit, li di i te rolli oat, wear, all ad oi operaio. Te raedal are lkel to ae oie i qiet ri appliatomage Descrpion: Two overlappi mior-irle at patter are ow o te al ae (oe marked wit two arrow)ee wear mak ae made a amped teel (rio tpe) eparator witi wi te all a dexed to two differet axe orotaio.Suspece Causes: e mot like l ae o te ra mark i oli d otamat i e reae etaied ito te i oeparato/al otat wee it i emedded i te eparato ad rate te all. Sra mark ma ao form i a eparatormafari error leave arp ede o te epaator poket

2



Fare ode: . Chapter 7 Mild Wear

DATA

Pa N: 7.5hv N 093-1 1 .11Imag t: SEMSaa 5 m (mros: 0% oters + 1 00%50%mt: SRB IR uSd:adurat:Fau d 001 4 ear of gidngomponetsupport surfaeFalu d : Abrasve mld wearFalu d -Falu d 4

DESCRPTONSFau Ds: Uform "mild (o-gallingabrasve wear of guidering suppor lad by fie solidontaminant Mulple small pits and long sratmarks diretoal i sliding diretion All finisigmarks are oblieated by ablatio of te suae At igmagifiaio fin e abrasive wea produes ti s pitted appearane wit te sl idi g direton ideniied by srates ear o tsseverty desroys geomery ad may ase seuremag Ds: Uiformy wor slidig suae sows slidng diretion rising at about 0 from S to NE (arow Mulplewear evets ave let most of te surae a jmble of overlappig so marks. Some ree deeper sraes as at ASustd auss: Severe ontaminato of lu brian as introdued abrasve patles between g de ing a nd I R land of issperial role r bearig. T e otamiat podue d advaned abrasive wear.

DATAPa N: 7.6hv N: 031-901Imag t viewSalbar 0 mm (miros 0%oters: 1 00% 50%m: CRB IR runSd 5 KdNad: 14 GPauba: mineral oil 150°CFaur d 001 4 ear ofguidigompoet suppo surfaeFau d 0013..1 ea takentered in otat

Fau d 001511 Geeralied rettigradial fit su rfaeFau d 4 1 1 33 Abasive otamiant in ol

DESCRPTONSFau Dst: l nerrig lad ridin g retainer produed ir merential wear marks at two sides of roller trak Ro ler raksows matte feaureess worn surfae rom over-roig wit otamination Bore sows geealized frettig orrosion to nomaldegree Te bearing is not failed bt may ail by separator wear (FC 0113 ea imbalane ailure (FC 00.19 o spallig (FC00.1 6 in ontinued ung wit ontaminationImag Dst: wo poli sed a d irmfeenially srat marked s idi ng wear bads outside ro er trak edges wereseparator ontated. Roller tak is matte somewat pebby rom abrasive wear ad possble denting. In bore paty bakappearing frettig orroso marksSustd auss: I te presene of solid otamiaio sding ontat betwee (maied separator ad ierrig podueswear. Same otamiatio prodes detig ad wear in roller otat Mirosopi motio in bore under load ases (normal

feting orrosion

29



Failure Atlas for ertz Contact Machine Elements

DAA

Plate No: 2Achive No: 01-008mage type: ligh mroScale ba 0 mm (miro: 20% ohr: 100%, 50%Compoet: SRB mby, uSpeed: 25 KdNoad: 4 Gubcatio: mnr ol 10Cailue Code 00.12.4 Wr of guidig-omponn uppor railue Code : 00.12..211 Wr k rd i onailue Code 00.1 8. 1 2 Shrp idividu d( from m dbripiiailue Code 4 1 1 .01 Iipin oil onminion

DESCIPIONSaiue Descipto: Sphril rollr bring oprd in omwhonmid lurin. Crumfri wr mrk o rolr rompror o olr o M wr from rollr D o rig oModr onmi dnig of rollr D. Suh omiion lmi hwr lif d fig lif of h bring nd riouy l m gr lfImage Desciptio: mg how IRprorrolr mbly pivod oof R pl n h m kground of h rolr D ur worn inroll i g o brigh rumril rk how pror on w(no rk r i n u rf r ond by pro pong Svrlmll dn on h roll D from rolld-ovr hrd omiSuspected Causes Thi bring oprd in modrly omindviromn whih hd onmind h oi l. Comin i rrid ino

aire ode: ..

h prorrollr o wh my odg i h of pror nd rh h rollr. M wr lo our i h rolrrig on whr hr Hho lidig wih h rolig. Comi pil rppd i h rollig o form h dn

DAAPlate No 28Achive No 018-2Image type: ligh mroScaleba 0 mm (miro 20%,ohr: 1 00%, 50%Compoet: SRB; R nru & rSpeed:oad:ubicatoailue Code 00.1 2.4 Wr ogui digompo uppor urfaiue Code : 0012.. W dg oflidi g onaue Code 0012..2 Wr rd nlid ing onaiue Code 4 00120.2 Abriv mild wr

DESCPONSailue Descptio Wr of oll r hru u by pror pok wih brv. Con wih I R hru flg mod if wrpr. Comiio lding o hru u wr prod high friion rulig in rollr kwing wh poib prorwr gl ig or rr (C 0 1 1 . Evully h mb filur (FC 001 9 my or.Image Desciptio: A A rollr h ru r rom D o hl dimr piyli mrk from flng o d irumfrlpor w rh Nx in hy bd flg dg hn pror wr h Cr uwor. A C m A bpror o wr r i hiy houghou wih irmfrni h. A 8 d D nw roll r only fi rulr onmrk, riig from mnufuingSuspected Causes Spor pok on wih rolr hru f, wih briv onmnn. oiion of wr mrk i A

gg flg dg on, i C full flng o

130



Faiure ode: 001251Faiure ode: 001252

DATAPate N: 7.9Acive N: 099-1 1 8Image type: ligt macrocaeba 30 mm (micos ± 0% oters 1 00% 50%)mpnent: BG ig ardess, rnpeedad:ubicatinFaiue de 001.5.1 oot polisingFaiue de : Faiue de Faue de 4

DESCRIPTONSFalue Desciptin: Slo, smoo ear of etire contac aea

t gradual emoval of finising mas, durig operato alo ED ilm ticess, especall i ig ardess (caseardeed gears Toot polising is not a failre, less tprogresses to m ore seriou s ear.Image Desciptin: Spral bevel gear set Toot cotactsufaces ave form, smoot appearace; finisig marslargel obliteated Polisg during running is see as ligtersuface clor extedig ear, bt ot up to, W edges on teflas of te for S-most pinion teet.

Chapter 7 Mild Wear

uspected auses: Normal operation of gea set, nder o EHD film ticess coditon (slo speed operatio poducedpolisin g as a (desrable ruin peome o.

DATA

Pate N: 730Acive N: 009-1 3Image type: lgt macrocaeba 30 mm (micos ± 0%otes: 1 0 0 % 5 0 %)mpnent: HG; W, g ardess, grond, rupeed:Lad:Lubicatn:Faiure de 0015. Smoot toot eaFaiure de 2: 001.3.. Scratc mas,iemaic ear mars i rol li g srfaceFaiure de 0010. Abrasve mild earFaiure de 4 -

DESCRPTONSFaiure Desciptn: Scrac mars i contact surace, in e directio of slidig caused b o concetatio of ard cotaminantin te lbrican If clea lbricant is substitted, gears it tis evel of scratcmaring geerall remai seviceabeImage Desciptin Ma small patces of fie, arced scratc mars from abrasive ear of toot cotact surface ru E to NW, ediecton of slidg i is elca gear nderling, less pronouced mars runig SW to NE are gridng lines Blac stai ontoot tip o some teet s maring compond ('bng used examinatio.uspected auses: Moderate level of fie sol d contaminaio i l b ricat prodces fine scatc mas i ear. If te l bricant isreplaced b a cean sppl, t e ea is arested, oterise it progresses and ma become destuctive of a iel ground gear

3



Failure Atlas fr Hertz Cntact Machine Elements

DATA

Plat No: 7.31Archv No: 099119 a & b & cImag typ: lig ht macroScalbar abc 30 mm (micros 0% others 100% 0%)Componn: G W; med hard (a 1 (b: 1 (c: 4 year runSpdoad:Lubrication:Falur Cod 001 Smooth tooth wearFalur Cod 2 001 0 3 Tooth spallingFalur Cod 00133 Step worn in roling surface or dimensionworn offspecFaiur Cod 4

DESCRPTIONSFalur Dscription rogressive wear of mediumhard (throughhardened gears wih i nitial spalls subseque ny worn of andsteps worn into tooth face. In sl ow speed ind ustrial gears thisdegree of wear s often acceptable. Change n backlash andpossible destrctive wear may fai gea r durng fuher ru nn ng.mag Dscrption: (a Smooth wear on tooth contact suracesinterspersed with dedendum micropitting (NE quadrant and somespalln g (n ear both ends of teeth at N) O ne tooth chp ped at Eend (b Steps prodced by wear visible near tooth ends copio smicropitting oose contaminant at tooth roots (c : Un iormsomewhat rough wear across entire tooth deepest in dedend mSuspctd Causs Pogressive wea rom op eration i n low EH ilm thickness regime with possible ab asive contamination fromgear wear andor other sources Some spali ng in ow sld ing areas

no largescae craters One tooth chipped (from passage of a largepiece of debris?.

13

Faiur od: 0012.52

a

b

c



Faue ode 0012531Faiure ode 0012534

DATAPae N 73Arcive N: 099-1 1Image type ligt macroScaebar 5 mm (micros: 0 otes 1 00 50)Cmpe HG; W, med hard, nSpeed:adubrica:Faure Cde 001.5.31 Arasive (desrctive ooth weaFaure Cde 2 -Faure Cde Falure Cde

DESCRPTONSFailure Descripti Arasive wear o gear conac srfaces y

cotamiated l ricat. Srace fi sh is destroyed ad heaviygrooved sface created, with grooves pedomiatly i te sidngdi eco. Gearig with wear of thi s seveity s geerally notserviceale.Image Descripti Eire conac area o srfaces of loaded flaksis heavily gooved in radia directio. Grooves vary i depth adlegh, as f podced y hard paices o vayg dimensiosSuspeced Causes This gear is kown to ave operated i acamer where l ricat was severey coaminated y spali gderis from case hardened earigs he deris ae mch aderthan te gear mateial ad o widely varyng size The deris operateas a coase arasive i the gea mes.

DATAPlate N: 7.33Archve N: 099-19Image type: ligt macroScalebar 0 mm (micos 0 ohers + 00 50)Cmpet: HG P med ard, rSpeedad:ubricatiFailure Cde 00153.4 Adesive (destrctive o-gallingooth wearFailure Cde 2: 00133 Step wor i rolling srace ordim esion wor ospecFailue Cde -

Failure Cde 4

DESCRPTONSFailure Descripti: I n cotac of wider pi ion with arrower whee,i the presece o progressive wea, te pio wear does otexted over the etire tooth egth, leavg 'pads of wor maeriaat the ooh eds. If d rig maintenace or operatio, the co tactpattern is sifted axally, edge cotact etwee te 'pads ad thecorner of the wheel teet may occr, lea ding o fractre or oter ail re from edge loadi g .

Chaptr 7 Mild War

Image Descrp: Wo sep i cotact area of teet, heaviest dedendm. At oth tooth ends, step leads to wor materialotside coact area (arowsSuspeced Causes: Progressive wear codito i te pesece o pinion/wheel comiato of eal width.

133




DATA

Plate No 74Arcve No: 099-20Image te: vewScaebar 60 mm (micros ±20%, ohers 00% 50%Comoet HG; , me har, nSeedLoad:Lubricatio:Faiure Code 00.2.5.2 Ahesive (esrcive nogalling)ooh wearalure Code 2 0025.2 mooh ooh wearFailure Code 002..2. ep worn in rolling srace orimenson worn offspecalure Code 4 006024 Icipien spall ig mlple spalls

DESCRPTONSFailure Descrtio: Deep wear sep i eenm o gear, whspallig ("piig) The eep local wear sggess geomer erro(misalgme?) The wear has le o a ooh fracre (noshow)Image Descritio: Wfacing ooh lanks are o wor (showhob marks) E-facing flanks show generalie smooh wear wihsep wor n a N ege W of line wh arrowheas is a we wearrogh wih sharp emacaio lies a E a W bonaries Lineof fie spa l craers js W of line wih arrowheasSusected Causes: Geomer error s sspece case of heavwear zone pall ig resle from hi gh local loang moohwea (icling wear sep) is epece aer long operaion hisevironmen

DATAPlate No: 75Arcve No: 099-27Image te: viewScalebar = 50 mm (micros 20% ohers: 00% 50%Comoet: G P me har rnSeed:LoadLubrcatio:alure Code 0025.2 Ahesive (esrcive non-gallig)ooh wearalure Code 2 002. Rolling srface gall ing o e orck vsiblealure Code 006.022 Conac faig e cacki gFalure Code 4 00220 42 Tooh corner racre

DESCRPTONSalure Descritio Geeaize wear o ooh coac sfaceicl ing sep a one ege Gall i ng (FC 00. an icieal

Faiure ode:

spallig (FC 006 i aen m ear oher ege The amage has le o a ooh fracre (FC 0022 The gear has aileImage Descritio: Nmos fl visi ble ooh is fracre a lef Tooh flanks reache fs whe ravelin g o he image areame rh lanks, he ohers sh flanks rh flank sraces are as machie (see image ) Sh anks (see image N) areworn wih sep a E coac ege (wear marks r aiall) W mage q arer shows plasic flow an gall ig over mch oaem Aia elogae spall craers i gale areaSusected Causes: verall wear from low ED ilm Heav wear a galling from neve loag (misalignme?) palls reslfrom galig amage Fracre is e res of gallig an spalls

34



Faire ode

Faire ode

DATAPlat No: 7.36Achiv No: 099-27Imag ty: lig maroScaba 30 mm (miros 20%, oers + 100% 50% )Comonnt G W med ard rSdLoadubicaton:Falu Cod 0012.532.1 Wav oo wearFaiu Cod 00.22.01 .44 oo ip ippgFau Cod Failu Cod 4 -

DESCPTIONS


Failu Dscition: Radall progressig waviess o oo srfaes wi wave ress paale o oa e waviess is eleved

proded wear proal de virao operaig odiios Te wear does o eprese immediae aire ma aggravaee virao ad limael ead o failre. Some oo ips are (iideall) pped.Imag Dscition: Te lser of e oa srfae sows lied axial sreaks (arrows) diaig wav wear wi ressparallel o e oa i is elial gear. Te waviess is ideifiae profile rag. Two oo ips ear mage N are ipped.Susctd Causs: Te egieerig ase of wav wear s o firml esalised Viraor operaig odiios ae sspeed

DATAPlat No: 737Achiv No 099-303 & 302mag ty: a view lig maroScalba a 75 : 1 5 mm (miros 20% oes: 100%,50%)Comonnt: HG W med ard rSd:Load:Lubcation:Failu Cod 00.25.32.2 Bmp oo wearFailu Cod 2: 00.12.5.31 Arasive (desive) oo wearFailu Cod 00.6023 ipie spallg sigle spallFailu Cod 4 002201 4 Gear oo ak o r frare

DESCPTONSFailu Dscton: Elevaed mps exedig i e direio ofe oa lie o e oo fak formed maeral removal i esrrodg area appearig i sm ilar form o several oseiveee o b oa eds. Arasve evirome likel Spalls o' mp. Te 'opig of mps o several ee sggess a selfreiforig viraor aivi Maig gear elieved o sow

orrespodig depressios (Maig gear is los.)Imag Dsciton: (a) Bmps o similar sape a o eds o allfor Sfaig oo flaks (visile es i N alf of gear). N-faigaks (visile i S alf of gear) are damaged. e oo ip i E israred () ip area of a oo fak (seio from a oo)Wear pad eads o origia oo sfae a W edge. Elogaed'mp exeds axial aross smool wor oo flak. Few smallspall raers.Susctd Causs: Sel-reiored viraor moios oo mesare ojered as ase of mirror-image wear o maig ee( mps o is gear oll ows o maig gear) wi opies samewear paer o ma ee seqee. No mealrgial deviaio(eg ard areas) are prese Arasive oamiaio is assmed oeae deep wear Prese asaio meaism o kow.

e maig gear s availale for examiaio.

a

b

135




TPlate No: 738Archive No 064101Image type: liht macScaebar 50 mm (micrs: 0% thrs 100%50%Component: HG W md had rnSpeedLoadLubrcation:ailure Code 00533 Ridi tth warailure Code 00160131 th pitchlin rdddm spallinailure Code 00133 Stp wr in rllin suacr dimnsi wr ffspcalure Code

PTFailure Description On adddm tth ridiwar cnsistin f dstctv adhsiv rmval f

alure Code 00..alure Code 00..

sbstantial matria t v dpth frmin radial rds At cntact d war stp I ddndm fin spallin War f thssvrity and spalli impairs tth mtry causin isy rnnin and vtal failr by dp spalls r tth fracturImage Description Gar shwn in chambr with lbricat (thick black il stll prsnt Nar S ma d ar OD th tw

tth laks ca f il O bth flanks radialrnin rids wrn int adddm and stp at W nd f cntact War diminishsat ptchli ad a bad f small spall cratrs and dnts is visbl i ddndum Nst tth f frrund ar ad a fbackrnd ar carry dark tary ilSuspected Causes: Hihlad slw spd prati f mdiumhard ars ay rsut i ridi war whr sldn is sbstantialCncurty spalli ar pitchli may aris in dddum

Pate No 739Archve No: 099130Image type: lht macrScaebar 10 mm (micrs + 0%thrs: + 100% 50%Componen SG P, md hard hbbd ruSpeed:Load:Lubricatonailure Code 001534 urrwi

tth warFailure Code

Failure Code : Failure Code

PTFailue Descrption: rrwin war ccurs i la rhfinishd ar n shrt adal war marks (rrws crss thfishi lis f hbbin Numrus axal bads cmpsd f frrws may aris h riinati f furrwin war is nt clarlystablshd r slw spd havy ars furrwin is t an immdiat cas f falurImage Descripton O th ar flak sac N th (arfical fractr axial bads f radial war arks which dcrat hbbinlis f viwd ndr maificatn thy ar rndbttmd furrws his urrwi has n rlati t indi furrws (C000Suspected Causes h ninri caus furwin war f ar tth is t carly stablishd t is bsrvd as a waphmn i casish lar ars prat undr lw EHD ilm thicknss and may b rlatd t rh srac fishs

136



alure Code 00.

TPlate No: 740

Aive No: 011001Image type: clor macro [SEE IMAGE IN APPENDIX]Salebar 1 mm micros: 20% ohers 100%, 50%)Component: 0 impac priner hamme, rSpeed: impacLoad: impacLubiaion sca mnera oil, 50Caiue Code 00127 Impac wearailue Code ailue Code : ailue Code - PATE 71

PT

aiue Desption: Wear o impac priner hammer saceagais elasomeric pushro ip Hammer srace brisheTasferre elasome a oher ahering ebris This egreeof wear is o a hamme faire The elasomeic pshro sually ails firs


[ mg App]

mage Desption: The or gray/yelow ro-shape elemes are meal hammers from a aa processig impac prier A hebroaee ail aea a elasomerippe pshro his urig operao ar-rimme oal wih sreaky gree ierior) Slghburnishing wea of mea, where yellow pach appears Ahesio of elasomer ebris gree) a ol ark).Suspeted Causes: Some aa processing impac priers asmi ypecarier orces hrough a psho o a hammer Thepushro/hammer impac, which is essenially o omal incience wih a smal siing componen, rasfers some elasome o hehammer while inflicig mil wear on is meal suace

TPlate No: 741Arive No: 011002

Image type: ligh macroSaleba 5 mm micros: 20% ohers 100%, 50%)Componen ; ype elemeSpeed: impac & sieLoad: impacLubaon:aiure Code 00127mpac wearailure Code 0012.33 Sliig coac wearailure Code : ailure Code PATE: 730

PTailure Desption Impac wea wih sg o rear of impacpriner ypeeeme Oe wear sca fom impac beween he ypeeeme an a hammer The oher is a ype/backsop conac ae o ibraio a impac As wear coines, imensio is osresling i priig egaaioImage Despon: Three ypecarriers are iewe rom he backace The aere face caries chaacers a he p image N). Thehie shank s elasc Wieing of sharp NS ege a is romhammer impac Some EW wear maks E of eges EW rnngrecanges a are reing marks, from backsop coac uebraon.Suspeed Causes: Impac prier ype carrers hae characers o he ip The back face slies pas a bacsop whe o priga is hi by a meal hammer o make he impri bricaion is marga Misaligme may exis Impac wear an some sligwea occur a he hammer conac reing a some impac wear a he backsop coac Eealy geomery is esoyesfficely o reqire repacemen

137



GIN, KID MRKIN 8

Failure Code -

GALLNG FALURE CODE:

DefoGallng (o a contact componnt) s dind as t tans o componnt suac mata n

macoscopc patchs om a ocation on on contacting suac to a location on t ot contactingsuac, and possibly back onto th ist suac, by t action, in svc, o g tactv ocs nmultaspity dmnsions Galing qus suacpaa atv moton (slding) n th contactGaling s distnguishd om

Mild wea (FC 0012), dind as mova o suac matal as loos paticls by th acton otactiv ocs in aspity dimnsons Suace distess (FC 007), dnd as suac mata plastic low and mcopttng by t action

o igh nomal ocs in aspty dimnsions Fetting wea (FC 0015), dnd as moval o suac matal, otn wit oxdaton o dbs,

as a sut o micoscopic suacpaal ativ movmnt o suacs n nomnay staticcontact und nomal oad

Sid maing (FC 0014), dnd as matial tans btwn suacs n single-aspeity dmnsons

NomeclaureGallng s aso dsgnatd as sv wa, smaing, o scung tm 'scoing may dsignat

galng o altnatvly, t omation o a scatch by plastic powng Occasionaly t tm 'weais usd loosly to dsgnat al mods o suac matal mova incuding galing, as w as toth mods std und Dinition In ts Atlas, galng is ony usd to dsgnat sv wa,wc s always twobody wa

In som ga itatu [8, 9] gallng s cald adhesive wea atoug this tm is gnaly svdto dscb twobody md wa (FC 0012). In tis Atlas, galg is nv dsignatd as adhsv wa

alure Processh mcanism o gallng in a olling contact is visuaizd in t oowng stps

1 Slidig taks plac i t contact, usualy in addton to oing, though t acton o sucinttactv oc

2 combnation o opatng paamts suc as noma pssu, sdng spd, tmpatu,mcotopogaphy, ubication d ots, is suffcinty sv tat wding o aspitis occusin macoscopc dimnsons

3. h suac-paal dsplacmnt o t suacs n t contact plasticaly tansposs somwldd matial om it o both suacs

I t conditons cang to lss sv (g, by ducton n sding vocity), thn t wdgo ut asptis stops

5 As th oling contact aa tavls on, th wldd aspitis bcom spaatd n th suacnomal diction, aving bind a patch o tansd mtal on on o both contact suacs matial may hav oiginatd om it o t suacs, gadlss o t suac to wichit is fnay wldd

13




14

My common theories describing the micro-mechansm of gaing hark back to the Blok fashtemperature model [1], according to which two asperities contacting under severe conditions heatup momentarily to a temperature which (a) vaporizes the ubricant and (b) welds the asperitiestogether More recent theories have added the conjecture that loca heating causes therma distortionof the surface in effect creatng a "transient asperity" which becomes overoaded by being higherthan the surrounding surface

It is beieved that galing requires an' avaanche process whereby a sma patch of weded surfacemateria is moved aong the surface by sliding then weded onto a next asperity thereby increasingin area This process continues unti it is externaly interrupted t is beieved that for the macroscopicmaterial transfer process to take place a galling event must bridge more than one asperity so thatmateria dragged from one welded asperity is welded onto a second asperity is further dragged toa trd etc his sequence expains the cascading nature of a· gaing failure which is its mostsignificant characteristic.

Neither the fash temperature nor any single macro-variable of operation (speed oad roughesslubricant etc) contros the onset of galing over a broad range of contact configurations At presentthe effect of the parameters infuencing galing is known oy for fixed configurations Thus thereare experimental data on threshod values for speed oad temperature and ubricant combinationsthat do not precipitate galing in a precisely dened contact configuration including defined contactmaterial and surface fish However extrapolation to untested configurations is reliabe only oversmall incremental configuration changes

Gaing is a weldig phenomenon that is of adhesive bonding between materia voumes Accordingly it is primariy a failure mode of metal or thermopastic surfaces Surfaces that resist welding(such as ceramics) and ayers of ubricant or hard coating that combat welding a resist galing

It is beieved that asperities must deform plasticaly in order to itiate the weding needed forgaing. Therefore the sope ange (or tip curvature) of an asperity must exceed the limit of pastic

flow under the operating conditions in order to initiate galingThe cascading nature of galing expains the tendency of galing faiures to be catastrophic Agalg event once started tends to continue and spread the transferred metal patch in the slidingdirection as ong as the contact lasts For this reason galing does not take place in pure roingsince there is no surface-paralle reative motion to spread a welded patch to multi-asperity dimensions Galling in combined roling-and-sidg contact increases in severity as the slide/rol veocityratio increases Galling in simple sliding is particulary evere as there is no surface-norma motioncomponent to separate the contact

Galing is a threshold event such as cracking If contact conditions are made progressively moresevere a regime of mid wear wi abruptly convert to one of galing However since many variablesifuence the threshod severity some of which vary potwise on a surface (roughness) galingoccurrences show considerable scatter in repeated experiments

Galling is selfaggravating The transferred metal patch is higher than the ungaed surface andacts as a arge and gh asperity on which load concentrates Therefore galling tends to propagatevery rapidly by incremental transfer of more material onto the galed patch of origin If galing is notarrested it can rapidy ead to gross faiure by buk fracture or seizure of parts as the transferredpatch of material becomes too hgh to pass through the contact without destruction

In contrast to the sef-aggravatig nature of galing is its abiity to "heal" If a (temporary) externachange drops the severity of the operating conditions beow the gaing limit the galed patch maygradualy wear down ("heal") and the galing can be arrested Among the many possibe servicechges that may arrest galling are: (a) termination of contact by surface separation in roling;(b) arriva of a fresh ocal supply of cool ubricant; (c) cessation of a momentary overoad or impactoad (d) a small change in the relative position of contacting parts during the next overroing; and



Chapter Galling, Skid Marking

(e) a eiberate or cocieta reucto of spee or oa or a icrease coolg lubrcat flowby te operator.

Te ost sigficat operatg variabe cotrollig galg s sdng speed Gallg occurs above afixe slg spee t for ay gve set of operatig coitios a cofiguratos Howeverslg otio a ertzia cotact takes pace oy if suffciet tractive forces are applie to balacete slg frctio i the cotact The frcto i a cotact uergog galg is usualy higer tha a ugae ietcal cotact a ust aso be overcoe to sustai galg Therefore racve orcea con te cotact are tur the cotrollig variables of slig spee

Other sgficat operatg variables cotrollg gallig are teperatre cotact loa surfacecro-geoetry a bouary lubricatio

Dscve AppearaceGaig s recogze by observato of the cotact surfaces a if ecessary te ieiate

subsurface atera Distctve appearaces are escribe beow I ifferetal iagoss of galligit s iportat to observe that the istictive appearace of other surface atera reoval failureoes (i wear frettg surface istress) is no presen Depeg o te severity of a galigoccurrece te appearace ca be recogize o tree leves

Gross sezure Avace galig ca ea to seizure of relatively ovg parts (especally cofieparts suc as those of a rolig bearig) proucig bulk fractre bulk plastc eforatio a/ orgross overeatig faure The ost estructive faiures i rong bearngs te to arise fro galgI tese cases etecto of the tatg galg evet ay be ifficut or ipossible havg beeoblterate by subsequet estructio of surfaces f t s observe that o oter obvous iitiatigfalure is preset i a seze assebly (suc as a arge spall or oose cuks of ateral fro aaor fractre) the ts strogly suggests tat galg cause te sezure Te reverse howevers ot te casefractures ca well be secoary to galg evets

I a operatg acie a gross seizure evet s ofte accopaie by vioet vbratos louoise rapi teperature rse sowow or ueve oto of te ovg part loss of postoigaccuracy etc

Macroscopc gang Gaig ultpe-asperty esios appears as a raise patc of trasferreetal seare oto" a cotact- or fit-surface. Profe tracig over the galle patc sows raiseateria The surface topograpy of the trasferre ateriaLis ofte rough a score the sliigrectio as te opposg part surface is force over t here are o fiishig arks o te trasferrepatch as it covers over the fshg arks o te uerlyg origal surface. e trasferreateral is ofte ple up at the e of te galle patc where t is left we te galig evet isteriate by surface-ora separato of the rollg cotact surfaces

Macroscopic gallig i progress a achie tes to create cckg or haerg sous gpitce screas" or eep rubles" epeig o operatig cotios

Mcroscopc appearance o gang. A SEM age of te galle surface shows trasferre aterialplastically seare oto the origia surface The trasfer patc briges several (up to a great ay)asperities. The trasferre ateral s presse ito origial surface frrows ay sow plastic fowarks fte-off eges where welig was icoplete or cracks were te plasticity of a aterialvoue was exhauste by te searg Sice gallig arks are ost ofte observe folowgfurter rig after terato of te galg evet te gale ateria ay be rolle owsoote or burse as a resut of beg role over

Microaress of te trasferre eta is geerally igher ta te orgal surface as it s heavlyworke (but subsequet teperg is possble)

A (Nitaletche) etallograpic secto throug a trasferre eta patch geerally shows thewele terface a ay show off-specifcato atera structure a Ior plast�c flow lies.

141



Failure Atlas for Hertz ontat Mahine leents

14

1 Causes

eneral auses of alling

Susepible maeia ass (mea emoplasi polyme) nsuffiien galng esisane of maeial due o low adness ease of welding ak of poeie

sufae aye e Seee sliding in ona (in exess of iial alue) aused by exessie aie foe and

maintained or suient time o pem maeial ansfe in muiaspeiy dimensions Seee noma load (in exess of iial alue) Oeeaing. Unfaoable sufae mio geomey (oal damage genea ougness) nadequae boundary ubiaion. emialy aggessie enionmen (ubian o amospee) emoes poeie laye

alling auses Speifi to Rolling Bearing ontat oponents. Te folowing iumsanesend o aiae some of e geneal auses of galling

In the rolling ontat:

Exessie angula aeleaion Exessie sepaao fiion Sudden ea imbaane Nik o den wi aised edge

In roller-end to ange ontat

Edge ona due o geomey eo

Exessie nomal sess andIo sliding eloiy due o axial load o oe sewg

In Hert ontat element to separator ontat

Edge ona due o geomey eo Exessie sepaao foes in ona wi suppo elemen nsuffiien eaane beween sepaao and ona omponen

auses of alling Speifi to as. ams and am folowe oles o appes suffe e genealauses of gaing ised aboe of wi ey ae paiualy uneabe o e following

Sliding. Te ole in am and olling foowe sysems undegoes ig angula aeeaions ineey am ye as e ole aemps o follow e aying inea eloiies enouneed alonge am pofie Angua osillaions e amsaf may add fue aeeaions Te ona

beween am and foowe ole mus ansmi e aion needed fo (ig and possiblyosilaoy) oe aeeaons and o oeome e fiion beween ole and ole suppoeemens ona pessue aailabe o geneae aie foes aies fom zeo o maximumalues along e am iumfeene Fiion on e ole suppo elemens may be eai andig Al hs an ead o inemien sliding in e ona f e siding aes plae wi aeloiyIpessue ombinaion a exeeds e gaing imi of e sysem en galg esusam and appe sysems ae designed o opeae wi oninuing eaie spin whi is oleaedunde design ondiions Tese sysems may suffe galing if opeaing ondiions ae moeseee an designed fo.

Edge ontat Roling am followes ae diffiul o mainain in peise aligmen. Pofile owningneeded o aoid edge sesses is no always poided Tappe wea may elimnae edge leaane



82

Chaer Gaing Skid Marking

Cntaminatin. Ca systes ae ofte lubcated fo geeal ccuatg o systes whchcay cobusto poducts teal cobusto eges) ad wea poducts

Rugh suraces. Cashafts ofte ae age copoets ca geoety s copex ad the specazed achey fo fe ca fshg ay ot be avalable

Nicks Ca sufaces ae extea ad cashafts ae ofte age copoets dffcult to hadepotectvely

Gaing Causes Secc o Gears

Hgh, keatcaly foced sdg speeds hgh-velocty geas, at tp, oot, ck o edge Oveheatg

Effects of Galling

Galg s ofte the pay cause of goss sezue of a ache eleet, due to sevee geoetcalteato, gh oa ad tactve cotact foces ad extee oveheatg

Ealy stages of gag ceate opeatg afuctos, as folows

Cckg, haeg o ublg ose adal o agula vbatos Postog accuacy ca systes

Eay stages of galg ake the ache eleet vuleabe to deteoato fo sa causes

Excessve ad tevaable foces asg the galled cotact educe oveoad safety ag The ough suface of tasfeed eta s vueabe to futhe galg wheeve ubcato

s paed

Patcles wo off the fast weag) tasfeed etal cotaate the ubcat ad aypecptate gallg at othe suface pots he tasfeed ateal has ow esstace to spag ad suface dstess hs, cobed wth

local oveloadg fo excess heght of tasfeed ateal ay cause ealy spag falue.

Mache eleets wth cotoled ceaace ollg beags, geas) ay ose al ceaace ove thetasfeed atea, esutg paastc loads ad faue fo that cause

og beag sepaato gag agast olg eleets o g gude sufaces cause thesefaue sks

Sepaato atea tasfeed oto ollg eeets s ot cotactfatgue esstat, but ca asethe suface causg ocal oveloadg

actve foces exeted o the sepaato dug the galg pocess ay cause sepaato falue

see FC 01).

SD MAR<NG FALURE CODE: 0014

DefinitionSkd akg s aspety-scale suface ateal tasfe t s anagus to the acoscopc pocess

of galg FC 003), but istinct fo gag whch the eeetay ateal tasfe evet akespace o a ut-aspety scale Galg s a cascade pocess bdgg sevea aspetes by tasfeedateal, wheeas skd akg o cascade of tasfes takes pace I soe cases, galg steaksae so sa that the dstcto betwee the ad skd aks caot be ade wth cetaty

143




144

. Nomenclature

Skd makng s a ecognized aue mode o (gseed) ong beangs, wee t s aso caedkidding ooting A sima (o dentca) aue mode in geas s desgnated n ome gea teatueas cung weeas te tem 11scung" n ong beang tecoogy s synonymous wt gangSkd makng aue as been dented n cam and oe oowe systems, wee t s usuaydesgnated as mcogang n ts Atas, te tem 'skd makng s adoted, as dstngused omskddig, wc s aso used n beang tecnoogy to descbe te knematc condton o gosssdng n te contact, as, wen a ong eement as to mantan ecycc seed o otaton'Fostngas been used to descbe an advanced degee o suace dstess (FC 0017) and teeoe s notused n ts Atas to descbe skd makng

. Failure ProcessA skd mak aeas as a muttude o asetyscae sots o tanseed matea on te contact

suace t can ase wen g sding veocty s mosed on a Hetzan contact o a semted, veybe eod, dung wic te eatve suaceaae dsacement o te contactng comonents oneac ote s ess tan a tyca asety sacng, so tat te cascading tanse o matea caactezng gang as no ootunty to deveo

n olling beaing ts ccumstace can ase a ong body (ba, oe) obts wtout mantanng ecycc ong veocty (as, wen contact oads ae sma and seaato cton g) and sten suddeny acceeated to ecycc veocty uon te onset o say nceased contact oadTe tactive oces necessay o te g acceeaton may cause skd makng Once te ongbody s u to seed, te g tactve oces omty dsaea. te duaton s sot enoug,skd makng can esut; o onge duatons (eavy ong eements, esstent g cage cton),macoscoc gaing may take ace

n gea, skd makng (scuing) may occu n te sdng zones o te toot contact o sde/o

atos nsucent to cause gangn cam/olle systems, skd makng can aea at secc ostons on te cam ccumeence,

wee condtons eque aticuay g taction to matan ong contact A comex o oeatngvaabes, ncuding (momentay) nadequate ubcaton, tosona cam vbatons, and toque excusons n te oe suot eements can contbute to skd making

Vsbe skd mak aeas bud u gaduay as oosed to gang, wc can occu as a sngecatastoc event ndvdua maks ae o asety dmesons te ectatng condton eeatstse (tycay once e seaato evouton n a beang, once e cam cyce n a cam/oe system),a atten o skd maks deveos

A exstng skd mak s a natua statng ont o a new mak dung te next cyce Teeoe,skd maks tend to ne u n ows n te sdng decton Because te eementay skd mak ssma, ute extenson o a ow o maks s easy ated by a scatc o uow n te suace

wic cosses te sdng decton

.. Distinctive AppearanceTo te unaded eye, skd maks aea as ndvdua ne steaks o ccumscbed macoscoc

aeas on te contact suace, avng a dstnctve 11ostedgass aeaance nde ig magniicaton, skd maks ae asetysze wed sots ned u n steaks uing n te sdng dectonndvdua skd maks may custe n naow cosstack bands on cams n a ong beang, teedge o a skd maked aea may be eateed t extends on a unnteuted suace, o cut osay by a suace uow (coon on bas wc ave uows unng n andom dectons)

I etced metaogaic section (eaed ate oveatg o te sace o te esevatono a s edge at te tesecton o secton and sace), skd maks may aea as eadened



Capter Galling Skid Marking

weded-o matea ovelayig a tempeed surface Asde fom ts sma scale, ths appeace s smlao hat of gallig (FC 0013, but not o surae distress (FC 0017) wch shows o sg of weldg

CausesSd mag, e galg, s caused by he appcato of hgh tactve foces to an asperity ontat

so as o cause sldg at a speed suffcet o duce wedig of suface maea ude exsgcodtos of matea tempeaue, ubcato ad suface mcogeomety. Fo sd mag tooccu as opposed to galg (FC 00.3, the duao of the hgh tactve foce must be oo shot todeveop a mutaspety cascade of weldg

Effect of gag sestvty factos (such as ougess, bouday ubcao ad tempeatueupo sd mag ae ot wel documeted, but ey

rolling bearings sd mas ae the cosequece of ematc aomales he moto of olgbodes Examples

• Sowdow of olg body autootato ude ow cotact oad (ad sgfcat sepaato fcto, foowed by a brie acceeato whe oad steps up

• a hgh-speed beag, abup chage of epcycc olg body speed upo a step load chage.

I am and rollerollower systems, sd mag ases as a esut of mometay sdg ude hghcoact pessue, at the etace to he ft lobe whee the folowe mus apdly acceleate, ad atothe agua ocatos f apd olgspeed chages ae foced by the cam pofe, by aguaosclaos o specal opeatg codtos of the cam system A agua ocato whee coactpessue s suffcetly hgh, momentary hgh toque demad of the oe suppo sysem ca pecptate sd mag alling (FC 003 may occu f the sdg ude hgh pessue s of oge duato.

gearing, sd mag (scuffg has bee obseved sow-speed, smoothsuface, subsatayoaded geas opeaig below the gag mt

Effects of Skd MarkigIn rolling bearings and ams

• Sd maed sufaces ae oughe ha asmaufactued sufaces, ad the tasfeed meastucture s defectve These factos acceleate falues ueced by EHD fm ato, such assuface dstess, suface tated spag ad wea TheY ae, fo the same easo, moe poeo goss galg

• The maeal a sd ma s seveey pastcaly woed, ehadeed ad pobably mcocaced, mag t much ess essa to suface-ogi cotac fatgue (suface dstess adsufaceog spalg.

A sd maed ghspeed beag s moe osy ad vbatoy tha a tact beag Fcto bewee a sd maed olg body of a beag ad the sepaao may be geate ha

omal Sepaato wea, o oveheatg o both may esut.

I gearing sd mag (scuffg s ot cosdeed catastophc faue Howeve, t may ac aspecuso to moe sevee faue by wea, galg o coact fatgue

145



Failure Atlas for Hert ontact Machine lements


Failure de

146

Plate N

4

65

65

554

55

5

55





ailure Atlas for Hertz Contact Machine Elements

tPlate No: 83

Archve No: 0338Image type: SEMScaebar 30 m (mico 20%, otr + 00%, 50%)Component CRTB IR, rSpeed: 50 KdNLoad: 20 GPLubrication: mirl turbi oi Falure Code 0032 Rollig fc gllig o d orick iiblFailure Code Faiure Code : Faiure Code

PTFalure Description: Microcopic gllig t A gog crtd by

prity or dbri picl idg or t rc i filld by pticllyfowd, microcckd d wlddo mtrl A ioltd microcopic

Faiure Code: 00

gllig t my "l by rr orrollig O, owr, it itt dditio mtril trfr d fil brig by timblc fir zur poibly pligmage Description: W mrk (d fiiig li) r trgt li rig SW to NE A wr gog (50 m wid) rudigoly SW to NE, to E of mrkr l B. lt i filld by mot ftrl mtri cotiig icrocrck (t i B) d toy pltic workig T dpoitd mtril rlt from t gig t Fit wr li o glld mril uggt tt it wrolld oSuspected Causes: Gllig ruir lidig locity compot (I CRTB t lidg compot i lrg or mot of tcotct widt) A g priy or dbri pticl gog wr mrk lidig Sbuly, tril brougt from prm i t lidig dirctio i rolld ito t goug d wldd o

tPlate No: 84

Archve No: 033mage type: SM Nil tcScaebar = 20 m (micro 20%, otr 00%, 50%)Component: CRB R tool tl rSpeed: 80 KdNLoad:Lubrication: yttic polytr oil, 38CFailure Code 0032 Rollig urfc gllig, o dt oick iblFaiure Code Faure Code :

Falure Code

PTFailure Descrption: Lmi of mtril trrrd oto urfc by

gllig coti ig ridul tr fro cold workig Upo Nitl c, omridl tr wr rlid by micocckig drlyig uc iibl d ily wokd Microcopic glig ow my Moroft, it iitit lgc gllig, t imblc filr, izur oplligImage Descrption: Mtt, pbbly gy urfc i t tcd rfc o t

trfrrd mtril At img N lly of prumbly origi c ISW ud two curd fc crck lif of lmi of rfrrd mtlSuspected Causes: Glig rqir lidig locity compot Mtrilbrogt fom ptrm i t lidg dirctio i rod oto t c dwldd o T cold workig i , lig g rid tr mkg t il lrbl o crckig mtrl i oft id bo t rroudig rfc, cig tr coctrtio dititig frr gllg

148



Failure Code: 00

Pate No: 85

Archive No: 08111Image type: viewScalebar 20 mm (mros: 20%oters + 100% 50%)Component: SB transportedSpeed: Load:Lubrcation:ailure Code 00321.1 olling sfae gallingno dent or n visibleailure Code 00.09.2 Galling from foribleassembly or montingailure Code : aiure Code

PT

Chapte Galling Skid Making

aure Description: Galling streas on roler OD's from axial motion of rollers against rings nder load wtot rotation Smotion may or in transporting a bearing monted in a maine. I tere is no axial motion fase brinneling mgt reslt witdomnant axial sliding galling streas ae geneated. Te bearing is nosy wen rn and iely to fail n galing or spalingImage Descrption: Near maximm diameer of rollers sor sarp axial lnes are galling (soring) mars Metalograpiexamination wold sow transerred materialSuspected Causes: Transpoation of manery wit bearings monted may expose e bearngs to reatve moton witotrotation e most ommon resting failre mode is false brinneling (C 00.15) However in te present ase te axial motionwas o large enog amplitde to ase galling (sorng) mars by materia transfer between te ontating srfaes.

Pate No 8.Archive No: 093-131.1Image type: ligt maro

Scaebar 3 mm (miros 20% oters + 00% 50%)Component TBB; I rnSpeed:LoadLubricationailure Code 0013.21.1 oling srfae galling no dent orni visibeFailure Code 001302 xtensive gallingailure Code : alure Code

PTailure Descrpton: Bal groove irled by galling steas rnningin spin diretion probably rom exessive speed for e appliedload Te bearing is noisy and may seize sffer eat imbalanefailre or spallImage Descripton Te ball groove is te entral ar on te trstbearing ring (waser') Dar-appearing streas f transferredmateial ( rn from groove enterline toward groove OD in tedireton of bal spin veloty (image S to NE). Te galledmaterial is siny te dar appearane in e mage is de to ligtrefletion away from te amera.Suspected Causes: Trst ball bearings rn wi ig spin to rolveloity ratio. en rotatonal speed is exessive and loadrelativey low entrfgal fores agravate spn. Galling is a ommonfaire mode espeally nder marginal briation.

149



iue As fo Hez Conc Mchine Eemens

Plate No .7

Archive No: 093-027xmage type: viewScalebar 40 mm (micros: 20%oters 1 00% 50%)Component: CRB; R, runSpeed:Load:Lubricatonailure Code 00132.11 Rolling surfacegaling no dent or nck visibleaure Code 001302 xtensive galingalure Code 001232.1 Smoot rollingsurface wear (finis marks removed)ailure Code

PT

Failure Code 00

aiure Descrpton: xtensive crcumferential galling streaks on rolling srface, concenrated on 2/3 o roller pat widt on botrollers e rollers are extensively worn on te rolling track. Bearng is noisy and may run ot. Wt contnued galling, seire islikelyImage Descrpon: Bot rollers (from te same bearing) sow wear acoss oling pat Many inermittent circumferentia gallingmarks appea matte and igt coloredSuspected Causes: Te wear and galling appears to ave arisen from soid contaminant. Contamnation nicks, skiddng of rollersjammed in te separator and bearing misalignment are sspeced as galing causes

Pate No: 88Archve No: 074-1112Image type: a ligt microgram, b: metallogram etcedScalebar a: 100, b 20 m (micros ± 20%, oters + 100%, 50%)

Component DGBB R, runSpeedLoad:Lubrication:alure Code 00132.1.1 Rolling surface galling no den o nick vsbleailure Code 001712 Microspallng (advanced srace distess)ailure Code : 00195 ocal strcre damage from frictiona eatngalure Code

PTalure Description: (a): Material transferred ono suface by gallingsubsequently overroled and faigued srace distress microcacking andmicrospaling e ransfered mateial is expected to nitae a spall. (b):Mateial underying te galled srface sufered structre damage(overempering) Te transfer pacle is reardened or eavily cold workedmage Descrpton: (a) Largey featureless gray backgrond is material

transerred in galling. in NS lines are wear marks sbseqent to gallingBrancng irregular lines are microcacks o surface distress in te

transferred materal Black spots are surace distress microspals (b): S 2/3of image is cross section ecing darker from overempering near surfaceransfe paicle near image N etces ligt (woked or reardened)Suspected Causes: xcessive sliding under g load may nitiate gallingDeposited material is eavily cold worked, wit ig resdal stress, leading

to early microcracking pon overrolling. Tis creates surface distressmicrocracks and microspalls. Sliding events sfficent o case severegaling may overeat and retemper subsrface materal. ransfer particlesundergo sevee eaing and pastic working.

150

a

b



Failue Code: 00Failue Code: 00

TPlate No 8.9

Archive No 093030Image type: lght macroScalebar 40 mm (micros: 20%, others: + 100%, 50%)Component: SB O rnSpeed:Load:Lubrication:Failure Code 00.13.2111 ig gallig at oad zone etryFailure Code 00.12.3211 Wear track centered in cotactFailure Code : Faiure Code

PTFaiure Description: Both roling paths in the SB O show

Chaper alling, Si Maring

wear tracks i the load zoe. At the load zoe entry poit a patch of galing precedes each wea track. he rollers i this large

bearg sowed atorotation in the loaded zoe (separator brakig) ad accelerated rapdily at load zoe enty casig gallig. I the load zone wear tacks from cotamat or galled roler. alling may case seizre heat mbalance o spalingImage Description: wo matte gray W wear tracks bordered by darkappearg shiny bads extend over 3/4 image width fromimage W Over most of thei ength the tracks ae costant wdth bt arow ear end Jst to the of each tack is a lightcolored rreglar patch of galing otlined i a dark-appearig shiy hao he tracks mark the load zone this O the gallig is atits entrace.Suspected Causes: ollers i the noaded zone of a large horizontal-shaft beaig may lose epicyclic atorotaton speed de toseparato friction he high accelerating momet eeded to restoe speed at load zone etry may exceed contact tractio and ead to slip with galing he wear bad may be de to contamnat or ring marking by the galled oller

TPae No: 810Arcive No: 07 48&9Image type: a: light macro b SM

Scaebar ab: 50 m (micros: 20%, others + 100%, 50%)Component: CB rnSpeed:Load:LubrcationFalure Code 00.1321.1.2 Cotact galling from hgh acceerationFailure Code 00.12.322 Scratch marks kinematc wea marks inrollig sfaceFailure Code : Faiure Code

PTFaiure Description: Patch of thin discotios lamia of tasferred materialo otherwise sod rolling path rasfered material has bee worn by

sbseqent rng. Sch gallg occrs when sdden acceleratio is imposedon roller with insfficent fricton so that momentary high sidig reslts Ifacceleratio is ot repeated galling may heal (be wor smooth) which hasalready started Frher slidig tends to add gross galig at same area.Image Descrpon: (a) Par of I roer path. Dakappearig ireglar patch atarrow is galled. Othe srfaces show normal wear (b) Discotinos laye of trasferred metal (shiny) iterpted by may roghly circlar patches oforgial sface dicating that material trasfer occred i may smallincrements ransferred material s higher than srondig srace ad wearsprefeetially (W wea scratches from slding)Suspected Causes In some highspeed CB applcatios (as i gas trbine

a

b

egies) load is low and variable (maeveing loads). oller atorotation and obitig speed may slow down whe loaded andis rapidly accelerated whe load retrs Uder light load friction does ot sffce to prevent high-speed slidig casig thegalling Dring cotied operaton the transferred materal wears

151



Faiue Aas fo Hez Conac Machine Eemens

Pae No: 8.11

Archive No: 107001a&&cmage ype: SMScaebar a 100 100 c 10 (icros: 20%others 00% 50%)Componen ACBB B, rSpeed:Load:Lubrcaion grease, sFailure Code 00132.12 Cotact gallg fro high accelerationFailure Code 00.12.3.22 Scratch aks, kineatic wear arks inrollig sraceFaiure Code 00.120.1 Adhesive ld weaFaiure Code

PTFaure Descripion: Conned slidig ark on all srface The alspn ad ecae wor y adhesive wear ad, at points of ostsevere conact, galled Sch daage occrs i highspeedapplcations whe kineatic anoalies precipitate sdden highsiding rates (for exape rapid all acceleration). As the alapproaches epicycic speed, sliding rate dnishes and galligoccrrences fade ot Galled srfaces tend to gal agai, spall orseieImage Descripion: (a) O gray atte ackgrond, circlar sector owear arks (dark ackgrond, scratch arks). At W sector edge,several deep tears, exendig alog arcs, are galling. Galing fades to

the . (): Galling initiation area, already soothed y rollig over(c) Detail o gallig, with plastically flow aterial oved andwelded o sface Sall rado ackgrod scratches are

kieatic wear arksSuspeced Causes: f i a hgh speed earig, loadig of a allad/or high separator friction cases drop in all atorotation speed,ad load sddeny retrns the aglar acceleratio ecoes veryhigh. Friction ay ot sffice to prevent gross slidig, localoverheatng, asperty wedig, tearng ad redeposition of ateralesewhere on the srface See also FC 001 Skid arking.

152

Failue Code 00

a

b

c



Failure Code: 00..

TPate No 8.12

Achive No: 00532&33Scaeba 1 mm b 100 m (micros ± 20%others + 100% 50%Image type ight microgrph b EM bcksctterComponent M runSpeed 1. 8 25 m/sec roingLoad: 1 0 125 GPLbcation egie mer ol temp vryingaile Code 003.2 1.2 ontct gllig from highccelertoailre Code 00.1301 Icipiet gllingailre Code : 00.18.0.1.2 Dentg of ollig srfceminor sldigaire Code PLAE 1037

PTae Descipton Fie glling mrks o the vlveopeingmp of engine cm contcted by ole olower trvelngover the cm surce rom tip to blunt end of the mrk thepresence of substtil siding. Gling strek progressivelywidens by trsfered mteril pileup nd bruptly ends whenroller chieves pure rollig velocity. lose lgnmet of gllingmrks especilly t edpoint suggests they were formed i

the sme rolle pss ove the cm suce. Isolted shordets (scoremrks elsewhere my develop ito icipietglling Overrollg drection is mge E to W slidg velocityof roller ove cm is E to W th s the oller is beigccelerted to cm speed nd the oler is he gging surce

Image Descrpton: ( Light microgph of p of cmsurfce o vlveopenig rmp. Finishng mks ecircumferentil. Three strogly elongted trnglrrrowhed shped light gry fiely mottled gling steksre see with shrp incepion points t slighly stggeredvetc postion /4 from E imge edge Gllig mrk brptlyeds i piledup trnsfered mterl the sme EWpostio e imge center. For much shorer thiner brightdents (scoremrks N o the ending lne o he glling mrks.(b EM o edpoin of mos glig strek shown in (.Fiishing mrks obliterted i gllig strek Arcte rows ofne stippled idettons on plstcly displced metl with tps of rcs poitig E Blgig pilep o trnsfered met t

hater Galling, Skid Marking

a

� tOOMX 1 0 0 2 k V B S E # 0 0 7

b

W end of stek ce roled over epetedly fter gllig event resultig i smoothed ppernceSspected Cases: Roler followers in terlcombustio egne cm sysems cn follow the gry vrying cm surceveocity without sliding oly by degoing high cceletios. The orm contct pressre vries rom ero o high vlues duringech cm cycle he rolle follower s sppored on sliding pinbeig n which shrp frcio tore excursons were foud tooccur The trction force vilble i the cm/roller cotct my t some points i the cm cycle be isuficiet to provide theeuired ccelertion nd overcome pin frictio esulting i sidg in the contct. I the sdig velocity d preving contctpressre exceed the gling limit o the contct gling occurs t consists typicly of fie streks wideig s hey progess ndedig shrply when the combition of ccelertio reuiremets nd pn torue drops sufcently to permit pre roing Osubseen ollovers the combito of oller ccelertio reireme nd pin iction my remi below the glg threshold

153



Failure Atlas for Hertz Contact Machine lements

TPlate No: 83

Archive No: 00-06c&gImage type: a: ligt macro metalogam, etcedScalebar = a 5 mm 400 m(micros 0%, oters: + 00%, 50%)Component: CRB OR 500 seel, rSpeed 009 MdNLoad 0.8 GPaLubrcation syntetic poyester oil, 49°CFailure Code 00 3. Rolgsface gallng, dent or ic vsileFailure Code 00. 8. Sarpidivida dent(s) from metal deris,asperities

Failure Code:

00.04. Forming lapFaiure Code

154

REAR LAND

Failure Code: 00

PTFaiure Description Foreig steel cp roled ito contact

sace welded i gang of te cip srace extended laps oveoriginal roling sace Tis sal damage seqece createsig stress cocetration ad was oseved to ave cased lkcrackng.mage Descripton: (a): I all groove (S of 'rear lad), rodended W streak of ligterclor materia srronded y darkarea s for - t is a olled-n foregn steel cip Tinlaminae o transferred meta at lack arrows (): Mealogapicsection, Nita + Zepran etc Heavily plastically worked cip(swirl fow-lies) in NW image qadrat Dark weld lie to asemetal from SW corner to arrow Lap at Suspected Causes: A steel cip was etrapped on te OR rollerpat we operatio was iiiated lt was olled nto te orignalsface, welded i ad lamiae were ransferred along te edgesIncorporatio of sc a large cip into a rolling srface drigoperation is extremely rare.

a

b



Faure Code: 00 Chapter Gallig Skid Markig

TPlate No: 84

Archve No: 93-2Image type: viewScalebar 5 mm (micros: 2% others + %, 5%)Component: SRB; R rnSpeedLoad:Lrication:Falre Code 32.2 Galli of sldin cotact sfaceFalre Code 3 ncipent allalre Code alre Code

PTalre Description: Epicycloidal alin marks o roller hs face

extendi from the roller corer radis to flane heiht. The maks trace the path of a locally overloaded f la e point over the rolle thrst face as it tasfers material to that thrst face n this imaeno si of sharp ede contac is visible ndicai tat he eometyis correct Galin is selaravati, may case seire, heatimbalance or separao faile.mage Description O ray backrond o roller thrst face dark-appearin cycloid streaks end radally ea the corer ad crve

to tanential directio at the lae heiht The streak materia is shiny; dar imae is de to liht reflection. If maniied traserred mateial wold be discerible. n the imae an entire half-cyclod s visble since flae and roller face coformOtherwise marks appear only ear corer adis or at ane ede levelSspected Cases: Excessive thrst load inadeqate lbicaton, skewed rollers contamination, oh srfaces Galli near edeindicates a sharp ede at the flane

TPlate No:

85Arcive No: 8-28Image type: liht macroScaebar 2 mm micos ± 2%others: + % 5%)Component: SRB; IR & R rnSpeedoad:bricaionFailre Code . 32.2 Galin of sidicontact sraceailre Code . 3.2 Extesive alinFailre Code : . 2.3.3. Wear at ede ofslidin contactFailre Code -

PTare Description: Shot epicycloidal all marks on roller thrst faces, ad IR thrst flae face cetered i thrst contactbad Step wor ito roller thrst aces to flae heiht, as alled workhardened matera slides over mati pa. The step worito the roller ed sests excessive cotact wth R flae ede Damae destroys eometry, cases roler sewin ad debris that may lead to spal in Heat imbalace failre is ikely.mage Descrpton: Short aled alln streaks of ht clor on visble face of IR thrst lane, nea both E and W imae edesDepessed anls wor o role thrst faces with anled allin streaks ear ceter of ans. Streas may appea iht or darcolored depedi o lihtin.Sspeced Cases: Contamiatio roh contact srfaces or iadeqate lbication o thst srfaces, probably actin combiatio prodce the allin Rolle skew shfts cotact toward fane ede

1



ilure Atls for Hertz Contct Mchine Elements Faiure Code: 00.

TPlate No: 1

Archive No: 099-125aImage type: igt macroScalebar 40 mm (micros ± 20%, othrs + 100%50%)Component: SG W, md ard, ruSpeedLoad:LubrcationFailure Code 00.13.3 Toot cotact galigFaiure Code -Failure Code : -Failure Code - LAT .1

PTFaure Description: Major gaing of toot adddum surfac, also dsigatd as scoig. Wdig o asptis btwn piioand wl, wit immdiat tarig as tth sparat Lavs transfrrd matria o on tooth and a matcig pit o th mating tooth. Hig load ig sliding vlocit and isufficit lubricatio produc gallig o tt wit usuitab fsh ad/or hardssTis s a dstructv failuImage Description: rom W dg of gar troug 2/3 of imag width multipl rada gallg staks addndum appar lghtcolord o gra background Dark ao aound gallg is si, polshd (wor) surfac t appars da du to lgting. Miimalgallig in dddum.Suspected Causes: Gomtical inaccurac or misalignmt (ovrload ar o sidfac), rough surac, insufficit ardnss,ovrload, high spd and iaduat lubrication all ma cotribut to galling S also Plat .17 showng matrial tansfrd bgallig btw mating ocations o pino ad wh

Pate No: .1Archive No: 04-404

Image type: igt macroScaebar 30 mm (micros: 20%, othrs + 100%50%)Component: HG W surfac hadnd, uSpeed:Load:Lubrcation:Failure Code 00133 ooth cotact galligailure Code 00.1024 Incipnt spaling multiplspallsFailure Code 00.12.5.31 Abrasiv (dstructiv)

toot warFaiure Code 00.1.1.2 Sharp idividua dt(s) frommtal dbrs, asprits

PTFalure Description: Advacd toot surfac damagcomprising galg, dstructiv mid wa (probababrasiv), dntg ad spallig. T galling is conctratdin th adddum, dnts ad abrasiv war i t dddum, with spalls in both aras, mor toward o sid of th ga T garma still ru but would b ois, with incasd backlas lt ma vntua fracturImage Description: Across tooth flaks (spcall wl sown on tooth stang i S cor) four distct contact bads avsibl. At t tip, a narow bad wit adia war marks, followd b a bad o ma axia galling straks (light) and som blacspal cratrs Aftr a sarp dmarcatio at t pitchin, a band of svr dbis dtig with som adial war bads and maspall cratrs (in W), ollowd b t appartl uwor rootSuspected Causes Contaminatd oprato with av war ovr log priod, at spd sufficint to promot gallig (at rougdspots?) ad vntual spallg

156



Failure Code: 00.

Plae No 8.8

Archive No 099-6a&bImae ype a,b light macroScalebar a,b 30 mm (micros ± 0%othrs + 00%, 50%)Componen HG W&P SpeedoadbricaionFaile Code 0033 ooth contact galingFailre Code 006 Surac origin spallFalre Code : 00 53 Adhsiv (dstructiv,ogalig) tooth warFare Code

PFailre Descipion In a matg gar st, asprtorigi cracks fom i ddndm of gar (whl) (a).h wakd matral is wldd to th opposngpinio surfac Trasfrrd mtal o pion (b)forms protrusios, matig with cratrs lft o thwhl War, dtig of wh tooth tips Ga st ispron to arl failur rom ovstrssig o damagdflaksImae Descripon On whl (a): cratrig (dakpits) on dddum. O pino (b) transfd mtalstaks o th addndm ar gnral ight colordo th adddum ad mat with dddum spalcrats. Tooth tips on (a) ar worn and dtdSspeced Cases High-oad lowspd gar sts

of mdium hardss, with poor lbrcato, madvlop this combd conditio of spaling andgallg, whas at high spd, galing, i prsnt,gnral occurs bfor spalls ca orm, ad tnds to lad to gross ailu.

Chpter Glling, Ski Mrking

a

b

157




TPlate No: 819

Archive No 027-178mae type: viewcalebar 4 mm micr ± 20%, ter 00%, 50%)Component: ACBB B, rupeed: 20 KdNoad: 1.8 GPaubrication: greae, 60°CFailure Code 0014 Skid marking micrcpic evere wear)Failure Code Failure Code : -Failure Code

TFailure Descption: Multipe rt kid mark in adm directi entie ball urace, frm ma acceleati evet uderiuffcient lad. Skid marking caue ni peratn in quietruning beaig ad ma eventual lead t pallingImae Descption: Te mirrr-finied ball urace i iluminated b

tw ptligt wite circle reflecin) Te lgt tand and camerarefect a black ape, cvering m f N emipere. lewere,

te ball urface i gra Multiple back bru mark i randmdirecti are kid mark Tree are idetfied b arrw.

Failure Code: 00.

uspected Causes: Ti agular cntact ball bearig mut perate under prelad I te preent cae, prelad wa inufficient adat eac tartup te macie kdding ccurred, makig a kid mark. Te ball repeatedl caged rietati

TPlate No: 820Archive No: 007-109Imae type: ligt metalgram unetced urace

calebar 400 m micr ± 20%, ter + 100%, 50%)Component ACBB; B, rupeed:oad:Lubricaton:Faure Code 00.14 Skid making miccpic evere wear)Falure Code 00021 Grinding ing, lapping furrwFaure Code : Falure Code

TFalure Description: epeaed kid marking f a lapped bal uace.Ball aumed tree rentatin. Skid marking reut fmmmetar ig liding peed i te cac, aring frmiufficiet tracin t tramit equired accelerati. In ig-peedbearing, kid marking ma lead t pallingImae Description: In t view f te ba uface trug ametalgap, ligt incidence i nrma ad cllmated An ufacereflecting pecuar awa frm nrma appea dark afected ballurface i gra backgud apping mar are t, dark randmtraig line. ng kid mark iterrupted paalel black treak)ru NW t S; ate cre it W ear ceter e eac in Sad N crner, runing SW t Nuspected Causes: xceive radial lene, udden l f ladr exceive fricn in eparatr ctact ma reduce balautrtatn peed requirig ig acceleratin wen lad eturwic lead t kd mark.

158





lre Atls for Hertz Contct Mchne Elements

TPat 83

Archv 09314.1.3&&8Imag typ a light microgam,b: SEM c: mtallog., tcdScalbar a: 80, b: 0, c 12 m(micos: 20%, othrs: 100%, 0%)Cmpnn a,c: ACBB I, b: CB; O, rnSpdadricatnFar Cd 0014 Skd making(microscoic sv war)Falr Cd 009. Local strctrdamag rom rictiona hatingFail Cd 3: -

Fail Cd

PTFailr Dscrpn Skid markng rrsnts mltilasrtyscal gallng vnts that do n individalygrow into microgalling. Tis occrs i tactiv orcsmomntarly rird to ovrcom roing body/ringsrac sd dirncs ar xcssiv so thatskidding occrs. Skid marking may cas strctrdamag by local ovrhating In higsdalications skd markng may lad to sallng.Imag Dscriptin (a) Gray nmarkd srac n NEadrant. Whit W lins in ara a sid marks.At C, t skid mak ara athrs ot. Isolatd marksat B. (b): Two skd mark straks (wit atchs) rn

S rom N imag dg ( and witin dasd oval).Skid marking stos at honing lin B. Otr honinglns at C. (c): Sction trog rolling srac (aaB) Wit rardnd skid mark dosts on dark

tmd matrix at Sspctd Cass Excssiv radal loosnss inbaring, or nxctd loss o load or xcss rictionn sarato to rolling body contact may slow downatorotation o roling body otsid th load onWn oad rtrns roling body mst acclratraidly. Tractiv contact orc may b insicint andskidding (gross sliding) occrs momntarily, casingskid maring Onc oling sd is acd, slidngstos so no macroscoic galling occrs.

16

Failu Cod

a

c



Failure Code: 00.

TPate N: 84

Archve N: 007 & 0708Image type: a e, b, SMScaleba a 5 mm, b 00, 40 m (mros 0%,oters + 00%, 50%)Cmpnent: DGBB , runSpeed ayngLad: 35 GPaLbricatin grease, temp. ayngFaile Cde 004 Skd markg (mrosop seere ear)Faile Cde 0000 Geeraled orrosonFaile Cde 3: Faile Cde

PT

Faire Descrpn: (a) Masse skd markng (mrosop seee ear) of al pat as a result of numeros bre g-aeleraton eents underg oad ndental generaed oroson. (), () Detals of skd markgasperty sale materal tanser t subseent mospallg, n burnsedsae. Te raterng l eetually destoy te rg by seure or ature.As no seen, rg s stll sereale (separator may ot e)mage Descptin: (a) Vayng dt streak of mottled (fosted) surfaedon ente o all pat proaby darkeed by peerental oroson aftedsmotg. Coroso spottng elseere. (b) On featureless bursedsuae, agular raters t NS orentato () Featureless tanserredmeta lamnae n S mage alf, oelap at edges (jagged lak lnes)n N /3, mosop aters and raks at exfoated lamnaeSspected Cases: s bearg s used n a naal araft arestng gear operates y absorbng landng araft knet eergy a an arestngale nndng om ts gear Beargs undego g aelerato der

g oad dug ea arrestng ye Skd markng arses om nabty ofall omplement to aelerate to epyl eloty

Chapter Galling Ski Marking

a

c

161



FRING WR 9

9.4

Failure Code 00.15

DefntonFretting wear adheve wear akg place a oaly ac coac uder oral load ad

microscopic urace-parale relave oo he wo ype o reg wear are (common) etting adfalse brinnelling. Boh are urher deed beow

. Nomenclatue Ala he eretting wear adoped o cover boh coo) reg ad ale brelg

. Falue PocessFreg wear a adheve wear proce wh pecal eaure reug ro he coed

geoery o he acrocopcaly ac) coacFreg wear requre oral oad o he coac ad crocopcally all urace-parallel oo

whch ca be vibrato coo reg or ale brellg) or creeping coo reg)

FRETTING FAILURE CODE 0015.1

.. DefntonFreg coo reg) deed a reg wear a coorg coac ypcaly a er

ace)

NomenclatueFreg wear a coorg coac degaed a coo) reg. he word wear' o

ued or cae) A cooly ued aerave degao etting corrosion h aer degao o ued he Aa o avod pobe couo wh checa aack corroo) ureaedo reg ad alo becaue o all aeral ubec o reg how dcoored corroo produc

.. Falue PocessFreg coo reg) occur uualy erace ha ra radal or cobed radal

ad aal) load ovg wh repec o he ed par a bewee bearg rg gear or ca aded ha or bearg rg ad houg. he u be gh eough o ha rapd pg o

he ed par preveed bu o o gh a o preve erely a low creep or reverg oo) he erace. h creepg oo creae ooe wear parce whch or coo eeodze he oygearved) erace o or a blackh red ghy adherg ayer covergporo or al o he erace. cor ue he ae reg corroo' ahough hereed ode ha bee oud o be checaly dere ro he brow a o coo corrooored o ree urace he preece o oure

.. Dstnctve AppeaanceA reed ) urace o ee a pachwork o hree ype o appearace

• Odzed pache varyg clor ro dark reddh o vrual back.

163




Notes:

164

• Bushed areas o metallc colo whch the oga shg maks ae eaced these aeasmay show wea marks the sdg drecto

• Aeas wth oga shg maks

hee may be galled aeas (FC 003) tespersed wth the othes, the teace uderwetapd sdg

Fetted suraces o materal othe tha the usual bearg stees may poduce rettg debs thats ot dscoored

de the (scag eectro) mcroscope, retted aeas (ate lght etchg to emove the adhergode) show mcopts, whee retted partces have bee wo o. hey may also show clustes oshort scatches, made by the wear partces dug uther moto

Causes

General Causes of Fretting he cotolg pating parametes (commo) ettg are ormalcotact pessue ad the speccs o the mcoscopc suacepaae moto (tota dsplacemet oumbe o eversg cycles, amptude)

he cotolg cnac parameters ettg are ot completey deted Ft teerece, whchcotros cotact pressue ad lueces surace-paae moto, s the domat paramete Suacemateral ad mcrogeomety also eet uece, as olows

Had materal appears to ret less tha owe hardess matera o the same composto:

• Hadeed stee parts (beag gs) et less tha sot stee shats o housgs

Materal composto appeas to have a eect o ettg

• Cast o housgs ret ess tha sot stee housgs•

Had-chomum plated shats o housgs tted to hardeed beag rgs esst ettg bettertha sot steel shats ad housgs It s ot clea whethe the chomum mateal o ts hadesss the pcpal acto

• wo smooth suaces cotact appear to ret ess tha oughe suraces• Ceta plastc coatgs o a t surace retad ettg• Sutable chemcal coatgs (eampe phosphate coatg) retard ettg• Ceta compouded lubcats ae beeved to aeate ettg

. Most epeece wth rettg s eated to corodble stee ad cast o t suraces "Staessstee ad oerous metas also et, but the odato to vsbe eddsh ode s ot obseved

. Ltte ormato s pubshed egardg ettg o ceramc gs (meta) housgs Frettgs beleved to occur

Fretting Causes in Rolling Bearings. Frettg the ada t suaces betwee olg bearg gsad shats or housgs s a wdespead pheomeo ot ecessaly regaded as a (dsablg) aue

he ttg pactce o olg beag gs s adapted to thee casses o oad oetato as olows

Load o statoary drecto wth respect to the t teace I oder to pemt aal algeto the beag, such a t s ote made wth postve looseess he statoary oad dectoteds to hod g ad moutg part a ed elatosp ad ettg ca be avoded I theload substatay chages decto wth some equecy ad the t s loose, rapd spg the t suace s lkey, producg polshg ad gag, but ot rettg Beag techoogygeeay hods that ths spg s ot eectvey couteed by ed clampg t may, at the



9.5

Capter Fretting Wear

sk o aks e peveed y keyg Sma ages oad deo a ou w someequey may pepae eg

Load o movg deo w espe o e eae Due o e aveg deeo dee movg oad e g eds o eep umeeay w espe o e mog paad eg s proae To m reg a or movg oad s amos aways made weeee egave ooseess) I g ed movgoad eaes reg dereases weased eeee Howeve exessve ese oop sesses eavey -waedgs ad moug des m e permsse eeee so a reg may oe oay avodae

3 A spea ase s wee o rgs a eag see oads movg w espe o e eaeexampe sake sees) Ieeee s o o rgs may e mpaa due o eesg ay o aommodae deea ema expaso o mae ompoes Iese ases surae oags may e ep oeag exessve eg

Fretting Causes in Gears and Cams eas o ams ae geeay o ed o osgs we posse exepo o a era gea) oe ae moued o sas Te oad deo e eae o a gear o am o a sa s vey aey saoay

ears asm oque so a ey ae oe keyed o sas Eve so eg s oasoayoseved om ases dea o ose sed o eags

Cams dego oqe weever e oma oa ore o e am oe as o ese esa axs su as aog a ramps e am s ed o a sa eg may ou.

Effecs of (Common) Fettingeg a oad ayg eae may ave e oowg ees

• eg may preve smoo dsassemy y geay easg o agas axa emova

o eag rg o gea rom sa o ousg Te osruo may e severe eog o auseaues o eque ug o gs o geas• Freg oges e suae ad damages e geomey ausg eased ae o eg

o spg w wear o gag Te geome dsoo may sue o weake oad suppoad ead o g o gea oss seo rakg

• A seveey eed suae may oa moaks I e ompoe s sue o y edgsesses exampes: eag gs geas or sas) e k ague akg may ae omese moaks. Ts s a ommo aue pogresso sequee

FALSE BRINNELLING FAILURE CODE: 00.152

Definition

Fase eg s deed as eg wea a Heza oa.

NomenclatueTee s o ommo aeave desgao or ase eg

Failue PocessFalse bnnellng desres e eao o a suae depesso a oaded maosopay sa

Heza oa y e eg wea podued ewee e oag eemes we sue oepeaed mosop vraory moo Te moo may e a sma agua osao ad oepeaed wdeg ad aowg o e Hez area as a esu o me-vaae oma oa oad

165



Failure Atlas for Hertz ontact Macine Elements

166

he urae a fals brel ark wor a d ro ha o a tru bre ark FC 00.8),whh a pla deao reaed by he oee appao o a hgh ora oad o a aoa or o a hok oad o bre durao o a lowly ovg oa

Dstnctve Appeaancehe ae brell ark o a Herz oa urae a depreo he hape o he a Herz

oa area h ark dea hape o a rue brel ark reaed by pla deaoo he oag body ee FC 00.8). he urae he ae brell ark a wear uraeorga hg ark are eaed ad a ae o-dreoa urae appear. By ora heurae o a rue brell ark rea he orgal hg ark

Causes

Rolling Bearings wo d aue o ale brelg bearg are kow Bearg uder load whe o roag bu ube o abe vbrao or hok a durg

he rapor o a pakaged bearg or a ae by ra o a eer degree by ruk) udergoroop relave oo he Herza oa ad develop ae brellg he eeo bearg rapored ahery ay be orolled by akg hage hppg arragee uh a uloadg he bearg or uhog he vbrao. he ee o bearg hpped pakage appear o be led o era lae o large bearg ad oroled bypakagg ha appe kow ela oad aro he oa

Bearg a erve eag oad arred uder low-angl olaory oo ay uer aebrelg whh ay be gaed by deg oad adue d eeo o lubra.However ale brellg o away avodable uh erve odo

I beeved ha oa preure reduo harder oa aera udg oe oag adooher oa urae redue he every o ae brelg

Cera opouded lubra are repued o allevae ale brelg bu her eay appearo be ed o argal ae

Gears an ams ear oaded oa uder roop oo eape ple ouplg)ay uer ale breg

Fae brelg a ye o beeved o be a oo alure

Effects of False Bnnellng

Rolling Bearings

• A ale-breled bearg wl be oy vbraory) operao.• Severe ae brelg ay produe ue load reae upo operao o brg o

preaure palg• he ale-breled urae beg dere opography ha he auaured urae h

key o par EHD lubrao ad be ore proe o urae dre ad oeque pallgha udaaged urae area

Gears an ams Fae brelg o geeraly odered a aure gear ehoogy ule ake he ye vulerable o eodary wear ague or gallg alure reulg ro urheroa o he aebreled ad hereore geoeraly pared urae. Caue ad orolare lar o rollg bearg



hapter Frettin Wear


Failure de

67

Plate N

9

677676

9

16



Failur Atlas for Hrtz ontact Mahin Elmnts

PLATESDTlte No 9Arcive No 093-5 .3Imge tye M HCI eScler 20 m (mirs 20%ters 00%, 50%Comonent DGBB; OR, ruSeed 450 KdNLod 3.5 GPaLubricon syntet plyester il 80CFure Code 005. Fetting (freting rrsiFlure Code 2 Fiure Code

Flure Code

DECRIPTION

Failure Code: Failure Code: .

Fure Descrition urae vered wit sr parallel sra marks ased by te aspeity sale sidig mtin f IR mvig saft nde rtain g lad. Legt marks sugg ess 2040 m sl idi ng amplitu de Numes smal l ( < 0 m pits in diate ettingA few frettig rrsin lakes. Fretig destrys saft gemetry fr mnting a replaement bearig xessive frettig may initiaterakig r ead t rig spining sat ad seizure.Imge Descriton Bakgrnd sae, were visble, is a featureess gay indiating remval f grindng lines Mayirmsribed pates filed wit W ( sligy f runig wear marks. Nmerus pits due t fretting wi gt-lredals (idiating sarp edges?. Frettig rrsi prdut remved by etng, exept a few islated dark flakes.Susected Cuses IR perating der ratig lad (statinary agaist OR, ad ftted wit mderate inteerene may defmunder lad t eate a gap ppsite te lad ad ten it desribe epiyi mti n e saft I mtin is slow, ten mderateretting rs. If it is fast eavy frettig, plisng r galling may ur.

DTlte No 92Archive No 093-22. 4mge tye ligt marScler 2 mm (mirs 20%ers + 00% 50%Comonent DGBB IR&OR, rnSeed 450 KdNLod 3.5 GPauriction miera il, ooFlure Code 0015. 1 Geeralizedretting, radial fi sraeFlure Code 2 0022.2 Blk aige rakFlure Code 006. 2 pall frmsbsurfae deet

Flure Code 0022 Ovestess rak

DECRIPTIONFlure Descrition: OR f eavily laded DGBB mved mispially in using, pssibly aided by using wear r iaurayausng eavy fretng rrsi. A inwad-ging rss-sei rak was intiated in bending fatige at te OD were te suraewas damaged by te rettig We te rak reaed te Herzia sear stresses a sbsurae-rgin spall was preipitated.vetually, an verlad rak split te ring. Te bearing as failedmge Descrition eed uterrig viewed frm OD (part a wi eavy blak frettig pates and a gray rnd spt wereusig was interupted by a sensr bre Crak sufae is fae (nt see Oter rig alf viewed frm D (pa b, wt matingrak surfae at Fatige rak stars at OD (al-m sape; spal exends frm it Remaig set sffeed verlad akngSusected Cuses Very eavy radial ad f (fatigue test bearing fen auses OD fretting reqing speia tting preautisWen retting is exessive, fit srae bemes vlnerabe t bending fage rakg wi may be fllwed by spallig at tentat surfae and, finaly, verlad fratre

68



ailure Code: ....ailure Code: ..

Chapter Fretting Wear

DTlte No 93

Arcve No 027-9Imge tye l mar [EE MAGE I N AENX.Scer 0 mm (mrs 20% ters: + 00%,50%Comonen GBB, ruSeed 250 KdNLod 2.7 GaLurcton grease 60CFlure Code 00 5. 20.3 Exessve frettg, lse ri narate radal fitFlure Code 2 Flure Code Flure Code S also LAE 94 t 98

DECRIPTION

[See Image in Appendix}

Flure Descrton OR O veed wit retting rrsin ( alized lad e diates radal lad and lse r inarate fit.Exessive vbrai f rtr as same effet ee lates 94 trg 98 fr mpasn Fretg f is severity may lead bulkraking.Imge Descrton Reddis-brw atig vering OR O t fll O widt, extedig agulary trug ad zne. Frettingrrsin prdu may be mre reddis ta emal rrsi (t distingisable i ts image. Lan ad pattern bearing are diagst.Susected Cuses igifiaty radialy laded rg may mve in lse fit even if ad s nminaly statnary if fi is exessivelylse r i naurate r i srg rtr vibatins exist Tese auses prmte eavy etting

DTe No 9.4Arcve No 027 20Imge tye lr view [EE IMAGE IN AENIX.]

Scer 20 mm (mirs 20% ters: + 00%,50%Comonent ACBB (wit plasti separatr uSeed 80 KdNLodLurcton grease, 60CFlure Code 00. 5 .204 isplaed radial t rettigfrm ig trust ladFlure Code 2 Flure Code Fure Code

S also LATE 9.3 9.5 t 98

DECRIPTION

[See Image in Appendix]

Flure Descron Exessive trust lad aused fretting bands n bt OR O and R bre fset i ppsite axial diretis(ea abve te ball ntat plane ee lates 9.3 ad 95 trug 9.8 r mparis. Exessive trust may ase early faiures.Imge Descrton Reddisbrwn band su rrun dg OR O and I R bre (arrws rugly ver ball nta plaes Frettig badin IR bre is displaed fm enter pae t mage N, bad OR O is displaed image , indaig trst lad. Frettigrrsin pdut may be mre redds ta emial rrsi Lati and patter n bearing are diagnstiSuseced Cuses Very eavily trust laded bearing wil mve bt sig ad saf fits even if fit s pperly seletedFetting etrates ver plae f ball tat

6



Failure Atla for ertz Contact Machine Element

TPlte No 95

Archive No 07-4Ime ype lr vew [ IMAG IN ANDIX]Scler 0 mm (mrs 0%, thers: 00%,50%Component DGBB unSpeed 60 KdNLod 8 GaLuricton grease 60°CFiure Code 005 ..05 kewed radal ft frettngm msagnme ntFlure Code 2 Flure Code 3

Filure Code S also LAT 93 94 96 t 98

CRIPION

ailure Code: .ailure Code: .


Filure Description Frettng rsn n OR OD shws tw pathes dametaly and dagnaly ppste ndatve f msagnedOR n hus ng ee lates 93, 94 and 9 6 thrugh 9 8 f mparsn. Msal gned OR s lke ly t prdue parast ntat ladsand early spaln g als nsy runn ng an d pssbly buk rn g ratureIme Desciption Reddsh-bwn pathes n OR OD plaed dametrally and dagnaly ppste Frettng rrsn prdut maybe mre eddsh than hemal rrsn Latn and pattern n bearng ae dagnstSuspected Cuses Msalgned muntng f OR n husng may pae mment lad n t ths nentates ft pressures at twdametaly and dagnaly ppste areas hese areas are kely t fet

TPlte No 96Achive No 07-5me type lr vew [ IMAG I N ANDX.]Scler 5 mm (mrs 0% thers + 00%

50%Component DGBB runSpeed 30 KdNLodLuriction grease, 60°CFilure Code 00. 5. 0.6 Onesded adal ft frettngfrm tapeFilure Code 2 Filure Code 3 Filure Code -S also LA: 93 t 9.5 and 97 98

CRPTION


Fiure Description Frettng n O R OD , frm enter plane t n e rner adus ndatng nentratn f t pessure n nesde (tapered hus ng bre ee ates 93 thugh 95, 9.7 and 98 mparsn Fttng OR n tapered hus ng bre may ausensy unnng and rumferental buk rng rakng r nternal rada prelad wth ealy spallng.me Description Reddshbrwn streak rlng OR OD, far t ne sde f enter plane Frettng rrsn prdut may be mrereddsh than hemal rrsn Latn and pattern n beang are dagnst.Suspected Cuses Fttng an OR nt a husng bre wth exessve taper nentrates ft pressure near ne sdefae, ausngfrettng and pssbly nternal radal pelad

170



ailure Code: ....ailure Code ..

Chapter Frettig Wear

DTlte No 97

Arcive No 027121mge tye r ar SEE IMAGE N APENDX.]Scler 0 mm (mirs: 20% thers: 00%, 0%Comonent DGBB rnSeed 160 dNod 24 Gauricion grease 60°Filure Code 001 2.0 7 rega reting in disted radial tFlure Code 2 Flure Code Filure Code S also PLATES: 9 t 96 and 9 .8

DECRPON

[See Image n Appendx]

ilure DescritonPathy reting n OR OD highighting aeas heaver ntat with disted hsing. See Plates 9 thrgh96 and 98 r mparisn Distrted hsing ay prde rng blk atre r early spalling. al heavy ettng ay in itsel

lead b lk raking Imge Descrition Reddish-bwn irmerental pathes n OR OD interpted radaly where it nat is insient. Fettingrrsin pd may be mre reddsh tha n heial rrsin atin and pattern n bearing ae diag nsti. Patern rettingvaries wth d sed gemetry itSusected Cuses Distrted hsing weak hsng (r R disted hlw shat} nentrates retting at pints heavierntat

DTlte No 98Arcve No 027-26Imge tye lr vew [SEE MAGE IN APENDIX.]Scler 10 m (mis 20% hers: + 1 00% 0%Comonent

ABB (dbe rw rnSeed 20 dNoduriction gease 60°Fiure Code 001 208 Freting in hattermaked adia tFlure Code 2 Flure Code Flure Code S also PLATES 9. t 97

DECRPON


Filure Descrition OR OD itted in hsing wth high-rder waviness (hatte shws axial rettng arks spaed peridialy.Freng his severity is n a aile I exessive hate in a hsing may ase ring distin and lal nat verad withspalli ng See als Plates 9 thrgh 9.7 r mparsnImge Descrition Reddish bwn perid i axia arkings irli ng OR OD t ne side enter plane Sreaks are m re

prnn ed and m re dise in tw bands near the ente plane This pattern shws ltte ring rtatin in the hsi ng an dndates hatter in hsing Fretting rrsin prdt ay be mre reddish han hemal rrsin atn and pattern nbearing ae diagnstiSusected Cuses Vib ratins n he press mahnng the h sing bre may ase hatter marks (waviness high rdeThe ring its re heavily at the high pints and rets mre Litle ring rtatn has taken plae i arks reain distint (hatte this seveity n rng OD s nlkely

171



Falr Atla for Hrtz Cotact Mach Elmt

DTlte No 99

Arcive No 027-282Imge tye lr view [SEE IMAGE IN AENDIX.]Scle r 20 (irs: 20% , thers: 00%, 50%Comonent ABB R uSeed 1 60 dNoduriction grease, 60Filure Code 00.1 51 . Fit si deae rettigFilure Code 2 -Filure Code -Filure Code

ECRPTON

Failure Code: .Falure Code: .


Filure Descrition Thust sideae ABB R shws a iterittet ireretial streak rettng rrsi due t veentuder axial ad agaist shat thrst shulder. Seves as idia axial lad. Nt a alremge Descrition On hrust ae I R, a streak reddishbrw rettig rrsin rs a dashed uerenal i e. Mi rretting esewhere Dark bad ext t bre is ( ng rund rner radiusSusected Cuses IR ving slightly iteerene it against shat is pressed against thrst shlder uder bned lad withsgiant thrust pnent Frettig ay rest

DTPlte No 90Arcive No 014-61Imge tye viewScler 20 (irs: 20%,thers + 1 00%, 50%Comonent TRB; IR taspedSeed 0 dNodurictionFiure Code 00152 False brinnell ing ntat suraeFiure Code 2 Flure Code Filure Code -

DECRIPTINFilure Descrition Inipient ase brelling arks at rler spaing, n the rling path a TRB IR (e Marks as ld asthese ay ause nisy nig r ailreImge Descrition Duse axia streaks n rlle path at rler spang Marks bee visible by haging the luster thesuae as riginal iish ig lin es are bliteated. rile traing ay shw ittle deph Mirspy wld ind iate hange i n, reval , se ishin g l inesSusected Cuses Transprtati a ahie (sh as a rad vehle wih the bearig uted and weight-laded (as in a

wheel bearig ipses sal sillatry tins n stainay bearig

72



Failure Code: . Chapter Fretting Wear

DTlte No 9.11

Acive No 01411mge ye ight igraSclebr 1 (irs 20%thers 00% 0%Comonent TRB OR transpedSeed 0 dNLodLubriconFiure Code 001 2 False brinell ig nta sraeFure Code 2 -Fure Code 3 Flure Code

DECRIPTIONFlure Descrition alse briel ark r rller lie tat n OR. rsshath inishing arks bliteraed by rettig Falsebrinellig ay ase isy runig bearig ad i severe ay ead t spaligImge Descrition Bakgrd shws rss-hath hi ng pattern OR rll er pah NS band i g alg iage eter isalse-binnell ak. N rsshath arks i i. Dark ad lght areas n ark ay be due t light releti r pssiby retngrrsinSuseced Cuses False brnelling rs i statinary Hezian ntas nder lad subjet vibratin whh auses tins the asperity sale. Transp autbies arrer vehiles ay ause alse brine lig in wh eel beaings

DTlte No 912Arcve No 0904Imge tye light rgraSclebr 00 (rs 20%

thers + 1 00% 0%Comonen DGBB IR transprtedSeed 0 dNLodLubriconFure Code 001.2 False binnell ig tat saeFlure Code 2 Flure Code 3 Flure Code -

DECRIPIONFilure Descion False brielling hasreved iishig arks ver a path ithe ntat area leavig irreglar

rasverse arkgs alse brineligarises r vibrary lad stly i theabsee bearig ratin as a rettigwear press t eates nisy rn ig bearings and ay lead t spali gImge Descron Fiishig lnes ru EW Tw deep blak srath aks (i NE and SE iage rers are aiats. In iageeter iishig lines ae ssing due t retting ve blg area extending EW (the tat ajr axis is NS. Irregular NSarkngs in the alse-binnelled area were prdued i the rettig press.Suseced Cuses Fase brinelling rs in (eary statiary Hertia nats sbet t vibrai under lad ausig tisn the asperity sale he iruereial el ngati the alse-brine led area sug gess that the bal l psitins sh ited du ng therettig press

73




DTte No 9 .1

Arcive No 1 07-00abImge tye SEMScler a: 000, b 200, : 40 m (mirs 20%thers: 00% 0%Comonent ABB IR vibratry tesSeed 0 dNLodLurction grease 0Filure Code 001 2 False brinnel lin g n ntat suaeFilure Code 2 Filure Code 3 Fiure Code See lo PLATES 9 11 9 .1 2 and 916

DECRIPTONFlure Descrition: False-brinnelling alng utline Hetzianntat subeted t stritly nrmal vib raty lad n rtati nFretting starts at ntur predminanly near ntatendpnts where sliding is greaest Fase brnnellng beginswih smthing inishing lnes and prgresses t ratering.Appearane aters diers rm surae distress: n steepraer wals (mpare Pate 9.1 6. Imge Descrition (a: View entire ntat elipse, majraxis running NWSE and utlined as a light-lred eliptialline n darker bakgrund inishing lnes running SWNE(b Ellipse end expands and nrats with lad Smthing inis hing l nes ( NE rates aters ut inng min imu mand maximum psitin and dtting the area between. (:Smthed inis hing ines and raters at extreme ell ipse tip

Susected Cuses nat subjeted t satinary vibratryladng in nrmal di retin. Size nat elpse hangeswth lad wih s idng due t tridal gem etry ntatarea Sliding is mst prnuned at ntat endpints. Thismirspi sliding prdues the retting phenmennOverview alse brn nell mark in Plates 91 and 9.1 2.

14

ailure Code: 1.

c



Failure Code

DTlte No 914

Arcive No 001 0Imge tye SEMScler 20 m (mirs: 20%, thers 1 00%, 50%Comonen ABB; OR maresii stailess, ruSeedLoduricon sytheti plyester l ? Fure Code 00152 False binelling na sraeFure Code 2 00061 rimary arbdeFlure Code 3 Flure Code

DECRPTIONFlure Descriton Remval matrix material by alse brinelling

type etting rimary arbides i maesiti stainless steel arelarge and very hard, ths ret ess ad prtrude Ths gyrspegimbal beaing nderges slw intermittet mti, velaid bysmall ampitude sllati (hutig EHD lm at rm, retingrs ver etire verlled s rae. The bearig lses pre isi and riti trl is impai red

Chaper Freing Wear

Imge Descriton mage shws retted ntat srae S 2/ image shws EW ridgig rm asebrinelling ype rettingLage ptruding smth l mps ae pri mary arbdes N mage ed ge appears less retted, bt inish ing lies have bee b literated.Susected Cuses Gyrspe g m bal bearngs have extremely ine iish ad req ire hi gh pres. They are e made martensiti sailess steel Due t small am plitde sllatin (hun ting , s uperim psed n emittet slw mis, reting (asebrieig nditins exist. Fretted matrix material is iterspersed with pimary arbides

DTte No 915Arcve No 091521

Imge tye viewScer 1 5 mm (mrs: 20%, thers: 00% 50%)Comonen SABB OR tansped, ruSeedLodLuriconFiue Code 00152 False brinellig tat suaeFiue Code 2 001 22 1 1 Wear trak etered tatFiure Code 3 001 51 Frettig (rettig rsiFilure Code

DECRPTONFlure Descrition irular ase brel l maks at ball spag i thespherial ball path the OR. Wear traks rm sbsequet ruig net Athe alse brinel marks Fettig rrsi n OD Fase brnell maks whe

severe, as here, ause isy rug ad eary spalling May als damageseparatr thrugh hgh ball ntat lads. Visibe wear rak ad OD retigare nt alresImge Descrition OD sae OR shws irmeeial blak streaks retting rsi ver at least Y irmerene. Rig may have shed ihsg ID surae is spherial ball path, with reglarly spaed dark ad lightirular marks i bth ball rws, as a ad 8 rm ase briellig. hagei luse ball path bewee alse briell marks s wear tak, presumablyrm runig bere ae staay damage.Susected Cuses Bearig was prbaby adially preladed sie alse bielmarks exted ver a least irmerene Bearig was expsed t vib raty m i statiary dii, prbably du rigraspr the mahie taii g the bearig Lae, bea ing was ru , ausg th e wea path (aggavated by alse brin ell marksad reg bads OD

75



Failure Atlas for Hertz Contact achine Elements

Dte No 9.16

Arcive No 1 07 002a&b&cImge tye MScler a 00 b: 1 00 c: 10 m (micrs 20%thers: 00% 50%Comonent ACBB IR mnted tansred runSeedoduriction grease 0Clure Code 00.5.2 False brnneling n cntact suacelure Code 2 00.1 7.1 .2 Micsallng (adanced s facedistressilure Code 3 ilue Code See also PAT: 9 11 9 2 and 1 1 . 1 6

DECRPTIONiure Descrition False brinn el ing , that is fetting fstatinar ball/race cntact u nder ibratin in ishi ng makscmetel bliterated extemel fine micsall ing f aseritcntacts cnsttting suace distress. This whee bearingtansted n a ehice was sbjec t angl ar scillatinFalse brinnel marks case ns rnning and ma ead tearl macrsall ng ee Plate 9.1 and 9 .1 2 fr eriew ffalse brinnell ingImge Descrition (a: Oeriew f falsebinnell ed atchaearing sht blasted A few N fini shin g l nes tsideatches. (b: Medium magnifcatin iew f alse binnell.Dense c luster f black its' n featreless lasticall wrkedwrn suace. (c gh magnifcatin f the its' shws them

t be m icrsal craters hese ind iidua crates cannt b edistinguished frm suace distress mcrsalls (see Pate16 Macrcnfiguratin is diagnsticSusected Cuses False brnnellng ccurs in statinarHertzan cntacts nder lad sbject t ibratin whichcauses mtins n the aserit scae. ubsequent rnningma hae sueimsed sace distress (FC 00.17

76

Failure Code 1.

c



Failure Code ..

DTlte No 9 . 17

Acive No 018120mge tye viewScler 20 icros 20%,oters 1 00%, 50%)Comonent SRB OR SeedLodLuctionFlure Code 00.15 .2 ase briel g ocotact suaceFilure Code 2 00.20.1 Corrosio staiFilue Code

Filue Code

DECRIPTION

hapte etting Wea

Filue Descriton Dese paralle aia arks of alse riellig ot roller paths cocetated a load oe. Scatteredcorrosio stais i ads o sperical ID of OR ostly i two bads accopayg freted strips Dese ows of alse rellarks id icae vbraio su perip osed o rotatio as i a v iatory appl icato Water i gress ito the l bca ay eplai thecorrosio arly spalli g epectedImge Descition I te sperical D of the cut OR two circ feretial bads o light ad darkcoored sharp aia arks aefro alse bri ell g Black patches i the ID cocetraig i two bads boad fro alse bri ell arks are corrosio staisAt age S ceter hese ovelap ase brel l arks suggestig corrosio at a ate te. Cotrast with electric erosio flutigC 0021 ) sowig olte suace craersSusected Cuses Vibatory aciery for eaple saker scees) subect shaf spport bearigs to eavy vibratory forceswhch are ot sychroous wit rolle passage. False briell arks ca iiae at rado ocatos. A selfreiforcig process ispostlated to eplai serrated rater tha sooth frettig. Saer screes ofte operate wet ad water igress ito the lubricaca case corroso.

DTlte No 98Arcive No 0870Imge tye viewScler 1 0 icros 20% others + 100% 50%)Comonent CRB OR raspoedSeed 0 dNLodLurctionFilure Code 00.15.2 ase brellig o cotact sraceFilure Code 2 00.20.1 . Cotact corrosioFilue Code 00.12.2 Wear rollig suaceFilue Code

DECRIPTION

Fiure Descrton Bearig stored i outed codtio) wtisuffciet us proecto suffered patcy corrosio staig oroler path idicatig corrosve lbrica or presevatve. Rollesoscillated throgh several degrees reovig sta u der he Isoe positos oscillatio sufficed o cause alse biellig Thebearig is epected to ai fro wear or spali g i operaedImge Descrton Black patches te roller path are corrosiolabel) Wide recagles at roller spacig are wor clear ocorrosio. alse bri el ig label) cosi ss o arrow rectagleswit a luster differet ro te tact sace. Bearg otedwhe trasported sifted posito to wear away corrosio over te wde ecagles. I soe positios) ase riellig occred.Susected Cuses outed bearig traspoed wih isficiet rust protecio ad eposed to subsaia oscilato soe ofwhic persisted log eoug o create false briellig

77





Failure Atlas fr Hertz Cntact Machine Elements

180

and icrotre ateration egin to occur raidy. hee change in ateria tructure roughtaout y the icrolatic low have een decried variouy a deoration and, lightetching or whiteetching area, when dieinated in the highy treed voue. hey aredeignated a utterlie when ored around a oint deect uch a an incuion. he lightetching trucure aear in the or o thin lenticuar voue oriented at ixed angle to thecontact urace. When viewed in a ection arale to the roling direction, the deorationand aear a wo erie o narrow and riing at ange around 30° and 0° with reerenceto the direction o contact trave

Microcrac are itiated at oe tie during Phae 3 at " deect ocation within the laticalyaltered ateria voue he icrocracing uuay occur at the contact urace or eweenthat and the deth o axiu Hertzian hear tre. (See ucae atigue, elow, or cracinitiated at deeer evel.)

5 A acrocoic crac, driven y high Hertz hear tree, i ntiated ro one o the icrocrac contitute Phae crac oration and crac growth. ro a noral initiation oint

aove the axiu Hertz hear tre, the crac travel downward into the ateria, at anacute angle with reect to the direction o contact travel, untl it reache the deth correondingto the axiu (unidirectional) Hertzian hear tre.

6 he ateria volue underined y the crac spalls ut oring a crater (exoliate) aong acrac runnng uward at an angle o aout 30° to the urace and arae to the 30° deorationand, herey oring a crater ounded y racture urace 7]

7 T roce ay reeat ite to exand the ae al or to initiate other

Saling atigue ie i erently tatitica. i i the cae reualy ecaue deect everityand ocation, two deterining variae o lie, are tatiticaly ditriuted aong acrocoicayidentical contact coonent. Other aling ie ode oulate an erent dierion o cracgrowth rate in the atrix, without invoing deect o tatiticaly ditriuted everity

wo ajor clae o aling ailure are ditinguihed according to the location o the initiatingdeect

Subsurface rigin spalling ro deect in the ul aterial uject to the Hertzian cyclic treield he deect ot iey to roduce thi tye o al are located near (ut generaly aove)the deth o axiu alternating Hertz hear tre n t ye o alling, Hertz hear trelevel, aterial atrix atigue reitance, deect evrity, and deect location are the goveringvariae deterning lie to aling.

Surface rigin spalling ro deect in the iediate uurace ateria uject to aeritycae cycic tre ied. hee deect al into wo ain clae reexiting deect and uraceditre. t can e argued that al deect in the orer ca initiate alling y irt cauingocaized urace ditre. n thi ye o aling, actor rooting allng in addition toevere eve o the variae enuerated under uurace origin aling are: urace ditre

and high vaue o tractive tree in the contact interace. Reidua tre in the uuracelayer ay roote or retard aing, deending on whether it i tenie or coreive.

Nuerou dierent atheatical ode have een rooed a tool or the eection and deigno rong earing aed on the rediction o alng atigue ie A review o any uch odeli in alian [3] hat aer ao include a review o rooed aiure echani.

. Distnctve AppearanceSal, a a cla, how a highy ditinctive aearance A uly deveoed al (with it diaeter

uch arger than it deth) how a ditinct otto and wall. he wal ay interect the uraceat a tee or hallow angle, a urther eciied eow.



Chapter 1: Spalling

The spal botto conssts of a seres of crack surfaces As a whoe, t paraes the contact surface atroughy the depth of the axu undrectona shear stress n Hertan contact Spas substantaylarger n area than ther depth often show serratons n the spal botto, whch run transerse tothe rolng drecton. They are fored one at a te as a crack penetrates downward n the drectonof contact trael at an ange of about 30° away fro the surface unt t reaches the spal bottoee, and then the underned pece breaks away aong a pane rsng n the drecton of contacttrae at an ange of about 30° toward the surface. A subsequent crack fors further aong the rolngdrecton, proceeds down nto the atera and fors the next step when the underned ateralbreaks away As ths descrpton ples, spals tend to propagate n the drecton of contact trael

The sdewals of a spall and a band on the ext wal closest to the surface are often nearradafracture surfaces

The spal entry the end frst reached by the rolng body) ares n appearance dependng onspa orgn and s useful n dfferentatng between orgnaton processes see beow).

Notes on Atypcal Spals

. Spals on bas. The bas change rolng axs, causng spals to appear ore crcular Oerlappngcrcular spals, startng fro dfferent ponts, ay for a custer.

2. Spas near sharp edges or ne defects scratches) . These tend to be shaow, for a narrowband or becoe ess nuerous as one recedes fro the edge Spals arsng near edges or frolne defects ay show atypca outlnes refectng e defect or edge geoetry. A spal forngat a sharp contact edge often leaes a narrow unspaed lp of atera at the edge as a resutof the dstrbuton of shear stresses wch reach ther peak alue a sa dstce away frothe "cff fored by the edge.

3 Spas n scon ntrde) ceracs are not extensely docuented. Good scon ntrde s qutespa resstant and the lates showng scon ntrde spalng represent unusual test condtons.Nonetheess t appears that spals n scon ntrde tend to propagate slowy, and ay restartseera tes rather than propagate fro a sngle orgn

One or ore of the folowng dstngushng features of surface and subsurface orgn spalls aybe present n a spal. Howeer, spals showng no cear dstngushng features are coon and arecassfed as spas of neternate orgn.

Subsurface Origin Spall Any of the folowng dstngusng features ndcates a subsurfaceorgn spal

A teep entrane wall nclned by ore than a 45° ange to the contact surface).

An rgnatng uburae deet ay rean sble after the spal has fored or ay be ost wththe spaed atera.

Surface Origin Spall The dstngushng features of a surface orgn spa are n the entrance oneof the spal, wch ay show any of the foowng features

A hallow-angle entry wall nclned at ess than a 30° angle to the contact surface) An arrowhead confguraton fored by two shalow cracks eanatng fro a coon pont

defect The presence of a vble urae deet ck, dent, furrow, pt) just upstrea of the spal ntaton,

often wth a narrow edge of unspaled surface between defect and spa

8




82

Subcase Spalling In subcase spaling (see explanation of causation beow), spal depth is greaterthan the maximum Hertz shear stress depth The spal bottom follows the case core interface This

ype of spalling is often caled case crushing. (See aso core cracking under C 00.22.)

. CausesSpaing fatigue was ong considered the "default failure mode of Hertzian roling contacts. It

was believed that the fatigue limit stress for Hertz contact fatigue is zero, so that any load, if appiedlong enough, wi cause spaling even when no assignable faiure cause can be found. Therefore, acontact surviving all other failure modes was expected eventualy to fail in contact fatigue

Recent evidence obtained with very carefuly made roling bearings operating under highly favorabe conditions suggests that a non-zero fatigue limit stress exists so that at quite ow loads, and inthe absence of al significant surface and subsurface defects, spaling fatigue may not occur. Morecomon is the case that spaling fatigue is preempted by one of the many competing failure modes,

or is brought on by some practicaly unavoidabe damage incuding contaminationCommon Spalling Causes

Material (Matrix) Deienie

• Low hardne No low-hardness material is known which possesses good spang fatigue resistance. In steels, spaling resistace increases with hardness up to quite high vaues In bearings,oy high hardness parts have exhibited satisfactory fatigue ife under significant contact oads.In gears, where contact stresses are typicaly lower but sliding is substantial, both high andmedium hardness components show fatigue resistance that competes successfuly with the otherfailure modes

• Subae Salling In case-hardened components, a gradient of decreasing hardness exists from

the case to the core If the hardness gradient is steeper than the gradient of Hertz shear stress,then the stress to strength ratio is least favorabe at some depth beneath the norma maximumHertz shear stress region. Fatigue faiure may initiate in the core or at the case core interface

Matrix Inhomogeneity

• In stees, soft structura constitents reduce spalng resistance• Materials consisting of hard particles in binders (cermets and many ceramics) fail at binders.

Silicon itride components (most often used are bals or rolers) may spal from porosity, binderdeficiencies or as a consequence of surface damage such as a nick or dent, either on the ceramiccomponent or on the mating component (usualy a stee rng)

Contat oad Any operating condition bringing about higher than designed Hertz pressures onany part of the contact drasticaly reduces spaling life, unless the oad is so low as to be below thefatigue imit. (Life generay decreases as the inverse 9th to 12th power of Hertz pressure.) Exampes:

• Tota machine eement load in excess of design.• Load madistribution among roling elements in a bearing or among gear-teeth in gearing.• Ma distribution of pressure in a contact (through edgeoadng or profie errors) .

Contat Temerature Excessivey high operang temperature, at which the materia's workinghardness is substantialy ess than its room-temperature hardness, reduces spaling resistance (Otherfaiures, such as ubrication faiure are aso i<ely, unless special precautions have been taken.)



Chpter 1: Splling

Numbe of Ste Cyle Spang s a damage accumuaton aure mode so that ts cumuateproaty ncreases wth the numer o stress cycles. Ths does not mply that the haard o spang

wt a fxed ncrementa numer o cyces necessary ncreases wth tota accumuated le

Cuses of Subsurfe Origin Splling

Subufae Defet Sevety

• Inluon onmetac nclusons n steel and oregn metac ncusons n powder metas orceramcs can e spallorgnatng deects.

• In steel, had bttle nonmetalcs are more seere deects than ude ncusons o comparale se.

• age cardes may act as deects, athough some stees wth qute arge cardes exampe:hardenae staness stees) show acceptale spalng resstance Carde egegaton or netwokare detrmenta.

• Pooty ods) n the matrx, are spal ntatng deects just as ncusons are. Porosty s apartcular haard or ceramcs.

Cuses of Surfe-Origin Splling

Sufae Defet Sevety

Peextng Defet

• Nk and dent FC 00.0 and FC 00.) are drect aspertyscae stress rasers capae o tatngcracks Dependng on the se o the deect, these may e aspertyscae mcrocracks then theatgue ntated s surace dstress) or macrocracks then spalng s drecty tated).

• Fnhng mak grndng urrows, ushed areas, etc., see FC 00.0) may e drect stress rasers

or may cause suraceorgn spalng y precptatng surace dstress see FC 007) throughntererence wth EHD lm ormaton.• Gndng damage FC 00.0) may comprse tempered matera, rehardened matera or grndng

cracks. Upon cycc stressng, cracks orm ready n matera damaged y grndng, een nocracks exsted at the start o serce. Grndngdamaged matrx has ow atgue resstance, soether surace dstress or drect spalg may orgnate there

• Neaufae tutual damage to the matrx, such as suace decaruraton n stee FC 00.07)produces reduced atgue resstance specfcaly or aspertyscale crackng.

• Pttng rom manuacturng operatons FC 00.03), corroson FC 00.) or electrc erosonFC 00.)

Sufae Dte

•

he phenomenon descred under FC 00 7 as surace dstress or aspertyscae atgue producesa large popuaton o aspertyscale mcrocracks and mcrospas, whch act as precursors tomacroscopc spalng.

Gallng o kdmakng can e precursors o spalng.

Tatve Ste n the Contat Intefae Hgh tracton may resut rom hgh sldng speed, low ratoo EHD m tckness to surace roughness heght, or neecte oundary urcaton Hgh tractons eeed to exert a drect effect on suraceorgn spalng. It s osered that the copous mcrocrackng characterng adanced surace dstress does not automatcaly ead to masse spalng as twoud al mcrocracks propagated to produce macroscopc cracks and spals It s conjectured thatthe mcrocracks al to propagate n depth when there s a queent laye o materal etween the

83




Note

84

micocac ad the hgh Hetz hea te zoe, i which o ubtata hea tee pevai todive the cac T i the cae whe teface tacto ow Fo hghe teface tacto, th

quiecet aye ceagy ivaded by hea tee capabe of divig cac ad tiatigpag

Hydraulic Eect on rack Proagation. It obeved whe coiea idig accompae oigthat the trailing uface, i whch the idig dieco i forward the ame a the dectio of cotacttave), pa ft. Cac age dowwad in te direction of contact travel th uface. The leadinguface, o which idg occu i the oppote decto pa ate, to a ee degee, o ot ata. Whe cac fom th uface, they age dowwad away fom the decto of cotacttave. I geaig, the dedendum, which a taig uface, obeved to pa moe tha theaddendum, a eadg uface

1. I pheca oe beaig bae-haped oe), which omay pa ea the mdpot ofthe oe egth due to hgh oma peue, o cea evdece ext that oe, wch aethe eadig uface at that pot, woud be igficaty e poe to paig tha eig,whch ae the taig uface.

2. Ba beag ba, the eadig uface i ieig cotact, do pa e tha ieig.Howeve, ba ae hade tha eg, have moothe uface ad dex thei ax ofotatio, a of wch opeate to educe ba pag

A petet hypothei to expa eectivty i the diectio ad fequecy of cacig thatthe peece of a quid ubcat equied fo cac popagato cotact fatigue The motcommo fom of thi hypothe, attibuted to S Way [18], pouate that a cac extedgdowwad the diectio of cotact tave ad fed with oi the appoachg cotact eache theuface opeig, piche the cac coed, tap the ubcat ad put t ude hydauc peue

which exted the cac tip A cac extedg dowwad oppote the dieco of cotact tavei queezed empy of o by the cotact ad doe ot popagate

Agumet ca be advaced to chaege the xteivey quoted Way hypothei. Oe objectio that t caot appy to ubuface-og cac Yet thei fequecy ad diectio deped upodg decto i the ame way a fo uface-og cac Moe detaed agumet ae baedo ecet factue-mechaca aaye of cac popaato the peece of o ome of whch[19] do ot appea to uppot the Way mode. Noethee the iue of hydauc effect o papopagato t ueoved.

Ateativey, oe may attbute the effect of idig decto o paig to the aymmety the eatcpatc te coditio exitg ude ay taveg Hetza cotact The aymmety ofdefoato bad with epect to the diectio of cotact tave diect evdece of th te taiaymmety. Eatc-patc aaye of the te coditio duig cac popagatio ae udeway fo

dg ethe with o agat the decto of cotact tave 2, 23], but have ot yet poduced coeu

. Effecs of SpallingSpaig faue of dffeig eveity depedig o deig, matea ad appcato of the cotact

compoet. Geeay, pag diecty ead to o-fuctoaity, becaue t pogeve at timepopagatg vey apidy afte iiatio) ad ofte ead to factue o ezue

I ma o hghpeed, though hadeed tee rolling bearing, ad beag wth poo ubicato, pag i a dabg faue ue aeted by a eaxato of opeatg codtio It popagateapdy ad ca ead to bu factue ad o of fuctioaity. Accuacy of haft uppot ofte



hapr 1: Spallng

ompromise Virtion n noise from sple omponent is often unepte Seprtors ofsple sm erings my frture n use seizure

In rge so-spee rllr barng ith goo urition espeily if prts re se hrenespling my propgte soly n onsierle serie ife my e otne fter sp iititionHoeer tstrophi spl progression n fiure is so osere in suh omponents

n roling ergs spls o not hel They re rreste spontneousy oy if they he ourrein n re tht susequenty eomes uoe protruing "ip" ner n ege hih ers off; portion of the roling ontt hih ue to religent of the mhine element is no ongeruner o)

In gar progression of sps to funtion fiure is ommon Hoeer sping "pitting)onitions he een ientifie hih o not le to fiure speifily

• ine sping ("pitting) on ne ger ue to rough s-fishe surfes hih fter runingin eome smoother sustin further ying ithout more seere sping

•

Spling in orm gers wh remin funtion een fter onsiere spingers re me of mteris of iely rying hrness n ftigue resistne Surfe finishes

so ry gretly Therefore the retie preene of sping ompre to er or gling fiuresnnot e generly estishe s funtion of singe rie suh s hrness euse hrnessinfuenes resistne to these filure moes

Cam ytm espeily those uner hey Hertz pressure n high spee suh s in Diese enginesmy fi in spling often preee y mirogling hese fiures my ise the m system

85




Cross- o cory Flur Cos

Falure de late N Failure de ate N Failue de late N

6 6 6 6 6 6 9

6

6

6 69

9 6

6 9

6 6

6 6 6 9

6 6

6 6

6 6

6

6 6 6

6

6

6 9 6 6 96

6 96 6 6 6

6 4.9 9

6 6 6 66 6 6

6 6 6 6

6 99

6 6

6

186



Failure Code: ..Failure Code: ..

PLATESDTlate No 10 . 1Archve No 01602Image tye vewScaear 0 (icros 20%, othes + 100% 50%Coonent SRB; IR rnSeedLoadLuricatonFalure Code 001601 .1 1 Cetered spall ig, oa track widthFalure Code 2 001602.5 Advanced spallngFalure Code 3 0012.02 Abrasive ld wearFailure Code 0020. Corrosion stai

DECRIPTIONFaiure Descriton Advaced copod failure o several odes tensivespalli ng of both roler paths iitatg fro ay poi nts original y ay have beencaused by corrosio. Corroson stains foed in unspaled racks There isetesive abrasive wear and debrs dentig i tacks. Bearigs i heavy idstrialachiery often ru to severe copoud failre befoe dagnosis ad reoval.Image Descrition N eous spall craters, wth usp alled surfaces iteposed,idicae ltiple orgi n spalli g on both roller paths. Near he otboad edge o

Chapter 1: Spallng

both paths the any sall dark spos are probably corrosion sais. Debis dens appear bewee spals, ear track centers.Susected Causes ulple orign spalling of ths paper achne bearing ay have tiated fro corrosion due to water ingressinto bearng Spalls later prolierate fro debrs dets.

DT

ate No: 102Archive No 018-14&15mage tye a b: light acroScalear = a b: 20 (icros 20%, othes 1 00%, 50%Comonent SRB OR rnSeedLoadLurcationFailure Code 001 6.01 .1 2 Cetered spall ng, wde trackFailure Code 2 0016.02.5 Advanced spallingFailure Code 3 0022.2 B lk aige crackFailure Code 0012.4 Wear of gidingcopoen sppo suface

DECRIPTIONFaiure Descrton Eesively spalled S RB OR , i load zone of both roller pahs,etedig nealy full width of coact. (a) Load is radal spalls eend to edgechppng (b) oad is cobined, with thrust coponent uspalled bad is visibe atotboard edge of essloaded row Soe wear arks ae vsible separator supposrace I slow speed heavy achinery, these b earings a y have rn etensivelysice spall in itiation, but are not fit for further sevice.Image Descrton (a) In sooth spherical OR olig surace two wide, long loadones totally spall craered fro load zone start a V iage width fro E edge toW edge The oad one sta point in both tracks is aligned (radia load) . Spal liggradally wides as rol er load ncreases into the o e Several ed ge ch ips broke ot atS edge (b): Siilar spalling load zone starts fher i S tack. Unspalled bad at N edge (cobned oad)

a

Susected Causes Very heavy load (p ossibly acceptable i slow speed achiery) caused spallin g. Once spalln g is etensive loadcarrying abilty of suace is lost so spallig becoes progressively wider ad eventually covers ful cotact width. (a) Roler rowsae eqally loaded (radal load). Spallig fatigue cracks can separate chips at rig edges (b) S roller row s ore heavily loaded(thst load) .

7



Failure Alas for Herz Cona Mahine lemens

DTlte No 03

Arcve No 027-33Imge tye ligt acroScle 40 (icos ± 20%,oters 00% 50%)Comonent DGBB; OR rnSeed 30 KdNLodLuricon gease 60°CFiue Code 00. 6.0 .2 Cetered spall in g,wide trackFiue Code 2 00.6.025 Advaced spalligFure Code 3 23 Friction polyer, greasebricatoFlure Code

S asPLAS 0 ad 047

DECRIPTON

Failure Code: .Failure Code:

Flure Descrition Large circular spall etedig across ball pat to near a land edge. riction polye in loaded af of groove.Widt of spall, oal dept ad egular outline sggests absece of aor local deect and eistence of overload (wide conactpat). rictio polyer also suggests wide track fro eavy load. Plates 0.3, 0 2 a nd 047 sow diffeent spallig odes onsiilar bearigs.Imge Descrition Ball groove visbe between syetric land srfaces. N al o groove is dark (wit a separate ti dark line iceter); S al is clear. Roud spall cater spans virually al N al of groove Dark stan is brown friction polyer. Te separateline, also brown, is fro a siia cause. Separate fctio polyer lies are ofe observed. e deailed balance beweedepositio ad wea causing te s ot clearly nderstoodSuseced Cuses Heavily loaded bearig develops wide contact wit signiicant eatcote slip, creasg tepeatre andavorng frcto polyer oration fro grease. Overload ay cause spallg wc, de o wide conact, wil a so be wider tanusual (approaces lad edge)

DTlte No 0 4Arcve No 09362Imge tye SScler 350 (icros: 20%, oters 00% 50%)Comonent CRB; R, ruSeed 500 ? KdNLodLuricton sytetic polyester oil 00°C?Fiure Code 00. 6.0 2 Spallig at contact edgeFure Code 2 -Fure Code 3 Fiure Code -

DECRIPTONFlure Desction ultiple spalng eaates fro earoller corer and etends oward idlegt. Spal dept isgreatest nea edge, id icaing edge loadi ng. Te etree edge ,adjacent to radiu s, is u spalled Progressive spal ig will causebearig failureImge Descrition Obli qe S view of OD and endface o(sall) cylindrical role. Coer rads is -. Spal craers begi cose o coner (a B were tey are deeper ta frterinboard as at C ind icatng edge loadg Spal s do no t eend ito te corne Tis nspall ed l ip efect s see between ic ks orurrows ad spalls as well as i edge loadingSuseced Cuses dge loadi g is l ikely to ave precipitated te spall g. lt ay arise in a CR B, ro (a) skewig of roler iOR; (b) bearing saignet; (c) tape in rigs o outing surfaces; (d) tust loadig of rollers; or (e) isfficet cowning(edge elief) of roller profile

188



Failure Code 1

DTte No 1 05

Arcive No 014003mge tye SScler 1 mm micos ± 20% othes + 1 00% 50%Comonent 0 RC test rig r od; sl ico itride h ot isostaticressed; rSeed 1 9 m/secod 5.93 GPauriction mieral oi w additives; aro 40°CFlure Code 001601 2 Sall ig at cotact edgeFlure Code 001602.3 Iciiet sall ig sigle sallFlure Code 3 001 6 2.3 Shallow etry sall rom tesilecrackig ceramicFlure Code See also PLAS 6. 1 ad 1 29

DECRIPTIONFilure Descrition Cluster o small salls formig idividual

Chaper 1: palling

craters with flat bottoms about 250 m across oud to orgiate ear track edge where tesile Hezia stress is eset herectaglar sall shae ad flat bottom suggest liear crackig as sall itato his falure mode is chaacteistic of uly desesilico itride ceramicImge Descrition At image ceter N three small salls each about 250 diameter wth flat rectaga r bottoms ad shallowcrater was Udamaged s urace is featureless gay verrolli g directio is image S to N Note i dividual sall ottoms are large 250 m comared to ce amic gra size <1 0 m Susected Cuses tremely heavy Het ressue wel above lastic limit o stee ossbly also of ceramic bder cycled forvery log eriod creates high reetitive stresses. Lea tesile cracks are thought to coalesce to shallow salls.

DTlte No 10 6

Archve No 001-7Imge tye viewScler 3 mm cros ± 20% othes + 1 00% 50%Comonent ACBB; B rSeed 1 dNod 1 .4 GPaLuriction sythetc oyester oil 1 20CFlure Code 001601 .2 Sall i g at cotact edgeFlure Code 001821 Rolledi lie at cotact edgeFlure Code 3 00161 Subsurface origi sall high Heshear stessFlure Code 001602.5 Advaced salligSee also PLAS 1 0.1 3 ad 10 14

DECRIPTONFiure Descrition Bad o severe sallg alog great cice ofball his ball was foud to have cotacted the sha edge of theIR al groove uder load. e or more close-saced les were rolled i FC 0018.21 ad sallg origatig from the edgeoverload occurred. he all has failed See Plates 1 0.1 3 ad 1 0. 14 for detals of edge sall ig.Imge Descrton he W great circle of the all shows two arallel grooves clearer at image ) followg rolled-i lies whichhave begu to sall At image ceter ad W stee-etry sals have rogressed A olled dar k le followed y a sa is alsofaitly visible o N S great crce ad a sal N of the ed o f the W great circleSusected Cuses A geometry error i the bearig caused heavy cotact betwee alls ad the shar edge of the IR goove hisedge loadig roduced the olled-i i e ad sall ig.

189



Failure Atlas for Hertz Contact achine Elements

DTae No 107Arcve No 031103Image tye viewScaear 30 mm (micros ± 20% oes 1 00% 50%)Comonen TRB (doube row); IR rSeedoaduricaonFaure Code 001 601 .2.2 S pallin g a conac edge fom geomery eroFaure Code 2 001 601 .1 Spallin g ceered in coacFaiure Code 0032 .2 Ro ll ig surface gal ig den or nick visbleFaiure Code 00.1 31 i sace gall ing

DECRIPTIONFaiure Descrtion Advaced compo nd failure o sevea modes Spal ig

occurred a e rack edge and separaely i ack cener (peraps from spalldebis) Gall ing resled from rack ceer spalls Tere is severe IR bore ·

damage probably galling Bearings i eavy idsial macnery ofen r osevere compond failre before diagosis and removalImage Descron W mage al sows oe of wo roler pas o a mulirowTRB. Te al of image is e wde noconacing cener ange o wicback deposis may be caboized lubrica. Row of spall craers a rolle paedge nea rus flage Two grops of spalls are in e rack cener (a N adceer) srrouded by dark-appearg (bu sy) gag seaks. A W imageedge e bore surace is seveey baered possibly by gallig)

Failure Code

Susected Causes: Te ow of spal craers ear e rus flange sggess edge loadig (geomery eror). Debris from esespalls may ave riggered spallig a rack ceer wic in r led o galling probably as rolles jammed i separaor from debrisiereece Bore damage is o cearly imaged bu if i is galling i would require fas roaion of rig o sa de o loose fioveeaig or seire in e bearing.

90







Failure Code

DPlate N: 1 01 1

Archve N: 122-6&7Image type: a,b: SEScaleba a: 500 b: 100 m mcros: 20%, oters + 1 00%50%)Cmpnent CRB; IR rnSpeed: 46 KdNLad 1 GPaLbrican: mineral oil , ? Faie Cde 00160122 Spaing at contact edge, from geomeryeroFaie Cde 2 0016032 Spall propagatig by reiniiaion a suaceFaire Cde 3 -Faie Cde -

DECRPTIONFaire Descriptin: Conac etend g to edge o ndecu o I R,wit eavy stess concetation at edge probably rom edge geometryerror) orms dese band of sallow spals near edge, wt deepelarger craters etedig no e contact area. Te beaing as failedImage Descripn: a) EW bad wit dark ad l igt li nes at imageN is udercut S teeof is a desely microspalled ad rolled dowsuace. Net adjacent to S are lager spas of ormal dept, wicoriginated from e microspaled bad b) icrospaed band witfeaureless srace betwee crates, at iger magnifcatio.Appearace is simila to advanced surface disress but some craters

a

250 m long would be utypica of surface distress bSspected Cases: m propely dressed grind ng wee may leave

Chapter 1: Spallin

promiet l ip adjacen to ndecut Wen roled ove, te lip is eavily overoaded plasticaly roled down and spals at tesalow) dept of ig He sear stress i ts edge cotact Small dep of stess field makes suc spals virtually

idistigisable from surface dsress. Spalled ip iitiates normal dept spals n adjacent normal contact area

DPlae N : 1 01 2Archve N: 027247Image type viewScalebar 1 0 mm micros: 20%, oters 100%, 50%)Cmpnent: ACBB OR, rSpeed: 160 KdNLad:Lbcatin: grease 60°Falre Cde 006 01 2 2 Spalling a conact edge, from geomety errorFalre Cde 2 0016 1 1 S bsrface origin spal ig He sear stress)Falre Cde 3 0015 1 1 Generalied freting radial it srface

Failre Cde S also PLATES: 103 ad 104

DECRIPTIONFailre Descrpn: Narrow elongated line o spalls o edge betwee low lad dam) of teOR ad ball groove Te dam must remai u nloaded for proper fncto but becomes loadedif bearng is installed reverse so te dam faces te rust direction Pompt spall ing anddamage to bals occrs Plates 03 1012 and 1047 sow diffeen spallig modes n simiar bearigs.Image Descriptin: On te ne r surface o is OR, te low lad dam) area s to mage E rom te groove. A sarp edgeseparates it from e glossy) bal pat wc etends W o te dark gay lad at te trst side. Sigtly S of image cente s arow of dark spall crates at e edge. Tey lie i a circumfeential wear track sggestig tat te ball rolled over onto e and.Norma frettig visible on D.Sspected Cases: If a sym metical ACBB one land ig for tst te oter ow fo assembly) is i salled i reverse adtrst loaded te load overides te groove edge ad spalig ailu e at or st over te edge occurs.

93



Falure Atla for Hertz Contat Mahne Element

DTPate N: 1 013

Archve N: 001-8Image type: l ight icrograScaebar 500 icros: 20%, others: 100%, 50%Cmpnent: ACBB; IR runSpeed: 1 dNLad: 1 .4 GPabricatin: synthetic poyeser oil 120°CFaire Cde 00. 601 .22 Spalin g a contact edge frogeoetry errorFailre Cde 2 001 61 1 1 Steep ety spall subsu race origiFalre Cde 3 001 821 Rolled-i line at contact edgeFailre Cde S als PLATE: 106

DECRIPTIONFailre Descrptn: Rolled-up groove edge ro edge contactunder heavy oad he edge has spaled fro subsuace orig

Failure Code: .

fatigue due to the high edgestresses. he spalls ay inflict uher daage o balls see Plate 1 0.5 . The bearig has ailedImage Descriptin: A bright EW band S of age cee divides the ball track lying to the S ro the lad lyig to the N. Thesharp edge of the land is the N bounday of the bright area Four spall craters with seep wals are visble at the edge The shadowcast o the N of the edge idcates that the edge is elevaed plastcally rolled up above the lad surfaceSspected Cases: A geoetry error in the beaing caused heavy cotact betwee bas ad the sharp edge of the IR groove. Thisedge loadng pr oduced a rolig up of the edge above the land surface and sub sequent spallin g o the IR see Pate 1 0.5 bysubsu aceorig fatigue due to the hig h edge sresses.

DTPlate N: 10 14Archve N: 00517Image type: SE, backscatterScale bar = 400 cros 20%,others + 100% 50%Cmpnent: C; C ruSpeed: 7 /secLad:Lbricatn: ineral oi l 115°CFaire Cde 00.1 601 2.2 Spall in g at cotact edge,fro geoetry errorFaire Cde 2 00.182.1 Roled-in le at cotact edgeFaire Cde 3 00.1 71 .2 i crospallig advacedsurace distessFaire Cde 00 .171 .1 Glazig icipient suracedistress

DECRIPTIONFaire Descriptin: Narrow bad of sal shalowspalls at contact edge n ad ear a rolled-n line at theedge. Icipiet glazing surace distress appears wthnthe cotact advanced glazig ad crospalligbecoes visibe as edge is appoached The bad o sall shalow spall s resultig ro sharp edge cotact is i ndstinguishabero surface distress icospalling i the edge area. arge-scale spallig ad ailue are likelymage Descriptin: Finishig arks u EW The N iage hal is outside the contact. A sharp edge deleates N side of darkroledin ie at cotact edge n which ultiple, sall 50 wide, shalow spal caters are visible To the S adjacet to theroled-in edge, finishig les are obliterated by suface dstress gazg and a few spals are see. S 1/3 o iage shows icipietglazig.Sspected Cases: Ca follower was ot crowed it was a true cyider up to the coner radius This possibly cob ied withsalig ent causes sharp edge cotact with hig h stresses resulting n rolledi line ollowed by spallg General surfacedistress due to low HD fil is typical o edge cotact.

94



Failure Code

DTPlate No: 015

Archive No: 07-01Image type: l igh viewScalebar 0 (icros: 0%, ohers: 100%, 50%)Compoet: BB (aiu copleen); IR & OR nSpeed:Load: aialLbrcatio:Failre Code 001603 Spalli ng a con ac edge fro hrus loadFaire Code 2 001605 Advanced spallingFaire Code 3 Faire Code

DECRIPTIONFaire Descrpto: Eensive spalling aond circuference o IR ballgroove ofse aially as und er hrs load and nn ng over oading sloedge. Failure fro edge conac a ha poin has spread over os of

he ba ll groove dui ng eended addi io na l ru nn ing . h is is a grossfalre

Chapter 1 Spalling

Image Descriptio: OR srrounds IR n iage On R ball pah a band of spal craers covers uch of he groove boo b is ose o he W side where he loadng slo grond ino he land is seen. The edge o he slo ( labe ed loadng noch) eends ino he bal lgroove and was ove-rolled. Drecion of hrs load on innerrng as deduced fro offse of conac pah o he W is labeledSspected Cases: aiu-copleen ball bearings conain ore bals han can be assebed wihou a loadng slo or heinseion o he las balls Such bearings can ake hrus load only on he IR ace away fro he loading slo so ha he conac doesno overrol he slo edge This bearing was iso ned resuling in load applicaion oward he oading slo causing edge spallin g.

DTPate No: 1016Archive No: 031-005&0Image type: a b: viewScaebar = a b 5 (cros 0%, ohers: 100%, 50%)Compoe: DGBB; IR rnSpeed:Load:Lbricato:Fare Code 0016013 Spalli ng a conac edge fro hrus loadFare Code 2 00605 Advanced spallngFare Code 3 0001 3 Roling eleen (ball oller) cackFalre Code 001 Ovesress crack

DECRPIONFaire Descrpto Advanced copound failue o ore han oneode hs loaded goove s half spalled; land edge is overroledLarge chip has broken ou of he land and anoher adjacen chip ou

of he groove (bulk fracure). Thee are spalled and racred balls.Probable bearing seiure. Bearings in heavy indusria achinery ofenrn o severe copound faure befoe diagnosis and reova.Image Descriptio: (a) IR covered wih heavy grease (on lands andin chipped area). S half of ball grove spalled and spalls rolled down.In SE half o S land a lage chip is broken of Near ring cener chipbroken o of rack; he caviies o he two racres erge. (b):Spalls on several ba lls Two bas a NW shaered. Second ball froN has a row o spalls along a grea cicle suggesing edge oading.Sspected Cases: Groove spalling appears de o aia overoad(spalls etend pas groove edge). Afer conined rnn ng soe balsspalled one or wo shatered and jaed. They chipped he bal pahand a land

a

b

195




DTPlae No: 0 . 7

Archive No: 00-25&26Image ype: ligt macroScaebar = a b 4 mm (mcros 20% oters 00%, 50%)Compoe: DGBB IR&OR runSpeed 700 KdNLoad: GPaLbrcaio: sytetc polyester o 20CFaire Code 00 60 .2.3 Spallin g at cotact edge from trust oadFare Code 2 00.23. . Contact pat roldown i bearigFare Code 3 00. 6.025 Advaced spaingFare Code 00. 2.4 Wear o gi ding-compoet support su rface

DECRIPTIONFaire Descrpo Rigs of a DGBB uder eavy trust load sow etensivespallig o opposite edges o ball grooves. O bot ings, te spaig etedsto one (sarp) groove edge and as serrated tat edge. A trust loadsufficiet to produce severe edge cotact caused plastic roldown at te edgesad early spalig rom te stress concetration at te edge Somecircumferetial wear marks are on separator (cage) guide suraces of IRImage Descrpo: (a) IR ball groove etesively spalled S of label Ceter ofraceway (b) Simar spalling on OR ball groove N of Cete of raceway."Tese are te two diagoally opposite groove alves under tust load. Edgesof spalled groove alves are serrated by rolout and spalls etedg to teedges Fant circumferetial wear marks on separator guide suraces labeedCage Pilot Damete"Sspeced Cases: Ecessve tst load for te design and looseessselected cause cotact ellipse to override groove edges sigificantly. Stresscocetratio at edge intiates early spalling Wear at separator guide suacesmay be due to debris from spalls.

DTPlae No: 0 . 8Archive No: 080-23Image ype ligt macroScaebar 0 mm (m icros 20%,oters 00% 50%)Compoe: SG W case ardeed, runSpeed:Load:Lbrcaio:Fare Code 00.603 Toot spalligFaire Code 2 00 3. 3 Toot cotact galligFare Code 3 -

Faire Code

DECRIPTION

Failure Code .Failure Code .

a

b

Failre Descpo ultipe gallng marks (scorng) ruing radialy over addendum act as sorces fo fatigue spalls. I its presentcoditio, te gear is still operable but cotinued spali g may lead to toot fracture (FC 00.220 .4).Image Descripio: Ligt-colored radia galig streaks i many locatios on te addendum, o first ad secod fully visible toot fomN On all toot fanks dark spal craters are iterspersed wit te gallig marks. icroscopy would idcate tat spals origate romgalling marks as defectsSspeced Cases Gaig (scorg) of gear teet may occur due to overload insuffcent EHD film ecessive operatig spee surfacedefects or ecessve ougess. Gallig streaks are significant sources of spalling fatige. Occasionally gear galling may eal" wenoperating condtions become subsequetly ess severe However spal iitiation may ave take place wile te galling was fres andspal l formatio may proceed afteard

196



Failure Code .. Caper 1 Spallng

DTPae N: 10 19

Archive N: 0991 07 & 1 02Image ype: a lgt acro, b ligt icrograScaebar a: 30 b: 3 icros 20% oters 100% 50%)Cmpnen HG; W, ediu ard, runSpeed:Lad:Lbrcan:Fare Cde 001601 .3 oo spallingFare Cde 2 001602.4 ncipiet spallig, ultple spasFare Cde 3 00.1 252 Soot toot wearFaire Cde See aso PLAS 1 0.22 and 1 02

DERIPTION

Fare Descripin: In edu-ard gears, sal spals ay appear oc of te dedend area during early unig. Spalng is believed tobe ore sliding-diectio sensitive in ediu-ad steel enanced wensliding is o-drectioa to rolng, as dededu). Sc spalls ay wearaway and stop to proliferate, allowig te gea to continue rig Seealso Plate 1 0.22 I oter cases, fale progresses See Pate 02Image Descipin: a): Al v isible toot contact sraces sow ay sallspal craters aigned fro pitcne down into dededu Cratering is oreprooced in alf of toot age possbe isalignent) b)Dededu suaces of two cosecutive teet ae otled dark gay areasat N and S of iage. Intervening toot root, tp ad addend are lgtgray. Craters ae rouded by wea i dedend; no new craters. Witerectangles are atifacts.Sspeced Cases: Higy loaded ediu-ard geas, ote wit

a

as-acined ad reativey roug surfaces, tend to wea drig run-in bNear pitci e, toward dedend, were sl iding is ow, bt o-directioalto olling, sall spalls ted to appear, rater tan wear. Spallig ay be aested i ts class of ateral as suaces becoe sootern n-in

DPae N: 10.20Archve N: 099-116Image ype: ligt acroScalebar 25 icros: 20% otes + 100%, 50%)Cmpnen: WG; W, brone, rSpeed:Lad:Lbrcan:Fare Cde 00.16.01.3 oot spallig

Fare Cde 2 001602.5 Advanced spallingFaire Cde 3 00.1233.2 Wear centered i sliding contactFaire Cde -

DERIPTONFaire Descripin Spall cratering coverig ost of toot cotactsu race i wor gear wee. Wea aks ae on all nspalled areas Wor gear weels, generaly of brone, reai unctional witetreely eavy spalling wea. Data on spall pogresson n broe are scarce but t appears slow nder tese coditiosImage Descripn: Wor gear weel s viewed on lan wit ais W Two fu teet ad pat of a trd N age edge) sowgeneraly spalled contact srface, ecept at W and NW edges, wic sow kieatic wear arks. Hig areas betwee spall craters areaso wor soot.Sspeced Cases: Severe sace destructon, ncl udin g wear, spallng ad possiby galln g is encontered n wor gear cotacts wcundergo ig slidng arge cotact area keeps stresses suffciently ow tat ctionig ca be aitained at slow wor gea speeds)even in te presence of significant sace destructon.

7





Failure Code ...

DTPae No 1 023

Arcve No 0991 1 1Image tpe igt macoScaebar 20 mm micros 20%, otes 100% 50%)Componen HG; W, medium hard, runSpeedLoadLubrcatonaure Code 00160131 Tooth ptchlie or dededm spalligaure Code 2 0016024 Incipiet spaling multiple spallsaure Code 3 -aure Code 4 -See alo PLATES: 1 0 1 9 ad 1024

DERIPTION

aure Descrpton Icipient pitchline spalig i medimhard gear,etending to dededum. Spall craters are too deep and large to epectcotined safe operaio o gear. Compare o slow-progressig spallig inPlate 1 019 See also Plate 1024 for moe advanced spalling i similar gearImage Descpton Gear is viewed fom above its side SW image corner issideace Visible toot flaks all sow rows of spall craers of varyng size addep arranged alog pitchne and etedng into dededumSuspected Causes Highly loaded medim-ard geas ote wt as-macinedad relaively rough suaces may deveop spalls ear ptclie wee sli dng

Chapte 1: Spalling

.

-

I

is low and contact pessres ig. They tend to eted to dedendm wee slidig is codiectional wi rolng In medim-admaerial spallig is promoted by is sidig directo. Rate of progresso depeds on severity of operaig coditios and o matea

DTPlate No 1024

Achve No 0991 1 2Image tpe light macroScalebar 25 mm mcos ±20% oers +100%, 50%)Component HG; W, medim ard SpeedLoadLubrcaton:alue Code 00160131 Toot pitcline or dededum spaingalue Code 2 0016025 Advaced spalli galue Code 3 alue Code 4 See alo PAS 1019 and 1023

DERIPTIONalue Descrpon Advanced spaling i medim ard gear covers

enire contact area and is eavest i dededum Caters are too deepand numerous o permit safe operatio o gear Compareto lesser spalling i Plate 1023 and to slow-progressig spalling in Plate 019Image Descrpon elical gear ee are viewed on flanks. The gear is eavily spall cratered o all visile toot contact sfaces witdesiy of caterig greater in dededum a n addedm . Oig inal machied gear OD saces.Suspected Causes Higly oaded medium-hard gears often wit as-mached and relatively roug suaces may deveop spalls earpitcline were slidig is low ad contact pressures igh. They tend to e most poonced i dededum wee slidig is o-diectoalto rollig. Spallig i medium-hard material appeas more sensiive o slidig drectio Rate of progressio of spallig depeds oseveiy of operaig condition and on material.




DTPate No 0.25Arcve No 064-409mage tpe view (paial)Scaebar 30 mm (micrs: 20% thers: 100%, 50%)Component HG W high hadess, runSpeedLoadLubcatonalure Code 00.1601 31 Tth pitchlne r dedendum spalligalure Code 2 00.1603.1 Spall prpagatng by crackig at spallbtmalure Code 0022.014 Gear tth crack r fracturealue Code 00125.1 th plishig

DECRIPTION

Failure Code: ..

alure Descpon Alng pitchli ne, several smal spalls may teeth. On e tth, large spall extedig int addendum and frmiga chp u f the tth tip. Radial wear maks ad pl ishing f cntact surface are visible ea ne ed f the mesh, idicatig pssibl emisalig met. The tth has faled.Image Descrpon W end f mesh shws plishi g f all tth su aces gea fill ing S % f image N image is matng gear. At spall crater n dededum. Crsses pitchl ne t addedum , where a deep chi p has bre ut, extedig int tth tip O the tthmarked , ad teeth t bth sides f t are multiple, fine spall craters bew pitchlie.Suspected Causes Pitchlie r dededum spallig f gear teeth ccus under heavy lad ad lw HD ilm cnditi n (elatively wspeed). I hig h hardess geas spals ca gw explsvely and ccasially resul n bu lk fracture, as n this image

DTPae No 0.26Arcve No 080-204&205Image tpe SM f tthface and sectiScalebar a: mm, b 50 m (micrs ± 20%, thers 100%,

50%)Componen SG; W, carburized hard runSpeedLoadLubrcaonalure Code 001601 31 th pitchlne r dedendum spaigalure Code 2 001 61 .21 Shalw ety spall frm suace pit-defectalure Code 00.16022 Ctact fatgue crackigalue Code 4 0012 52 Smth tth wea

DECRIPTIONalure Descrpton cpient spallig ear tth pitchlie shwigshallwety spalls and cacks enterig at agle 25° rm suace. Theuspalled suace is very smth, fm surface distress ad/r smthwear. Pitchli ne spa lling may nt immediately fail gear when it is as small

(1 mm dia) as shw here, but is expected t lead t evetual spalli ngfailueImage Descrpton (a) Sectied tth. Fa W dark muntng mateial,ext t ight gray th flak he t dark gray (labeled) plishedsecti Spalls ae dark spts just W sectn edge (i n bx) (b) Fieldwithi bx at 200x . W image half shws craters. Shallw entry frm St N ad breakut at N ed Crack uns 25 N int plished sectin.Unspalled tth face is featureless (surace distress, wear)Suspected Causes Spallig (fen desgated pittig n geartechlgy) ccurs in highly aded gears i dededum ea pitchlinewhere slidig is mderate Ths gea was fud t have lw suracehardess. Wear ccurred n the high slidig areas, suace dstress andicipiet spallig in the lwer siding aeas.

200

a

b



Failure Code .Failure Code .

DTPlate N 1 0.7Arcve N 080118Image tpe clr mcr [S MAG IN APPNDIX.]Scaebar 1 mm (micrs 0%, thrs + 100% 0%)Cmpnent SG W, md high hrdss, uSpeedLadubrcatnalure Cde 00101 .31 Tth pitchi dddum spllgaure Cde 2 001 91 Tmpr clrs i ctct sucsaure Cde 3 0013 Dstuctiv tth waure Cde 4

DECRPTION

Chapter 10: Spalling

[See Image in Aendix]

alure Descptn splld (ptd') pichli r d dply wr dddum d dddum hghhrdss gr Tmpr clrig

fm ht imblc. Wr f sucs wth high slidig lvs pitch vtd This ltr splls, grtig dbrs d ggvtigwr lswhr High wr rt my xpi why spllig hs t prgrssd t lrgr crtrs: surfc wrs wy mst s st scrts frm. Gr is fild.Image Descrptn Vw fm gr c idcts svr tth shp dstrti du t wr bth dddum d dddum.Pitchli shws xl bd m ultp, mdrt-si sp crtrs (pttig'). Th hu th tr gr is blush frm tmpclrigup prti t xcssiv tmprtur. Th rd bckgrud is t sgfictSuspected Causes If dddum d dddum f gr wr rm ctmiti dqu lubrcti r xcssiv surcrughss, th th pitchli bcms lvtd d crrs xcssiv d his pssby cmbid wih vrhtg d mtrilsig, my prciptt pitchli splig.

DTPate N 10.8Arcve N 00-7Image tpe light mtllgm, tchd

Scaebar

0 m (mics 0%,thrs 100% 0%)Cmpnent C CF, ruSpeedLadubrcatn mr il bsd dsl gi l aure Cde 001 0. Micr plstic drmtiidctiaure Cde 2 -alure Cde 3 alure Cde 4 See also PLAT: 101

DECRPTIONalure Descrptn Slidig cmbid with rlig

pducd sufficit tcti i ths sliding pe cmflwr t cus shr f rsurfc mtri, withfwd bdig visibl vrticl structus i th sid g d ircti. S ls Plt 1 00 fr splli g frm surc distrss.Image Descrptn Ctct surc rus i W dircti -urtr frm img dg. tchd stuctur mts (f flw) rprpdiculr t suc xcpt i th 40 m clsst t th suc whr thy bd t th W du t plstic dfrmti cusd byhigh tctiv frcs prducd by t W sdig.Suspeced Causes Cm t fllwr ctct is pdmitly slidig wth rllg cmpt sultig rm rtti f th (sphrdd) flw rud its xis I th prst cs slidig/rllig cusd surc distrss d spllig, d ls pstcly dfrmdth subsuc mtil.

201




DTPlae No 1029Arcve No 0931 63mage pe repli TM f eted etinScalebar 25 _m (mir: 20%, ter: 100%, 50%)Component DGBB; R ruSpeed 420 KdNLoad 3.4 GPLubcaton mner il 1 oocFalure Code 00.1 6. 02.1 1 Mirplti defrmtin bnd rbterflieFalue Code 2 Faue Code 3 Faure Code S lso PLAT: 10.31

DECRPION

Faiure Code

Falure Descpton Swn i te truture wti defrmin bnd. Te ld-wrked meiti trture wit dilti ell iiterpered wit ewly frmed letilr rbide nd me untrnfrmed glbulr rbide. Te letilr rbide itee rebelieved wek d pre t eg exitig rk i n teir d iretin See l Plte 1 031 Image Descpton Gry bkgrd wit mltipe r drk wirl d lie i ld wrked mtenite i te defrmtin bdSmt li gter gry blng trture runn ig SNW t A nd 8 re lenti ulr rbide Rd trutre i SW mge rer i nrigi l gbul r rbide. Blk rklike lie nd pt er lentilr rbide my be mrrk frmed in ylin g but mre lkelyrie frm etigSuspected Causes Defrmtin bnd re eet f mrteite wit my diltin ell frm yli d wrking in te bebydefet-free mtrx Crb migrte t te bundre f ee eet d frm lentilr rbde. Wek itere betweedermtin bd, lentiulr rbde d mtrx my nnel rk i pll btm

DPate No 0.30

Arcve No 1 07-02&bmage tpe SM f Nitl eted etinScalebar : 10 b: 5 m (mir +20% ter: 1 00% 50%)Component ACBB IR runSpeedLoadLubrcaton gree, 50CFalure Code 006.02. 1 . Mirplti defrmti bnd r bterlieFalure Code 2 0006. . Hrd mriluinFalure Code 3 Falure Code S lso PLAT 1031

DECRIPTIONFalure Descrpon Mirplti defrmtin bd (bur frm ftigue

yig frmed rud luer f mll (but 5m), rd -metlibetwee w wng" f te bnd. Pible mrrk t ne wig edge.Defrmtin bnd ti evily ldwrked mrenie bnd eprted bylmelr rbide frmed dri ng defrmtin .Image Descrpon () Mtled bkgrund i meit trutre witrbide wite pi. I mge eter everl blk gged pt re nmetli. Tw wing-ped pte f urved le, extending SWN re60 m lg dermtin bnd (butelie) Blk ie witin te wig reentiur bide nd/r dilti tgle (b ) Wng , ige r mgnifii.Hevy blk line t N wig brder i prbby rk enned by eigSuspected Causes Repeed ig-te tt yli ng teel uemultive ll plti dermt wi my prde defrmtin bnd

a

b

eiter i te defetfree mtrix r t defet Defrmtn bdig iree wit tre d tl yle ut but i t eerily rk rig intr. Crk if frmed, my fllw defrmti bd d ireti (See Plte 1 0.31 )



Failure Code: Failure Code

Chaper 10: Spallin

DTPae N 1031Arcve N 093163.6Image pe gt metallogram Pcal etced sectioScaebar 1 0 m (micros 20% oters + 00% 50%)Cmpnent DGBB; IR ruSpeedLadLubcatnalure Cde 00.1 6.021 .1 icrolastic deormatio bads orbelies'alue Cde 2 00.1 6.02.5 Advaced saigalure Cde 3 aure Cde ee ao PLAT: 10.29

DECRIPTONalure Descrptn I crcmeretial sectio o salled rig may arallel staig traces o matix deormato bads (ot at observeddeects). Te sall bottom ollows deormatio bads iermitetly wit breaks rom ad to ad Deomatio ads are microasticevets rom cotact stress cyclig Tey icrease wi stress ad cyce cout. Tey are ot kow to ntate cracks bt will caelexistig cracks. See also Plate 1 029.Image Descrptn Dak gray mottled backgroud is Pical etced maesiic marix ltle SWN ruig stragt witeadblacklies are secios o lamiar deormatio ads Jagged le ear N mage edge is e secio troug te sall bottom Segmets obotom sig to N ollow deormatio ads (at abo 25° ari agle).Suspected Causes Reeated ig-stress cotact cycg o seel cases cumlative loca lastic deomatio wic may roducedeormatio bads i te oservaly deecree matrx. Deormato adig icreases wt stess ad otal cycle cout t is otkow to be a crack origiaor Cracks oce ormed may ollow deormatio bad directio jmg rom bad o bad to ceateserrated sall boom

DT

Pate N 1 032Acve N 05-1 03& 11 1Image tpe a b SScaleba a 60 b 30 m (m icros 20% oters 100% 50%Cmpnent CRB; R caruried steel rSpeedLadLubrcanalue Cde 0016021 3 crosere sallig debrisalure Cde 2 aure Cde 3 -alure Cde -

DECRIPTIONaure Descrptn Tis Plae sows te S aeaace o serica debris

ormed salg cracks. Te geeratio o suc deris is beleved caacteistic osallig atigue Te maerial is te same as te matrix seel bu s ossblyoxidzed at te sace Ateratig mcro-motios betwee crack aces aresseced cases Te seres rage 10200 m i sie (a): 200 !m (b ) 50 m.mage Descrptn (a) e large dark emisere a image ceer wit aderglamiae s a arly ormed serical debris aricle Oter amiae sroud it i te cack ace. Grayscale reects tess o e lamia (tier is ligter). Te ;

ackgrod area is a crack ace. (b) Large wite sere a image ceer is llyomed serical ders aticle. Texture ad ue id icate te resece o oxides(coirmed y X-ray aalysis)Suspected Causes ost debis ormed by micro-motio o suaces der load slamiar (examle rettig ders) Sercal (ot merely cyidrical) debrs avebee observed oly uder ollig cotact atigue sallg coditios e seciicmecaism o ei geeratio is ot derstood

a

b203




DTPlate No 1 033Arcve No 1 0706a&bImage tpe SM f Nial eched seciScalebar a 5 b 3 �m (m icrs ± 0% hers: 100%, 50%Component DGBB 8, ruSpeedLoadLubrcaon gease socalure Code 001 6.0. Cnac aigue crackigalure Code 2 001 61 1 . Spall frm subsuace deecalue Code 3 00061 Sulfide iclusialure Code 4 See also PLT: 10.30

DECRIPON

aure Descrpton Iiia f mcrscpic faigue cracks frm subsurfacemangaese sulfide incusns f (a) 5 �m ad (b) 3 �m diameer under highlad ad prnged cycling. Sulfide iclusins are believed be less seveespall-rginaig defecs han are hard inclusis and 3 r 5 �m iclusins areminimum size cause spallng. The pssibiy exiss ha hese micrcracks115 �m ng) wll n ppagae.Image Descrpton (a) Nial eched meallgraphic seci a high magnifcanin SM Whe ds are carbides n dark marix wih maresie needles as faiulines. The black val in he cener is a magaese sulfde inclus i. Blackhrizal lies n we bads are miccacks (SM shws sharp edges aswhie) (b) Smilar image f anher inclusi. Cracks are hrizal darkpenings exedg fm N ed f inclusiSuspected Causes The m icrcracks riginae fm he sma ll subsuacemangaese sulfide iclusin acing as a sress raiser (lw srengh sf maeriali vd) Lad and cyclig ime mus be exreme cause he faigue cracking

(see Plae 1 0.30 .

20

Failure Code:

a

b



Failure Code: 0016022 Chapter 10 Spalling

DTPlate No 34

Achve No 2-5a&cImage type a vew b light metallgam etchedScalebar a 6 mm b 3 m mic rs 2%thers % 5%)Componen AC tl steel rSpeed 8 dNLoad 2.2 GPaLubcaton synthetc lyeser il 49°Calure Code 6 .22 Cntact fatigue crackigalure Code 2 . 6. . 2 Sall frm sbsuace defectalure Code 3 . 6.2 . icrastic defrmatin bands bterfliesalue Code 4 ..3 . In ciie meing frm frgig at ecessivetemeratureSee als PA 53

DECRIPTIONaure Descrpon a) Several radia cracks frm cntact lading fcrack-re tl steel frged at ecessive temeature Secdary salseist at three f the cracks. Great-cicle wear marks FC 24)bably searatr ctact) b) Sall. Defmatin bands btelies) atmicrrsiy and elsewhere. Cracks grwig it material frm salbtm are due t cackrne material See als Plate .53Image Descrpton a) Three radial cracks lightclred sraight lines atarrw airs). Sall craters eist each crack ght-clred halsdecrate sal edges frm redced HD fm Several crclar wea mars

a

b

u W ne NWS ssibly frm searatr cntact). b) Crss-sectin Rig directin t W. Sal btm at N cack at Wedge arws) Dark hairline cracks ad white defrmatin bads buterles) SNW. icr-vds visible at Suspected Cases T steel is sesitive t ecessive frging temeratre which causes lcal meltig and rsity Strcture isdamaged Such matera s sall ad crack-ne. This elais the radial crackig uder cntact lad with subsequent salli g in an

element ball) t sbject t tensle h stress

205




DTPlae N 0.35

Arcive N 0 8-60&606&60mage pe a light mar b SM light mir Nita ethScaebar a b 00 m (mis ± 20% thers + 00%, 50%Cmpnent DGBB; IR har tre he rnSpeed 00 KNLad 3.7 GPaLubricatin mieal il 66Cailure Cde 00. 6022 Ctat fatige rakingailure Cde 2 008.2 Sharp iivial ent(s) frm metal ebisasperitiesailure Cde 3 00 6 2. Sha lw enry spa rm suae pint-eetailure Cde 4 00 602. 2 Dark-ethig mirplast efrmai zne

DECRIPIONaure Descrptin (ab) Debrs ent srae is fllwe by shallw-etryspall iitiatin thrgh suae-rigin fatige rak enterng at apprximately o t surae. () the setin shws altere (ark-ethig)irplastially wrke strutre surrig rak inating netraesess atig ve a sbstatial yle n Nte the intat ige between etan spall he rng has fae.Image Descrpn (a) Rllig srae with W finishing lies. Dent (N farrwhea) is the anglar strutue ark at W a lighter than sruigsat V-shape ak extens NW a SW frm a pnt W ent. NS rakurther W. (b) Ring srae is t the N f sharp ege sei is t the SCrak seen bth. Blak verial retange is ariat. () the seiRllng surae with rak (arw) is at N Darkehig struture s visiblearu rak tipSuspected Causes Det is mmn ause f ealy spalli g by reating stressentrati lss f HD film an pssibly material amage Typaly a

spallig rak stas a small istae away rm et ege leavig an intarige sine maxmum shear sress nentratin is n at the vey ege.

c

206

Falure Code: .

a

b



Faiure Code: ...

DTPlate No: 1036Archive No 014-8004Image type SEMScalebar 1 00 m (micrs 20%ters +100%, 50%)Component 0 RC test rig rd silic iridet sstatic essed runSpeed 1.9 m/secLoad 93 GPaLubrcaton mineral il, wit addtives arx. 40°Faure Code 0016023 Iciet salligsinge sallFaiure Code 2 0016 23 Sallw enty sallrm ens e crackig (ceramicFailure Code 3 0016022 Cntact atigue crack ig

Failure Code ee also PLATE 61

DECRIPTIONFailure Descripton One smal blng sal abut500 m lng, rmed n a cluser ur curvedaralel tensle cacks Additinal l inear tensie

Chapter 10: Spaing

cracks t yet salled Tis alure was und t rigiate ear te track edge, were tesile Heria stresses are resetmage Descrpton At mage center W e ritally elngated sall crater bitle (sady aearace. N wall stee, tessallw. Fur gt gay crack lines dark gray udamaged surace lead SN int te sall cuig W as tey eter e sall Furadditinal lig gray crack lies run NS at 1/3 rm E image edge. Overrlling drectn is image N t SSuspected Causes Extremely eavy He ressure (well abve lasic mit seel ssibly als ceramic bnder cycled r veylng erids creates ig reeitive stesses Tensile cracks rm and sme calesce nt a sall. Sme te cracks curve wle ersare sraigt. lt is cjecured tat te cuvig cracks wee aaced by a material deect wic ten salled u.

207




DATAPae N 1 0.37Arhive N 005-36Image ype SEM backscatterSaear 100 m (micros 20% ohers +00%,50%)mpnen C CM, runSpeed 11825 m/sec olligad 1.101.25 GPaurain egie mnera ol temp vayingFaure de 0016.02.4 Incipient spalig, mulplespallsFaiure de 0032.12 Contact gallg from highacceeraionFaure de 00.123.2.4 Scog wear (macroscopicgougig withou gallig)

Faure de 00.18012 Deting of roling suace,mio slidig S s PLATE 812

DESCRIPTONS

Failure Code: 00.16024

._

_ SOO.M

X5 kV BE #

Failure Desrpn Multipe smal, shallow spalls formed in galled, trasfered material on the valve-opeing ramp of an iternalcombustion engie cam cotaced by a oler folower May debris dents Scoremarks. Pimary falure s galling in he presece ofsubstatial sliding under high nomal pressure with conditios exceedig the gallng lmt of the system. On the mage overrolligdirectio is E to W Arow-shaped pileup of galled metal dspaced to W indicates sldig velocity of the roller over the cam isalso to W, that is, the cam is the leading surfaceImage Desrpn Area of cam surface on valveopenig ramp. A few log EW scoremarks traverse image Betwee two Wscores is galled, rolled-over streak wih severa but arow-shaped tears poiting Three ears show shalow spalls at tips NearN ad S edges of mage, may debris dets, some microspalled. Circumferetal fiishig marks largely obliterated trasferredmetal smoohed by repeated rollovers subsequet o gallngSuspeed auses Roler folowers interalcombustio engne cam systems ca follow the angularly varyng cam suace

velocity without sldig oly by udergoing high acceleratios. The ormal cotact pressure varies from zero to high values durgeach cam cycle. The follower is suppored on a sliding pn bearig i which sharp fiction orque excursos were foud to occu.The raction force available i the cam/rolle contact may at some poits in the cam cycle be isufficient to provide the requiedacceleration ad ovecome pi fricton, resulting in sldig in the contact. I the slidig veocity ad prevailing cotac pressureexceed the galing lmt of the contact, gallg occurs. As soon as the torque demand drops galling stops. Repeated rollover ofgaled matera produces spaling, concenrated whee trasfered metal stads poud of suface and/or s crack-sesitive afterplastc wokig

208



Failre Code: 0016025 Chapter Spallig

DATAPae N 10.38

Arhive N 093-16.10Image ype SEMSaear 2 (icros: ±20% others +100% 0%)mpnen NRB; R runSpeed 40 KdNLad 13 GPaLurian neral ol 60CFaiure de 00.16.02. Advanced spallingFaiure de -

Faure de

Faiure de -

DESCRPTONSFaure Desripin: Spall cratering on needle roller. Craters ae shallow

show ultiple origns and propagation drecions (straions) Soeunspaled areas appear underned by cacks Spalling of sall (3 )daeter needle rolers s shallow due o sall depth of Hertz shearstesses and s not generally a gross faiure but bearing is noisy andinaccurate Roller racture ay eventally esltImage Desrpn: Spall caters are irregularly shaped areas with astriated racture suface as botto. Unspalled eatureless rolling suace ofroller finshed by tubling is underined by fatigue cracks at its edges(see dar shadows aog curved EW edge just N of iage center).Suspeed auses: Spalling is due o high-stress cycling with low EHDfil containaton and rogh ating suace (shaft as nerring) as likelycotributors

DATA

Pae N 0.39Arhve N 03-701Image ype viewSalear 30 (icros 20% others +100%0%)mpnen TRB; R runSpeedad:urainFaiure de 0016.02. Advanced spallingFaiure de 006.13 Subcase-fatge spallFaiure de 00.22.1 Ovestess crackFaiure de 00.23.2 Plasic dsorion of bulk shape

DESCRPTONSFaiure Desripin Advaced copound alure ofsevera odes. Several deep spalls fored on each rolerprobaby due to oveload and subcase fatigue (conac stressig of core below case/core boundary). Edges of craters were thenchipped off due to overrollng of debris. General roller shape was lost de o plastic worig Bearings in heavy indusrialachiery often run to severe copound failure before dagnosis and reoval.Image Desrpn Sevea rollers of a TRB show deep cavities which are spal craters batteed and roled over after oration.Edges of all ollers except those in the NE and SW end postions ae chipped Overall roller shapes are destroyed by overroling ofdebrs and/or sding after seizure of the oller i the separatorSuspeed auses The orgin of the roller spalls is uclear in the absence of the oher coponets Severe debs denting(perhaps fro ring spal debris) or ateria defects ay have initiated the Furher destucion of rolers s due to ong rnningater failure iception.

209




ATAPlae No 1040

Arhve No 026-6Image ype view (partial)Salear 60 mm (micros ±20%, others +100%, 50%)omponen CB (multiow); I, ruSpeedLoadLuriaon mineral oil mist, ? Faure ode 0016025 Advaced spalligFalue ode 00161.2.1 Shaow etry spall from surace poit-defectFaure ode 002013 Contact corrosioFalure ode 0012.0.2 Abrasve mild wearSee as PLATE 10.51

ESCRPTONS

Faue Desipion he roller path on this CB I is spalled over the etirearea. The bearing sufered roller failure (see Plate 10.5 producing sharplyirregular coact suaces and copious debrs whch indeted the I roller patheverywhere. Application is know to suffe from igress of aggressive steelrolng oil ito beaig, which damages rolling sufaces and thus promotes spalling

Fau Cod: 00.602

mage Desripon oller path exteds om S mage edge to N ad NE ad is flaked by undercuts ad guide lages. Entireroler pah is covered by spal crates of somewhat uniform depth, except near N ed where a SWNE runng curved deep spall isfollowed by a relaively unspalled ridge. This feature may be due to an accident of overolng or possibly a local material hardnessdiffereceSuspeed auses The initial failure of his large multirow seel mi roll eck bearg is the oller aigue show in Plate 0.51This I failure may be secoday. Loads, speed neria ad noise i a mill stand are great Mills are not isrumeted to detectearly bearng failure. Mills canot be stopped abruptly without serious consequeces. Accordigy, the bearig was u ong aterinitia failure, causig this severe secodary damage

20



Failure Code: 0.161.1

DATAPae No 10.41

Archve No 1 07025a&b&cImage ype SEMScaebar = a 1 mm b, c 400 �m (micros: + ohers + 00%, 50%)Componen ACBB OR runSpeedLoadLubrcaon grease, soc

Faure Code 00.161.1 Subsurace origin spall (high Hertz shear stress)Faure Code 0016.02.2 Contact fatigue crackingFaiure Code 3: 001602.3 Incipient spaling, single spallFalure Code 4 -

DESCRIPTIONSFaure Description: Spalling originated n subsurface (surfaceparael) crack whch

exfoiated via a number of concentrc surface cracks. The subsurface def ect tatoriginates the failure is not sown. This mechanism of spaing results from hghload and subsurface defects in the absence o surface distress or other severesurface spall orginatorsImage Descrpon (a): Concentrc (ligt clor) elliptical cracks surround twoncpient spals (b): NW image half s rollng suace; SE: circumferential secton.Subsurface crack (in section) undermnes surface and penetrates to it in fourcracks (c) Oher locaton. N image quadrant is the rollng surface; E quadrant:circumferential cu SW quadrant: axial cut. Subsurface crack in SW and Equadrants. Dark spot at W is artifactSuspeced Causes Spall-initiaing subsuace defect caused suracepaale crackat he appoximate maximum Hertz shear stress level whch broke hrough to hesurface in several cracks Exfoiaton of the spal crater has begun

Chapter 0 Spalling

a

b

c

211




DAAPae N 1 0.42

Archve N: 07 422&23Image ype: a,b light acroScalear a,b 80 (icos 20%,others + 100% 50%)mpnen DGBB; B ruSpeedLadLuricanFaure de 0016.1.1 Subsuraceorigi spall (high Hert shea stress)Faure de 00.16.03.1 Spallpropagaig by crackg at spall botoFalure de 00.16.1.1.2 Spall rosubsurface defecFalure de 00.06.2 Iclusio strgerSee als PLA: 1 0.59

DESRPONS

Failure Code: 00.6..

a

Faiure Descrpn Subsurace origi spalls o a ball propagatig by syetrical extesio of the spal boto, as the ballchages orietatio ad the spall is overroled ro diferet directios (a) Oigiaes fo poit defect (circular syery)(b) fro a liear icuso (bilateral syetry). The bal has faied See Plate 10.59 for surface origi ba spalligImage Descrpn (a) Buls-eyeshaped spal crater, iitiatig at the ceter of coceric circular striatios, just W of iageceter. Two furher arcs of crack propagatio exted N ad S beyod the origal spall. (b) NS black lie at iage ceter isiclusio striger Bilatera (orage slce) spa propagatio to circular shape ad beyod Due to sal depth o focus outerostaeas of spall are il resolved i (a) ad (b)Suspeced auses Balls i radialy loaded bearigs chage axis of rotao frequetly Afte a spall has itiated t ay beoverrolled i ay directio ad thus grow circularly Oce the spall becoes sizeable it ay exert a oretig effect o the ba sothat axis chages becoe ore rare ad further spall exteso proceeds oly i two directios.

DAAPae N 1 0.43Archive N: 08-701Image ype SMScalear (icros 20�ohers +100% 50%)mpnen DGBB; B silico itide hot isostaticpressed, ruSpeed 105 KdNLad 3.65 GPaLurican: ieral oilFaiure de 006.1. Subsurface origi spall(high Hert shear stess)Falure de 00.16.03. Spal propagatig by

crackig at spal botoFalure de 00.05.4.2 Bider defect ceraicFailure de -See as PLATS 10.57 ad 11.29

DESRPONSFaiure Descrpn Macrospal o silico-itrideball, showig three ajor ad several iorreitiatio pots circula popagatio fro each, relatively steep walls ad very sooth flat bottoImage Descrpn Spall origi ear iage ceter oe circular propagatio phase at iage ceter, aother W the third S of firs,all partly overappig Three io propagatio spurts exted spal boudary toward N. No visible defect o uspalled surface.Suspeced auses This ball repoed to be oe of a few early ailues i a bearg est group with trided low-cabo tool steelrigs No artificial deect was troduced Most other balls i group survived ayfold loge, suggestig uidetifed aeraldefect (perhaps bde defect) i faled bals

22



Failure Code 001611

DATAae N 1044

Arhve N 00-34&3mageWpe a b SEMSaear a 1 mm b 100 _m (mics 20%ers 100% 0%mpnen ; R, siicn iride (gas ver-pressresiered rSpeed 094 m/secLad 2.8 GPa max. pressreLurian mnea l w. bndary br. addiiveFaure de 006.1 Sbsace rgi spall(ig He sear sressFaure de 00 6.12 Spal frm sbsrfacedefecFaure de 00.1 MicrprsiyFaure de

DESCRPONSFaue Desptin (a: Mlipe spalls, riginaingfrm disribed prsiy i e blk maeria. argenmber f spall rgis a dep g sear sress,spreading rapidly ad remvig e enre verlayigmaeal. Pe a . (b Exended pre clser swni image (a a remaig visibe i spal bm.Pfse pis i spall bm srface srrndingpre clser were silicn niride grains aveseparaed a e bider.Image Desrpn (a n N alf f imageelgaed flabmed spall rigaing a preclser 1/3 E fm W image edge and 2/ S fm N

image edge. Rler axis rns EW image. Aerspall wi large ndermned amina i SE iagecrer. Fine lggray sps b in spall bm and nspalled srface may be e pis described inimage (b. (b Magnfied view f pre cser swni (a. Siicn nide grains ply bnded rnbded arge pe. Prfse small pis and piclsers, a few m sie pebbly appearg spallbm srace side arge pe. Pis are lkely sem rm pled silicn iride gains wicseparaed a binder drig spal frmai.Suspeed auses Sineed silic niride freqenlyas sme prsy de incmplee cmpacinand bnding dring mafacre. Prsy in ceramicis a pe spalliniiaing deec b fr irs

spalling and r spal reiiiain dring spallprpaga.

Chapter Spalling

a

23



Failure Alas for Herz Conac Machine Elemens

DATAPae N 10

Arhve N 122.3Image ype SMSaear = 00 Jm (micros 20%ohers 00% 0%mpnen DGBB; B, ruSpeed 10 KdNLad 28 GPaLurian miera ol ? ocFaure de 00.16.1.2 Spa fromsubsurace defectFalure de 000.2 Formig seamFalure de 0016031 Spal propagatigby crackig at spall bottomFaiure de -

DESCRPTONSFaure Despn Spal origiatig from aformig seam has popagated i cocetricstiatios primarily dowstream i directioof cotac travel. Some spall formatio has


occurred upsteam from he seam Cotued spallig from this subsurace defect is likely to cause fuctioal falure of the ball. its preset coditio, the ball is osyImage Desripin Seam us W across image at oe-third image height from S edge formig dark straight lie with ledge atseveral locatios To N o seam (dowstream i overrolg drectio), the spal exteds i seveal cocetric sriatios ito he NWimage quadrat propagatig by cotued spall bottom crackig. Spall edge has collapsed ust S of seam, cotiug crater about00 Jm i that directo.Suspeed auses Seams are discotiuous iteaces arisig durig rollig (or drawig) of ball wie, ad are ofte oxidized. Theyare weak iterfaces causig sevee stress cocetratio that is likely o lead to early spallig.

DATAPae N 10.6Arhive N 122-Image ype SMSaea 100 Jm (micros 20%others: +100%, 0%)mpnen BB IR, ruSpeed 0 ? KdNad GPaLuian grease, ? cFaure de 006.1.2 Spall from subsuracedefectFaure de 00.06.1. Hard micro-iclusioFalure de 0016.02.2 Cotact fatigue cackig

Falure de 00.18.021 Light or icipet detgDESCRPTONSFaiure Desrpn Icipiet spall origiatig at a(cluster of) hard subsurface microiclusios.Cicular crack edges emegg o cotact suace,with small exoliatio Smal (10 Jm) hard iclusio at spall botom, wth others probable Uspaled suface has may fe debisdets. Spall is likely to propagate, causig uctioal faureImage Desripin Image ceter is occupied by cacks extedig threefourths of a circle from through S ad W to N S hafcircle has spalled out A lamia of material is udemied by crack at the W diameter. White gobular body wth black outliead white hao at is believed to be a had ometallic iclusio A iclusio probably spalled out ea N spal edge (. Debrisdets are visibe o cotact surface.Suspeed auses Clusers of hard ometalics may remai i steel from steelmakig ad are a classical source of eary spallgfailure The icusos show are relatively small (3 Jm) but may still be sigificat stress cocetators uder very heavy load.

24




DATAPlate No: 10.47

Archive No: 027-67mage type: lght macroScalebar = 10 mm (micos ±20%, others: + 100% 50%)Component: DGBB; IR ruSpeed: 130 KdNoad:Lubrication: grease, 60°CFaiure Code 00161.2 Spal from subsuace defecFailure Code 00.16.023 Icipien spallig single spallFaiue Code 3: 00.16.01.1.1 etered spaig ormal track widthFaiure Code 4 001232.05 Wear track fo centered axial oadSee also LATES 103 and 012

DESCRIPTIONS

Chapter 0 Spalling

Faiure Description: liptcal steepedged spall ear center of ballpath (under thust load) with a lie-depresso i the spa botomsuggesig an inclusio strnger as origi Plaes 103 1012 and10.47 show various spalling modes in smilar beargs forcompariso he wear track ofset o oe side idicates axia load.his bearing is osy ad has faled the quiet unnngappicatioImage Description: Obog spall crater with major axis in axia directio at arow Shot black axia lne centered i spall botommay ndicate inclusio striger (requies metallographic examinatio). wo fa dark circumerential les run ear spal tipsdcating the rolig track Note the clean udeed surface away rom the spall.Suspected Causes: An inclusion sriger under the suace s a lkey cause of this single spa i a normally loaded bearigoperated i clean environmet

215



Filure Atls for Hertz Contct Mchine Elements

DAAPlae No 1048Arhve No 014-005&00mage ype a b SEMSaear = a 400 ; b 10 icrs 20%thers 100% 50%omponen RC est ig rd sicn nitride uSpeed 9 /secoad 593 GPaLuration iera i w additives arx 40°CFaure ode 001 12 Sall fr subsuracedefectFaure ode : 001023 Inciient salingsingle salFalure ode 000541 Micr-rsity in ceraicFalure ode 000542 Binder defect in ceraic

S als LATE 1

DESCRPTONSFaure Desrpon Sall rignating at asubsuace stucture defect f the ceraicrsiy and/r bnder defect sreads atshallwer deth uside defective structureImage Desrption a On dark gay ctactsuace an irregular sall at iage ceter I hesal btt a darke gray veical val utined inlight gay is renant subsurace defect areaOutside the va the sall is shallwer ad has stee walls Overrling diectin is iage E t W.b Fracture surface f the sae aerial t thesae catin shws at age center ad 1/5

E w black bubblelike vids styarxiately 5 diaeter he center vid issurruded by whiteaearig excess bideaterial exteding W in a sreak t within 1/ fW edge and esen in atches near he vidSuspeed auses sity in ceraics is thest deleteris aterial deect and degradessilicn nitride salling fatigue lie drasticallyPrly distributed and rly adherig binderaeal rduces salls by intergraua cracking

26

Falure Code 16112

a



Failure Coe: 0016.2 Chapter Spallng

ATAlae N 049

Arve N 002022Image ype light micrgramSaleba = 2 mm (micrs: 20%thes: +00% 50%)mpnen: AC IR t steel runSpeed MdNad: 4 Gaubran synhetic yeste il, 6Faure de 00162 Sal frmsubsuace defectFaure de : 006025 Advanced salingFaure de 00082 Rehardened gindngburnFalue de

S als PAT: 625

DESCRPTONSFalure Desrpn A dee grndng bun (see Pate 625) has creaed a 200 m dee weak zne which salled ut rematureywith an unusua smth fa craer bttm Subsequent salling nmal maerial has rgessed bh wih and against the rllingdirectin creang a nma sawtth-bttmed sa. An extensive netwrk f angled cracks is the recursr f furher salng.Image Desrpn Oblng cmlex sal crater ccuies image center. Cental t the sal a hrseshe shaed flat-bttmed areabetween three arrws is the saledut gindng burn. ust sall crater an extensve netwrk f cracks emeging t surfaceas white lines n dark backgrund as at arws will frm additina craering f running cntinuesSuspeed auses A dee ehardened ginding burn is a very sevee sall initiating defect Once salled ut the sal rims aestess cncentatrs driving fuher salling.

ATAae N 050

Arve N 04 09mage ype ight macrSaebar 0 mm (mics: 20%thers: +00% 50%)mpnen TR; IR carbuized runSpeed:adubran: synthetic lyester i, ? Falue de 0062 Sall rm subsurfacedeectFalure de 00.6032 Sall ragating byrenitiatin at surfaceFaure de 0012 Lcalzed surface distress(hal at defect)Faure de

S as PATES 046 and 062

ESCRPTONSFalure Desrpn Sall initiated at subsuracedefect first frmed elitical crater as in Plae 046Due t margina EHD cnditin ragatinrm surfacerign cacking then tk ve, adding ireguarly shaed shallw-enty craes in rllng directin This ragatinmde is yically me rad han subsurface crack agatin. Cntas with Plate 062 which shws a sufacerign sal.Image Desrpn TR R (cne') rler ath wth E inishing lines. ndecu nea S mage edge. Overrling directin t .Smal ellitical sa at E end f catering fllwed n verrlling directin by seveal irregular shalwentry craters. Light-clredging (hal) is visible n the caters frm surace dstress glazing.Suspeed auses After initiatin f salling rm subsuface inclusin the rimary craer creates a surface defec (ssibyaugmented by debrs denting) w HD ilm clases at craer edges causing reeated initian f surfacerign sallng.

27



Failure Alas for erz Cona Mahine Elemens

DAAPlate N 1 01Arhve N 02616mage ype vie (aal)Saear 0 mm (mics: ± 20%, ters + 100%, 0%)mpnen C (mltir); & G, rSpeedLadLurian mineral il ms, ? ocFaue de 00.16.1.1.2 sall m sbsface efectFalue de : 00.22.01 ling element (ball rler) crackFalue de -Failure de -See als PLAE 10.40

DESCRPTONS

Faiure Desrpn Te casearee llers in tis C arerille t accmmate ins ele in te searatr rngs ic

Failue Code: 6.2

seve as giing elemets. Te rller failre itiate as a atige crack at te rlle bre (rbably frm a macnig mark),ragate trg te sectin an case te axally elgate stee a ee sall Overlig case astic eeing nearlle en e rller is ikely factreImage Desipin lers, el betee te ings a i-tye searatr are remve rm bearng. Wele is are tvisble e secn rller fm te W ss irreglar axial craterig S t-tirs f leng. Nea cener crateig, te blackaxial eg is a crss-sectn crack. Near S en salls, crack crves t W an is ay eee st by rl-ver.Suspeed auses ler bes ae rlle bere eat treatmen an may s macining marks. I carbrizing bres ae sallymaske t kee carb , bt sme cabrize sts may ccr, ceaig lca esial stress ening sresses frm cntaclag eak at e bre an may iitate fatige cracks at tese srace eects r esial stress areas. Te cracks evenalyragae e rler OD Plate 1040 ss saling I.

DAA

Pate N 102Arhve N 00202c&eImage ype a SM, b SMcmsteSalear = a mm, b: 200 m(mcrs: ±20%, tes: + 100%0%)mpnen AC; , l stee, Speed 17 MNLad 14 GPaLurian syntetc yester 176C aFaiure de 0016.1.2 Sall frm sbsrace efecFaiure de : 00.22.01 lling element (ball rer) crackFaiure de 00.01.1 Lcal nickFaiure de 00.1202 Abasive mi ear

DESCRPTONSFaure Despn (a) Aarent aile rgressi is (1) inetatimarks as frm rllg ver a sar· ege (ssiby assembly) (2) inetcracking, () sallig Tl steel balls are gt t be mre crack-rne Inbearng steel bals a blk crack rm ickig an befre sallig l be bare. Te ball s faie. (b) Nicks frm ege cntact riginate an -etcrack an sbseqent sall. Sall sace is sigtly r by ebris. Te bal is aile.Image Desrpn (a): Sall rllei lines ball srace, as at Tee ar airs i NE qarant mark n-et gigairne crack Sal rign is at tis crack srea i bt irectins. eac marks' (crve riges) fm sall igin t SW(b) Smt cntact maks at A, frm rling ege ver ball srface In-et crack tavels frm N S t SE (ars) Crack stasse sall (N image ege) Wear maks are visible n te SW crer. Suspeed auses In assembly f bas int seaatr (r bearing assembly), ineatins may be mae n te ball srace by

a ege In crack-e material tese may initiate a blk crack n rnnig Saling flls.28



Fu od .6. Chapter 0 Spalling

DATAPlate No: 1053Archive No: 002-002dImage ype: light maco of racureScaleba = 1 mm (mcos: +20%,othes +100%, 50%)Component ACBB; B too stee runSpeed 0.8 MdNLoad: 22 GPaLubcation: synthetic poyeste ol 176°CFailure Code 1 0016112 Spa fromsubsuace defectFaiue Code 2 002201.3 Roing eemen(ba, ole) crackFaiue Code 3 000732 Lamear cabideFaue Code 000431 Incipien meltig

fom fogng at excessive empeatue

DESCRIPTIONSFalure Description Spa oiginag in defective mateia stucture has pogessed to buk aigue cack The ball was boken nhaf foowing the cack fo examiation. he stcte defecs (vefied by metalography) ae lamear cabdes poes due oemetng and defecive matensie strucurea attbuted o oveheatig n manuactue They make he pa racurepone Thebeaing has faiedmage Desciption: At arows crosssecon though spa cate The roughaceed fracure surace extending fom hee aongthe ba sace and o he mateial is the buk fatigue cack showig (fthe away) eiptca steps concetric to the spal Thesmooth suace nea S mage edge s the aifca fractue made o expose the cackSuspected Causes Too stee s sesiive o excessive fogig tempeatue which causes ocal melting and poosity. mpropeanea afe ogig causes ofspecificatio maenste needles Such maeria is spa ad cackproe This expains he adiacacking unde conac oad with subsequet spaing n an eemen (ba) not sbjec to tese hoop stress

DATAPlate No: 1054Achve No: 014523mage type: ight maco of section etchedScalebar = 3 mm (micos: ±20%othes +100%, 50%)Component: CRB (oe/ole test) R runSpeed: 50 KdN (eqv)Load: 39 GPaLubcation: miea oi 65°CFailure Code 1 0016.1.13 Subcaseatigue spaFailure Code 2 0016022 Contact fatgue cackngFailure Code 3 Failure Code 4: -

DESCRIPTIONSFailure Descpon: Vey heaviy oaded (39 Ga Hetz pessure)oer to ole es o cabued specime Case deph exceededby depth o high He shear sesses causes sufacepaaecacks which epeatedy se to the suface One has penetaedthe case ad caused a spa; ohes ae tapped beeath the caseSubcase contact fatigue is a desig o applicatio ero (case tooshallow o oad condtion)mage Desciption: Meaogaphc coss secon though cyindrica ole Core etches ligh gay case dak gay Circua crack atgeat depth (2 mm) with case about 03 mm deep Nmeous braching cacks ise to the suace n the oveoling dectio(cockwise). One cack peneaes the case (at N edge) ceating a spaSuspected Causes: In casehardened pas the fatigue sengh o the maeial dimnshes as the inne bounday of the case seached due to diminishing hadness he atenatig Hetzian shea sess ampitude peaks at depth equa o onequae cotactwdh and then gaduay dmnishes I he sength dops faser wih deph ha he shea stess then the most cical deph fo

cackig s n the coe causig deep cackng9



Filur tl for Hrt Contct Mcin Elmnt

DATAPlate No: 0.55Archive No 0803&5Image ype a: gt acr vew (etce sectnScaebar a 20, 5 (crs 20%, ters: + 00% 50%)Componen G; P case arene SpeedLoad:LubicaonFaue Code 0063 casefatgue sallFaue Code : 006022 Ctact age crackgFaue Code 002322 cratc arks kneatc wear arks rllg suaceFalure Code

DESCRIPTIONS

Faiure Descrpon Cntact atge alue n te lw-aress cre fa casearene gear. Te a was s g tat g sea stress wascreate eneat te case/cre terface. Ater cracks re te cretey enetrate t te surace as axal cracks a create stragegesas. Gears wt scase fatge wll sffer grss falue atnal rng Esewere n te t are raa wear arks.Image Desciption (a At center W-st fak ee sallcater wt stragt ege. Case aears erne Metallgraysws tat sall et excees case et lsewere n te tt aregtcre raal wea arks (: Gear crss sect O sec antr t r W arrwea-sae lack les ae sucase cracks

Faiure Code: 0016113

Faiure Code: 001612

a

b

flwg case/cre terface wt ranc cacks t surace On Wst tt te sal exens t case/cre teaceSuspeced Causes Case et ay e ew secfcat r te gear ay e severely velae n eter case te agntuef Hert sear stess ses swer wt et an te ateral fatgue resstace (aress. Fatgue cracks fr at tecase/cre terface uerne te case a eventualy exlate te surface.

DATAPae No 056Arcive No 093624Image ype: EMScaeba 20 (crs: ±20%, ters: 00% 50%)Component DGBB; IR, rSpeed: 450 KNLoad 35 GPaubrcaion nera l 1 cFaiure Code 0062 uace rgn sallFaiure Code : 006022 Cnac fatgue crackgFaiure Code -Faure Code -

DESCRPTONSFailure Descrpion rface rg sall ery area (at ustreasall en n verrlng rectn Unsale rllg srface sflwe y a saw-entry sall ege. Te entry se s at40 ee (at ne-egt te axu He sear stresset) ncatg surface rg Frte crack fratn s nrgress. Te g as faleImage Desciption Area n te N age quarat s teunsalle rlng surface B, te NW qarat s te salltt Te sallwentry ege s a cex curve etween teC s te sectn cut trg te sall. D s a sallw crack sa t te e tat ntate e sal.Suspeced Causes allwenty salls rgate srface efecs clug suace stress ccurg e lw HD flcns

220



Faiue Code: 00.1612.1

DATAPae N 057Arcve N 04-60 &602Image ype a b SMScae bar a 400 b 40 (icrs ± 20%ters +00%, 50%)Cmpe DG siicn ntride; ru DP iden n ballSpeed: 2700 r/inad .9 GPaubcati yese sytetic l 66°Faiure Cde 0062 Salw entry sall rsurace nt-deectFaiure Cde 0004 Ced nick in ceracFaiure Cde 0072 Lcalied surace distress(al at deectFaure Cde 006032 Sall ragating by

reiitiatin at suaceS als PAS 043 ad 29

DESCRPTONSFalure Descrp Sall initiated by a 05 widediad-yrad indetati causig a cied ick(FC 00014) n te silic itrde ball srace (a Sallswing rst iitiain as lcalized sallw suace distressicrsaling at te ideati sbsequet gressi tacrsal det wit ultile reiiiatin and erratice-sided ragat. (b: Al bt te ti and crssededges te identatin ave saled ut e srrudingsal is s sallw ta te indentatin t is let itactug e ndetati is nly seveal dee. is isaagus t te "al seen arud deecs in steelsuraces bu i ceraic i is nt a "glaed bunisedsuaceImage Descip (a Sall wi ltle lbes at iageceter. Iitatg idetatin is at A at te ited NWrtrusin sall inear ridges rnig W nea N salledge NWS at SW bundary NS at budary adW ea S cstricti sall idcate restaing nes sall. (b NW rtrusin sall agiied sws ti DP idet N iage ceter ad straigt edges yraid idente ning rugly NS and W r tSall ear indeer s a sallw srace distesscrsall. Macrsall det is reaced ure away initiatiSuspeced Causes (H issac ressed silc nitrde

Chapt Spalling

a

b

balls are igly sal resistant. dce salling DP dentatis were ade n severa est balls rir t endrance testing ibeargs O tis ball e indeter lad was 5 Kg t was bserved ta te indetati rduced rased sulders ad at acritical sulder eigt was needed intiate a sall lt s rerted ta salls intiate in tese silic itide balls r te raisededges te identan ad t te cacks ed wti te indetati ude te ideter edges. I e detatin is saeug ailure is arested a suace distress stage.

22




Pte No: 1058

Archive No: 107024a&bImge type: SEMScer a: 30 b 5 m micrs 20%, thers +100% -50%)omponent: AC R, ruSpeed:Lod:urcion: grease, 50°CFiure ode 00621 Shallw entry spall frm surface pt-defectFure ode 0016022 Cntact fatgue crackingFiure ode 0018.11 Runded dent frm sft ctamiatFiure ode 007.2 Lcalied suface distress hal at defect

PNFure Descripton: Small (120 m lg cack runing rmal t

rlling drecti ad ncipient spall fmed frm alumina micriclusinat the surace. Calcium ad alumium were verified by micrprbeaalysis This is the earliest phase f spall crate frmatin A rundeddet (15 m is unrelated t spalling, but shws a hal f surfacedistess. The bearng is likely t ail m prgressve spallngImge Descripon: a: NS finishig lnes in NE crner, runded dentfrm sft cntaminat particle, decrated by darer suace distressha i which ishg lines are partly bliterated. At mid-image, twEW cracks are black EW lnes with whte rim sharp edge. Theymeet i thee dark patches which are the aumia inclusis. Spallingmay have begu at the incusins b cluss ad cracksigiating frm them, at higher magnificati.Suspected uses Hard fr example alumina iclusins are surcesf spalling. A suace inclusi is a severe spall itiatr, especiallywhe suace distress is present due t lw ED flm thckness This

cusin is clse t the miimum size that has bee reprted t cause spaling.

Pe No 1 059Archve No 0742Imge type: viewScer 20 mm micrs 20% thers +100% -50%)omponent: DG , ruSpeed:Lod:LurctonFure ode 0016121 Shalw entry spal frm suace pt-defectFure ode 0016031 Spal prpagatig by cracking at spall bttmFure ode

Fiure ode S s PLATE 1042

PNFure Descrpon Extensve spalling f ball surface, by remval f a unifmdepth layer. The spall is beieved t riginate frm a suace deect dent, c, etc.

Failure Code: 00.16.1.1

ad then prpagates i all directis as the bal changes axis f rtatin. The ball has faied. Cmpare with Plate 1042 shwigsubsuface rigin spallsmge Descrpton: Large val spa exteds frm NW t SE The spall is cmparativey shallw and the spall bttm s relativelysmth, ndicating extesive verrllig. Fm stiatis i spall bttm, rigin is prbably near N ceter spall Smth, evenbttm and relatve shallwness sggest surface rigiSuspected uses: Damage t the ball surface by suace distess, denting r ther causes may precipitate spalling alls inradially laded bearings chage axis f tat frequetly. After a spall has itiated, t may be verlled diferet directinsad thus grw in me than ne directin



ailure ode: 00.16.1.1

Pte No: 1 060

Archive No: 087-10Imge type: vewSce 30 (icros 0%, others 100%, 50%)omponent: ACBB OR, ruSpeed 1 ? MdNLod:Lurcton sytetic polyester oi, ? Fue ode : 00.16.1..1 Shllow etry spl fro srfce poit-defectFue ode 00.16.03 Spl popgtio by reititio t surfceFue ode 001.3..0 We tck whe lod rotes over oterrgFue ode 0018.1 Shrp idvidul det(s) fro el debis, sperties

PNFue Descption: Two Hethcote bds or circfeeil we rks

dcte ero-slip zoes i bll/groove cotc. A rge spll, cosistg oy shllow spls, coied essetilly betwee he Hehcote bds,dictes surce oigi prooted by slidg he berig hs iledImge Desciption: Glossy surfce of bl goove is divided by two sets ofcircfeetil gry ies: the Hethcote bds Lrge spll SW udrt iscofied essetly betwee Hetcote bds. Jgged side edges d shllowdepth o spl idcte reiitto t suce Sigifict debris detg (drkpos) e vsible esewhere i he groove.

Chapter Spalling

Suspected uses: his OR o ighspeed berig hs hig cerfugl lodig, prodcig 360° od zoe (see Hethcote bds)Srfce-itited spllig y ve bee ided by debris deg d cocerted the higstess, high-sldig zoe beweeHethcote bds

Pte No: 10.6

Achve No: 0068&1Imge type: : ligt cro b: SEMScer : 10 , b: 00 (icros 0% ohers +00%, 50%)omponent: C CF (slidig), uSpeed:LodLucton: e ol bsed diesel egeoil, ? Fiure ode 00611 Shlow etyspll fro suce poitdeectFiure ode 00603. Spll propgtigby reititio t sceFiure ode 006.01.1 Spllg ceteed i cotctFiure ode 00..33 Wer, cetered i slidig cotc

PNFiure Descrpton () xtesive srfceiitited spllig o c olower roded i slidig-rolig Hertz cotct wih c (b): Ftige spls ro ()Spllig ftige i Hezi coct wit pedoit sidg is less coo h wer (FC 00.1) o gllig (FC 00.13), but does occu s show ere Usplledres re fetreless ro we.Imge Descption: () Circul edfce of o-roller c ollowe Roughly circulr drk wo res re er O d t idrdis Circle of lght-colored splls t cee d 1/4 i ro edge (b): S qurter o ig is usplled re with few itNWS wer rks. N threeforts of the ige coprises wo spll cter res wih ieposed li peprig to spl otSuspected uses: No-roller c ollowers re sphere cpped rod-eds i cotc wit slghtly tpeed c surfce wic isplced so s to iduce otto of the ollower rod roud is ow xis, while he rod-ed sides over e followe. Duig the litpse, high pessures d (de to he slidig) igh trctive forces exist wic y cuse spllig.



ailre Atlas or Hert Contact Machine Elements

Pe No: 1062

Archve No: 04520a&b&cImge ype a b c: light macroScer = a b c 10 mm (micros ±20% others: +100%,50%)ompoe: TRB R carbrized uSpeedod:uco: eral ol (low viscosity) 135Fure ode 00.16.1.2 Shallow ety spall from sufacepoit-defectFure ode 00.161.2.2 Shallow ety spall from surfacelie-defectFure ode 00.16032 Spall propagatig by reiiiaioat srface

Fure ode S s PLAT 10.50

NFure Descrpo Three examples of spallig orgiatig fromsace iteractio (low HD film rough or deted suaces).I (a) te iitiator is a det i (b) a frrow ad i (c) twodets Spals propagate i the shape o a arrowhead opeig the rollig diecto. The etry area is a shalow-age crack.otas with Plate 1050: sbsurface oigi spall.Imge Descrpo (a) (b) ad (c) TRB IR (coe) roler trackwith W fishig les ad dercuts at image N ad S. (a)Rolig is to W spal iitates at det (arrow) progresses toNW the to SW ad aga to NW (b): Rolig is to W; spaliitiates at furrow (deep fiishg lie a arrow) ad progesses to

SW (c) Rollig is W to ; two iiiatios at dets (arrows)progress i a arowhead shape All iitiatig ages are shallowSuspeced uses: ow viscosity oil (hgh temperatre) caseslow HD film thickess ay srface defect (det frrow)deplees HD film ad may iiae spallig Spall edge acts as asecodary itiatig defect

Faiure ode: 00.16.1.1

c



ailure ode: 00.16.1..1

Pte No 10.63

Achve No: 93-22Imge ype: a b c d vewScer = a12 b:2 c16 d2 mm (micros 2% oters 100% 50%)omponent: DGBB IR runSpeed:Lod:LurctonFue ode : 00161.2.1 Sallow enty spall rom suace poin-deectFure ode 00.1711 Glazing (ncipient suace distress)Fure ode 00.112 Microspalling (advanced sace distress)Fure ode 001602.5 Advanced spalling

PNFiure Descpton Progression of sace-distress (F 007.1) origin spaling

on for IRs from te same est group o bearngs (a): gaing only; (b) sacedisress micospallng (c): incipien spallng; (d): advanced spalling. (a) and (b)serviceable; (c) nosy bu may n (d) failed If operating condions causingsuace distress (insufficient EHD fim aggressive lubrican roug srface)persist progression from (a) to (d) may be rapdImge Descripion: Fou views of difeent rings from te same beaing testgrop (note te sligy diferent magnifications) after pogessvey ongerrnnng. (a) entered band of canged user in ball groove s ealy sacedistress (b): Fosted appeaing areas (one-o W of ing center) aremicrospalls. (c): Seies of spal crates independeny nitiated. (d) Generaledspall craterngSuspected uses Surace distess occus wen asperiy interactions in conactare excessive suc as fom insficient D ilm og sraces o possiblyrom aggressive lubricant. Microspalls develop tat seve as severe iniiatingdeects for macoscopic spalling fatigue Pogression rate varies sarply wt

condtions. arbrized pas may be more resistant tan troug-adened pats.

c

Chapter Spalling

d




Pte No 0.64

Archve No 22-8&9mge tye SMScer a 1 mm b 100 m(mros: ±20% oers 100% 50%)omonent DGBB IR, runSeed 170 KdNLod 28 GPaLurcton mineral oil ? Fue ode : 00.16.1.2.1 Sallow entryspal from sae pointdefetFue ode 00182 Sarp indivdualdent(s) from ea debris aspertiesFure ode 00.16022 ontat fatigueraking

Fiure ode PNFiure Descrton Several sarpedgedsallow dents as from roledin flakes(possibly from plating) some formed beore(some possiby after) spal initiation A fansaped spall oiginated from one denonentri raks are visible downstream ofte spall rae (in te rolling diretion).Spalling is likely to propagate asingunional faiuremge Descrion (a): Fansaped spallrater overs image enter. At ip of fan atmage S te angular sallow depression in

te suae is a dent from a tin dutileard ontaminant. At N edge of rateronentri aks are ready to exfoliateadditional material Several dents possiblyfrom spall debris ross rak lines N of terate (b) A detai view of spal originsows edge of iniiaing den S of spall tipfollowed by raks.Susected uses Debris dents ause(1) oss of HD film (2) loal stressonentrations near dent edges 3 damageto material ndelying dent Tese fatorsontibte to make dents spall iniiators.Spall typially originates some small distane

downstream (in e diretion of ontattravel) rom te dent leaving an unspaledip between den and rater.

ailure ode: 001611



ailure ode: 0016.1.1

Pte No: 10.65

Archve No: 018-104Imge type: viewScer = 20 mm micros: 20%others 100% 50%)omponent: SRB; IR runSpeed:LodLurcton:Fure ode : 00161.2 Shallow etr spallrom srace poit-defectFure ode 00.201.3 otact corrosoFure ode 00.123.2.1 Wea tack centeredin contactFure ode 00.124 Wear of gdig

compoet suppor surfaceN

hapter Spalling

Fiure Descrpton: 1) otact corrosio streaks spaced at roller spacing o one rolle path which caused 2) extensve spallingi that roler path wth cratering most severe at corrosion streaks 3) Deris denting and wear o other roller path caused at leastone spall (4) enter guide flange wear rom deris trapped etween separator and flage. Te bearig was sed in heav slowspeed machier ad ma have rn a log period to reach ths ailure.Imge Descrpton: Roller path to image N shows five dark axial corrosio streaks at roller spacig underneath generaized spallcrateing Te craterig band is widest aroud the streaks Roller path to image S is fiel deted ad matte from debris dentigad arasive wear One spall is ear the ceter lange at W. entra guidelange sows a step wor i the center plane were twoseparator alves meet.Suspected uses: ontact corrosio arises from water i the luricant proa grease) of the monted earing or possilfrom water n the package drig shipmet prior to mounting. Severe contact corrosio wit pittig) is a serious spall-iitiatingdefect Spal debris from the extesive cratering act as arasives and denting particles



Failur Atla for Hrtz Contact Machin Elmnt

Pte N 1066Archive N: 16-003&002Imge type a vew b ighmetallogram Nital ethScer a 4 mm b 60 m(miros: 20% others 100%50%)mpnent: DGBB IR ruSpeed: osilatgLd 2 GPaLurictn grease w slia thikeeH0 + atmosphereFure de : 00.161.2.1 Shallowery spall from suae poit-defetFue de 00.224 hemial

origi (stress orroso embrittlemet)rakFiure de 0012.02 Abrasivemild wearFiure de 0018.02.2 Severe oradvaed detg

PN

ailure ode: 001611

Fure Desciptn (a) Bearig operated i highpressure atmosphere of ad water vapor wih osilatig motio. Failureorred a oe-teth o the atalog alulated life from massive spallig ad irumeretial bulk rakig hemial effe ofgrease o ailue mehaism is assumed but o explaied. The surae betwee spalls is wo ad deted by spal debris(b): raks at the spall bottom are uusual radia-goig ad brahed (may be tergraular)Imge Desciptn: (a): IR viewed o bal groove. The otat area s overed with idepedet origi spalls i a wor ad detedsurfae A jagged irumfeetial bulk rak rus through midgroove (b) thed metallographi setio through a spal Radallyiward-goig heavily brahed raks suggest itergraular rakig of hemally weakeed material

Suspeced uses: Uusua hemial eviromeal of this bearg applatio produed (i repeated rus) the atastrophispallig ad rakig failure show I waer odeses i grease uder these oditios ailure may be explaied theeby.hemial effet is also suggested by uusual spall-bottom raks ad bulk fatigue failre orrosive effet o o bearigs is otrepoed by oher soures



alure ode: 0016.1

Pte No 1067

Archve No 12-001 & 002Imge type a ligt macro b SMSce a 20 mm b 1 mm (mcros 20%oters: + 100% 50%)omponent ABB (split IR), B & silico-nitride BM50NiL rigsSpeed 1.2 - 20 MdNod variableuction poyester synteic oil 121 19Fiure ode 001612.2 Salow entry spall from suraceliedefectFiure ode 00011 Local nickFiure ode Fiure ode

PNFue Descpton Multipe-iitiatio suface origin spall oslicoitride bal resulig from electrodiscarge maciedaxial oc (aifcial defect) across outerrig ball track Ringsand cage were severey damagedImge Descrpton (a) Segmet of separator wit balls ipockets Silicon itride bal at image cene sows spall (atarrow). Separaor damage not visible (b): owmagificatioSM image of e ball spal sown in (a). Te spaling formsa cluster of many initation points wic overlap ndicatigtat spalls propagate slowly fom a iitiation poit uder tetest codiosSuspected uses Te est was ineded to study spalnitato and propagatio i sicon nitrde balls In order to

produce a spall, a severe sface ick (noc) was made byM o te OR ball pat. Te first effect of rning wit tenotc was foud to be separator fracture, followed by spallingof rigs and finally spalling of silicon itrde balls.

Chapter Spalling



Filure Atls for Hert Cott Mhie lemets

Pe N: 1 68

Archive N: 9316.66Imge type: SMScer =5 m (micros 2% others +1% 5%)mpnent: DGBB; IR honed rnSpeed: 45 KdNLd: 3.5 GPaLurctn: mineral oil cFiure de 6.122 Shallow entry spall fom suacelinedefectFiure de 2.1 Grnding honing lapping rrowFiure de .16.2.2 ontact fatigue crackingFure de

PNFure Descriptin: Two honing frrows lead nto a fatigue crackedand spalled region. Srace cracking has begn at one frrow end.The other urrow apparently initiated existing suace-origin spallrrows are serious fatigueinitiating defects especaly when highEHD ilm thickess otherwise ofers long lie The film breaks downa a urrow and high stress concentrations arise.Imge Descrptn: Gray backgrond wth faint NS lines is hehoned srface. At and NS rnning furrows with rolled-down

aiure Code: 00161

feather edges at suggestng hnng origin At surace crack initiates from furrow which ends at the bend in crack. D is thespall bottom area (only abou 4 m below the suace), a shallow spall entry Very smal 23 m) contaminan dens o thesuface The lage lightcolored obect at image SW is an arifactSuspected uses: Grinding frrows may be let n honed surface if too deep o be removed in honing. Detached honng grit mayaso create furows of its own Since the area adjacent to the furrows shown is ndisurbed and the furrow has eather edgessuggesting no subseqent finishing these seem to be honing furows

Pe N 1.69Archve N: 18-68Imge ype: SMScer =2 m (micros 2% others +% 5%)mpnent: DGBB carbrized tool steel, runSpeed: 1 KdNLd: 3.7 GPaLurctin: mneral oil 54Fiure de .16.122 Shalow entry spall om srfacelie-deectFure de 2.1 Grnding honing lapping furrowFiure de 8.13 Mti-fagment dent (bittleconaminant)

Fure de .18.1.2 Shap idividua dent(s) from metaldebris, asperities

PNFure Descrpin Several finishing urrows the deepest ofwhich intiates spallig. Vey smal mlti-fragment dentssome smal debris dents The ring has faiedImge Descripin: S twothirds of image of rolling surace with finishng marks unning S to NW. Abot midimage a whiteheavy line marks frrow with sharp point leading to the edge of the (dak) spall crater in the N onethid of the image The craterhas a sharp edge extruded toward the frow tip. Several lesser frrows are in N quadran Dark clusteed points with ight haloesare multi-fragment dents. Wide depressions with fnishing lines a bottom are debris detsSuspeced uses: ontac srface was grond and subseqently honed. The grinding le several deep furrows not removed byhoning one of which cased he spall. Multifragment dents arise from brite conaminant Debris dents cold be caused by spalldebis The cater edge appears raised n this SEM but probably is not.



ailure ode: 00.161.. Chaper Spallng

Pte N 17Archve N -18bImge type lght macroScer 3 mm (micros: 2%, others: +1% 5%)mpnent: CRB; OR rSpeed: 19 MdNd .9 GPaucin: synthetic polyester ol, 176Fiure de 16.2.2 Shallow etry spa from sace linedeectFure de 16.2.5 Advaced spallingFiure de Fiure de

PNFue Descrpin Log circmferetial spalled area on one side of OR roller pah bt away from edge, ormed by mltiple spall

craters. xeral evdence sggests a wre gasket eemet may have bee rolled ove (before beg expeled) to create severedetig Dening is no loger idetifiable Shallow spalls srrod deep craters at several points, possbly de o overolled spaldebris creatig secodary spalligmge Descptin Log area of cotigos deep spall craters s lined p circmferenally (arrows). The area s srroded iseveal places by shalowly spaled friges, as rom secodary spals de to overrolling o spall debris.Suspected uses: From evidence o olled-over wire gaske element, it is sspected that the wire became rapped n the rollerpath ad created a long heavy dent before beig expelled in rig. Sch a den explais the ong line of deep spals. The shallowperipheral spallig may be de to debris.



SURFACE DITRE 11Failure Code 00.17

11.1 DefinitionSurface distress is defined as microscae spaling fatigue. It is faiure of rolling contact surfaces

resuting in asperity scale microspall craters. In ductie materias such as steel, the failure processproceeds by the formation of (a) gazed (burshed) surface areas; (b) asperity scae microcracks; and(c) asperity scae microspall craters in that sequence. Surface distress in ceramic surfaces does notdiscerbly exhibit the glazing of step (a)

Surface distress is the result of predominanty normal contact stresses acting in asperity dimensions.Tractive forces may be present but not dominant (no large-scae sliding is likey). Surface distressis distinguished from:

• Spalling (FC 00.16) which is ertzian contact fatigue in macroscopic dimensions.• (Mild) wear (FC 0012) which is the ablation of surface materia in the form of oose partices under

the ifluence of predominant tractive contact stresses acting n asperity dimensions (substantialsiding is likely)

• Pit formation as porosity (FC 00.03) from materia casting sintering or processing; as pittingwear (FC 002); as a result of corrosion (FC 00.20) or of eectric erosion (FC 00.2).

112 NomenlatureSurface distress is widey used to designate this faiure mode in roling bearing technology

Another designation for the early, pastic flow stage of surface distress failure is glazing.The ater microspaling stage is also designated peeling, fatigue wear, delamination wear micropitting

or microspalling The term "frosting" has been used for surface distress as we as for skid marking(see FC 005) ue to the possibility of cofsion the term frosting is not used to designate surfacedistress n this Atlas

11.3 Failure ProcessSurface distress has been reported predominantly on steel rling contact surfaces. owever silicon

tride ceramic components aso exhbit the microcracking and microspalling of surface distress.Two theories describing surface distress in metal are by Taian [4] and Suh [21]. Both define the

faiure process as fatigue in asperity densions but differ in details of the failure mechansm.Sh's delamination theory is described in detail in 2]. Talian's 4] description of surface distressdeveopment used in this Atlas folows

When two surfaces are in predominant roling contact under oad and with ubrication theirasperities approach each other in a direction cose to the surface norma. epending on the averagethickness and rheology of the (liquid or soid) lubricant ayer between the surfaces stresses substantialy exceeding the macroscopic ocal ertzian stress may develop in asperity encounters

If the lubricant is an film and its thckness is three or more times the composite RS surfacerougness height then the extra asperity stresses are statisticay negligible As the film becomesthiner or if oy a boundary film is present then the asperity stresses (which can be modeedas microscale ertzian stress fields) become dominant in an increasg fraction of the asperityencounters

The magtude of asperity stresses increases with the composite "sharpness" of the asperitiesparticipating n the encounter. Ths sharpness can be measured by composite RS slope or compositeRS tip curvature.



Fail Atla f Ht Cntact Machin Elmnt

Nt: The parameter determng the sharpness of an asperity encounter is the omposite slope or curvatureof the two surfaces at the encounter point Combng a very smooth surface with a rough one (balin rough groove) does not protect the smooth surface from surface distress.

For asperiy encounters in which the alternatg shear stresses exceed a imit that depends onmaterial properties, the folowing faiure sequence is visually observable in (ductie) materials suchas steel:

1. Asperity-sale plasti ow Both cumulative and alternating pastic fow occur in the asperities.

• The umulative plastic deformation occurs eary in cyclg and leads to fattening of asperitytips, especialy the sharp 'feather edges that often decorate the crests of asperities in groundsurfaces. The appearance of the surface wil become progressively more burnished glazed)as the topography eft from surface finishing is gradualy leveed d oly smooth low

frequency waviness and scratches at the bottom of deeper fshing marks remain. The surfaceand immediate subsurface material are heavily cold worked.• The alternating plastic fow produces structural changes on the asperity scae wch are

quaitatively simiar to those suffered by macroscopic Hertz contacts under fatigue stressng.

Nt In silicon nitride ceramic, the plastic fow phenomena leading up to microcracking have not beenobserved. However, the similarity of the spaling in steel and silicon nitride suggests simiarities inthe changes leading to microcracking

2 Miroraking With continued cyclic stressing, the pasticiy of the materia is exhausted andmicrocracks form. These tend to run surface-parale, at depths comparable to that of the highasperity-scae shear stresses They may or may not be open to the surface A heaviy distressedsurface is densely popuated with these microcracks.

3. Mirospalling As microcracks grow and proiferate, the surface becomes undermined in asperitydimensions, and multipe microscopic spals form


Stl Sfac. Gazed and microspaled surfaces appear macroscopicaly quite different A microcracked surface appears just glazed Al three may be present side-by-side on the same spcimen.

A glazed surface differs from an as-fiished surface in that fishing lines are crisp and evenlydistributed on the latter, and party or wholy obterated on the former When viewed under differentanges of iumination from a smal ight source, an as-fished surface gives a "brushed lightrefection from the combined reflections of many parale fiising marks. A glazed surface tends

to show a mirror-like reflection.

Nt Extremely smooth origa fishes (in roling bearings, especiay bals) may show a virtua mirrorrefection even if not surface-distressed.

Under low magnification (scang electron) mcroscopy, a glazed surface shows the smoothingof asperity ridges into amost featureless flat areas (with valeys st discernibe), possibly with someincidental wear marks or dents. I contrast, mild wear produces a pebbed, profusely scratch-markedor micro-dented surface.

Gazed areas may be generalized on the contact surface (generaized surface distress); or loal, inthe form of "haos around ocal depressions (dents, ncks) or glazed bands folowing furrows.



Chaper Surface Disress

miccacked surface s not usualy dstngushabe from a gazed one by the unaded eyeHowever, mcrocrackng and mcrospallng most often appear together See below for unaded eyedentfcaton of mcrospalng.

Under low magfcaton (scaing electron) mcroscopy, mcrocracks openng to the surface maybe vsbe n gazed areas. Mcrocracks can be seen n carefuly prepared metallographc sectons fthe ntersectng edge at the orgnal surface s preserved by surface overplatng.

A micspalled surface appears frosted to the unaded eye, possbly wth barely vsble back spotsrepresentng the mcrospas. No safe dfferentaton between a mcrospaled dstressed surface andone wth skd markng s possbe by the unaded eye. However t s suggestve of skd markngf the frosted surface s a crcumscrbed patch on the rollng surface and suggestve of surfacedstress f t runs more or ess crcumferentally around the rong track folowng fnshng lnes

Under low magifcaton (scang electron) mcroscopy, mcrospas n a gazed surface show atypcal peeling pattern remnscent of smooth wet so that underwent freezng and thawng Themesas are burnished and flat (uess there was subsequent mld wear, when they are scratchmaked) the pts are fracture-surfaced spall craters. Pt rms are sharp and often feather-edged

Mcrospals tend to decorate fshng nes remaning wthn (generalzed) gazed areas and tocluster wtn the haos of oca surface dstress.

Mcrospals can be seen n carefuy prepared metalograpc sections f the ntersectng edge atthe orga surface s preserved by surface overpatng.

Ceramic Surfaces Slcon nitrde ceramc surfaces show no recogzabe glazng Under the scannng eectron mcroscope surfaces wth mcrospals resembe fracture surfaces of concrete there areno burshed mesas the mcrospals run together n a rough pebbly surface. Surface dstress nceramcs dffers from macrospalng prmarly n the shaow depth and small scae of ndvdual craters

15 CausesTwo domnant varables contro surface dstress

1. EHDlm thickness n the presence of a suffcenty hgh EHD flm thckness to surface rougessheght rato surface dstress does not occur because he film prevents hgh mcrostresses nasperty nteractons.

• Fm thckness may be suffcent to prevent generalzed surface dstress, but not loca dstressn the vcity of surface features such as depressons whch ocaly depressurze and therebytn the fm

2. Suface micgemety Both the height and sharpness of asperties (RMS rougess heght andslope) infuence surface dstress

• Composte ughness height (S) enters the EHD fm thickness I roughness heght ratoAbove a rato of 3 genealied surface dstress does not occur. The lkehood of surface dstressncreases as the rato drops beow tis vaue. Loca surface dstress can occur where locasurface features are hgh compared to the average, or where the fm s depleted by a sik,such as a sharp surface depresson or edge

• Composte shapness (RMS slope, tp curvature) of aspertes nfuences asperty stress levelsfor a gven fm thckness I rougess rato Because sope and rougess heght are correatedfor a gven fishng method, surface dstress s ukey between very smooth, unblemshed surfaces



Faiur Atas for Hrt Contact Machin Emnts

Othe fat nfuenta n ufa_e dte ae the fwng:

• Srface aterial fatie resistance. Matx ppete that ehane pang fatgue etanea mpve etane t ufae dte.• The bndary lbricatin abty f the ubant an etad ufae dte athugh th effet

nt vey tng. Th mean that bunday ubatng ·addtve ae a muh e ptentemedy t ufae dte than a thke EHD f mthe ufae Hweve a ubantwth vey p bunday ubatng abty (me unmuated ynthet) may pmteufae dte.

• Se slid lbricant catins appea t etad ufae dte. In hgh-peed ng beangbak-xde atng (and atng) have been fund be f me hep.

The ue f tngy adheent akfee lblar chri platin the had patng (nt themmn had hme patng) may be hepf n peventng ufae dte unde peatngndtn whee effetve EHD ubatn ant be aheved.

Cmment n the mtatn f methd t etad ufae dte

• ubant hemty de nt ffe a ptent and fexbe a emedy a EHD fm and ufaeughne nt In fat ufae dte dffe fm md wea (FC 0012) and gang(FC 00.13), n that ubant hemty a pme ntng vaabe f wea and gangbut nt f ufae dte. Sme beneft fm d ubant atng ha been beved

• Matea fatgue tength nt geneay a vaabe avaabe f the nt f ufae dten a gven matea a n the nteet f pang peventn degn he f buk mateafatgue tength have aeady been made and aey be mpved upn t etad ufaedte Hweve n tde eam hghy etant t ufae dte f fee fpty and bnde defet

• Due t appatn pbem the ue f uenty avaabe had atng eeved f

expementay pven ae

.6 EFFECTS OF SURFACE DSTRESS

The mt hazadu nequene f ufae dte pallng fatgue. In the abene f peextng ufae defet (k gndng bun et.) dent aqued n eve ufae-gnpang ntate fm ufae dte that fm apety-ae fatgue.

The apdty wth wh ufae dte ead t ufaegn pang vae geaty The pnpapeatng fat nfuenng the ate f pang fm ufae dte tractive ntefae te. Whentatn hgh pa fm apdy and pfuey fm ufae dte The pa ae key tappea fm many ntatn te and an dety a mpnent n ht de See [5] f deta.

If eay pang de nt temnate the peatn f a mpnent that ha uffeed ufae dte

then ufae matea deamnatn may u. The gna ufae theeby t ve wde aeaand the mpnent beme uneveabe thugh f dmenna auay thugh ne thugh enday faue.

It pbe f ufae dte t be aeted epeay n the gazng tage wthut futhedeteatn. T may u f md wea (FC 0012) peent and ufae ae uefuy unn t a mthe fh f ubatn ubequently mpved. In th ae the ufae dtemay nt pevent funtnaty. Hweve t unafe t unt n ufae dte t be ntentybengn even n ma appatn n epeated un f the ame appatn

Gea and am appea e entve t the nequene f ufae dte than ng beang.Th may be due t the geate dutty f wehadne gea and am tee Hweve ufaedte beved n a thee mahne eement.



Chater Surface Ditre


Failure Code

0070

00702

007

007

0072

0072

Plate No

567

892022223

28

00632825923

72738896

00256

2627282282

66050057058528





Failr Cod: 111

Pte No: 11.3

Archve No: 027-234Imge type: ight macroScer = 0 mm (micros: 20% ohers 100% 50%ompoet: ACBB; OR runSpeed: 30 KdNLodLucto: grease 60°CFiure ode 001711 Glazig (incipien suace distressFiure ode 0012.32.0.7 Wear track for misaigned ouerringFiure ode Fiure ode 4 -S s PLAT 7.3

PN

Fure Descrpto: Early indcation of surace disress i misaligned bal track ofOR The bearig may be oisy but as ot aied Conned srface distress maylead to spallig.Imge Descripto: Ball groove of OR with ig lad at image W ad low land at EFrom S extremty, over approximaely a 0 arc he E half o the ball groove showsa gray finely rosted appearance suggestig surace dsress Te ball tack shifts toE, towad the owland edge as t poceeds to the N, suggestig OR msaignment

Chapter Surface Distress

Suspected uses Isfficiet EHD film thickness possibly combied wit relativey rough suace finish n bal path ca lead tosurface distress n the cotact zone OR misaigment ca case te cotact zoe to sit to oe side of the goove See drawingsi Plate 7.3.

Pte No: 114Archve No: 007101 & 1 02

Imge type: a, b: SEMScer a: 0, b 12 m (mcros 20% others: 100% 50%ompoet: ACBB a OR b B (stailess steel, ruSpeed:Lod:Lurctio: sythetic polyester oil ? Fure ode 1: 00.17 .1.1 Glazig (icipie suace distressFure ode 00.17.01 Srface disress no slidigFure ode 00.152 False brnelling o coac suaceFure ode 4 00.061.3 Prmary carbide

PNFure Descrptio: xteme plasic flow o suace asperities om surface distesswithout microspallig Removal of material (possbly alog gan boundaries by tealse brnellng type o freng wear his gyroscope gimbal bearing ndegoes

small ampiude oscilation (htig EHD flm canot form ad freting of weakermaterial elements occrs ove the etire overrolled sace The texture ischaacteized by blocky hard prmary carbides o 440C stee.Imge Descriptio: (a & (b: Image covered wih flatteed, deformed areas witrregular cotours (plastically deformed asperties with delyng blocky carbidesDarke gaps are believed to be retted depressions along grai boudaries. (aFinisig les are visible as one cotinuos ad oe partialy roled-over frrow neaW edge. (b Radom thin dark lies may be appig marks. (a & (b Iregular witespots are imagig ariacts

Suspected uses: Gyroscope gimbal bearigs have an extremely fine fiish and reqir igh precison They are ofte made ofmaesitic staless steel. Ther motion is ofte oscillation (hunting Surace distress ad etting condiions bot exs I tecase show, exreme plasic asperity deformatio wthot microspallig is iterspesed with freted oes (perhaps graibondaies. Bocky cabides disor suace topography





Falure Code: 001711

Plte No: 117

Arcve No: 03-174&5Imge ye: a b SMScler a 35, b: 10 m(micros 20% oters 100% 50%omonent: DGBB R, ruSeed: 50 KdNLod 5 GPaLricton mieal oil 1cFle ode 001711 Glaig(incie surface dsressFle ode 00.18.1.1 Roudeddet (rom sot cotamiatFle ode 00.18.1.2 Sa idividualdet(s from metal debrs, aserities

Fle ode 4 00.12.3.22 Scratc marks,kematic wear marks i rolling srface

PN

Chapter Surface Distress

Fre Decriton: Mulile cages i a as-ru suace under mild suface distress coditios. Glazng as obliterated manyiising lines Kiematic wear marks from ball sin Dents are rom sot and ard cotamiats, e latter decoraed by suracedistess alo ad some microsalig Condition dagnosic for ball bearng oeraing nder margial HD film, wi somecontamination in te resece of some ball slidg (Heatcote sli.Imge Decrion (a, (b Fiisig lines ru NS and are exesvely glazed over by lastic low (areas were lies areineruted, missig, or doted. Mcrosalled dens are kiemaic wear marks [see (b]. In (b: Knematc wear mark a ad D,sligy micosalled debris dets a A and B.Seced e Isuficie HD film tickess comaed to rougess leads to aseriy coac under iger stress causig asticow of asery dges, initiating srace disress glazig wc gradally covers finising lies by smootig tem or foldig materialover tem. Dentig on microscale is univesal fom cotamants below flerig level, wic are larger tan te film ickness




Plte No 118

Arcve No 005-18a&bImge type: a b SEM(backscattered electonScle = a b 40 (cros ±20%oters: + 100% 50%omponent: C CM ruSpeed 45 /secLod: 1.4 GPaLrcion: ineral oil 115°CFlre ode 00.1711 Glazing(cpet surface distressFre ode 00181.2 Sarp indivdualdent(s fro eta debris asperitiesFire ode

Fre ode -

PN

Fiure Code 001711

Fire Descrpton: Coparison of finised unru and ru surface o ca. Unu suace (a as even grindig lies wit anoccasiona line unig at a low agle to te oters. On ru suace (b ay griding lines are plastically oblterated by surfacedistress (glazig leaving only te deepe lies Fie dets are due to olled-n cotainatio Glag and fine detig to tedegree see are not failures but erely warg idicationsImge Descrpton: (a Noral grnding lnes proceed W and are soot ad sap-edged. A few lies are at sallow angles tote oters e backscattered electron SM iage exaggerates contrast ad sows les steeper ta tey are. (b Seveal wideoizotal strips wit itte texture, were giding lines are pastically obliterated. Deeper lies reain Severa ound dents arecaused by rolledover debrisSspected ses Surace distess o te agnitude sow is coon we olling contacts operate witout full HD filDebris dents of tis agitude (23 diaeter are inescapable in al but te ost exree cleaness conditions fo debriscared in even well-iltered lubricat.





Filue Atls fo Hetz Contct Mchine Elements

AAPate No: 11.11

Archve No: 00-20 &202Image type: a b M (bacscatter)Scalea a: 1 mm b 400 m(micos ± 20 others: +100 50)Component: G W hgh hadess rSpeed:Load:urcaton:Faure Code 0017.2 Microspalling(advaced srace distress)Faure Code 0016013.1 oothptchline or dedendm spalligFalue Code 00.1252 mooth tooth wearFailure Code 0016024 Incipien spallg mltple spallsS s PLA 111

RP

Faie Code: 00.17.1.2

a

Faure Descrpton: race distress microspalig (ofte designated pitng) has occred near the pitchline A few macroscopicspals are in the dedendm at the edge of the srface dstressed area. Addedm ad dedendm are wo dow in the highslidig areas casing high pressre near the pichlne he gear was fond to be of insficiet hardess lt has not faled b sepected to ail i spalling ee Plate 111 for detailmage Description: (a): Vew of tooh cotact sface from ip to roo (labeled) The black line crossing from N to marks plaeo sbseent sectioing (see Pate 11.1) Microspalls i W rows tansverse o slidig direction cover addedm near pichlne.mooh wea near tp ad root For macoscopic spalls wih straight W edge ear image ceter (pitchlie) appear origiatingfrom dstress (b): Details of micro and macrospalls.Suspected Causes: Gear was fod to have insfficiet srace hadness. Wear occrred in high-sliding zones away from pitchlieleavig the pitchline raised and de ecessive cotact pressre. rface distress occrred in he maerial followed by spalling(I ormal gear spallig s more commo i dedendm where slidig raction redces fatige lie)

AAPlate No: 1112Archve No: 00522&26Image type: a Mb metallogam Nital etchScaear a 10 b: m(micros + 20 ohers 1 00 50)Component C CM nSpeed: m/secoad 1. Gaucaton: mineral oi 115°CFaure Code 0017.12Microspalling (advanced asrface distress)Falue Code 00.16022 Contac fatige cackingFaiure Code Faiure Code -

RP

Faure Descpton: (a) rface distess with plastically worked maerial reaing some fishig lies. Microspallig folowsfinish nes (b) ectio throgh srface distessed aea showing microcack (4 m deep) Cotied rning nder similarconditons eads o ealy spallng faile of camImage Descripton: (a) Coac sace ollig direcio is -W along ishig lines which appear as black frrows withinteveng ridges. rface distress gaing by plastc ow beween fnishing lies. esive micospaling of glaed ridgesconfined beween frows. (b) tched sectio throgh srface distressed materia. oling direction to W Dark line of shalowagle microcack rns fom srface to 3 m depth.Suspected Causes: Heaviy loaded cam/follower contact n high speed egie dergoes high pressre ad traction at etry poitto lit lobe. With adeate D film srace dstress arises

44



Failure Code: 00.17.1.2

AAPte No: 113

Archve No: 0741mge ype: viewScebr 10 mm (micros ± 20, others +100 50)Component: D I rnSpeed:od:ubricton:Fure Code 0017.12 Microspallng (advaced srface distress)Fure Code 00.16.121 hallow etry spall fro srface pont-defectFlure Code 00.123205 Wear track for cetered aia loadFlure Code -

RP

Chpter : Surfce Distress

Fure Descipton: Dobe-row ball bearig I operated nder heavy aial load shows ball track on one side of both grooves heball track area is sace distressed (frosted) by a profsion of asperity scale mcrospalls. In one groove a row of macroscopicspals has ormed in the groove bottom. he bearing has ailed.Imge Descrpton Doblerow ball bearing , wth two symmetrcal ball grooves and three lads Origial finish of grooves ishigh lster as seen on hal o N groove. N half of both grooves appears frosted. A ctered band of spal craters i N groveDark ad lght colored refections i half of both grooves are de to lightigSuspected Cuses: Insfficiet HD fil possbly cobied with ogh sfaces or aggressive bricat may prodce srfacedistress, that is, plastic flow ad microspalig on an asperity scale Unde cotied rnning, srace distessed areas are proe tomacroscopic spallig where load is heaviest this case that locato is the bottom of oe groove

AAPte No: 1.14Achve No: 0742&29Imge ype: a view, b light microgramScebr a 10 , b 100 (micros: ± 20 others +100,50)Component: DG rSpeed:od:ubrcton:Fiure Code 0017.12 Microspaling (advanced sace distress)Fiure Code 006.121 hallow entry spal ro srace poit-defectFiure Code 00 .12 harp indivdal dent(s) ro etal debris,asperitiesFiure Code

RPFiure Descrpton: all with band of spalls arond a geat circle,idicating operatio withot ideig of ball ais (a). Neros sracedistress microcracks and microspalls eist i the vicity of the spals

servg as initating defects (b) al ay have sf fered srace distresswhen cotacting a rogh rig srface der low HD il. palling wassecodary he ball has failed.Imge Descrpton (a) Nmeros spall craters along W great circle of aball. lsewhere, the ball sace is debris deted, probably rom spallingdebris (b) ackgrond is light gay glaed ball srace rom sacedistress fishig nes are stll visible here are ay jagged N ringmcrocracks and bacappearg microspalsSuspected Cuses: I prodcing srface dstress, the composte srfaceoghess in the cotact governs A sooth srace (bal) cobined wth aogh oe (rig) can prodce sace distress. Often the sooth sracesffers the distress, possibly becase the work hardeed asperities of theogh srface progressively overroll all areas o the smooth sface

b

4



Filue Atls fo Hetz Contct Mchine Elements

AAPate No: 1 1 . 15

Archve No: 1 0701 5&Image type: MScaear a 100 b 1 0 m (micros:+20% othes: 100%, -50%Compoet: AC I unSpeed:Load:Lurcato: grease 50°Faure Code 00.17 .1 .2 Micospallig(advanced surface distress)Falure Code 00.1701 urace distressno sldingFaiure Code Faure Code S PLAT 1 1 2 1

RP

Fue Code 00.712

a

Faure Descrpto Advaced generaized suace distress. All inishing lines are obliteated by plastic workg of the surace; adese distrbution of ie 15 Jm dia.) microspals has fomed. No preferred oientaio i microspallng. This characerizesabsence of sliding. ee Plate 1 1 2 1 for slidg. apd macrospallig s likely upo cotiued runing due to the profusion ofmicospalls acting as suface defectsImage Descipto: (a) (b) ackgroud is featureless gray surace of plastcally smoohed aspeities harpedged black shapesare microspalls ome of them have a white halo indicatig a feather edge of lamia udermned by cracks The ondirectionaiy of crate shapes is more clealy see at higher magnifcation in (b). Suspected Causes: urface distress is contact atigue i asperity dmesons arising when asperty iteractio stresses areecessive as fom isuficiet HD film ad sharp asperity slopes (rogh surface). Plasic glazing o surace wth obliteraio ofiishing lies occus first microspallig of heaviy worked asperities folows. The area show is i or near a Heathcote bad wheeslidg is mimal (Plate 1 1 . 2 1 shows contact edge).

AAPate No: 1 1 . 1 6Archive No: 09317.1 1 &1 3mage Wpe: a b MScaea a: 140 b 1 0 m (mcros20%, ohers +100% 50%Compoet: DG I ruSpeed: 450 KdNLoad: 2.8 GaLuicato: synthetic polyester oi 130Faure Code 00171 2 Micospallg(advaced srace distress)Faue Code 00.17.01 uface disressno slidig

Falure Code Failure Code

RPFaure Descpto: and of suace distress micospalling

a

with a dense population of spall craters on a backgoud of gazed plastically fown surface. Feather edges are roled over crater rims. pal bottoms show a typicalfacture surface Adacen to the spaled bands is a suace aea tha is glazed ony The beaig wil soon spall in cotinued rungImage Descrptio (a) Wide WN band following roling directio covered with mcrospall caters n a featureess gazedsurface. I NW ad image corers are glazed but uncratered surfaces. (b) High magnificaion shows: a featureless gazed suaceat A the eather edge of plastically flowed material at B ad a spall bottom ractre suace at Feaher edges are not wor of.Suspected Causes: ythetic ois used in high speed (aerospace) applicaios at high tempeature oten have ow workingviscosity forcing thin D fims ad promotig suface distress. Chemical aggressiveness of formulated ubricats which mayarise ater log use appeas to accelerate surface distress microcracking ad microspallng.

46





Failure Ala for Herz Conac Machine Elemen

AAPate No: 11.19

Archive No: 1 07 020a&cImage type: a, b SEMScaea a 100, b 10 m (mcros: + 20%, oters +100%, 50%)Component SRB IR, runSpeed:Load:urcaton:Faiure Code 00712 Mcrospallg (advaced surace dstressFaiure Code 007.02 Suace dstress, wt sldngFaiure Code Faure Code

RPFaue Descrption: Surace destroyed by geeraled mcrocracg ad

ncpet mcrospalg due to surace dstress te presence o gractve stresses rom sdg under poor EH lubrcao. Immet grossalue rom macroscopc spallng or bulk crackg s lkelyImage Desciption: (a Suace cosss o dese SWNE rows omcrocracks ad mcrospalls Orga surace s o longer dscerble Neacenter o mage N edge, a ew at NS lnes may be remnants ocrcumereta nsg es. (b Hger magcato. Complex wndngmcrocracks rug n a oveall SWNE drecto overlap and create a"sscae surace patter, wc, wtout magncaton, appears"rostedSuspected Causes: Te asmauacured surace was probably raterroug Heatcote sdg, combed wt axal slp, created a et SE to NWsldg dreco. Mcrocackg rom poor lubrcaton as a ma drectonperpendcuar to sldng Ts surace as muc reduced logterm spallng resstance

AAPate No: 11.20Archve No: 018301&304mage type: a lg mcrogram, b SEMScaear a 200 b 20 m (mcros20%, oters: 100%, 50%)Component: DGBB R, tool steel, ruSpeed: 400 dNoad 3.1 GPaLuricaton: sytetc polyester, 150°Caure Code 00.17.12 Mcrospallg(advaced surace dstess)Faiure Code 0017.02 Surace dstess,wt sldng

aiure Code 00.06.1.3 Pmay carbdeaure Code -

RP

Fae Code 001712

a

aure Description: Generalzed suace dstress mcrospallng wt drectonalty caused by sldg Intaton o mcrospalls tends to be assocated wt ard carbdes o te toolsteel. Cacuated EHD lm tckness was 008 m, resultng lm tckess/RMS rougess rato below 1, wc s conducve tosuace dstress. Eary macrospallg alre s lkely.Image Desciption: (a Area on IR ball pa. Bad o srace dstess mcrocrackng ad aglar mcospal caters runs EW atmage ceter. Rollg and ball sp are EW. (b) Sows apex o oe angular mcrospll. Rolng, ball spn and nsng les allru WE. Mcrospalled area s a rreglar racture surace extedg E rom agula, smootsuaced carbdes, o a sarp stepsow as black due to sadowng.Suspected Causes: Low EHD lm tcess/rougess rato, ad knematcally requred sdng o ball n groove (Heatcote slp),ave produced srace dstress. Hard, somewa promnet cabdes ac as mcrospall tators.

4



Faiu Cod: 001712

AAPae No: 1121

Archve No: 1 0-016a&cImage ype SEMScaebar a 100, b 10 m (mcros + 20% oters: +100%, 50%)Compoe ACBB I, runSpeed:Load:Luicaio: grease 50CFaiure Code 007.12 Mcrospallng (advaced suace dstressFaiure Code 00.7.02 Surace dstess, wt sldngFaiure Code 00.12.3.22 Scratc marks, kematc wea marks n ollngsuaceFalure Code S s PLATE 115

RPFaiure Descrpo Advaced geeralzed suace dstress All sng lnes aeoblterated by plastc workng o te surace a dense dstrbuto o e (15 mda) mcrospalls as ormed Tere s a strog preered oretato mcrospalls and may parallel kematc wea marks. Ts caracteres tepsn o sldng. See Plate 11.5 wc sows te bsn o sldngMacroscopc spallng s ley n urter rung, due to mcrospalls as suracedeects.Image Descipio: (a): Backgroud s eatureless gay surace o plastcalysmooted aspertes. Sarpedged black sapes are mcrospalls, some wt awte alo ndcatg eater edge. (b) Hger magncaton sows densepopulaton o stragt NS lnes, wc are knematc wear marks te sngdrecto. Aso, NS elongated mcrospalls. Bot wt wte aloes. Wea markscreate aspertes w c tate mcrospallngSuspeced Causes: Surace dstress s contact atgue asperty dmesons

arsng we asperty teraco stresses are excessve, as rom nsucent EHDlm ad sarp asperty slopes (roug suace) nematc wearmarks, rom sldnguder asperty cotact codos create addtoal mcrospalntang deectsTe area sow s near te cotact edge wee sldng s substatal (Plate 1115s at or ear Heatcote band)

Chapter urface Distress

a

b



Failur Atlas for Hrtz Contact Machin Elmnts

AAPte No 11.22

Achve No: 0746& 7mge type: a lgt mcrogram b metallogram (etced)Sclebr a 100 b 50 m (mcros ± 20% oers +100% 50%Component: DGBB R unSpeedLodLubictonFure Code 00.1.1.2 Mcrospallng (advanced surace dstress)Fure Code 00.1.02 Surace dstress, wt sldngFure Code 00.16.022 Contact atgue crackngFure Code 00.16.1.2 Suace orgn spall

RPFue Description: (a): Exreme mcrocrackng o surace tansverse to

rollng and sdng drecton (b) Mcrocracks pogress down n rollngdrecton at about 30° angle rom surace At least one deep (over 100 m)crack n same drecton suggesng unusualy g tractve orces drvngmacocrack deeper wtout pelmnary mcrospalngmge Desciption: (a): Mcrogram sows a genealy dstressed suacewt only a ew EW nsng nes emanng, and numerous jagged NSmcocracks. (b) metallogram (secton) wt several mcocracks NE to SW,to about 20 m dept. One crack progressed to about 1 00 m dept wcs macroscopc n contact dmensons. Cracks proceed nto matera atapproxmatey 30° angle wt E to W rollng drecton.Suspected Cuses: Suace dstress mcrocrackng s usuay mted oaspery dmensons (a ew m dept) nder eavy tractve orces (sdngwt poor lubrcaton) sear stresses are g at all depts, rom te suraceto te normal dept o te max Herz sear stress. Ts may drve cracksdown to macoscopc dept, producng macrospallng

0

aiue Cde: 001712

b



Faiue Code: 00.171Faiue Code: 0017

AAPate No: 11.23

Archve No 018-124&125Image ype: vwScaebar b 30 mm (mcros 20, otrs: 100 50)Component: SRB : R&G&IR b: R, ruSpeedLoad:Lubrcaion:Failure Code 001712 Mcrosplng (dvncd surc dstrss)Failure Code 001702 Suc dstrss, wt sldgFaiure Code 00612.1 Slow try spll rom surc pont-dctFaiure Code

RPFaure Descripton Glzd nd mcrosplld (rostd pld)

bds wt mcrospg nr ds o ll rollrs, du to ndutlubrcto ggrvtd by t gr sldg vlocty t rolr ds. IRcotct coormty my b too g, cusg strss cocntrto rds, sutg n spllng nr t dgs. T brng s ldImage Descripion: (): IR/R/sprtor ssmbly o sprtorguddSRB. Frostd pprc on l rollr s, wt mcro nd mcrospllcrtrs two srply dd bds t rolr ds. Sllow crtrs srom surc org. (b) Smlr ur to () rollrs o notr SRB.Frostd pprc xtnds n ptcs, rom dgs to cotct ctr.Mcrospllg rom x suc crcks du to trcton n sldg Edg

Chapter 11: Surface Distress

a

spg n bot mgs. bSuspected Causes: Edg lodg n SRB suggsts xcssv cotctcoormty T H lm, possby wt rougr surcs, tts suc dstrss, ggrvtd by gr sldng r rollr dsnd ldg to surc-nttd splls

AAPate No: 124Archive No: 1221&2Image type: SEM compostScaebar 100 m (mcros: + 20,otrs 1 00, 50)Component: SABB; I R, ruSpeed 120 dNLoad: 37 GPLubrcaton mrl ol ? cFaure Code 00.12 Loclzd surcdstrss (lo t dct)Faure Code 00021 Grdg, ong, lppg urrowFalure Code 001612.2 Sllow try spll rom surc -dctFalure Code S s LATE 53

RPFaiure Descrpton Grdg urrow kd by glzd lo on bot sds sows svrl surc dstrss mcrosplls d ldsto ldct orgn spll Grndng urrows r spllnttng surc dcts, bot by csg cops o ED lm (surcdstrss) d s drct strss rsrs T rsultng spll s n cpt uctol lrImage Descrpton: Img s compost o two SEM mcrogrms. At mg W s t tto o spll crtr wc orgtdrom t gdg urrow rung EW cross mg ctr T urrow strts dpng st W o E mg dg nd progrsss tot crtr. N nd S o urrow grndng ls r obltrtd by glg lo. Mcrospls n l o o. Furrow ds just so ospll crtr dg lvg lp o mtlSuspected Causes: Grdg urrows r cusd by dtcd grdg grt d r ot "comt-tl spd (s Plt 5.3). Tsurrow dpd towd t spl but ts ndpont s obltrtd by rolldow t spll dg Surc dstrss rss t t urrowsnc t lubrcnt drs nto t urow out o t EHD lm Locl strss coctrto tds to tt splg



ailure Atlas for Hert Contact Machine Elements

AAPate No: 125

Achve No: 093-.22&3Image type: a, b: SMScaear = a: 40 b 12 m (mcros 20%others 100% 50%)Compoet: DGBB; IR, runSpeed: 450 dNLoad 35 GPaLuricato mneral ol, 65°CFaure Code 00.1.2 Locazed surace dsress (haloat deect)Faure Code 00.02.1 Grndng honng, lappng rrowFalue Code 00.18.1.4 Mulple regar dentng omne, loose hard debrsFalue Code -

S s PLATE: 126RPFalure Descrpo A par o urrows (FC 0002) wth abrupt

Faiure Cde: 00172

a

endng, probably prodced by detached grans o grndng o honng gt. The surroundng surace shows mnmal remnants onshng lnes, extensve glazng and dentng here s severe plastc workng o surace matera aong urows, wth oldng andcrackng, due to a draned HD lm. he surace dstress s due to nsucent HD lm, the dentng to contamnants. arly spallngs lkely.mage Descrpto: (a) wo urrows, apparently ormed smultaneously n nshng by two grans o grndng or honng grt,extend rom N mage center to an abrupt end. There are many sharpcornered debrs dents on the suace Fant NS nshngnes are vsble near S edge nte surace s glazed, most severely nea dent edges, wthn contour A. Matera s olded at and (b) Same urrows, a hgher magncaton, show cracked, oded materal a A and Some densSuspected Causes: Grndng or honng urrows, when severe, dran the HD lm n ther vcnty, causng severe asperty contactn the debrs-contamnaed, low HD lm envronment evdenced n ths Plate, severe plasc workng o matera n urrow vcntyesults. Sharp urrow edges old and crac under plastc workng. Surace dstress also modes dents by owng the edges and

possby spallng he bottoms See also Plate 11.26.

AAPlae No 1126Archive No 01831Image type: lght mcrogramScale ar = 100 m (mcos: 20% others: + 100% 50%)Compoe: DGBB IR, tool steel, runSpeed 400 dNLoad: 2.3 GaLurcaio: synthec polyester, 150°CFaure Code 001.2 ocalzed surace dsress (halo at deect)Faiure Code 001.12 Mcrospalng (advanced surace dstess)Faiure Code 0002 Grndng, honng, lappng urow

Faiure Code -S s PLAT 11.25

RPFaure Descripto: Grndng urrow, possbly caused bydetachment o a prmary carbde n grndng Halo o suracedsress wth mcospalls along the rrow Surace dstressed urrows are serous srace deects kely o case prematurespalng aureImage Descipio: Background s contac surace wth W nshng nes. In mage center, heavy black W lne wth sharp endss grndng rrow N and S o urrow, oblong 'halo, where nshng lnes are partly olteraed. Iregular, szeabe black spots nhalo are mcrospals. Back spottng and stanng elsewhere on mage may be de to etchng and s not dagnostcSuspeced Causes: Fnshng o ool steel components s more dcut than o 52100 type bearng steel, n part because o manylarger carbdes. Such carbdes may become detached and gouge he surace n nshng to make a urrow (See also Plate 11.25.HD lm collapses near a urow, causng asperty contact and surace dstress glazng and mcrospallng



Faure Code 0072

AAPate No: 1127

Archive No: 1 07023a&Image type: SEMScaea =a 100 m (miros ± 20% oers +100% 50%)Compoet: DGBB R ruSpeed:oad:urcatioFalue Code 00.172 oalied surae disress (halo a defe)Falue Code 00.171.2 Mrosaling (adaned srae disess)Falure Code 00.181.2 Shar indidal den(s) from meal dersaseriesFalure Code -

RP

Failure Descrpto: Sharl delineaed deris de ases a glaing ao ofsrae disress wihin wi surfae disress miroraking andmirosallng ours. he earing is no failedImage Descrpio: (a): Bakgroud wih NS finishig nes s undamagedsae. In image ener is a oori-shaed deris den wih ishig linesreseed i oom. Rim of den sows olieraed nishing lies (halo)gradual adig oward. Mirosall NW of den (): Mirosal from (a) s So image ener srrounded 'glaed surfae wih fods alog ishinglies. Glazed de rm ns fom S sall edgeSuspected Causes: Deris den ma ae raised edges aig as sressoenraors. I EHD fim a loal deression oenraes sress arondedges ee if ese are no raised as a resl of he olase o he lm.Surae disress alos resul wi ma iniae mirosalig

AAPlae No: 1128Archve No 093172.5Image type SEMScalear =55 m (mros: 20%, oes: +100%, 50%)Compoet: DGBB IR rnSpeed 450 KdNoad: 35 GPaurcato mineral oil 1cFaure Code 00.172 Loalized surfae disress (halo a defe)Faue Code 00.181.2 Shar indiidua de(s) from meal derisaseriiesFaue Code 00.171 Geeralied srae disressFaue Code -

RPFaue Descrpto: Cirar ders den of ao 240 m dameer wihinishing lines in he den oom. Raised maeria im aound de isasial woked sufae dsress eseial a raiig edge (in rolig

Chapter 11 Surface Distress

a

dreion) where EHD fm ends o e iner Thee is some geeazed glazig of e surae Des wi disressed haoes aresignifian sall-originaig defesImage Descipto: Fiishing lines are dark doed NS lines. A A, a irar den is illuminaed oliqel ausing lig-oloedwal in S and dark i N. Fnising ies onne in he den A B irar eleaed rim who finishng lnes is sae disresshalo Rollig direion s S o NSuspected Causes: Insuffie EHD film ikess omared o rogess ors refeenal a defes s as he den a Awhee he ilm dais. Aseries oa under iger sress ad low asiall iniaing srae disress in e rm suroundighe den wehe eleaed in deng (as ere) or no. Film hikess anno ild rom downsream from de in rolgdeion hene more aser ona ors ere

3



Failure Atlas for Hertz ontact Machine Elements

AAPate No: 11.29

Archve No: 014-001Image type: SEMScaea 10 m (micos 20% others 00% 50%)Componen RC test rig rod; silico nitride o isostaticpressed; ruSpeed: 1.9 m/secLoad: 5.93 GPaLurcaton: mineral oi w additives approx. 40°CFaure Code 007.1 Gra pullout (surface distressof ceramic)Faure Code Faure Code Faure Code S s PLAES: 61 105, 057

RPFalure Descrpton: Separaton (at binder) of sigle suracegrais o small grain clusters (surface disress), the surface

Faiue Code: 0073

of silicon nitride ceramc fished to 0.090 m a, ru uder very heavy ert pressure fo 26 0 cycles This failure modeis chaacteristic o fully dese ceramic. Imperecy desiied ceamic produces microporosity (FC 0005.41) or binde defects(FC 00.05.42).Image Descrpton: Prouse micropis outlned by black ad white edges on dark gray roig surace.Suspected Causes: Extremely heavy Hert pressure (well above plasic imit of steel possibly also of ceramic bider) cycled forlog period creates high repetiive sresses, eventally destroys cohesion at bider and causes indvidual silco ntide grans orgrain clusers to sepaate (pull out) of srface his ailure is analogous o microplasic surace disress (glang) seen in steelsuraces

4



DNING 12

Failure Code 8

121 DefinitinA dent is plstic depression (short gsh, roundededged holow, shrpedged singe or mutfc

eted impression, depressed solid or stippled line) cused in working surfce by reltively incompressible object pressed into it by the pssge of contcting roling element Denting is the process by which dents form t is often combined with wermrks (FC 002 Denting, by the definitionused in this Atls, occurs in service.

Dents re distinguished from

• Nicks, which re pstic indenttions formed prior to service (FC 000 ;• Wear marks, tht is, scrtch mrks mde by n opposing sperity or third body in siding

contct (FC 002;• Pits, which re point depressions mde by mens other thn plstic indenttion (FC 0003

FC 002 FC 0020 FC 02);• Spalls, which re crters cused by contct ftigue (FC 006

12.2 NmencatueDenting is commony used designtion for this filure mode The most common terntive

designtion is nicking wherein the distinction between preservice nd inservice fiure is lost Inthis Ats, the distinction wil be mintined wherever it cn be estblished A designtion foundin some ger literture is peening, lthough the defition of peeng does not cerly exclude wer

123 Faiue PcessDenting is the result of plstic impression mde on surfce when shrp sperity or n

entrpped foreign body is pressed into the contct surfce under normal od It is most distinct onrolling contct surfces, where the retive motion in the contct is predominntly norml to thesurfce (Sliding motion in the contct results in wer mrs (FC 002 The process of forngdents resembes n indenttion hrdness test: The indenter penetrtes the surfce in n pproximtenorml direction, crries surfce mteril down with it nd generlly tows up sigficnt risededges The rounded dents formed by soft debris, however, hve no rised edges An indented inecn form by pstic flow beneth roling denter (n edge on n opposing rolling eement)

The detiled morphology of the fiure depends on the nture of the indenter, s follows

Debris (hard particle) dent. A sngle, shrpy outined dent, mosty with rised edges, is mde by hrd (met) prtice pssing once through the contct n the process, the prtice isgenerly fttened, but retins its distinctive outine, often with shrp corners nd edges

2 (True) brinnell mark. This is plstic depression of simpe outlne (eipse, truncted elipse,rectngle, dumbbel) mde by mting roling body under hevy sttic or impct lod (SeeFC 005 for false brinnelling)

3 Rounded (soft particle) dent without shrp corners or rised edges is mde by soft, essentillyincompressibe prtice entrpped in the contct A Hertz contct (with HD fim) effectivelycofnes ny entrpped prticle during the short contct pssge so tht prticles of pstic orfiber fil to escpe lterlly nd produce dent Some grese thickeners hve been found toproduce dents under shock loding of the contct

55



Failue Atlas fo Het Contact Machine Elements

6

Mul-agmen den is produced by hard, brittle particles, such as sand or abrasive grit, if theyshatter in the contact These dents show many sharpcornered facets and, at times, embedded grit

5 Rlledn lnes are made by sharp circumferential edges on the mating roling contact surfaceThey are plastically depressed lines formed by high edge-pressures. Deep circumferentia scratchmarks on the mating surface can aso produce roled-in ines

6 Sled lnes in the roling direction result from sharp asperities on the mating surface, includingraised carbides and frmly embedded debris grains, which make a dent at every contact passageA sight axial shift among the contacting bodies may produce bands of stipped lines

7 Cnamnan denng giving a fne, matte surface with a pebbled appearance under magfication,is produced by copious oose fine hard debris, generaly n the ubricant, passing throughthe contact

24 Distnctive AppeaanceA dent appears as a depression with a shny surface Origina fnshing marks generaly remain

visible Raised edges often arise during denting but may be worn or roled down in runng A lineindentation has a shiny surface if formed pasticaly.

lasses of dents can be distinguished as follows using a microscope, preferaby scang electronmicroscope, for detais):

Debrs (hard arcle dens are sharpedged depressions corresponding to the shape of the indenting particle, originay with raised edges, which may be roled or worn down in further runnngThe most common indenting particle is a metal chip, whch forms a dent that ooks roughychipshaped Also coon are dents secondary to spaling, with shapes refecting spal debristhat are blockier than chips

2 (True brnnell marks are regulary shaped eliptic, round, rectanguar or dumbbell shaped indentations The true brel mark on a Hertz contact surface is a plastic depression in the shapeof the static Hertz contact area, and is identica in shape to a false brnel mark created byfretting wear between Hertzian contacting bodies F 005 The surface of a true brelmark, whch is formed by pastic deformation, retains the original fnishing marks n thedepressed surface By contrast, the surface in the fale brine mark is a wear surface on whichorigina fshing marks are effaced and a matte, nondirectiona surface appears

3 Sf arcle dens show rounded or drop shapes and rounded edges They result from theentrapment of soft materias such as pastics, fibers, or wood chips) which deform under thecontact pressure Snce such materias are essentialy incompressibe, they can form dents inthe much harder contact material because the Hertz contact cofiguration aows them noescape Roughly padde-shaped rounded dents with an extending narrow neck) have been

observed in grease-ubricated contacts undergoing impact oading and are apparenty the resultof the delayed escape of grease thickener) from the contact through a narrow chanel

Mulagmen dens appear like the imprint of shattered glass into a soft surface They consistof many sharpfaceted angular impressions clustered and overappg in a smal area Theirsource is a entrapped brittle partice which shatters as the contact rols over it Sand fromexterna contamination or sandcast parts), and also grains of abrasive, may provide the partices

5 Rlledn lnes run in the roling direction They appear when a sharp edge on a roling bodycontacts the opposing contact surface under a sufficient oad to cause plastic deformation ofthe opposed body at the encounter with the edge Roled-in lines, when viewed under magnification, are distinguished from scratch marks by the absence of sharp feather) edges on the markand possibly by the preservation of finishing ines crossing the rolled-in mark



Chpter 2: Denting

A lling elemen wh a cicmfeenial scach-ma fnishng fw f sbsania dephcan pdce a led-n ne n he ppsng bdy Cmmnly, cyndca apeed les fa beang, scached n he sepaa cnac, pdce led-in lnes in a ing ing-ac

6 Stiled lines in he llng decin appea n cnacs wh vey lle slding, n he pesencef shap, had aspees fimly embedded debis n he ppsng cnac sface heycnss f lng seies f dens f idenical shape and ae ms cmmn n cylndcal apeedlle beangs in whch an aspey cnacs he ppsng sface ve and ve alng hesame ac, essenaly wh slding Spped lnes can cc as spped bands, if he cnacshfs axaly f hee ae many ndenes

A specal case f sipped bands fmed f gemecally simia dens ccs n bal beaings,fm an ndene mbedded n a ball slwly changing is axis f an indexing

7 Cntaminant deLting s pfse dening fm fne se had debs Macscpcaly, a maesface s geneaed whch, nde magnifican, appeas pebbed ahe han scach-maedas in wea C 0012 In he pesence f sme sldng, cnaminan dening and scach-maingmay be nemxed n he same sface

Dsincin beween nicks pe-sevce indenains and dents n-sevce indenans is aided bycnsdeng he lcan and decin f he indenain Nics can appea n any sface and nn any decn snce hey ae he esl f andm impacs Dens, by cnas, ae fmed n hepeang cmpnen s ha hey ae imed cnac sfaces incldng sepaa cnac sfacesand hei diecn ms be cmpaible wh he nemaics f eaive mn

I may be pssible deemne whehe sbsanial ning ime was accmlaed by he sfacesnce denng A fesh den s ey have shap, pehaps aised edges and any fshing masin he depessn appea simila hse side A den ha accmlaed mch ng meends have n ased edges and fnshing mas inside i may be shape han hse n he mewn sface sde he ndenain nhe ndca ha he cmpnen was n snce dening

is sface dsess decan FC 0017 sndng he den

.5 CausesDens ae cased by ndigens exgens pacae cnaminans shap aspeiies Cm

mn sces ae lsed belw

Sources Indigenous to the Mchine-Element

Hard article dents:

• se wear debris fm llng cmpnens, meal sepaas n llng beangs seading sfaces;

• Sall agments fm lng cmpnens;• Hard carbides exendng abve he sface

2 Brinnell marks Sac mpac velad f Hezan cnac

3 Sft article dents

• Wear debris fm plasic sepaas n llng beaings elasme seals;• Grease hicene cnjecal Sme sf dens n lng beaings appea be eaed

he behavi f he gease hcene nde impac cnac lading

Rlledin lines Rlng bdy wh edge cicmfeena scach Rlng bdy wih embeddedpaice sppled ines

7



Failur Alas for Hrz Conac Machin Elmns

Sourcs nal o h Machin

War dbri fom othe contact components n the chambe (beangs, geas, seas) o fomunntended contact of msocated components

2 Contaminant n the lubcant 3 Contamination eft n the chambe fom manufactung o assemby

No: he named contamnants may poduce (a) had patcle dents, (b) soft patcle dents, (c) multfagment dents o (d) stpped lnes, dependng on whethe they ae (a) loose metalc o nonshatteng ceamc patcles, (b) oganc patcles, (c) shatteng ceamc patcles o (d) embedded

had patcles

Exal SourcsSolid ontaminant fom the envoment that have enteed though the seals hese contamnants

usualy poduce hadpatcle dents, multfagment dents o stpped nes

EFFECTS OF ENTING

Nos:

ents have damagng effects on contact components though the foowng pmay mechansms:

• he pastc ndentaton pocess fomng the dent mposes hgh ocal stesses on the sufacehese can tate cacks

• Shap edges may fom at the dent whch, when olled ove, cause cyclc edge stess eadng tospallng faue nea the dent

1 Spals (FC 006 tend to tate downsteam of a dent n the olng decton A naow

unspaled dge s often eft between the dent and the spal edge 2 hee s some expeence to show that a dent fomed n a suface whch has pevously accumulated substanta Hetan stess cycng s moe lkey to cause a spa than the same sevetynck made po to cycng t has been coectued that the ablty of the matea to accommodateplastc defomaton wthout mcocackng s exhausted n Hetan cyclc stessng, so that aate dent s moe pone to poduce mcocacks th' an ognal ck

• he dent epesents a ink fo the EH flm n the contact, whch may locally depessue thefm, esutng n loca flm thng aod the dent edges Aspety nteactons may occu,poducng loca suface dstess (a halo decoatng the dent, FC 007 he suface dstess, ntun, may ntate spalng fatgue

• Rased edges aound a dent n a contact wth sgfcant sdng may ntate galng (FC 0013)• When oveoled, dents cause a cckng nose that may epesent a faue n quet ng

components• n an aggessve envonment whee cooson s a sk any dsupton of the smooth suface

fsh, such as by a dent, may be the taton pont o cooson pttng (FC 0020



Chapter 12 Venting


Faiure Code

Plate No

59



Failure Atlas or Hertz Contact Machine Elements

PLATESAAPat o 121Archiv o: 1 044&8Imag typ: a b: lig maoScaar a: 40 b: 20 mm miro: ±20%o: +100% 50%Coponnt: TRB; IR ruSp:oa:urcaton:Faur Co 00 . 18 .0 1 . 1 Dg ofolling ua no lidingFa ur Co : 00.1 8 .1 .2 Sap indivdal dfrom mal dbr apriFalu Co 0018.02.1 Lig or inipin dningFaiur Co 008.02.2 Svr or advad dng

RPFaiur Dscpton a: Uifom g ding o IR olrrak from oama pail arg noug o produmaroopi dn b mallr a oa wid No

aiure Code 00180111

(a)

-

(b)

rak or goug wr formd. Baring a v in avy ow appiaio. b: iform vr ding o IR rollr rak fromoamina pari a arg a oa ara wd T ar raid d dg. Ti IR may fai by palig paaor faur ora imbala falrmag Dscrption: a Sid viw of TRB IR on larg d a N. Fag dark rolr pa gray ppprd wi blak dorprning d Magnifiaon owd moo-boomd ndao No rak goug or raid dg ar viib. b: Sidviw of TRB IR lag d a N Flag appa dark rollr pa gray and ppprd wi bak or lig indaio of may z

wi ovrlap i pa. Magnifaion owd raid d dg and poibly mall rak.Suspct Causs: In a oamiad viromn igr of dbr i a m navodabl Dig amula gradaly.aig lf i dd bu may b apab if dig i lmid a in a If al falr or or au admi umro largoamina pai a i b many dt lag by oa dimno or y ow raid dg und owmagifiaio may podu rak ad a ary failur

60



Faure Code: 001812

AAPlat o: 122

Archiv o: 002006b&cImag typ: a: lght maco b: SEMScaar a: 5 mm b: 50 m(micos ±20% others: 100% 50%Componn: ACBB; I too steel rnSp 0.9 Mdoa: 15 GPaurcaton synhetic polyester ol 149°CFaur Co 001812 Sharp idividaldent(s rom mea debris asperitiesFaur Co Falur Co Falur Co -

RPFailur Dscrpton: Sevea debris dets are show wih raised edges bal pah after a minimm of operatio. Sliding s evident in theshape of he des Embedded brile debris is vsible i some deshe bearing is nstable fo high-speed sevice.mag Dscrpton: (a: Ligh macro showg par of .Land wth a "ple groove is dar gray i image haf the ballgroove s whitish i S image hal edig i he "split sface of spltinerring design. An ol goove is c i the edge For gray dens arei the bal path near he oil groove (arows. (b: A cster o desGoging in W det from slidig. Dark spots are embedded debris.aised edges o SE det appear rolled down.Suspct Causs: Irreglar slidig decios sgges that contaminantwas entrapped in the bearing a monting ad deted srface drngmoning operaio. Some roldown of raised edges occrred ing.

hapter 12: Venting

. .

- �

-

�

� : _�

>. • � ._ .

;

(a)

()

6




DATAPlate No: 123

Archve No: 00713Image type: light microgamScalebar = 2 mm (micros: ± 20%others + 100%, -50%)Componen: TRB; R runSpeed: 50 KdNoad:ubrcaton: mieral oil based grease 040°Failure Code 1 : 0018 .1 2 Sharp ndividualden(s) rm meal debis, asperitiesFaue Code 2 001202 Abasive mld weaFalure Code 3 0012.32.4 Scorng wea(macoscopic gopig wihou galing)Faure Code 4 00.16022 Contact fatigue

crackig

DESCRIPTIONSFailure Descrpton: Severe deting was cased by debrisfrom fine to 1 mm diameter. The enre contac srace isseveely worn Scoring (goge maks) occurred in thecircmeretial direction Axial fatige cracks conect thedes Bearng has lost precision s noisy and may sferblk cracking and/or spallingImage Descrpton: TRB R (coe) conac sace coversmost of image. In W the lght bad is the n-cotactededge of roig srace. Beyond it he pa is c. Cotactsrace is covered with mltipe scratch- and scoremaks nNS (rollng) directio. Origial fish lnes are wor ofNicks o may sizes ae sharp-edged iregular depressions


with smooth botoms ad ae also abasively wor EW faige cracks are at A and B.Suspected Causes: The bearng was sed as wheel bearing in a rck working in dusty eviromet Seal was observed o havefailed The igress of dust and debris caused wear ad detig



Fae Cde: 001812 Chapter 12 Denting

AAPlate No: 124Archive No: 107008Image type SMScaebar 20 m mcros: +20,others +100 50)Coponent: DG IR ruSpeed:Load:Lubrcaion:Faiure Code 0018 2 Shp idividuldets) fom metl debis speritiesFaure Code 0018.22.2 Stippled lies)or bds) from rolledi debrisFaiure Code Faiure Code -

RPFalue Descrpion: Twophse detg dmge o rollig surfce. A 80 m log rectgulr det om ductle debris s visiblewith iishig lies t bottom. The sufce outsde the det is desely coveed by fie shp idettios csed by the rollig-i ohrd cotmit prticles embedded i the mtig suce hese pcles were too smll to rech the bottom of the 80 m widedetImage Descpton: The bckgroud is surfce desey covered by fie shrp idettios less th 5 m i dmeter blckceters light rims idictig shrp edges) the imge ceter ery rectgulr lrge flt det is visible s from olledoutmetl chip. NS fiishig ies i ths det idcte tht it occured befoe geer detig by roled-i gritSuspected Causes: Deormble debris metl) fltte but reti geel shpe whe rolled over formig correspodigshpeddet The origil sufce emis udisturbed t the det bottom Whe ie hd cotmit etes the beig it my embed the rollig suces d mrk the mtig suce evey time it is roled over. I the presece o hevy cotmitio the wholesuce my become deted except the pre-existig lrge det bottom.

AAPlate No: 125Archive No: 064401Image type: viewScaeba 40 mm mcos 20othes: +100 50)Componen: HG &W high hrdessgroud ruSpeed:Load:Lubrcaon:Faure Code 00182 Shrpidividul dets) fom metl debrissperitiesFalure Code 0022.01.4 Ger toothcrck or frctureFaure Code Faure Code -

RPFaure Descpion: Extesive rdom detig of cotct surces o both mtig gers om corse hrd debris. A chippgfrcture o oe tooth my hve cotributed to the debis. The chippig itself my hve origited from overrollig of lge hdpiece of debis he ger hs filedImage Descrpton: io is t mge ceter. Ner W d E edges re mtig ges. Al cotct sufces o both gers W-sidemesh show irregul light gry) det mrks iio teeth er Eside mesh pper itct with fiishig lies still visible A lgechip is broke out of the tooth tip t ASuspected Causes: A mss of debis ws ijected ito the ger mesh cusig extesive detig of cotct suces The chipmissig fom the tooth if frgmeted would cotibute to the debis lt s ot evidet whether the chippig occured fromuelted cuses o ws itself due to overrollig of lrge pece of debris

63



ailure Alas for Herz Conac Machine Elemens

AAPat No: 12.

Archv No: 093-8.128&29&30Imag typ: a b SEMScaba a 20, b 25, : 3 �m(mirs 20% ters + 100%, 50%)Componnt DGBB; IR, ruSpd: 450 KdNLoad: 3.4 GPaubrcaton: mineral il 0°Calur Cod 001813 Multifragmentdent (brittle taminant)aiur Cod 001201 Adhesive mld wearaiur Cod aiur Cod -

RPaur Dscrpton Multi-fragmet det in hed surfae aused byte shatteing ad subsequet indetai f a hard, brittletaminat parile Sharply ut edges are intat i sme areaselsewere adesive wear as remved edges eavig tesile fratresurfaes Su denting an lead abrasive wear (frm embeddeddebris) surae dsress (thrugh terrupti f ED film) andspalling.Imag Dscipton: (a): In a well-peserved ned suae with NSiishig lines, a luster f sarp-edged dets ad rded pisupy the image eer (b) Sharpedged pasti defrmativisible at A ad B ad a fded edge at indiate plastiidetatin by sharp hard partes () Tesile frature surae in apit frmig pa f te det luster prbaby frm tearig f a asededge i adhesive wear.

Suspctd Causs: Brttle tamiat (sad abrasive pressmaerial et.) may eter a rlig ntat ad itiate e f reepresses 1 dentig by lse pariles FC 00.18.1.4) 2. dening byembedded debis FC 00.18.22) r 3. shatteing ad fmati multi-ragmet dets as sw.

(c)

64

iue Cde: 00113

(a)

(b)



Faiue Code: 001813

AAPate No: 12.7Archve No: 1 07-007abImage ype: a, b SEMcaebar = a 1 00 b 20 20 m(miros: ± 20%, oters 100%, -50%Component: GBB I rupeedLoad:Lubricatonaure Code 00 . 18 1 .3 Multi-fragmen den(brttle otamiat)aure Code 00 . 18 1 1 onded dent(om soft ontamian)alure Code 00.181 2 Sarp dividual dent(s)rom metal debris asperities

aure Code 00 18 01 . 1 enting of roligsrae o slidig

RPaure Descrpton: Present ae dets from ardoamiat from soft defomable onamia 2060 m)and a mti-fragment dent rom shattered bittle otaman.So iemai wear mars ae from ealer uning. ebearg was operaed at low EH ilm (inemat wear marsC 0012 and onamated evionment wi abasive(bittle) die (metal) ad sot (oga) debris The bearighas ot yet faledImage Descrpton (a): Overview of 1 mm srae a NSstipes at A are lbiant deposits Te dese lster of smallindetaios at 8 s a multi-fagment dent here are detsfrom deormed (metal) debrs as at Gete depressioswere aused by soft pariles as a D. Feature 8 is magnifiedi (b) feaure in () Note prior fne dets in Knematiwear mars ("fgernail mars) at E are sort (de to lowspn/roll ratio) ad partly won ofuspected Causes: eormabe (metal) debis flatte butretain eir geeral shape we roled over Sot materialsuh as plasti trapped in te otat maes a ronded dent(D). Gridg grit or oter bittle abasve may satter uponoverolling to mae a lster of ne (multifragmet) dets BHad (overolled) asperities o te mating srae may maefingerail mars de to bal spin durig oa.

Chapte 12 Denting

(a)

(b)

(c)

65




AAPate No: 128Archve No: 09318 .1 .1 5Image type: SEMScalear 1 5 m micos 20%othes 100% 50%Component: GBB; IR, rSpeed: 450 KdNLoad 34 GaLubcaton: mieral oil, 60°Faiure Code 00181 4 Mltple irregardeig from fie loose hard debrisFaure Code 002322 Scratch makskiematic wear marks rollig srfaceFaure Code 00 . 17 . 1 Glaig icipietsrface distress)

Faure Code 0017 .1 2 Microspalligadvaced srace distress)

RPFaure Descrption: Mtipe deig has occrred o aver small scale, from fe 15 m) cotamiat Lightsrface distess glazig is visibe with oblteratio ofmost iishig lies Small sace disress mcrospalswere iitiaed at the dets Kiematc wear markg.amage of this evel permts achievig ormal lfe foridstrial applicatiosmage Descripton: Backgrod is a hoed sace

Fiue ode: 001814

wit some fiishig lies rig NS, large obliterated b glazig Etesive scattered debis detig is visible as at A, 8 ad wit srface depressed bt o efolated At D, E ad are microspalls, from the actio of srace distress o dets Isoatedkiemac wear "figeral marks) are preset.

Suspected Causes: Fie detig ad kematic wear markig) of the size show are viall escapable i most idstralapplicaos with circlatig oil de to cotamiat igress past the filters filterig to less tha 1 0 m paicle size s commo).Mild sace distress is o sal bt prevetable if ample H f ilms ca be provded

66



Faiue Code: 001814

AAPae o: 129Archve o: 1 07013&&mage Wpe: a b c SMScaebar a 1 mm b 10 c 1 0 _mmicros: 20% otes +00% -0%Compoe: DGBB OR, ruSpee:oaubicaio: grease 30aiure Coe 0018 .1 4 Mtipe rreguardentng from fine oose ard debrisaure Coe 00 8 .01 1 . 1 Denting of roingsuface o sidigaue Coe aue Coe -

S s PLATES: 12 0 ad 12 . 4RPaue Descrpio In ba groove o a DGBB is a fie matteband magfied as dense irregar sap-edged dents due tooverroing of fine oose ard debris suay in te ubricat.Tere was no sigificant sidig. Te suace finis isdestroyed ad e beang is oisy f contamiation continesdestructive wear is ikey oterwise eary suace orginfaige is expected. See ate 12 14 fo dening by embeddeddebris and Pae 12 10 for deting wth minor siding.Image Descrpio: a Te backgoud is an undamaged bagoove wi NS runing fisng ines. n image center is aNS bad of matte pebby appearing surface from debrisdenting b c): High magificaio detais of fie 1 m)dents wic densey cover the srface on wich a signs oforigina fiis ave bee obiterated. Te dent bottoms appeardark; any sap edges appear igt Tere is o vsibedirectionaity whic idicaes no sigifica sdigSuspece Causes: Loose ine debrs wear partices saddus) wi e grain sie ot exceedig m is suspended inte ubricant Te fiter is o ie enog to removecotamation Wit itte or o siding detig o te saceoccrs. With severe sidig abrasve wear wod ake pace

Chapter 12: enting

a)

b)

c)

67




AAPate o: 1 21 0Archive o 1 07-04a&b&cImage type: a b, c: SEMScaebar a: 100, b 0 c: 1 0 m (micros + 20%othes +1 00%, -0%Compoet: TRB; R un with grit addedSpee:oa:ubricato: oil, 30°Faure Coe 00.8.1.4 Muliple irregular detigfrom fine loose hard debrsFaue Coe 00.18 01 1 2 Detg of rollig surfacemior sidingFalure Coe Faure Coe -

S s LATES 12 9 and 12 14RPFaure Descpto On the rollng path of a RB roller s afine matte band magnifed as dese iregular sharpedgeddets due to overrolig of fine, loose hard debis usually nthe lubrcan There was some mior sidig. The sufacefnish is destroyed ad the bearig is oisy f cotamiaocontiues desructive wear is likely otherwise early suraceoigi fatigue is expeced. See Plate 12 14 fo detig byembedded debris ad Plate 12 .9 or detig wthout slding.Image Descrpto: (a Surace covered with dese irreguarsharpedged dets (black ceters and white, sharp edges I(a and (b few scrach maks NWSE ad SWNE madesubseque to denting, are probably ncidenta. (b ad (c

Population of dents elogated i EW direction indcatigsome slidig (a few m per contact i that directio.Suspece Causes oose fie debris (wear partces sand,dust with the grai size not exceedig m is suspended nthe lubricant. The filter is ot fe enough to emovecontamnation Wth lite o no sliding dening of the suraceoccurs (With sevee slidng abrasive wear would take place.

6

Faiure Ce 00.181.4

(a)

(b)

(c)



Flu d 00.8...Flu d 008

DATAPlate No: 1211Archive No: 018625Image type: viewScalebar 15 mm (micros: ±20% others + 100%, -50%)Component: ACBB; B, tool steel, runSpeed:LoadLubrcation: synthetic polyester oil ? ocFailure Code 1 0018211 Rolledi lie, oe cotact edge onlyFailure Code 2: 00.16122 Shallow enry spall fom suface ie-defectailure Code ailure Code 4 -

DESRIPTIONSaiure Descrption: Depressed bad along minor circle o balls, with several spall

caters The liear depression reslts rom plastic olldown agaist the ball grooveedge i the bearing whe cotac overrns the edge. Spas arise i the damagedmaterial. The balls have ailed.

Chapter Venting

Image Descrpon: Three balls o each is a mior circle otlined by spall craters. The unspalled sface n these circles is seen tobe depressed below the srrondg material (best visible on ball at image S, near ball center, where a SWNE rning dark lieoutlies the edge of the depressed bad). Dark and bight spots on the ball otside the spalled circle ae light reflectios.Suspeced Causes: If the contac area exteds beyond the physical edge of the avalable groove, de to geomety error excessradia looseess or axial overload the edge loadig reslts which may generate sficiet stress to rol dow the ball (and thegroove edge) pastically Sufaces so damaged are prone to early spallg, especaly if the edge load onines he edge oad alsotends to prevent balls from idexng fixing the rolling track.

DATAPate No: 1212Archve No: 10701Oa&b

Image type: SM (a) secondary electron,(b) backscatterScalebar = a b 100 1m (micros +20%others +100% -50%)Component: TRB R rSpeed:LoadLubrcation: o, 50°Cailure Code 1 0018222 Stippled line(s) orbad(s) rom roled-in debrisailure Code 2: -Failure Code Failure Code 4

DESRIPTIONS

(a)

aiure Descrption: Mltple paralel wear marks circmferetialy o he rolg path of a TRBoller Uder low magnificatio these maks appearcotinos as if caused by slidg. At he (b)magnificatio show they resolve ito rows ofindentaios made by the overrolling of hard conaminants embedded in the mating suace. They are classified as 'stippled lies.Slidg is not evidet but the sace finish is destoyed and fatige life is shotenedImage Descripon: Images (a) and (b) are identical except (a) is a secondary elecro image and (b) a backscattered electroimage. These create diffeet gray values o the same eatre Viewing both images clearly shows rows of olledidens. Eachroledi stippled lie consists of geometrically simila detatios Most lines are made y fie paicles (approximately 3 m)bt a lie at mage W is about 12 1m wide ad a few others are also wider tha 3 JmSuspeced Causes: Abrasive cotamiant enterig the bearing chamber ( a gearbox bearig) became embedded n a rg trackad repeatedy overrolled a line on the roller D ad created circmferential lines composed of multiple idenical idetatios.

69





Fu d 00.8.

DATAPlate No: 2.14Archive No: 07-012a&b&cImage ype: a, b c: SEMScaleba = a b: 100 c 10 m (micros: +20%,others + 100%, 50%)Component: ACBB; B, runSpeed:Load:Lubicatio:Failure Code 1 00. 18222 Stippled le(s) or bad(s)from roledi debrisFaiue Code 2 00.091 Scorig rom orcibe assembly ormountig (o gallg)Falue Code 3 Falue Code 4: -

See also PLATE: 2.5

DESCRIPTIONSFailure Descrpon Mutiple debis detig o ball suraceincludig a bad of idetically oriented dents oled i by ahard partice embedded i the mag suface. Damage to ballsurace pomotes surace distress and subseque suraceorgin spaling; with moe coamiation, damagg wear isalso expected Some scatch maks ae vsible probably as aresult o dsassembly.Image Descpon: (a): 1 mm o ball surace I N 1/3 oimage the SWNE running lightcoloed lies are disassemblydamage NS bad W o image ceer are mulple debrsdets (lighcolored points ad unesoved light-clor bands).(b) Det bads are enlarged showig dese marking i Eimage hal (c): Dense part o de bad wth may identcallyshaped shapedged dets rom a partcle embedded in thematig suaceSuspeced Causes Whe ine hard cotaminat is preset itmay embed a rolling surace ad mark the mating suraceevery ime i is olled over A given gra continues o makethe same shape det. a ball conact, i which the balidexes agast he mating surace umerous rows o paralleldets may orm See also Plate 125

Chptr Dnting

(a)

(b)

(c)

7



Failure Atlas for Hertz Contact Machine Element

DAAPlate No 1215Archve No 093817mage type SMScaleba 20 J m (micr: 20% thr 100% 50%)Compoent DGBB; B runSpeed 300 Kdoadubrication minra i 60°CFailure Code 0018222 Stippd n() r band() frmrdin dbriFailure Code 00171 Gang (incipint urfac dtr)Failure Code Faiure Code See als PAT: 1214

DESRPTONSFailure Description w f paa rintd harp dnt with raiddg appar du t indntatin rm an abraiv paric mbddd n th mating cntact urac aid dg and undntd urac arghty gad frm ufac ditr Dnting f thi dnity intrrupt

ailure Code: 00.18...ailure Code 00.18

HD fim and prmt urfac ditr with ubqunt paing Abraiv war may a tak pac S a Plat 1214Image Description Gay backgrund i th ighty gazd appd ba urfac Sm apping in ar ti vib ( imag dg)w f darkbtmd wdgapd dnt ar ngatd in -S dirctin with tip pinting and with ightcrd rm (raiddg) Sm dffrnty hapd dnt wthut rad dg (nar and S imag dg) ar dr Th dark quar in th imag ian maging arifactSuspected Causes Whn fin hard cntaminant i prnt it may mbd n a ring uac and mark th matng urfac vry

tim t i rd vr A givn grain cntinu t mak th am hap dnt n a ba cntact in which th ba indx againt thmating uac numru rw f para dnt may frm Any ding vcty cmpnnt wi ngat th dnt in n dctin

DATAPlate No: 126Archive No 018109Image type ght macScaebar 20 mm (mcr +20% thr 100% 50%)Component SB runSpeedLoadLubicationFailure Code 00183 brinningFailure Code

Failure Code

Failure Code

See als PAS: 1218 and 220

DESRPTONS

-

Faiure Description Mutip axa brinn mak n bth rr path f SB I wr infictd by a high tatic ad r impactMark in n path bradn tward th cntr fang uggtng axia ading (piby whn pring th ring nt th hat

thrugh th O and th rr) Such mark may bcm mr viib aft runnng bcau thy wa difrnty frm thunbrinnd ara Th baring i niy and wi pa arir than nrma Mr vr brinning appar in at 1218 and220mage Descrption Sid viw f a SB I wth fang and undrcut at and S dg cntr fang xtnding -W at midimagr path ar gray aring fuzzydgd axia dark mak hwing brnn dnt xtnd acr nti path width and in path atimag S brad tward th cntr fang Dpnding n ighting a mark may appar dark r ghtSuspected Causes Amby f a SB n a tight haf may prduc tatic ading pciay if munting prur i appidacr th rr cntact A baring damagd niy but may run fr an apprciab tim br aiing Bcau binnmark a dprin r traving v thm undg ad and ractn vaatin which may b rfctd n difrnta wahighighting th mark by a chang in utr

272



ailure Code: 0018 Chapte Venting

DATAPlate N 21Achive N 0931811Image ype igh micgramScalebar 10 m micrs: 20%,hrs: + 100%, 0%)Cmpnent DGBB; IR runSpee 40 dNa 34 GPaubicatin minra il, 0°Cailure Ce 00183 brinningailure Ce

ailure Ce ailure Ce

DESRPONS

ailue Descipn ight brin mark in grv f a DGBBIR h mark s y 02 m dp (by racig) and bngwith majr axis acrss th ba gv Th barig is nisy

fr qt rnng appicatis but unky t fa sn frm th briningIage Descriptin d grv srfac is shw wih fiishig ns runig E-W. At imag cntr, a ccuarapparingdprssin is mad vsib by shadig f highy dirctina mtagraphc lghting Th crsscurvatr f th grv dists ighrfctn furthr, makig part h bng mark appar circuar Sch marks ca b dtctd by mving h pa undr abicuar micrscp and bsrving a brak i th dg f ightng crssing th markSuspece Causes Impact adng r high staic ading f ba cntacts caus brinnling

DATAPlate N 218Achive N 0804

mage ype ight macrScalebar 20 mm (micrs +20%, thrs 100% 0%)Cmpnent DGBB; IR & R ruSpeeaubricatinalure Ce 00183 brinigalure Ce 0012320 War track fr misaignd utrringalure Ce

ailure Ce

DESRPTONSailue Descptn brin marks ar prsnt at ba spacing, xtnding ba grv dg i bth R ad IR n ppsit sids) h barig is isyand may fa in high spd appicat fm sparatr actr ary spaig

at brin marks is ikyIage Descriptin I srvic, vsib I R si dfac matchs avrtd Rsdfac R ba grv dg ar avrd fac shws hr indtatins atba spacig at Nms pit ad n ach sid) whch ar trianguar withbas at th dntd dg Ths a brin marks xtndig acrss th dg th IR, tw ptica brinn marks at samspacing a gray shadw, i th grv tbard triaguar ight rctins Th shftg circumfrnia ins in th R grvar th war tackSuspece Causes Assmby r dsassmby f baring ight fitd shaft, by pssng n R fac idnts ba grvs nardg Th dark war track which vars i axia lcatin arud th ing circmfrnc suggsts misaignmnt in rnig

273



Filure Atls for Hertz Contct Mchine Elements

DATAPate N 121

Arcie N 011501Image type viwScalear = 10 mm (micr ± 20%thr 100%, 50%)Cmpnent SRB amby runSpeedLadLuricatin gra, ? oc

Falure Cde 00.8 brinigFalure Cde 00.1612.1 Shaw try pa

frm urfac pintdctFailure Cde 0018212 Rdin ,bh cntact dgFaiue Cde

DESRPTONS

ailure Code: 0018

Faiure Descriptn R rr path, an iatd pal f iptica cnur fwng a brinl mark, prbaby utaind by impacn hippig mutig f th barig Rdi crcumfrtia in ar hwn manating frm bth d f h pal, prbaby frm dt mad by h pa dg n th r Th baig ha faidImage Descriptin Barig i hwn with IR/lr amby wivd ut f alignmnt, xping R rlr path at W imagctri jut S f IR idfac At h imag ctr i a barrhapd pa cratr wth harp cntur t crpnd t thctur f a havy brinn mark xtdig vr th tir rr gh Cicumfrnia rdin i f ditinct utr xtd and W f th paSuspected Causes If a baring i drppd during hpmnt, r uffr a v impact ad i muntng havy bn mark mayb mad n bth ring (and n mr rr) vring f uch mark n rvic i liky t prcipitat ary paingu thdamagd matia h pa dg cp nt h rlr which thn may ri circumfrntial in int th ring ctact path

DATA

Pate N 1220Archie N 0818Image type viwScalear 15 mm (micr ±20%, hr 100%, 50%)Cmpnent DGBB IR, ruSpeedLadLurcatinFailure Cde 0018 brinligFaure Cde 0112 Sparatr fractur crackingFalure Cde 001224 Scring war (macrcpic gugigwthut gag)Failure Cde 15 Carbnid i dpit

DESRPTONS

Failure Descriptn h innrring ba grv i vry brin markd at bapacing Th bri mark a gugd and th adact ara i batrd Thar patic fw vt. Th dicati n th grv ad n th and iprumd t ari frm i carbnid n vrhaing Th brning i atributd

t fracu trapm and ckup f th paratr und th bamage Descrptn th grv bttm a fu brinn mark hat th bahav pwd frward circumfrtialy t frm gug Th adjact gvurfac i paticay batrd Backih dcrai i viib arud h grvbtm (xcpt whr wr ff) ad dak trak appar bth ad, a frm carbnid du t vrhating.Suspected Causes Th brintyp idtati ccurd thrugh a tampd t paratr faiur Sht t wa trappdbtw th ba ad R ad ckd thm agait th IR h baring izd diipatig mmtum th rt drv thckd ba ang th grv, making pwd gug. Prr t ckup th paratr maia wa vrrd, dntig th inringvrhatig durng iu cratd th back dpit mark (carbizd ubicant)

274






DATAPte 1222

rchve 099133Ige type ght macroSclebr 8 mm (micros: 20%,ohers 100%, 50%)Cpnent SG; W high hardness runSpeeddubrctnilue Cde 001842 Gear tooth rpplig(trasvese wavy pastic fow)iure Cde lure Cde ilure Cde 4 See als PLATES 1221 ad 1223

DESRPTONS

Falure ode: 00.18.Falure ode 00.18.

ure Descriptn I the gear contact surface, oca pastic fow under vbratoy coditions has produced trasverse rippeshese are wave suaces, with phase shits at rada lies or i a shscae pattern Rippig is beieved to rest when sotersbsuface matera fows pasticay under repeated oading, dsotng the harder surace The inceased roghness produces ocastress cocetrations which may evenuay spalIge Descriptin Gear ooh cotact surace is shown, wth tip at mage edge ad root at S edge Gancng ighting highights

transvese cess and troghs of waviess wth radia ines deineatg shifts i crest ocation (phase) The surace is geeraygossy (burished) in appearaceSuspected Cuses Roing contact at very high stresses prodces, in softe materias, pastic fow in he oing directio at thehigh Hez shea stress ayer A case hardened or wok hadeed sface may wap nder this fow producng the rippes he axiaphaseshifts may be due o geometric imperfectios in stress distribton, casing uneve fow rates See Paes 1221 and 1223

fo other forms of oca pasic fow in gears

DATA

Plte 1223rcive 099134Ige type ight macroScebr 30 mm (micros: ± 20%others 100%, 50%)Cpnent HYG P, high hardness, rnSpeeddubrctiniure Cde 1: 001843 Gear tooth ridging(pastc ridges in sidig drection)ure Cde 00125 Gear tooh wearlure Cde

ilure Cde 4 -

See alsPATES 1221 ad 1222

DESRPTONSiure Descrptin The ridge and vaey patter i a highsidig hypoid gear set shows ridges foowig the sidig drection tarises from combined pasic fow ad wea, whch is probaby initiated by maching imperfections Ths is not an immiet fare but the roughenig of he srface may ead o any form o gear aiure sch as gaing, spang, wea and eventua tooth fractureIge Descriptin Hypoid pinion teeth cover the image from NW to SE corer Tips are igh gray; fank suraces dark with ightobiqe streaks which represen the idges These ridgg are more sharpy deied tha the ripping of FC 001842Suspected Cuses In hghsiding gea sets such as worm geaing or hypoid gearing, a patter o differetia pastic fow and weardeveops foowing the sidg directon t is beieved to resut from a varation o cotact pessure across the contact wdth adresuts in ponounced prominent rdges ad vaeys Compae to Pates 1221 ad 1222 for oher foms of pasic ow in gear

tooth cotacts

276



HEAT IMBALANCE FALURE 13Failure Code 9

11 DefinitionHeat imbaace fae is a compex seqece of faie evets pecpitated by a macoscopc

tempeate excso i te Heta cotact macie eemet de to eat geeated excess ofte eat smtaeosy emoved.

Heat mbaace fae s dstict fom

• Galling (FC 00.3• Lubricant failure FC 1, FC 1

bt may be te pecptatg case ad/ o te est of ete o bot of te atte.Heat imbaace faie is not synonymous wt oveeatig, wic defies te tempeate excsoof te mace eemet. Te atte may o may ot pecpitate fae Heat imbaace faie isdagosed we, as a est of oveeatig, oe o moe ievesbe cages occ i te cotactcompoets

Heat mbaace fae diffes fom ote cotact compoet faie modes i tat it s a systemfaie Te effects may mafest temseves pimay o oe o a few compoets, bt te faemecasm s tat of oss of tema eqiibm of te macie eemet as a system.

1 NomenclatueHeat imbalance failure aso desigated oveeatg faie is a ecoged fae cass i og

beag tecoogy ess geeay gea tecoogy Tems fo oe of te sbcasses of eat

mbaace faie ae moe commoly sed, fo exampe ot pastic flow, tempe cooig, pemaetadess oss o oveeatg see

1 Falue Pocess

Sequence of Failure Events. Te fae pocess a eat imbaace faes compses teseqece of fo evets descbed beow

Evet . Te steady-state tema eqiibim i a vome ecosg te Heta macie eemetgives way to a excess of eat geeatio ove eat emova. Te eat imbaace caest fom ay combiatio of increased heat generation te macie eemet, ad reducedheat outow. See Causes beow fo opeatig codtos codcive to eat imbaace

Evet2.

Te tempeate of some o a cotact compoets, ad ofte tat of some ote compoets of te mace eemet icdig te bicat, ises a excso above temaxmm desig eve

Evet 3 Depedg o te magtde, ocatio ad datio of te tempeate excso, oeo moe of te foowg intermediate fae occeces takes pace

Lubriation Failure (See also FC 11.1 and FC 12.)

• a ogaic qid bcat o, gease, eoogca popeties cage as tempeateiceases Most mpotaty, viscosity drops, ad EHD fm codtos coespodigy deteoate. Above a mtig tempeate, te bcat evapoates o bs off befoe eacg igpesse te cotact, ad EHD bicatio ceases Tese peomea occ wit mima

277



Failure Alas for Herz Conac Machine Elemens

27

time lag behind the temperature change The direct consequence of deteriorating EHD ubrication is rther increased heat generation, providing positive feedback to the heat imbalance

failure• Grease surrounding the machine element may soften at the increased temperature, causing

it to slump as a ump into the path of the contact components and undergo violent churng.As a resut it may liquefy ad escape through the chamber closure, eaving the machineelement lubricated oy with a thin adhering layer of ubricant, soon lost to decomposition(see below).

• In any lubricant, decompositio and oxidation occur at sufficienty high temperatures, if theyact over sufficient time (See FC 1 and FC 2 for detais.) Minor changes in lubricant chemistrymay have ong-term deeterious effects on Hertz contact machine element performance; majorchanges immediately render the ubricant unserviceabe, converting the system to a dryubricated or unlubricated system.

The loss of fluid lubrication in the form designed into the machine typically eads to sharplyicreased eat geeratio creating rapid and often catastrophic faiure of the machine eement.

Loss of Operatig Clearace Due to differentia therma expansion of components, operating clearance can be ost in any machine element confined by its design. Exampes: roling bearings may loseinterna ooseness; gear pairs may ose cearance; and cam systems may ose the gap between camand folower or tappet at the bottom of the stroke. Clearance oss from thermal expansion is reversiblewith the temperaure and therefore may not be observable in the stopped macne.

Loss of operating clearance generaly leads to arge parasitic oads on the Hertz contacts. Anincreased oad further increases heat generation, creating rapid, often catastropic faiure.

In steel components with metastabe retained austenite, operation at eevated temperature forprotracted periods may produce permanent volume growth leading to an irreversibe loss of operat

ing clearance

Loss of compoet material stregt may folow operation at temperatures that exceed the designmaxmum.

• he hot hardness of steel is less than norma amient temperature hardness, eading to hotpastic fow under oad

Hardeed steel loses hardness permanenty at temperaures n excess of the tempering temperaure used in manufacture, peritting pastic fow der oad even after operating temperaturehas reverted to norma

• Plastic materials (gears and bearing separators) may soften or melt at temperatures toeratedby metals, eading to hot pastic flow or disintegration under oad.

•

Ceramic components are highly resistant to softening at elevated temperature and their thermalexpansion coefficient is typicaly ower than that of steel. Hybrid assemblies (e.g, bearingswith ceramic roling elements and stee rings) may fai by heat imbaance whie the ceramiccomponent remains intact, because the stee components change dimensions or hardness, theubricant or the separator fails from high temperaure

Cemical cage in structural component material may resut from operation at eevated temperature

• No-stailess steel develops thin oxide ayers when held at elevated temperatures in air. Thesetemper coors can serve to diagnose the order of magnitude of the temperature exposure.



Chaper 3 Hea Imbalance ailure

• ome plastic aterials become embrttled when hed at elevated tempeatue leadng to subsequent cackng durng operaton.

Event 4 The utmate aue from heat mbaance often reered to as a burn-up, s a unawaytemperature excurson. Ths occus when ubrcaton has been lost and Ior softeng othe contact matea has nduced massve galng. Components may be deomed out oal recognton (balls nto rolers and vce versa). Components may be weded together(rolng elements rngs and sepaator peces rom a olng beang nto a block ocngrotaton at the t nteraces). The alure pocess culmnates n goss sezure and I or bulkractue oten extendng to the shat housng or machne frame

Arres of Hea Imbalance ailure Heat mbalance aue can be arrested at amost any pontshot of gross sezue o ractue The oowng are scenaros wth practcal sgncance o thearest o heat mbalance.

• Quenching of icroscopic theral instability Momentay load peaks the passage o a contamnantpatcle o some other loca dstubance may oveheat one asperity contact durng operaton Icopous lqud lubrcant mmedatey floods the suraces upon separaton the nstabty can bequenched eavng at worst skdmarkng (C 00.4 or oca gallng (C 00.13). ome lubrcatonmethods favo quenchng more than othes (o over grease buk o over mst cculatng olover splash and et or unde-race ubrcaton over ree fow)

• Resupply of grease through softening (see C 12). Durng modeate overheatng the gease avalablen the mmedate contact area may deterorate (be contmnated harden be expelled resultngn a oss o ubcatng eectveness. Bulk grease n the warmed grease pack becomes soterhowever and may sump nto the contact path and replesh the supply. If the heatng andthus the softenng s moderate destructve churng o the whole grease pack may be avoded

• Moderating operating conditions n machney wth varabe operatng condtons a temporayoveload and I or overspeed may be releved as the operatng cycle progresses or be delberateyeeved by the opeato observng a temperatue excurson.

1 Distinctive AppearanceA heat mbalance condton may be dentfed decty b observng temperatues at sutable

ocatons on the machne. Morphologcaly heat mbalance alue s recogzed as one o the esutngrreversbe faure modes appearng as olows.

Ho Plasic low In metas and heatsoteing pastcs hot plastc fow s the decsve ndcatorof heat mbalance faue It can be dstngushed fom cold plastc fow by appearance. Hot plastclow s genealy much more extensve than cold flow; the shapes of components are dastcaly

atered; and surace oxdaton s common (but not nevtable) n metals No causes other thanoveheatng produce hot pastc low. Compae ths to cold ow under C 00.23

• Hot pastc fow s a late consequence o heat mbaance. Due to ts destructve nature hot pastclow s kely to oblterate sgns o earle events n the aue pocess.

• Wheeas hot plastc fow s certaly due to overheatng the overheatng tse may wel be asecondary falure mode. It s advsabe to seach a pastcaly deformed component for remanngsgns o othe alure modes (gang o spalng o contact components gallng or fracture o abeang separato etc.

• In ceamcs the dstnctve hot pastc low s not observed n heat mbalance aure. Indcatonso oveheatng may be cackng o ractue o the ceramc o hot pastc low of adjacent metalcomponents.

2



Failure Atlas or Hertz Contact Macine Elements

In hermoseng plascs, excessve overheang s manesed as decomposon leadng o rle

ness, urned surace appearance and dsnegraon

Secondary Lubrication FailureLubricant ouow rom he chamer Grease, when soened or lqueed y hea, ends o e

exruded pas seals or shelds closng he chamer conanng he Herz conac machne elemensI he ousde o he closure s vsle, exruded grease may e oserved Only substantial amounso exruded grease, appearng suddenly, are a sgn o hea malance alure, as gradual modesgrease loss may e due merely o mperec sealng or overgreasng

Deteriorated lubricant (see FC or FC 2) may e recognzale as havng een exposed o excessveemperaures I he deeroraon s severe, hen he lurcan appearance may perm dsncon

eween moderae u longerm overheang and unsale hea malance ongerm overheangends o cause dscoloraon and acdcaon unsale hgh overheang causes grease lqueacon

Secondary Galling FractureGallng (FC 00) or racre (FC 0022) are common nal modes o alure naed y hea mal

anceIn order o e dagnosed as hea malance, gallng and racre mus e accompaned y oher

sgns o overheang The mos dsncve are ho plasc ow (lsed aove) and surace changes(see elow)

Surace Canges in Structural ComponentsLow hardness o hardened seel componens may e a sgn o hea malance alure I may e

more pronounced a he workng suraces, hus dsngushng loss o hardness due o overheag,rom a hea reamen deec

Note: oss o hardness due o overheang s no narrowly localzed he way grdng emper (FC 00.08) s

Temper colors rom surace oxdaon a elevaed emperaure are clear sympoms o overheag

Note: The appearance o early srawcolor" emper s easly conused wh ha o rcon polymer deposrom he lurcan A specal ech es (quck wpng surace wh a coon p dpped n 0%dlue HCl acd soluon) derenaes he wo emper color s nsanly removed u rcon polymers no

80

Decomposition of plastics (urnedappearng suraces, emrlemen, surace crackng, melng,dsnegraon) resuls rom hgh overheang and shows derences n appearance dependng onhe composon o he maeral

3 Causes

mpaired LubricationThs s he mos common cause o hea malance alure and operaes y wo mechansms: ncrease

n hea generaon (y conac rcon and vscous losses) and reducon o coolng va he lurcan

Increase in Heat Generation

Increase in iction arses eween workng suraces hrough mpared EHD and or oundarylurcaon The hea generaon goes up whle hea removal or a gven emperare remansconsan, represenng hea malance Lurcaon may e mpared :



Capter Heat Imalance Failure

• Isuffcit qutty of (iquid) lubrct rchs th surfcs• Lubrict chmistry s mprd by ovrhtg, cotmitio, or rcto with compti

bl mtrls.• For lubrct lyrs formd t th surfc (vpor phs ubrictio), th rcto tdd to

form th lyr mlfctos

2 Inceaed vicou loe my b cusd by xcss oi flow or xcssv or poorly chldgrs pck With xcss ol flow, ht rmovl my lso crs, yt th icrsd htgrtio oft outwghs y crs ht rmov cusg imbc

Redution of Cooling by the ubricant. Espcilly i oi lubrctio, th ubrict ormly covctsht wy from th workig prts of th mchi lmt, t tims rprstg th prim htrmovl ch Coolg by th lubrict is impird th folowig circumstcs

•

Th qutty of ubrct sump is rducd• Th fow rt of lubrict pst th workig surfcs s rducd.• Th lubrct trc tmprtur to th workg surfcs icrss

Whrs ht grto my b rducd s ol volum or ol vscosity dcrs, th loss i cooigoft domts

Reduction o Conductive CoolingCotct compots ot oprtig coold ubrict crcultio ultimty rjct most grtd

ht to th vromt by trsfrrig t to th surfc of th mchi from whr it s crrid itoth tmosphr. This ht trsfr my b impird t y of th trfcs log ts pth Exmps

• oos or frttd fit of brg outrrg to housg, brg irrig or gr to shft, icrsg

th itrfc thrml rsistc ccurt ft of housg to frm (sm ffct). suffct cooig of compot by oil (mpird ubrictio) or isuffict ht rjctio from

oi to sump (ow oil lvl) or to ht xchgr (mpird crcutio)• Impird ht rjctio from mch xtror to r (hot viromt, sush, dust or mud

crustig th surfc, oss of forcdr coolg).

Added Heat Generation as Secondar FailureGlig, splig with dbris grtio, sprtor or rollg body frctur ( rolg brgs),

gr tooth frctur, utdd rubbig btw ocotct compots (moutig prts, tc ) dth igrss of lrg mouts of sold cotmt r commo primry filurs tht c cus lrguxpctd dditol ht grtio d drv scodry ht imblc fiur of th Hrt

cotct mch lmt For dtils bout ch, s th pproprit fiur cods

Macine Temperature Excursionf othr prt of th mch udrgos suffict htig to lvt th tmprtur of th

moutg prts or of th lubrct srvig th Hrtz cotct mch mt bov crtic lvth ht rmov vi ths lmts is rducd d my v b rvrsd (ht crrd to th Hrtcotct mch lmt) Ths c drctly prcptt ht mblc fiur

Load or Speed ExcursionA lrg xcurso of compot lod or oprtg spd my prcpitt ht mblc fiur

It is liky, howvr, to cus glg vt frst, wth ht mblc fiur folowig

81




8

3 Effecs of Hea mbalance FailureMajor hat mbaac vts dstroy th compot through o of ths sug falur mods

• Gang (wth szur)• Hot pasc derman• Fracure Meng of pastc compots

Lssr hat mbalac vts, f arrstd, may lav o obsrvabl ffcts, or av o of thfollowg logtrm ffcts causg possb falur latr

• Lss ubrcan suppy may cotu to mpar lubrcato ad or coolg ut rplshd.• Lubrcan decmpsn may mpar lubrcato utl th lubrcat s rpacd.• Frcn pymer s grally harmlss ad mrly a warg sg. Frcto polymr has b

obsrvd propry opratg bargs (aftr log srvc).

Temper crs ar a warg sg that compot hardss may hav b mpard; havyoxd ayrs also trfr wth compot accuracy, ca fak off ad cotamat lubrcat orcaus war.

• Lss hardness hardd st parts lav thm subjct to bulk plastc flow, spalg, war,brlg ad galg.

• Decmpsn pasc cmpnens may caus brttlss, crackg, loss of dmsoal tgrty,or outrght fractur.



Capter Heat mbalance Failure


Failure Code

0 0 1 9

0 0 9 1

0 0 1 9 1 2

00192

001 92

001 922

001 93

0094

001 95

Plate No.

1 6 1 0

1622

1633

027

133

137

721

1 34

1535

184

62

134

138

1 3 1 0

1 3 1 5

1 8 2

633

88

823

139

8



Failure Atlas for Hertz Contact Macine Elements

PLATESPlate No: 3.Archive No: 027-35Image ype: clor view [S IMA I APPX]Scalebar Component: 0, specimeSpeed:Load:LubcaonFaure Code 00.9 Hea imbalace emper colosFaue Code : -Falue Code 3 -Faiue Code

P

Failure Code Faiure Code


Failue Descpton Seel sampes wi empe coors, empering emperare ° a aress (RC) Coversio

° 300 360 400 450 500 550 750 49 82 204 232 260 288 399

Rockwel C 62 62 6 60 59 58 53PH 746 46 720 697 674 653 560mage Descpton Specimes of gro an polise seel empere a varyig emperaures sow emper coors rangig romlig sraw (W) rog eepe sraw brown, bue a gray () Temperaures (F ) a arnesses (RC) (for AI SI 5200 bearingseel) are sow o labels S of eac specimen.Suspeced Causes Temper coorig epens on empeig ime an amospere as well as emperaure e colors assme abouone ou empeig ime i air an may be se as rog ges only Haress nicaons ae srogly alloy epenen aapply o AISI 5200 bearng see oly.

Plae No: 3.2Achive No 087025mage type viewScae ba 30 mm (mcros: ±20%, oes +00% 50%)Component: CRB OR&IR&R& ruSpeedLoad:Lubcaion:Faiue Code 009.2 Temper colors i coac srfacesFailue Code 0022. Ovesess crackFailue Code 3 5 Carboize oil eposiFailure Code

PFalure Descipion: Hig-spee CRB operae wisubsaal axia loa Oe roller eace o several rolles aoe IR rus flange are severey emper-coloe (esimae

empeare 220320 C) Te IR flange is cippe fromoverollig o e flage ege by e rollers Te sepaaor is iscolore by carboize ol Te beaig is failemage Descipon: nac OR a image W IR, a image SW is iscolore mosly a or ear e seveely cippe flage (arow).All rolles sown are empe-coloe o or ear e visible en (arow). Te sepaaor is o severey wor b sows ark saswic, o a slver-plae separaor, canno be empercolore, b consis o carboize oi eposi.Suspected Causes: CRB-s, especially n e absece o suffcie aia loa, are sesive o rs loag. Rolers en o assumea age posiion i e raial plane ('ilig), causing large local pressres o e flange ege wic skews e rollers, proucingg sig. Te roller/lage inerace overeas er ig pressre a ege coac. allg is ikely a, as a secoary effec

e f lage may cp

8



Faiure Code: Capter Heat mbalance Failure

Plate No: 13.3Achive No: 027-143&44mage type: a, b clor view [SEE MAGE N APENDIX.]Scaeba a, b: 10 mm (micros ±20%, otes +100% 50%)Component: DGBB duplex IR & B, runSpeed: 100 KdNLoad:Lubcaton grease 60°C ?Falue Code 00.19.2 Hot plastc flowFaue Code : 00.1302 Extesive galingFaue Code 3 00.191.2 emper colors in contact surfacesFaue Code 00.123.2.14 Wear track at contact edge

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[ee Image in Appendix]

Failue Descpton: Dupex ball bearig assembly axially over-preloaded. Cotact n oe IR overra te groove edge Overeating

caused temper colors rollout and severe galng wit massive mateial trasfer to balls. e second IR was overeated and tempercolored but te contact did ot overru te edge e bearg assembly as ailed.mage Desciption: (a): wo IRs mouted in duplex as sow E IR as a straw temper clor (200°C) o te E alf W al is blue(260°C) and te groove edge is rolled out (arrows). W IR is straw colored on te E lad ad bue i E 1/4 o te groove. (b): reeballs macig E R Ball at W as a straw temper cor, a blue bad of ger eatig ad, W of tis band, a oled- line omte edge Balls at center ad E sow blue temper clor and large masses of weldedon galled steelSuspected Causes: Axialy preloaded duplex bearig pais may suffer excess preload if spacig of te beaigs is accurateOvereatg, loss of lubrication and tempe cooig may result. Oe alf may suffer more damage i external axal load adds topreload or if mior profile geometry dierences favor overung of te goove edge

Pate No: 134Achve No 002-014amage type view

Scaleba 20 mm (mcros: 20%oters: +100%, 50%)Component ACBB B, too stee, run &unrunSpeed: .7 MdNLoad: 1.5 GPaLubcation sytetic polyester ol 176CFaue Code 00192 Hot pastic flowFaiue Code : 00193 Scale formationFaiue Code 3 Failue Code

PFailue Descpton: Four balls are substatially redced from origial diameter by ot plastic ow and wea of eatsoftenedsurace mateial Oe ew ball is sown for reference. A bearig wit suc bals as ost saft suppor accuracy te balls overollte groove edge and te separato is damaged Material was oud reardeed wic i too steel requires local temperatures wellin excess of 700°C is is goss faluremage Descpton: All used balls are visibly smaller ta te uused ceter ball sown for reerece e used balls ave streaksfrom overrollig te groove edge pits from gallg agais te separator ad scaling om ig temperatureSuspected Causes: n a ig speed, ig load tube egie bearig, excessive eat was geerated, pesumaby from excessive IRbore/saft looseness wic pemitted elatve rotation. e eat caused lubricatio to fail balls galled agaist te separator pockets,stated sldig agaist igs, were eated to virtual forgig temperature wore greatly, scaled ad udewet plastc flow.

285




Plae N: 135Acve N 04-28mage type vewScaea 20 mm (mcros: ±20% otes 100% 50%Cmpe: TRB, complete ruSpeedLadLucat:Faue Cde 001921 Hot plastic flow withou weldig (rollouFaue Cde : 0013211 Rolling suace gallig no dent or icvisibleFaue Cde 3 01141 Separator pocet gaedFaue Cde 01133 Sepaator wear from uintended contact

P

Falue Descipi: Unstable overheaig (ea mbalace failureof bearig after oss of adequate lubricatio R roller pa, rollerends and IR trust flage ('rb suffered hot plasic flow (rollout

Failure Code

The roller ends ad Ds galled The separator is bet its D is worn against R. Ths is a gross faiure Complete seizure is imminentmage Descpt At image S, IR/roller assembly is viewed from the large sideface Par of te R is see at image N R rollerpath is generally bateed, wit iregular crcumferetial bads of gallig (ligt gray ear ceer plae ad near S edge The rolerends are ot-rolled down to form ceer protrusions Te IR thrus flage (rib is roled hin. Roller D has gallng steas. The separator s defomed ts D has ligtclor wear streas and galled metal at pocet edgesSuspected Causes oss of adequate lubricaton leads to progressive overeating as hea remova fails to balance increased heatgeneration from fiction. The material sofes and deforms te geomety is destroyed and gallng occurs The separao bends ands pushed agaist R were i weas. The roler ed/trust flage (rib pressue exceeds reduced yield poit and bot suaces olldown leaving protrusios at te roller axs

Plate N: 36Acve N: 018-122Image ype: viewScalea 30 mm (micros: ± 20%ohers +100% 50%)Cmpet: SRB IR & R, unSpeed:Lad:Lucat:Falue Cde 001921 Hot plastic fowwitout welding (rolloutFalue Cde : 00160112 Centered spallig,wde tracFalue Cde 3 0012323 Step wo in rolingsuace or dimesion worn off-spec

Faue Cde 00124 Wear of gudg-component suppo suface

PFaue Descipi: Unsable overheating (heat imbalace failure of bearig after loss of adequate lubrication. IR roller pats adroler Ds suffered severe ot plastic flow (olout, producig deep grooves in IR ad near bot eds of eac oller Generaliedsallow spallig, material removal by wear and contnued rolldown proceeded smultaneously Wear of R ceer flage Doccurred agast sepaatormage Descipi R design wit tree flanges Bot roler pats ad the flange faces contacting te roler eds are roled ou(depressio roler pats sharp flage edges. Roller D has grooves near boh ed faces cornes ad a circle ear the edge ofte vsible end face (not the trust face are deformed. Spal craters coverng rolle pats o R and roler D are mosly sallowand rolled dow Circumfeetial wear scratces appear o te ceter fange DSuspectd Causes: Loss of adequate lubricaton leads to progressive overheatig as eat removal fals to balace creased eatgeneatio from frictio Te maeria sofens and deforms and e geometry is destoyed Wear ad spalling of sofeed materialoccus, removing surace maeria. This may postpone or prevent gross seizure unless the separator fractures.

286



Failure Code 11

te No 13Arhve No 0931916mge ype: SEMSlebr 15 m (micros: 20% otrs +100% -50%)Componen: DGBB; IR tool stl uSpeed: 17 MdNod: 14 GPaubrion: sttic polstr oil arrstd ? Fure Code 001921 Hot plastic flow witout wldig (rolout)Fure Code : 0019.12 mpr colors i cotact suacsFure Code 3 Fure Code -

PFiure Desrpton: Ball groov sufac o tool stl baig tat

suffrd at imbalac failur ad plastc flow wit totaobitratio of oigial is. mp colors wr obsvd. barig udwt a ol sutof tst" to dtrmi itssurvivabilt if ubricat is lost. lt as suffrd gross failu.Imge Desription: Kadd" sufac o ball groov sowsmatrial displacd b plastic flow ovr t ti surac ara;amia formd ad rod o; ad total obltrato of t origasurfac fis Macro apparac sowd tmpr clor. obsrvd coditio is tpca of g-tmpratur ovratigdurig opatioSuspeted Cuses: Ultraig spd bargs, as sow rl olubicatig actio to cotrol t rat of at dvlopmt, ad o

Capter Heat Imbalance Failure

mass fow o t ubricat (or gas) for moval of gratd at. I a oil sutoff tst at rmoval troug lubricat covctiois lost at oc ad ubricatig ffctivss rapidl dgrads. V ig tmpraturs aris at wic v at rsstat tool stlsofts ad plastcal fails. Survival tim is limtd to miuts

lte No: 138Arhive No: 07436Imge ype: viwSlebr 10 mm (micos 20%, otrs 100% -50%)Component: CRB; R, uSpeed:odubiton:Filure Code 001921 Hot plastic flow witout wldig (ollout)Filure Code : 00193 Scal formatoFilure Code 3 0012323 Stp wor i rollig surfac or dimso wor ofspcFilure Code

PFilure Desrpton at imbalac failur i a (clidical) rollr barig All rollrs udrwt ot plastic rollout O rollrgald rpatdl agaist a guid flag ad was turd i t sparator pockt so tat its dgs wr rolld ad wor dow to aspr Scal as fomd o all rolrs. s is a gross failurImge Desription: rollr at imag W is battd b roldow ad sows blackis scal rollr i t ctr is sorr adsows roudd dgs ad lat aras o OD from sidig war. Ball-sapd objct at imag E orgiatd as smilar oll butrolldow of dgs is complt to form a spr.Suspeted Cuses: Clidrical rollr barigs xposd to sigificat trust oad a pro to gallig sizur btw rollr dfacs ad guid lags (for xampl, b ovrrolig of t lag dg) Suc a sizu frcs t rollr to slid o t ulagdig Sufficit war, rolldow ad skw momt ca rsult i turig t roll dwis i t rollig dircto. lt ma t warflat or b rpatd turs b roudd ito a spr.

287




Plate N: 13.9Ahve N: 018-617&619mage tye: a: vew b: light macro sectionetchedSaleba = a 12, b 5 mm (micros 20%,others: +100%, 50%)Cmnent: DGBB IR ruSee:a:batin:Fae Ce 0092 Hot plastic flowwithout weldig (rollot)Faile Ce 00.19.5 Local strctuedamage rom rictiona heatingFale Ce 3 00.13.02 Extensive galing

Falre Ce 00.232 Pastic distorion ofbul shape

P

Faiure Code

a b

Falre Destin: Bul of rig oveheated ad soteed so that olldown ball groove exteded to defomation of one lad, oesideface ad the bore A rehardeed ad tempeed aye has fomed uder the ball path Gallig ad scalig occred in the ballpath he material folded over the land OD his s a gross faiuremage Desritin: (a): Ball groove adius has increased, land OD at mage E is tapeed, edge is rouded ad folded over Eendface is dished in. E edge of bore shows circar groove from plastc deormation. Bal path surface is battered and showscircmferetal agged line i NW from gallig. Scale patches are i the S (b) Etched section wth rolled groove edge at W Whteayer at groove suace is rehadened dar patches beneath are tempered. Lightcolored arcs are produced by lightig.Ssete Cases: Loss of grease lubrcat s the most liely failure intiator Oveheatig occurs from creased fricton. hereatively light load prevents sere permittig massive rollot of the etire ig Galng i the ball path results from ball slidig.Rehadened layer with underyig retempeed one i cross section indicates that the surface temperature exceeded 900C.

Pate N 130Ave N 07 4-35mage tye: viewSaeba 20 mm (micros: 20% others: +100% 50%)Cmnent: DGBB R&B&G, runSee:La:bratn:Faile Ce 00.19.2.1 Hot pastic flow without wedig (rollout)Fale Ce : 00.22.013 Rollng element (bal, roller) cracFaile Ce 3 01.11.2 Separator actue, cracingFaile Ce 0019.3 Scale fomationS als PAE 1311

PFare Destin: Severe heat imbaance failure, probably intiated by a separator geometry error causg the separator tobecome trapped der a ball. lt prodced (1) separator fractre (2) severe hot worg of balls (ollot) (3) ormation of aconceric hollow in the ball (see Plate 1311) (4) fractre of the hollowed bal and (5) scale formatio on bals. his is a gossfailue.mage Desitin: Wellpreserved OR is at image E (IR, probaby damaged, was ot available) he disitegrated stamped steelribbon separator s at NW, with oe ball still i a pocet. Five bals, al show hot pastic flow ad degees of scaling. One ball(arrow) has a oblong concetrc hollow through which it has fractured.Ssete Cases: Stamped ribbo separators f too loose or stetched by high ball forces (misaligmet) may become trappedbetwee a bal ad ig locig the bal. Sidg nder high pressre occrs the bearig overheats and the separato breas. Ameta rolling process similar to tbe rolling may produce a hollow ceter i heaviy plasticaly rolled balls under strog tractivesface force. Cracig der contact load follows.

288



Failure Code: Capter Heat Imbalance Failure

late No: 311Archve No: 018621mage type: ligh macroScaleba = 3 mm (micros 20% others 100%, 50%)Component: DGBB B runSpeed:Load:Lubicaton:Falue Code 00.19.2.1 Hot plastic flow without welding (rollout)Falue Code : 00.23.2 Plastic distoion of bulk shapeFalue Code 3 00.22.01.3 Rolling elemen (ball, roller) cackFalure Code 00.182.2. Rolled-in continous ine from opposng edgeS als PLATE: 13.10

P

Faue Desciption: Bals subject o severe pastic srain while overheated haveormed a concenrc hollow eading to fracture of one ball in service (hesecond bal was broken or examination) The rolling suace of the ball isseverely batered, with rolled-down line from edge of contac. See also Plate13.10.mage Desciption: The ball at image E s nbroken with srface baeredthroughout, and a heavy rolledin lne running NWSE along a geat circle. The ball a image SW has a large spherical holow inhe center, whch is surounded by fracture srface showing wear (occured in sevce) The bal a NW has a smalle holow in thecente, which s surrounded by chpped and crosscracked impact fracture suace arficialy prodced in examnation.Suspected Causes: A meta-rolling process similar to ube rolling produced a holow center in heavily plastcally roled bodesunder strong tractive srface forces Cracing under conac load has ollowed The ncracked ba shows plasic battering o theoverheated surface and a line rolled-n by the ring groove edge, which was overrolled duing uncontroled overheated opeaon

late No: 1312Achve No: 027423mage type colo view [SEE IMAGE IN APPENDIX]Scaeba = 20 mm (micros: 20% others +100%, 50%)Component DGBB; IR runSpeed:Load:Lubcation: gease ? Faue Code 001921 o plastc low wihout welding (rollou)Faue Code : 122 Cabonied greaseFaue Code 3 001321 Rolling surface gallngFaue Code 0001 1 Nc with raised edges

P

[S Imag in Appndix}

Faiue Descpton: Severe hea imbalance failure has caused (1) oll down of goove (2) carbonied gease; and (3) seveegalling n groove (probably nvolving pressed steel separato and balls). Severe nicks a the groove edge may have occurred abearing dismountng. This is a gross failuremage Desciption: Black cabonized grease deposit on both ands and in sreaks, in he ball groove o IR Crcumerentia bandsof the groove were gouged fee of deposit by severe sliding (possbly caused by the sepaator caught under a bal) A imagecenter there is a sharp-edged black galling mark where the separator and ball ocked on the groove and made a depression laerfilled in wth carbonized grease. E edge of groove shows nicks with raised edges nea image N pehaps from dismounting.Suspected Causes: Severe heat imbalance falure n bearing probably due to loss o lubrcant, caused high friction; deviaon fromepcyclc ball speeds exteme balltoseparator forces stamped steel separator distoron with separato caught under a ball; slidingof separator and ball over groove galling and possibly seizure. High emperature cabonied the grease. ifficu dismouning ofthe seied bearing may have caused nicks.

289




Plate No: 13.13Achive No: 018-204mage type: view, OR sectioneScalebar = 10 mm micros 20%, others 100% 50%omponent: RB; OR & R, uSpeedLoad:Lubcation:Faue ode 001922 ot lastc fow with bulk weligFaue ode : 001302 Extesive galingFaue ode 3 001232.3 Se worn in roling surace orimesion worn off-secFaue ode

P

Failue Descpton: eele rollers misalige uig moutig ofsearator-less cageless rawn-c eele rolle beaing Roleshave jamme urng runing an galle against shaf an OR'cu The beaig overheate, losig lubrica; this cause grosslastic flow of olers a c followe by heavy gallig a wea,robably eig in sezure.mage Descpton: image half shows crosssectioe ORaw cu Several skewe rollers are welein at S cu halfOe is at sectio ege The galle, battee a worn cu

Failure Cde

rollig suace is show i image hal E image half shows bet, weletogether eele rolers with a arge fla won on each.Suspected auses: Imroer isallatio of cageless eele ole beaig may leave roles skewe. he loa is aie an shatturs, rollers wege in, requrig a high torqe to tur the beaing by sling the shaft over the ocke rolles. Overheating, mateialsofteing galing weling a wear folow

Plate No: 1314Archve No: 093034mage type: ligh macoScalebar = 20 mm micros 20%, others +100%, 50%omponent: TRB; IR & R & OR ruSpeed:LoadLubricaton:Falue ode 00.19.2.2 Hot lastic flow with bulk weligFalue ode : 00.19.2.1 Hot astic flow without welingrol outFalue ode 3 11.5 Carboize oil eositFalue ode

PFalure Desciption: Rolers ae severely rolle out awele to IR tack. The OR rack is seveely rolle ow. Darkiscoloration is reset, as from a carbonze lubrcat Allthe amage constittes a severe heat imbaance falure ue toloss of lubrcation. his is a gross failuremage Descrpton: The OR sectio is at image N with S half o tack olle out a batee by hot lastic flow. O the S hal othe OR track is a carboize lubricat coating. The IR secton is at image S t ae four rolles wele to the thrus flage ue toheat imbalance falure A o the IR roller track an the ollers ae covere with a ark coating of carboze ubcant hesearato has bee ejecte a rolers have role u against each otherSuspected auses: Loss of effectve lubricaton in a taer roer bearg is aily followe by overheating of thrust fage contactwith a heavy sliig comonent uner loa. That contact will gall a eventually seize wel In the rocess aacent rolligcontact areas also overheat, softe, gal a sufer rollou. The searator siegraes uig these events emitting the rollers oroll u against each oher.

290



Filure Code .1Filure Code 143

Capter Heat mbalance Failure

Plate No 1315Arve No 027-424mage tye: clor view SEE IMAGE IN APPENDIX]Saleba 10 mm (mcros: ±20% oers +00% 50%)Comonent: DGBB; B & G runSeed:Load:Lbriaton: rease ? Fale Code 001922 Hot plastic fow wit bulk weldnFale Code 2 0019.3 Scale formationFale Code 3 0013.21 Rolin srface allinFale Code 0111.2 Separao fractue crackinS als PLATE 133


Falre Deston: Heat imbalance faiure of ball beari as cased () plasic batterin of balls; (2) scalin of ball sace(3 allin and transfer of metal laminae from roove to bals ad (4) fracture of polymer separator Tis is a ross failre.mage Desrton Two darkened framets o macined polymer (peoc) separator at imae W Two browncoated batteredbals at mae E sow foil-saped masses welded onto te balls of alli. Clor may be from scain rease decompositionpoducs or possibly separator material (more detailed examinatio needed) Contrast tis wit Plate 133 were te rn at imaeE sows mdrat overeatin.Sseted Cases Severe eat imbalace failure in beari probably due to loss of lubricant (or primary separator failre) ascaused sotenin of steel alli betwee balls ad rooves; deviation om epcyclc ball speeds; extreme ball/sepaator forcesseparator ractre; and overolln of debris resltin in batterin of ball suaces. Hi temperatre cased scale fomao

Plate No: 1316Ahve No: 02-139mage tye: cor view [SEE IMAGE N APPENDIX.]

Saleba 2 mm (micros: 20%, oters +100% 50%)Comonent: ACBB; B rnSeed: 130 dNLoadLbraton: rease 60CFaile Code 001943 Frictio polymer on uidi pasupport suraceFale Code 2 123 Friction polymer rease lbricaionFale Code 3 Fale Code


Fale Desition: Fiction polymer bands of two orentations on ba wic as rbbed excessively aains sepaator ad wasstoy eaed Te ball remains serviceable. Te ifriction even tat prodced te overeatin may ead to rease loss andresulti bearn failure.mage Desrton Te souter emispee o ball s covered wit coaxial EW circles of yelow bown and ay rictionpolymer bands as ball rbbed witout ndex aainst (peolc plastic) separator pocke Te noren emispere sowsNWSE-oriented friction polymer circes from anoer bal orientaion. Te black damond i te center o te ball mae and teay rm o e mae are lii artifacs.Sseted Cases Relatively speed rbbin of ba i sepaator pocke in te absece of sarp aspeities to cause weamarks may eat te conact and promote fricion polymer formaion as well as its remova by it wear Te combinaion of tetwo efects creates te baded appearace See capter intodction or a descrptio of te etc test tat dstinuises frictionpolymer from temper clor

29




Plate No: 1317Achve No 00-6mage ype: ligh mtalogram Nital chScaleba 100 m (micros: 20%, otrs +100% 0%)Component: C CF rSpeed: 7 m/scLoad: 1 PaLubicaton minral oil, 11CFalue Code 0019 ocal srctr damag from frictionalhatingFaue Code : 26 pport barig damag (of gar cam)Falue Code 3 Faue Code

P

Faiue Descpton ighspd, isfficily lbricatd slidingbtw contact srfacs has casd strong intac hatig whchrtmprd and rhardd h narsrfac matrial Cocrrtly

Flr od

gallig (FC 0013) may hav occrrd Th rtmprd ad rhardd strctr rsmbls a grding brn tndng to cas arlyspallng failr Cotamiatio od in th cam followr rollr/pi gap casd braking of th rollr ad contact slidingmage Descpton: I this scto th rollig sac rs W (arrows) xtndig from this srfac whitsh oblong straksar lighttchng rardnd matrial Dirctly of thm is a wid bad of darktching ovmprd matrial blnding gradalyito th naltrd (mottld apparing) strctr Th mottld dark ara N of th rollig srfac is spcimnmonting matrialSuspected Causes I cam/follow systms th followr rollr sparats from th cam i ach cam rvolto at th nd of th litramp f friction of th rolr o its pi is high th rollr rotato th slows down ad drgos abrpt acclratio a th staof th nxt lift pas Th fricto forcs in th cam/rollr itrac may not sffic to prvnt gross slidng, ladig to cotacovrhating (and possibl gallng)

9



CORROSION, ELTRI EROSION 14Fau Cd 000-

CORROSION FAILUR COD: 000

4 DefnonCoosio of cotact compoets is defied boady i this Atlas as icludig all failue by chemical

(ad electochemical) attacks o sufaceshe tem coosio" applies specifically to meaic stcta mateials Pastics, elastomes ad

(to a lesse extet) ceamics ae also sbject to chemical attack which is boadly categoied udecoosio i ts Atas, eve though the tem does ot specifically apply

Coosio damage is distict fom

• Freing ( 00.5), the oxidatio of wea paticles geeated ad etapped i a fit itefacedegoig micoscopic sufacepaale motio;

• Piing (C 000) as a castig o fomig defect;• Temper cooring fom oveheatg (C 009); ad• Fricion poymer depositio (C o C ) fom ubicat decompositio

otective oxide layes, such as the macoscopicaly ivisible oxide laye potectig staiess steeo aumium aloys, ae ot cosideed coosio

4 NomenclatueI additio to 'coosio/ tems sed to desigate suface damage by chemica actio iclude

chemical attack, ust, ad staiigThee distict coosio faiue modes ae desigated as follows i this Atas

• Corroion aining, which ceates a discoloed suface without appeciable idepth attack itothe subsuface;

• Corroion piing, a idepth attack leavg pits with oxidied sufaces, souded by cooded(staied) o cooded suface;

• Inergranuar corroion, a attack o the ga boudaies of the mateia which may leave ittemacoscopic sface damage, bt weakes the cohesio of the mateial

43 Falue Mode

Coosion o Metals Coosio (ust) as oigialy defied, is the chemica (electochemical) attacko a stee o cast io suface by a wet atmosphee, covetig some of the easuface mateia tooxide o hydoxide I this Atlas, ay oxidizig chemical attack o meta whethe by moistue,acids o the eectochemical effect opeatig o a assemby of dissimia metals, is coveed decoosio of metals"

Depedig o the eviomet, o the coditio of the oiga sface ad o expose time,ee coosio may cofie itself to a vey shalow aye of mateia ad ths fom a brown ain; oit may peetate deepy ito the metal fom distict poits of oigi ad thus fom pi. No ceasepaatio of coditios leadg to stai o to pits has bee established, but the folowig cicmstaces favo oe mode o the othe

• Mild coosive exposue favos staiig, ad sevee o pooged exposue favos pittig

29




29

Fely fshed suaces (hoed, polshed, lapped) coode ess easly ad avo stag oughsuaces coode moe eadly ad favo pttg

The oowg ae commo foms o cooso cotact compoets

Genea csin attackg exposed suaces o the compoets dscmatey The sufaceso whch ollg ad sldg cotact takes place sevce may appea ucooded, wheeasfee suaces ae staed Whe the cooso has pogessed to pt omato, the cotactsufaces may show pts o metallc, ucooded backgoud

2 Cntact csin fomg steaks of sta outg Het cotact aeas Ts cooso appeas a coosve medum (exampe: wet ol) coats cotact compoets (example oles ad gsof a beag) whle at est The medum s etaed ude a mescus the aowg gapsadjacet to cotacts ad stas the suace thee, but may leave othe suaces uattacked

Csin aided by gavanic cupe occus whe a assembly cotas dssmla metas wth

stogy dffeg electochecal potetal, such as stee ad bass Whe a electolyte speset, such as wate o acd the ubcat o hgh humdty the a, cooso o bothpats of the galvaic couple may occu moe eady tha wth ethe metal aloe

Some speca cases of galvaic cooso of sgfcace fo Het cotact mace elemets ae

• Cooso o (had eabe) staless stee compoets wth suaces cotamated by adhegostaess steel patcles acd teatmet temed passvato potects agast ths cooso by emovg the ostaless patcles

Cooso of alumum compoets (example: olg beag sepaatos) cotact wthmatestc stee Aodg o the alumum compoet has lmted potectve value butpesets tbologcal poblems o wokg sufaces

Cemical Attack on Non-Metals. Chemcal attack o ometals may aso occu by oxdatio,but the agets causg t vay wdely

Some plastcs used as sepaatos ae compatble wth ceta ubcats (geases) ad embttewhe exposed to them fo og peods ad o at eevated tempeatues

Impopely omulated elastomes, as used i ubbg seas, ae attacked by meal ols moeae attacked by sythetc lubcats

Thee s lttle expeece wth chemcal attack o ceamcs cotact compoets due to thespecaled use Slco tde wll oxde at extemely hgh tempeatues Noetheless, ceamcsae amog the most coosoesstat mateas

ntergranular Corrosion. Ceta chemcal evomets ted to attack the ga boudaes

metal These codtos do ot commoly affect Het cotact mache eemets, but some exampleshave bee epoted, as folows

I compoets used the petoleum ad atua gas dustes, a "su gas" evomet,wch etals exposue to suphdes, ca pecptate tegaula cooso ad ead to chemcaly duced cackg of compoets Tis s geeay desgated as stess csin cacking(see FC 0022)

Some oxde ad phosphate suace teatmets used o cotact compoets to ad u adpotect om ust ca poduce tegaua chemcal attack at maufactue (FC 0008) ad eavethe metal suace (ude the coatg) usuted to cay cotact loads

Electoplatg o compoets, especally o hadeed stee compoets ca poduce hydgenembittement (FC 0008) which leads to cackg o akg o the suface



Capter Corrosion Electric Erosion


Corrosion Staining O steel surfaces, corroso stas are yelow, brow or backsh areas of radomshape ad extet Typcay, they oblterate the orga fshg les

Dfferetato from lght temper cor (straw clor") (FC 009) may be based o the greateruformty of the atter over arge surface areas (corroso sta s usualy patchy), ad o the factthat ght temper clor does ot obterate fshg marks Deeper temper cor s bush ad sedomcofused wth corroso sta

Frcto polymer deposts ted ot to oblterate fshg marks ad are cofed to cotact pathsCorroso stas ted to be poshed off cotact paths

Dfferetato of corroso sta from frettg may be possble by observg the more reddshtt of frettg However, t s more commo to dfferetate by locato If the sta s lmted strctlyto ft terfaces, the t s frettg f the sta s mosty o free or cotact surfaces, the t s corroso

O brass or bronze surfaces, corroso stag s mostly blacksh O aluminum surfaces, corroso

may show ether as a whte or backsh dscolorato the surfaces are usualy ptted

Corrosion Pitting Corroso pts ted to be shallow, rregularly shaped ad have a blackshsurface wch, uder magfcato, does not appear as a fracture surface

Dfferetato from spalls may be based o depth, whch s typcally greater for spals Morphologyof spall craters ad pts dffers sgfcaty, especally for fully developed large spals wth thertypcal fractre surfaces The dfferece betwee corroso pts ad smal spalls s easly obscuredby oly or greasy resdue left o the compoet after remova from servce horough ceag wthsolvets ad or detergets suted to the lubrcat resdue s ecessary (Removal of some greasethckeers wthout aso removg the corroso sta may be dffcut)

Dfferetato of corroso pts from pores (castg defects) may be based o two crtera )pores are ot surrouded by sta whereas corroso pts may be 2 o metalograpc sectog,

ope pores are lkely to be accompaed by cosed vods away from the surface, whereas corrosopts are ot Examato of corroso pts by scag electro mcroscopy, cludg electro beamaalyss, may revea the presece of oxdes (f the layer s thck eough) ad ad dfferetatgfrom small spals or ocorroso pts

ntergranular Corrosion Itergrauar corroso s dscerble uder the mcroscope, by examg the surface or by examg a metalographc secto for outled gra boudares

41 CasesCauses of corroso for dfferet types of mache eemet are ot dssmlar Rollg beargs,

gears ad cams a ca corrode from the same causes Dffereces betwee beargs ad gears arse

because materals used gears spa a wder rage tha beargs (softer steels, cast ro, osteel meta, more plastcs) ad so do gear surface fshes Beargs more ofte have ther owlubrcat supply (grease) whch may protect them or, f cotamated, attack them

Corrosion of Metals A st of commo causes folows

. Water

• Humid air (codesato o surfaces)• Liquid ater in air (spray, spash);• Water in the chamber (defectve cosure, submerso of chamber, leak coolg col, etc);• Water-contaminated lubricant. Seawater s a partcuary aggressve corrosve aget

295




96

Lubrican chemisry.

• Unsuiable lubrican formulaion exampe aggessve EP addtves)• Acided lubrican om chemical decomposto by oveheatig o exposue to active metal)• Incompaible lubrican and sysem exampe: yelow meta ad some poyeste ubicats)

Chemical vapors in amosphere4 Corrosive chemicals used in manufacure, o coosve decomposto poducts Mauactuig

coolats, pocess lubcats, appig compouds, ceag uds, ad eve aticoosio pesevatives may cotai aggessve cotamats o decomposto poducts The eactivty ocoosive chemcals iceases wth tempeatue y cotast, codesate may evapoate at ghtempeatue ad cooso may be peveted

5. Galvanic couples set up betwee metals with deet eectochemca potetal i the peseceo a electoyte

•Yellow-meal separaors in marensiic seel rolling bearings, the pesece o wate o acd)eectolyte

• Sainless seel surfaces conaminaed wih marensiic seel;• Aluminum alloy compoets with upotected suaces cotact wth stee

6. Liuid meal o sal evomet s voletly coosive Liqud metal may be peset i someuclea applicatios mote) salt may splash o a compoet some heat teatg uaces

7 Cyrogenic uids ae ecouteed as wokg eviomet some pump appicatos Thelud tsel s ot coosive, but t pomotes codesato ad ce omato ad has o ustpotective ablty

Chemical Attack on Non-Metals. Two types o chemical attack o ometas that ae ikey tocause coosio ae

• Incompaible lubricans; ad• Amosphere speccay aggessive to the mateal

Intergranular Corrosion hee ae may causes o itegaula damage see [0]) but elatveyew commoy aect cotact compoets Some o these causes ae isted below

Sress corrosion, whch maiests tsel oy ate stess cycig A aggessive evometweakes the gai boudaes ad they ai cycc stessg by extesve itegaua cackigsee FC 00) Some obseved souces o a aggessve evomet ae

• Acided lubrican geeated by decomposito o lubicat i sevice• Sulphide amosphere i sevice

Some phosphate) coaings appled by a etchg pocess dug mauactue poduce a deeta attack o the gai boudaies FC 0008)

. Hydoge eed at the suace duig heat teatmet o patig causes hydrogen embrilemen,which peeetaly weakes the ga boudaies

41 Effects of orroson

• Destuctio o suace geomety, whch causes ose, vbato ad accuaces• Fomatio o suace deects pts) which peciptate spalig• Pomotio o wea Stee o cast o cooso poduct is ot wea esistat It is eadly wo

o, makig way o uthe cooso a mutuay ehacg teacto



Chapter Corrosion, Eletri Erosion

• Ehacemet o corroso Corroded suraces produce addtoal rust aster tha ucorroded

suraces beg rustg• Ehacemet o crackg ad racture Corroded suraces crack more readly uder stress

Itergrauar corroso actvates specc crackg mechasms stress corroso crackg) wellbelow ormay tolerated stress levels

LCTRIC ROSION FAILUR COD 00

DefinitionElectrc eroso s damage to cotact suraces caused by the passage o eectrc curret

Nomencatre

Electrc eroso alure s also desgated electicl pitting electic cent dmge, cent eosion orsp eosion.

3 Faile ProcessElectrc potetal derece, developg betwee compoets Hert cotact, meets resstace

at the terace rom three sources:

A ocoductg EHD ubrcat lmNOTE: Electrcaly coductve greases are o the market or use where smal currets eed tobe carred by lubrcated cotacts To the extet that they suce to coduct the teded curretwthout buldg up a substata potetal drop betwee the cotactg suraces, they mayprevet electrc eroso

2 A ocoductg or poory coductg adsorbed m o boudary ubrcat, surace oxde orother depost

. Costrcto resstace at metalc asperty cotacts o lmted dameter

the potetal derece s sucety hgh, a curret wll be carred across the cotact teraceas a sp Sparkg s a hghy erosve process to the suraces across whch the spark eaps Theseverty o the erosve eect s a ucto o the curret cared ad the tme o exposure to curretWhe the electrc curret desty passg betwee the metal suraces the Hert cotact exceedsa crtcal magtude (ot geeraly establshed), t creates craterg by the mechasm utled spark machg o metals Smal volumes o surace metal are heated ad tor o, probaby byevaporato The surace s ocaly meted ad cratered

The materal the vcty o the eroded craters s ote tempeed by heatg rom the spark, adthus soteed I the heatg was greater, ehdened matera may be preset Rehardeg mayresut micoccing.

ote: The sulatg ayers ormed Hert cotacts are very th o the order o 0.1 �m or ess) ad thearea o each asperty cotact s very smal (o the order o 10-3 m2 or ess) hereore, eve amodest potetal derece o several volts sets up a very hgh eectrc ed stregth across thesulatg ayer Lkewse, eve a modest curret passes through the asperty cotact at very hghcurret desty Eectrc eroso ca accordgy be tated by codtos that are qute commoplace Electrc eroso may occur betwee t suraces, athough, due to the geeraly lower resstaceo that terace, oly very arge currets produce t

tally, eectrc eroso results scattered pits As a result o osclatory eects whch may haveboth a eectrca (chargedscharge) ad a mechacal vbratory compoet but are ot uy

297




298

explaed), severe eectrc eroson often concentrates in perodcaly spaced troughs ruing trans

versely to the rolng directon, designated asutes

1 Distinctive AppearanceElectrc erosion can yield two dstinct appearances: electrc pitting and uting

Electric pitting. Eectrc pts are usuay smal, approximatey conica craters Under magnificaton,ther surfaces appear melted They may requre some magnfcaton to be resolved

Fluting Advanced electrc eroson of roling surfaces may gve them a fluted" or washboard"appearance, wth perodcaly spaced depressons rug transversely to the directon of contacttravel Mcroscopicaly, the troughs or flutes consist of a muttude of densely spaced fine pts Thelands separating the futes may be more or ess undamaged

1 CausesIn most cases, transmssion of eectric current across a Hertzi contact is untended However,

some small roling bearng applicatons may be an exception and a smal current may deiberatelybe drected across the Hertzan contacts A conductve lubricant may be designed n, but may notbe used through oversght, or may not suffice to prevent electric eroson

Most often, the untended currents are generated by asymmetries in the stator magnetic feld ofan eectrc motor or generator In these machnes, the rotor turns n a strong magnetc fed whchs the vehcle of power transfer to or from the rotor. Idealy the fied s symetrical to the rotor axisand does not generate potental differences between the contact surfaces of the bearings or gearsmounted on the shaft However, untended asymmetres may exist or develop in service, and thesecreate the potential differences drving the erosve eectrc currents across the contacts

Magnetc fields may unintentionaly ntersect with rotating parts other than the rotors of eectrc machnes

Statc electrcity may bud up a potential across the Hertzan contact In large machinery n whchnonconductve material moves rapidy over rotors (textile industry, printing ndustry, conveyors,etc), the static electrc charges may be great enough and be regenerated at a suffcient rate to maintandamaging currents

Stray currents resutng from ncomplete nsuaton of ntended electrical potentals n a machinemay dscharge across the Hertzian contacts

Conduction paths ncudng springs and brush assembles are often provided to direct untendedcurrents away from Hertz contacts These devces may fa, exposing the Hertzian contacts to current

14.2.6 Effects of Elctric Eosion

Nose and vbraton of severe ntensity is an early effect of electric eroson. The vbration canreach destructve severity, especaly f futing is present

The pts and futes of electrc erosion are severe surface defects from which gallng (FC 00),spallng (FC 006) or surface dstress (FC 0017) may proceed

The tempered or rehardened structures surroundng eectric erosion pts and flutes are proneto mcrocrackng and represent ow fatgue strength materal



Chapter Corrosion, Eectric Erosion


Faire Code

0020

002001 1

00201

00201 3

00202

00203

Plae No

1 8 7

824

1 4 5

1 4 1 2

1 522

631

9 1 7

1 0

1 46

1 4 1 0

1 4 1 3

1 4 1 51421

7 1 0

9 1 8

1 065

1 070

1 4 1 1

1 4 2

1 4 3

1 4 1 4

1 8 1 7

5 1 5

7 1 0

47

148152

1 8 1 8

1 4 1 5

OTE: FC 00.21 occurs in o other chaper

299



Failre Atla for Hert Contact Machine Element

PLATESt No 14Acv No: 02-211mg typ: clo view S MAG IN APPNDIX.]Scb 20 mm (micos ± 20% othes: +100%50%omponnt DGBB assembly 2 nSpd:Lod:Lubcton: geaseFu od 002001.1 Geealized coosonFu od : 124.4 Gease decomosed by chemical agentFu od 3 Fu od

P

Filure Code 1.1Filure Code 1

[See Image in Appendi]

Fu Dscpton: Both beaings ae seveely cooded i seawate Cooso odc is on all exosed saces The gease sdiscoloed ad made gitty by chemical decomostio i the esence of satwae and metal saces The beaings ae sabemg Dscpton: he beaig at mage W shows heavy dak bown st o al visble saces. he gease is of simia cloafte decomosition ad st admixte The beaig at mage shows an ealie sage of seawate coosio. Steel sfaces aeaially coveed with st the gease is decomosed Note that he st clo s moe bown (less eddish tha the clo offettg coosonSuspctd uss: Seawate is kow to have fod access to these beaings (i stoage Salwate is exemely aggessive tostee ad also decomoses may be�ig geases and steventive slshes.

t No: 142

Acv No 064701mg typ clo maco [S MAG IN APNDIX]Scb 0 mm (micos: 20% othes +100% 50%)omponnt: HG & W high hadness nSpd:Lod:Lubcton:Fu od 0020 Coosio staiFu od 00182 Sha dvidal det(s fom metal debis aseitiesFu od 3 00601.3 ooth salingFu od

P

[See Image in Appendi]

Fu Dscpton: Cooso stai sots ae in the tooth oot adis o iion Cooded dents and smal salls ae visble onwhee contact saces. he cooded indetatons and sals on the contact sace may ceate a oisy gea ad can be soces ofmoe sevee saling ad evetally ooth factemg Dscpton: At N image edge, thee tooth flank sfaces of the whl ae visible o the S is the pinin. On the wheel lghtgay god flank saces show may iega bow deessions which ae dents o smal salls fom dets with coodedbottom. The deted flank sace has won clea of coosion. O the iion, lage, onded bow maks ae coosion sainsn the oot adis ot sbject to wea he shadow o the two S-most teeth may be a ight eflectionSuspctd uss: Ingess of wate to geabox may case coosion staig. The odish sots on the oot adis sggestdos of wate o a statioay gea. he dents o the wheel may be de to olledove debis ad may sal ot ad/o coode ithe esece of wate Coosio o the dented cotact sface may fom, bt wil wea off in ning

00







Failure Cde: 13 Chapter Corrosio, Electric Erosio

Plate No: 17Achve No: 08010mage tye: color macro [S IMAGE IN APPND]Scaleba 20 mm (micros 20% others +100%50%)Comonent: HG; P high haress ruSeed:Load:Lubcaton:Falue Code 0020.13 Cotact corrosioFalue Code : 0020.2 Corrosio ittgFalue Code 3 Falue Code

P

[See mge in Appendix]

Falue Desction: The tooth flak suraces of the gear are covere small scattere corrosio is with clea metal suraceetwee them. o ittig is visile o the gear OD. This te of corrosio is attriue to a aggressive sustace the luricatsuch as a aggressive P aitive, actig chiefl i the high ressure cotact eviromet The gear is ot aile ut ma sallrematrel or eerioate frthe if the corrosive evomet cotiues.mage Descton The image is of a ortio of a helical iio with tegral shaft All cotact suaces show evel scatere fieow-lack corrosio its The gear OD shows o its, jst circmfereial machig marks (which ma e coroe).Susected Causes EP aitives i some gear oils ma ecome aggressive if wae is amixe or temeature is excessive Thecorroe the steel eseciall where high local temeratures arise ue to cotact loaig a sg

Plate No: 1.8Achve No: 03 -1101mage tye: view (aal)Scaleba = 20 mm (micros 20%, othes +100%

50%)Comonent: SRB IR, ruSeed:Load:Lubicant mieral oil ? Falue Code 00.20.13 Cotact corrosioFalue Code : 0020.2 Corrosio ittigFalue Code 3 00.6.1.21 Shalow etr sal fromsurface oit-eectFalue Code 00.2. Wear of guiig-comoesuo surfaces

PFaue Descition: Nmerous cotact corroso sreaks are vsile a roler sacigs wth more tha oe roler set ositioCorrosio its aear i a otsie the cotact areas. Salls follow the cotact corrosio outlies Circmferetial wear marks areo he searator guie srface (OD) of the ceer fage. The earig has failemage Descition: O of SRB R (artial view) showig oth roler aths a three lages Rectagular axial as exeacross oth roller aths where the origia suface is estroe Black corrosio its are i a ousie the as. Sall cratersfolow straight eges of the cotact as o the roller ah facig image N. Circmfereial (shi) wear marks are o the OD ofthe ceter flageSusected Causes: Ths earig oerate a aer machie. Water (seam) igress ito the earig causes cotact corrosiooutliig the area with the flui meiscs ajacet to each cotact. Salls itiate a the corrosio its cocetrate wihi theliqi-lle aea ear the cotacts. Wea o the searator gie srface ma e e to arasio ers.



Failre tlas for Hert Contact Machine Elements

Plte No: 1.9Ave No: 087117mge type: viewSle b = 10 mm (micros 20% oters: +100% 50%)Component: ABB B rnSpeed:Lod:LubtonFlue Code 00.202 orrosion pittinFlue Code 2: 00161.2. Sallow entry spal from surfacepoint-defectFlue Code 3 00.1603.2 Spall propaatin by reinitationat srfaceFue Code See al PLATS and 1.11

PFlue Despton: ense corrosion pittin on bals asprecipitaed spalls on eac. Irrelar propaation suestsmulple spall stas from several corrosion pits. Te balls avefaledmge Despton: Fine corrosion pittin on all tree balls, best

Failre Coe

seen near te contor were dark spots contrast wit reflection from te wie backround orroson is mos advanced on teball a imae N least on te ball at imae SE One spal crater s visible on eac ball te most advanced is on ball at N wicsows severa intiation poins wi rides dividn te crater bottomSuspeted Cuses: e to fine finis unworn balls are more corrosionresistant tan oter pars o identical materia Wencorrosion occrs in an environment suc as water spray, condensation salt air or acidified lubricant smal stans or pis tend toform Pis are major sources o early spallin See aso Pates 1. and 111.

Plte No: 1.10Ave type: 031-502mge type: viewSleb = 0 mm (micros ± 20%oers +100% 50%)Component: TRB (mtirow) OR runSpeed:Lod:Lubton mineral oil, ? ocFlue Code 00.202 orrosion pttinFlue Code 2: 00.161.2 Sallow entyspal from sface point-defectFlue Code 3 00201 orrosion stainFue Code 02.13 Rbbin seal

counteace wear

PFlue Despton Geneaized corrosion of ree sufaces (sains) and contacts (pits) wit subsequent extensive spallincomposed of small craters emanatin from pits Spallin covers te rollin contact surfaces Te flane contact surace is eavilycorrosion pitted and may be aled Te bearin may stil urn but as no sefl life ef.mge Despton: e rn sdeface (facin imae N) and te of te center fane (wit oil oles) sow dark corrosion stainse roler pa is densely peppered wt pits and spalls (detais not discernible in te imae) indicatin corrosion followed byspalin e N-facin trst face o te center flane s corrosion-pited, and may be alled On te contact srace, adjacent ote N ede circlar wear bands are visible, wic may be de to seal wearSuspeted Cuses: Tis bearin operated in a paper macine, in wet envionment Wate nress (possibly steam) past damaedseal cased corrosion olowed by spalin On te flane trst suace pits and rst are vsible, and alin s sspected

0



Falure Code:

Pae No: 1411

Acie No: 1-1mage ype lght mcrogramScaeba = 4 m mcros 2% others 1%, 5%)Componen: ACBB; B, rnSpee: 1 MNoa: ? axal)ubcaion: sythec poyester ol, 12°CFailue Coe 2.2 Corroso pttngFalue Coe : .2.1. Cotact corrosoFalue Coe 3 .12.4 Wea o gngcompoetsppo srfaceFalue Coe See a PATS 14.4 an 149

PFaiue Descpon: 1) Raom corroson pts o ball srface;2) parallel scratchmarks alog a great ccle an a earby

Chaper Corrosion, leri rosion

mo crcle, flcte late than he corroson pts xposre to a aggressve envroment case by corroso The scrachmarksappear to be e to cotact wth abrasve parcles of aspertes the separato. Ths s cpent fale a hghspee beargSee also Plates 144 a 149 for ball corrosonmage Descpon: Gray backgro s bal srface. Lappng marks are ot vsble. Clstes o ark spots are corroso pts Theban of ark parallel acs across the N mage qarant cossts of scratchmarks. Smla bas ae the SW qarant Centerebetween the two sets o bans s one corroson pt from whch scratches etca ecto emanate, showng that scrachescoverg pts or emaatng rom a pt were mae afte the pts ha forme.Suspece Causes: De to the fe fsh balls are tscaly more corrosonesstat tha other parts of eca materalWhen corroson occrs a evroment sch as water spray, coensato salt ar or acfe lbrcat, pts, rather than stasten to orm The scrach markg appears to be case epeenty of the corroso except where t orgates at a pt that mayhave prove corroe ebrs.

Pae No: 1412Acie No: 14-1mage ype: vewScaleba mm mcros: + 2% others + 1%, 5%)Componen: TRB IR & OR & R rnSpee:Loa:Lubcaion: gease ? Faue Coe 22 Corroson pttgFaiue Coe 21 Contact corrosonFalue Coe 3 .2 .1 Geeralze corrosonFalue Coe See a PLATS: 145 14.6 an 1412

PFalue Descipion: I the OR roller pah on the rolers an less) o theIR roler path, axal bans of macroscopc corroso pts have forme omtrappe coensato srrong the statonary contacts. On the OR ODgeeral coroson a/o frettg s vsble. Corroson s agnose becaseof the ranom spoty appeaace exteng across the entre OD wth Cotact corroso pts fom severe spala tg sraceefects See Plates 45 4.6 a 14.12 for comparso.mage Descipion: An IR 'coe) at mage N s flake by two rollers. The OR 'cp) s at mage S Corroso pt bans at rollerspacg are ear N smal) ege of IR rack an at extreme . Many pt bas are o th roller OD. Heavy bas appear at rolerspacng the OR rack. The OR OD s ffsely rst sane Frettng s possble bt less lkely across fll wth an smalffse spots In clor vew, rettng tes o be more re corroson moe blacksh)Suspece Causes: Ths bearng was grease lbrcate an se a roa vehcle wheel. Coesao may accmlate at contactswhe vehcle sas the col, a proce the stang f grease s nstable to protect cotacts

05



ailure Atlas or Hertz Contact Machine Elements

Pae N: 1413Ave N: 0419&20mage ype: a, b: viewSaeba = a b 0 mm (miros: 20 others +100, 50)Cmpnen: TRB R & R, unSpeed:ad:uban:Faiue Cde 00202 Corrosion pittingFaiue Cde 2 0020.13 Contat orosionFalue Cde 3 00.201 Corrosion stainFailue Cde 0051 Generalized frettng, radial it surfaeSee als PLATES: 14 and 1412

P

Falue Despn: Thin wavy ines of orosion miopitting are onthe IR ('one) and the roler onta sufaes Compared to Plate14, the orroson ptting indiates more aggressive (or more longterm) orrosion over smal surae areas. There are some orosonstains. Pis are spallinitiating surae defets Early spallng failre isexpeted nidental fretting is present in IR (one) bore See alsoPlate 4.12 ilustrating signifiant TRB orrosionmage Desipin: (a): rolles with wavy axial dark lines fomed byorrosion miropits (disernible nder magniiation). Some diffuseorrosion staining is visible near end of roers (b) Thin, straightdark lines fomed by orrosion pits near S oller path edge in imageenter and 1/5 from image E. Minor staining exists at image W Broad

a

urved dark band at W s artfat Heavy dark spotting in the bore is bfretting

Failue Code

Suspeed Causes If an aggressve agent (water, aidified presevative or lubriant) enters ontats in small quantiy bu remains

in plae for long oalized orrosion pitting may develop Lesser onentrations may ause stains Heavy bore fretting indiatesthat the bearng ran extensively Corrosion may be a late ourrene; otherwise spals woud have formed.

Pae N: 1414Ave N 093201.4mage ype: ight mirogramSaleba 1 mm (miros 20 others + 100, 50)Cmpnen: SRB R, runSpeed:ad:ubian:Faue Cde 00.202 Corosion pittingFalue Cde 2: 00.2013 Contat orrosion

Falure Cde 3 11.2 Water in olFalue Cde

PFailue Despn The lubriant in this SRB onained amodest onentration of water whih formed fine droplets onthe stationary ontat sufae t appears that a small amount of relative motion ook plae in the ontat Where pue rollingourred, the droplets formed round pits Where a sliding omponen existed the points were smeared out into streaks. Extensiveorrosion produes many spallinitiating suae defets.mage Despn: mage shows SRB R roller path with rolling diretion EW. At imge S, dak points densely pepper thesurfae. Pogressing to , they oalese into bands and then, near A into individua streaks abou 00 m long t is assumed thatwater droplets in oil were wiped over the surae by slidingSuspeed Causes: Water in the lubriant is a serious soure of orrosive attak when its onentration exeeds a maximumdependent on the abilty of the lubiants anti-oxidant o prevent orrosion. Corosion pits ause loss of ontat fatigue esistane

06







Faiure Code 00211

TPlate No: 1 4 1 9

Archive No: 1 07006&bImage ype: a b SMScalebar a 50 b 10 m (mcros ±20% oters 100% 50%)Component: DGBB R, rnSpeed:oadubication: oil , 50°CFailure Code 00211 lectric eroson pittiFailue Code 001 71 1 Glazi ( incipiet srface distress)Failue Code : 00.123.22 Scratc marks kinematic wear marks inrollin sface

Failure Code S s PLATS 4.17 ad 14.23

ESCRPTONSFaure Description: Microscopic pttin of cotact srace tro ontimepassae o small cret Raised pt edes are bein rolled down (srfacelazin). Te srace as sffered damae comparable in its effect to sacedistress (aspertyscale spali) ad is prone to early spalli failre Te ewwearmarks are incidental.mage Descripton: (a) Backrond is dark ray rollin sface Finisin lesn SWN Many dese small blackcntered electrc eosion pits wt lit(raised) rims ae visible. Near imae ceter are two so deep wea scratces(b) Hi maificatio Gray rollin sace sows daker SWN rninfiisi ines. Back irelar electric pts wt srrondin raised (lit clor)edes, wic ae rolled down by contact passae Tere are no factre sfacesas fod n spallsSuspected Causes: ectric crrent passi tro te rolin contacts of abearin (wit nslati lbricat) makes sparks wic eode (melt) te srace.

Dependin on crrent itesty, fie pittin (as sow see aso Plate 14.17) omassive fltin (see Plate 1423) may reslt.

Capter Corrosion, Electri Erosion

a

b

309




TPlate No

Arhve No 7&bImage type: b SMSaeba = mm b m (micros % ohers: + % %)Coponent: DGBB IR Speed:Load:LbiatioFaile Code Electric eroso ittigFaile Code 8 Shr idividul det(s) fom metl deris seritiesFaie Code 3 Shlow et sll from srce oit-defectFaie Code S s ATE

ESCRPONSFailre Desription: () Circulr telets of surce meri were removed belectic curret ssge through the cotct Shredged crteig ws cusedb ocl melig. Removed teles were rolled ove to form circul dets (b):rosio crters with oleddow edges re sow ossib strig to sll. Altee begis to form its from electric crret erosio e mor oise sourcesd ted to ed to ver er sllig.Iage Desriptio: (): The drk gr bckgroud is he rollig suce withfiishig lies ruig NS. Ideticl-sied circlr ight d drk sots re detsof bot m dimeter. (b) er ceter of S imge edge: remeted erosio itwith stred bottom d rised looseed ltelet t S. Flt circlr deressios iSE NW d SW udrts e des At imge N re eroso its wit rolleddow edges. Tese ossibl iitite slsSspeted Cases Electic curret ssig through the rollg cotcs of berig (with sultig lbrict) mkes srks which erode (met) the suce.Deedig o curet itesit fie itig (s sow) or mssive flig m

eslt. See te

30

aiure Code: 00211

a

b



aiure Code: 00211aiure Code: 00212

Chapter Corrosion, Electric Erosion

TPlate No: 14.21

Archve No: 014-70&7Image type: : view; b lght mcroScalebar b: 5 mm (micros: 20%others 100% 50%)Component: TRB; : R&G b: IR rSpeeLoa:LubricationFailue Coe 0021 .1 lectric erosio ttingFailue Coe 0020.1 Corrosio stFailue Coe 3: Failure Coe

ESCRPTONSFaure escripton:

One lrge electrc eosion itech is n the oller d the R de to one-tmessge of hgh-intensit cret the sttionrberig Icidet corosio stinng is vsible on a bthe IR he beig hs filed.Image escription: () The rollers e light gr in the drk stmed-steel sertor O he cener roller mdw log thecontct is lrge circlr drk it wih rised rim. (b): IR (cone') roller th with the trst fnge t N imge edge At mgecenter is lrge it mtchg tht on mge () he rim of the it is ised ncidentl corosion sti streking ers o theroller th.Suspecte Causes: Ths bering sored rotor o which electrc c weldg ws erormed while groding the mchethrogh the sttor The fll weldig crrent ssed thogh the berig cretig mssive electric srkig d erosio ittig Theberig s nsble.

TPlate No

1422Achive No 01468Image type l ight mcroScalebar 1 5 m m (micros 20% others 100%50%)Component: TRB; R rnSpee:LoaLubrcationFailue Coe 0021 .2 lectric erosio fltigFailue Coe

Failure Coe 3: Faiure Coe s PAT 14.23

ESCRPTONSFalure escription: lted' electrc erosio dmge is shownwth trnsverse deressios in rolling srce i whic cosiderble ittg took lce ltentig with reltivel dmged bdsbetwee fltes ltig reires contg crent flow bove miimm strength lting erosio cretes extremel noisberigs whch ted to fl rdl b seizre or sero rctre See Plte 1423 for detiled ence of the fted sceImage escription: At the imge edge is the thrst flge (lrge-end rb') of RB OR (cone) t the S edge is the smll-endflnge (rib) nd derct. Betwee these the roller th is covered b roximtel eriodic shredged xil vlles (ftes') of13 mm width d extending comletel cross roler th.Suspecte Causes: ltig der electric erosion is ot fl exled Aretl vbrtor coditions ed to cocenttio ofcrret flow t m inim m sfce seron oints occr ig d ring the vibrtio d fles form there. ess crrent fows ermximm sertio oints. xistece of fltes rentl locks in the vibrton hse so tht fltig s reifoced See mgifiedimges of ftes in Plte 14.23.

3




TPlate No: 1423

Archve No: 093-2 .1 .8&7Image type: SM b: SM wit sectioScaebar 250 b 8 m (mcros 20% oters + 100%50%)Component DGBB IR ruSpeed:LoadLubrcato:Falure Code 00.21 .2 ectric erosio fltigFalure Code 00.1 71 .1 Glig (icet surfce distress)Falue Code : Falure Code S s AT 14.22

ESCRPTONSFalure escpto Flted electric erosio dmge wittrsverse deressos rolig surce. Tere is dese crterigi flutes d o dmge or dmge of cosiderbl lower detbetwee fltes Te crter bottoms i te flutes re moltesuces crte edges ve bee rolled over d re surcedistressed utig cretes extremel ois berigs wic ted tofil ridl b seiure or sertor frcture.Image escpon: () ortio of bll groove Te sce t is ufted. Fiisg mrks d rolig directo ru log terrow i NE corer. Te edig edge of flte s t , witcrters extedig to te NW S of lie is te trig edgeof oter flue wit crterig Tere is mior dmge D (b) A sectio le begis t ; te edg e of te flted suce is rrow A molte crter bottom is t rised overrolled glzed

ims re DSuspected Causes Futig from eectric eosio is ot fdestood. Aretl vibrtor occurrece cocertescurret log te tier film res formig flute bottoms Teexistece of ltes ers to lock i te vibrtor se so ttftes re reiforced. Fo erce of te fluted surfce seelte 14.22

32

aiure Code: 00212

a

b



BUK CRKING, FRUR,

RMNN DORMION 15Faiure Code 00.22-23

15.1 BULl< CRACKING OR FRACTURE FAILURE CODE 0022

General Note on Ceramics. Ceramics, especally slico trde, are sed as Hertz cotact compoetsCeramcs as a class are crac-sesitive de to teir relatve brittleess compared wt metas. Noexperimetal se o ceramic Hertz cotact elemets accordigly avors compoets sc as rolig bodies (bas ad rollers) ad gears itegral wit stb sats, i wc bl tesle stresses aremmzed ad wic tereore do ot ted to orm bl cracs service. As a reslt, docmetedcracg aires o ceramic Hertz cotact eemets i service are ot available or se i tis Atlas,ad ts te cracg o ceramics s addressed tis text, bt ot llstrated. Reer to FC . orcg (cippig) o ceramic compoets, wc represets local (bt ot b) cracig.

111 DefinitionI a cotact compoet, bulk rakng desigates cracs extedig beyod te stress ied o te

Hertz cotact Bl ractre s ractre leadg to separatio o a volme o materia by a bl cracExamples o bl cracs ad ractres o Hertz cotact compoets olow

Rolling Bearings and Cams

Cracs startig i te cotact zoe bt extedig i dept ito te compoet, beyod teHertza stressed vome

• Cracs o tegral lages; ractre o lages. Cracs o a etre cross-sectio; breaage o compoet to separate pieces

Note: Cracig o bearig separators is covered der C .

Gears

oot cracig (bl); toot ractre. Cracg or ractre o gear body (web or b) Cracg o splie (toot or body).

Note Cracig or ractre o tegral sats, away rom te gear tsel, s covered der C .

112 Dianostic ObjectiveBl cracig ad ractre are, by ar, te most commo umae aire modes mecaca

compoets as a broad cass e cases ad types o cracg are a wde ield o stdy Itis Atlas, te descripto o bl cracig ad ractre o cotact compoets s limted to casesecotered as servce ares o tese trboogical compoets

Egeerg diagoss is amed at te deticatio o egieerg cases or alre. We diagosig cracg, tree qestios mst be aswered to idety cases

313




34

1. Bas rakng mehansm s te cacig itiated by oveoad, atige o cemical attac? (iss diagosed om te cac sace topogapy.

. Crak prpagan dren Wee did te stess ield tatig te cac opeate ad watdecto dd it dve te cac (is is dagosed by detyg te cac oigiatio poitad obsevg mas o cac gowt.

3 Crak age How mc o te cac is ecet ad at wat ate did it popagate (is is diagosedom te oxidato ad wea codto o te cac saces

1513 Nomencatureee ae o desigatos ote ta cacig" ad acte" o tis aie mode. Howeve,

tee s a lage mbe o dieetatig adjectives o ale mecasms, acte appeaaces,etc o avoid epetitio, tese ae ideted te descpto o te aile pocess wc olows.

1514 aiure ProcessCacg may be categoized, accodg to ts case, as mecaical stess cacig, temal stess

cacig, ad cemically pomoted cacg.

Mechanical Stess Cacking s categoy icldes bot ovestess (dctle ad bttle ad atigecacg, wic ae ote itemgled.

Rllng Bearngs

. Crakng under (tese hp sress occs i gs teeece-itted o sats ad te otatg

egs o g speed beaigs, de to cetgal oces. excessive, oop stess aloe may case atige o eve oveload cacig, statig at a ic

o edge i te boe o te olg tac. A lesse tesile oop stess may divet a atge cacstatig om Hetzia stessg ito pogessg adialy iwad, so tat a bl cac ateta a spa oms.

. Crakng under bendng sress gs may be de bdig stess tei motg pat (sato osg s ti, sot, dstoted o itepted (o exampe, by a ole o eyway Balls orllers may be de bedig stess i te bals ae olow, o te olles ae died o axiallymsocated, so tat tey ove te tac edge.

3 Impa r verlad rakng may occ i adeed, especaly tog-adeed stee (adeve moe, ceamc mateal, wic is ieetly o ow togess. Impacts o oveloads maacte, motig o sevice ca popagate cacs Loca deects ca ceate oveloads ad

be potet cac tatos.mpact o oveload cacig may occ o beaig igs ad oig eemets (especaly

bals. Patcaly veable to impact o oveload cacig ae tegal ages o igs. eseages ca come de ig load o mpact om impope motig pactices, om axasevice loads (cydica oe beaigs o excessve olle sewig. Cacs tat cip o beaages ae commo.

4. Crakng afer spallng Spals ae stess ases, ad olig ove spals ceates mpacts. Wete spals ae age, te codito may become scietly sevee to popagate a mecaicalstess cac i a bal, olle o g, de te actio o otewse wel-sppoted b stesses te compoet (oop stess, bedig stess, etc.. og adeed compoets ae moevleable ta case adeed compoets.



Notes

Chpter Bulk Crcking, Frcture, Permnent Deformtion

1. Cam folower rollers which are bored to accommodate a supportng pin bearing may undergo

cracing due to some of the same causes from whch bearngs crac2. Sicon ntride bals have not been noted for developing bu cracs from spaling.

Gears

1. ooh bendng fatgue fracture is a primary failure mode n gears.

• ooh roo aure s the resut of stress concentration at the tooth root.• ooh hppng removes portons of the tooth tip as a resut of concentrated stress in that area

such as from a ocal defect.

2. Web or hub rakng or both may occur as a sequel to tooth cracing.3 Spnes may crac when transmittng excessive torque or mpacts. Impa or overoad rakng of gears may occur as t does in roling bearings.

5. Crakng om spang is not uncoon. Spals are stress rasers and roling over spalls createsimpacts. When the spals are large the condition may become sufficiently severe to drive afatigue crac through a tooth under the action of tooth bending stresses.

Note Cams may undergo cracing for many of the same causes as do gears except for tooth fracuremodes which do not apply.

Terml Stress CrckingRubbng raks Cracs may form on (hardened steel surfaces in sdng contact under heavy loadas a result of cycic loca overheating. Ths failure mode is in competton with galing and maydominate if the lubrication the surface coating or fnsh succeed in preventng the welding necessayfor galing. The cyclc heatng and coog can resut in thermal stress fatigue cracng desgnatedrubbing cracs.

or forging cracs and heat treat cracs see C 00.07. or grnding cracs see C 00.08.

Chemiclly Promoted CrckingSress orroson cracing and hydrogen embremen cracng both result from otherwise we-toleratedstresses apped to weaened intergranular bonds caused b chemical reactons. or a descriptionof the hydrogen embrittlement process see C 0008 for that of stress corrosion see C 0020.

Distinctive Appearance

Three appearance features of cracs are important n diagnosing cracng processes and causes

(1 crac progression features whch provide indications of the nature of the stress drvng the crac(2 crac initiaton features and ocation which can identfy wea ponts and the drecton fromwhich the stress attaced; and (3) changes in crac surface appearance from events after cracigwhich are ndications of crac age and progression rate. They are preferaby examned n the orderlisted because interpretatonof each is needed to shed lght on the next appearance featre.

Crck Progression Fetures The folowing comments apply to the recogton of crac progression features.

Extensive fractography literature [22] covers crac progresson features in general. However the body of data pubished on fractography of hardened stees is qute limted. In this Atas oyappearance featres relevant to Hertz contact machne element dagnosis are covered




Great dereces crack surace appearace arse rom the structure toughess ad resduastress o the compoet materal ad aso rom dereces the apped stress codto. hardsteels the eatures are very e ad may requre (scag eectro mcroscopy or detcatoThe eatures may be less we developed ceramcs tha stee

The cassc dstgushg eatures o crack propagato oowTransgranular Cracking s the orma crackg mode the absece o gra boudary weakess

• Fatigue cracks resultg rom repeated applcato o stress below the "utmate stregth" show"beach marks" whch are rdges roughly cocetrc arcs cetered o the tato pot.atgue cracks may alowed to cotue servce covert to overstress cracks whe thecross secto has bee weakeed by the atgue crack to the pot where stresses exceed theultmate stregth.

• Ductile cracks are comparatvey sow movg cracks resutg rom stress sghtly excess othe "racture stress." They occur materas wth sucet ductty uder the prevalg stress

codtos ad show mcroscopc "dmples" that s cocal depressos where pastc ow hastake place durg crackg. Ductle cracks may occur teso or shear teso thedmpes are o-drectoal shear they are oreted the slp drecto. Ductle crackg sclearly detabe tough lower-hardess materas but hard steels the dstgushgeatures are very subte ad may be udetabe

• Brittle cracks are ast movg cracks wth lttle pastc low whch occur matera wth lowductlty uder the exstg stress codtos. They are drve by the apped stresses pus theelastc eergy reeased by the crack rom the stressed materal (cludg resdual stress. Thesecracks are at-aceted (udmpled. The acets are cleavage plaes across each gra. Cracks ceramcs typcally show brtte characterstcs.

Intergranular CrackingItergrauar crackg occurs whe gra boudares are weakeed ote by chemcal eects (see

C 00.08 ad C 00.20. These cracks oow the gra boudares There may or may ot be sgso corroso o the surace

ceramcs that cude bders tergrauar crackg the bder s commo.

Cack Initiation Featues. Crack tato pots may be surace deects (cks ceramcschpsdets urrows gallg or rehardeed areas materal deects (clusos vods large car

bdes cold worked volumes bder weak pots ceramcs edges or prevous macro- or mcrocracks or spals. Ote the tatg eature s lost crackg or s dscerbe.

Crack tato locato may be deted by the olowg crtera depedg o the ature o

crack propagato• I fatigue cracks: the buk atgue crack tates rom a pot (surace or subsurace deect

the the ntato pot s the ceter o the beachmarks (stratos o the crack surace. the bulk atgue crack tates rom a spal (or a Hertza atgue crack the the vsble rematso the spal are the tato zoe A bulk atgue crack may tate outsde the Hertza stressedvolume traverse the cross secto to arrve at the rollg track ad there serve as the tatopot o a spal. Ths ca be vered by observg the beachmarks.

• I ductile cracks The tato area may be a atgue crack a local deect or other detabeeatre. I the ductlty o the materal s hgh the crack may ed a lip, that s a rm at aage to the ma crackg drecto at the surace t reaches last. The tato pont s theto be sought o the opposte sde o the cracked secto



Chapter Bulk Cracking Fracture, Permanent Deformation

• n brttle cracks: Macroscopc chevron marks may be found on the crac surface whch pont wthther tp to the crac ntaton pont. Ths means that the crac progresses toward the open endof the chevrons. Mcroscopc rver marks may be observabe by SEM on the crac face consstngof depressons wth the appearance of a rver bed wth trbutares. The crac progresses downrver- ntaton pont s at the uprver end of the rver mars.

The ocaton of the ntaton pont on the component can ndcate the ntatn stress condton asdetaed beow.

In bearn arts

Cracs due to Hertzan stressng orgnate n the vcty of the rollng trac most often at depthscomparable to the maxmum Hertz shear stress. Cracs initatng from subcase alure itate at thecase I core terface.

Cracs due to mountn damae orgate from ncs scuffmars or n the undercut adacent to anoveroaded fange.Cracs due to tensle hoo stresses n rngs tend to itate at the bore where these stresses are hghest.Cracs due to bendn (n rngs or hollow rolng eements orgnate at the sde of the component

where the bendng stresses are tense.Cracs in flanges due to overload of lane contacts are bendng or shear cracs orgnatng on the

contact sde of the flange (tense bending stresses often n the undercut or at the outsde edge.Rubbn cracks are itiated on a surface undergong overheatng n sldng contact.or heat treat crac taton see C 0007or grndng crac taton see C 0008

In ears

Cracs due to Hertzan stressng orgnate n the vcnty of the tooth profe surface most oftenat depths comparabe to the maxmum Hertz shear stress. Cracs tatng from subcase alure itateat the case/ core nterface

·

Tooth root cracks tate from hgh bendng stress at the root bend radus on the (tensle stressedcontact sde of the tooth. The crac typcaly begns at the tooth radus travels down beow thetooth root then veers and ascends to the tooth radus on th uloaded sde of the same tooth

Note Tooth root crac nitaton near an axa edge ndcates a msalgned contact. £center ntatonnot near edge may ndcate contact geometry error

Tooth shear cracks may occur along wth or n pace of tooth bendng cracs f a hgh mpact force

s appled to the tooth contacts. The crac tates at the root radus but instead of traveng downwardnto the web cuts across the tooth dedendum.Web d hub cracks may orgnate from tooth cracs (usually as a result of overstress generated

by the tooth cracng or from the bore of the hub. Crac propagaton drecton must be establshedCracs due to mountn damae orgnate from nics or scuffmars.In splnes torsonal crackn due to moment overload or to mpact itates cracs ust outsde the

oaded area runng at about 45° across the splne tops and wth conectng axa cracs at thespne sdes

Changes in Preexisting Crack Face. reshly ormed crac faces are metalc When exposed to aror to lubrcant especaly at eevated temperature they oxdze and become dscolored. Dscoloraton

1



Fiur Ats for Hrtz Contct Mchin Emnts

38

of a at of a crack face indicates initiation of a crack which was subsequenty arrested and

recenty restartedAn extreme case of oxidation is a heat teat cack (FC 0007), which deveops a scaled face if itoccurs in the first haf of a two-stage heat treat cycle (example: carburizing with rehardeng) Acrack face wch deveops after (ast stage) quenching but before tempering, may show temper coor(see FC 0019)

• Cracks that undergo cycic stressing after formation may experience rubbing of the crack facesIf so, fine fracture features may be worn away and fretting or poishing appear

• The fracture surface of a spal bottom may experience direct contact with a roing element orwith spal debris and acquire a hammered appearance

116 CausesA list of common causes of buk cracking folows

. Casting or forming defects (FC 0004 and FC 000) Heat treatment defects (FC 0007)3 Residua stresses, such as

• Fomng stesses (especially in cod formed parts)• Heat teatng stesses These may be deiberate (the compressive stresses in carburized cases)

or unintended (residua stresses from uneven quenching)• Gndng stesses from the cutting forces and heat appied in grinding Extreme case: grind

ing burns• Sevcenduced stesses. Roling (or sliding) contact at high pressures builds up residual stresses

in the Hertz stress fied (from plastic fow and the decomposition of austete )4 Appied tensile or shear stress (steady-state, cycic or impact), such as

• Hoop stress in tight fitted bearing rings, gears or cams or in centrifugaly stressed rotatinggh speed bearing inerrings

• Bending or shear stress in bearing flanges or gea teeth der workig load; in bearing ringsfitted to outofround or interrupted housings or shafts

• Torsion overload in splines

5 Secondary failure to spaing or galing Chemica intergranuar attack

11 Effects of Buk Cracking or ractureDestucton of comonent is the most common consequence of a buk crack The crack grows at an

acceerating rate and the component becomes grossy unserviceable through fracture This may occuramost immediatey in high hardness steel components or be more deayed in medium-hard or casehardened components

Sallng may occur in bearing components Smal bulk cracks may be open to the roing surfaceand be the origating defect for spals

Destucton of othe comonents Pieces broken off one component may wedge other componentsand cause them to fracture or deform A split (but not disintegrated) bearing ring wil turn on theshaft and damage it by gaing



hape Blk acking Face, Pemanen Defomaion

152 PERMNENT BULl< DEFORMTION FILURE CODE: 0023

1521 DefinitionA contact comonent sues emanent u deomation i any o ts macoscoic dimensons

s emanenty ateed om the asnstaed conditonastc deecton o thema exanson ae not emanent deomation.Nics dents and oedn mas ae emanent deomation ut not blk deomaton.

1522 NomencaturePemanent u deomation is aso desgnated emanent set emanent distotion emanent

endng o twsting (deendng on shae assumed).The oowing tems designate vaous tyes o emanent u deomation:

• u astic deomation• oout• mateia voume nstaity (stuctua tansomation)• distotion y esdua stess.

1523 aiure ProcessThe thee aiue ocesses commoy oducng emanent u deomation ae isted as oows.

Plasic Flow A otion o the comonent s sujected to astic deomation Othe otons deecteasticay to maintan coheence. I the asticay owed voume is sucienty age maco geometcchanges o shae o sze occu in the comonent. xames ae

• Blk bending o a gea tooth ng gea oing eaing ng o cam oowe oe undesevice oveoad.

• Rolldown o the tac in a oing eaing ng o cam oowe oe unde vey heavy oadesutng n cicumeenta astc exansion. The ats o the coss section not aected yodown stetch eastcay and this esuts in ovea di amete ncease

• Hot deformation o ong eements o gea teeth in heat imaance aiue (C 19)

Noe: Ceamc comonents ae not oseved to a om u astic deomation ecause o thei mited ductity

Disoion by Residal Sess Pat o a comonent contains esidua stesses (om heat teatmentcod woing ghoad oeaton). These and the counteaancng stesses in the est o the comonent togethe cause shae dstotion. xames:

• A cauized comonent with asyetica coss secton is oten distoted in heat teatment.• A comonent wth symmetica coss section undegoes dimensona change in heat teatment

Defomaion by Phase hange of Maeial Changes n the stuctue o the mateia may causea change n secic voume eadng to emanent deomaton F exame: the etained austeitehase n hadened matenstc stees can decomose wth tme eevated temeatue o cycicmechaica stess The esuting matenste hase is o geate secic voume causng dimensionagowth o i the hase tansomation occus ocay dstoton.

39



Failure Alas for Herz Conac Machine lemens

320


Prmannt bl dormaton s dntfd b dmnsonal masrmnt o sz and shap o thcomponnt Svr prmannt dformaton ma b vsb to th nadd Dffrntaton romothr alr mods s ndd n two cass:

1 Whn th as-nstald dmnsons ar nown and a dmnsonal rror ma b d thr to b pastc dormaton or to manfactrng rror Dagnoss s gnrall possb b xamnnga scond srfac or xampl: th t of a rolng barng nrrng on th shat s too loosThr s no ntrac war h loos ft ma b a) a manfactrng rror b) d to rolot romrg ndr hav load or c) d to vom growth rom rtand astnt transormatonDerentiation (1) I th rolr path and rng wdth ar both n toranc and th rolr path sndamagd manactrng rror s l (2 I th rolr path shows loca pastc low ga p formd at th cornrs) thn rollot s (3) I th wdth o th rng aso xcdstolranc thn vom growth d to astt transormaton s ll

2. Whn bl prmannt dformaton s accompad b war whch has addd to or contractdsom dmnsonal growth In ths cass dagnoss s possb dpth of war can b masrdand sbtractd rom or addd to th prmannt dormaton or xampl: A rolng barngrrng s loos on th shat and th wdth s abov toranc bt ntrnal radal oosnsss corrct Th rollr trac s worn t s l that trac war has ofst som o th vomgrowth ct on ntrna radal loosnss

1525 CausesEach o th thr maor procsss prodcng bl prmannt dormaton has ts own st o

possbl cass

Bulk lasic Flow

• Overload xcdng th b srngth of a componnt can lad to bl plastc flow• Overheating to a tmpratr whr th matral looss hardnss wth contnd applcaton of

oad ads to bl plastc ow h ovrhatng ma b casd b xcssv ambnt tmprar bt mor otn b hat mbaanc n th machn lnt whr mor hat s gnratd trboogcal than s rmovd b al mans of hat dsspaton combnd

Disorion by Residual Sress

• Rsda strsss d toforming, n componnts not ndrgong hardng hat tratmnt marman and cas dstorton of th nsh-machnd part

• Heat treat rsdal strsss rom carbrzng ntrdng cas hardnng or throgh hardnngtratmnts ma b ntntonal as th comprssv strsss n a carbrzd cas) or nntnddstrsss lt from nvn qnchng) bt ach ma cas dstorton or dmnsona chang

• High contact load prodcs rsdal ovrrolng strsss whch ma combn wth plastc dormaton of th rolng trac to crat bl prmnt dormaton

Defoaion by hase Change in he Maerial Carbrzng and hardnng o stls hrntcrats volm chang as th hardnd parltc) strctr dffrs n spcfc vom rom thhardnd martnsc) strcr Manactrrs alow for antcpatd volm changs n dmnsonng th parts f hat trat rrors occr volm changs ma dffr rom thos antcpatd cratngdormaton or dmnsonal rror



Chpter Bulk Crcking, Frcture, Permnent Deformtion

Hrdened nd temered mrtenstc stees genery contn metste strctr eementretained autenite which cn trnsorm ror to or drng servce nto mrtenste, with vome growthhe trnsormtion s romoted y the oowng ctors

• Elaped time. At norm oerting temertres, retned stete tends to trnsorm sontneosy he ercentge o vome growth s roorton to the ercentge o tranforming retinedsteite Mnctrers seect het tretments imed t hodng stente trnsormton wthnermisse mts or the ction. However, tot dimenson stity o hrdened stee ssedom chieved Het tret errors my cse more stente to e retrned thn ws owedor, resting n dimenson error s tme eses

• Component temperature he temertre t which the comonent dwes is rte-controingctor in stenite trnsormton Oertion t temertres in excess o design ves mycrete nccete vome growth rtes

• Cyclic tre Cycc stressing ndces stenite trnsormtion Hertzin contct oertion gener

y rests n redced retned stete n the stressed mter vome Wth modest eveso retned stete, norm comonent dmensons nd oding, the vome o Hertz stressedmteri genery does not sce to cse signicnt ermnent deormton In heviyoded tnwed rings t my nonetheess hen

56 Effects of Permanent Bulk Deformationhe ncton eect o ermnent deormtion is genery tht o ny devtion rom design

dimensions or she he severity o the eect deends n ovos wys on its mgntde

• Maive permanent deformation renders the comonent nt or se throgh seizre, oss oostiong ccrcy, oss o ssemy integrty or ntererence wth other comonents

• Permanent change (growth) in ize, eseciy n dmeter, even when moderte, my rest in

oss o tererence t on sht, nwnted ntererence t wth oss o xi gment in hosg, oss o ntern cernce in rong ering or oss o y in ger or cm set

• Permanent ditortion n contct comonents my ed to gment errors, roer sew nd, isevere, edge contct



Filure Atl for ertz ontt Mhine Element


Failure Cde

00..01

0001.

00..01.

00..01.4

00..01.4

00..01.4

00..0.44

00..1

00.

00.

00.4

00..

00..1.

00..

322

Plate N

5.1015.7

15.

6.1510.4610.5110.510.51.0.11

5.56.97.7

10.511.9.5

7.35

1517

.61517

9.10.610.91.15.8

505.6.96.19.

10.5.45.515.615.915.01511151515.14

5.1515.015.

5.15

0.66

5.715.6

10.17

10.91.9111



Faure Code: 00220 Chaptr Buk Crakng, Fratur, rmannt Doaton

PLATESTPate No 1 5 1Archive No 08602&601Image type light mcro b lightmcro mgnetic ricle testScaebar b: 10 mm (micros± 20% others: 00% 50%Compoet SRB; R, runSpeed: 150 KdNLoad 1 .2 GP aLbricato: mierl oil 68°CFalre Code 002201 .1 Axil cross secton crck in ri gFalre Code 001 61 1 .2 Sll from su bsrfce defectFailre Code : 225 Shft deformedFailre Code 005 .1 20.3 xcessive fretig loose or inccrte rdil it

ESCRPTONS

b

Failre Descriptio: ( : Severl xil-rdil cck idctions re shown, from mgnetic rticle test Oe cross-section crckshows smll sll. (b : Crck ce of crosssectio cck s show rogtng from the contct through he secto ito thebore The shft underwet rge bendng deflectons which cused hoo stresses the IR These, combied with the contctstress iitied xil-rdi crcks d eventl cross-section cck filre Hev frettig occured i he IR boreImage Descriptio: ( : The R is viewed on roller ths. Hev blck xi lie 1/4 rom N imge edge is cross-secion crck.Obong widenig in roler h is sl. Fine xl blck lines on roller h e inciie crcks highighted b mgneicrticles. (b : Crced secto t imge ceter Crck intito is from the trck t imge W. There is dr retting on he crckce from extended runing; lso hev retting i IR bore.Sspeced Cases Shft is nown to hve dergone hev deflectio i beig se Hoo stresses were geeted the IR. Acotc th under tesile stress is know to fom xirdil ccks o overrollig (eve t the light stress of this service Oe

crck hs sit the cross sectio freted nd sled out Bore fetting is secondr

323





Fiue Code 0022011 Chapter Bul Cracing racture Penanent Defonation

T

Pte No 1 5 . 3Archve No: 87-23mge type: viewScer 3 mm micro: ± 2%, oter + 1% 5%Component: CRBB; aemby ruSpeed:odurcton:Fure Code 22.1 .1 xial cro ection crack in ingFure Code .22.1 .2 Crcumferential crackFure Code : Fure Code

ESCRTONSFure Descrpton: Flange fracue ad axial cro ection crac

i te OR of a CRB i due to trut impact load o greatlyexceive axial load. i i a gro failure.mge Descrpon: R at image W ORRG aembly a image E.18 of trut flange o OR facig af i factured cippedoff axial cro-ectio cack i viible a . Tere i noevdece of roler damage or eparaor fracture i ti image. o clear evidece of IR damage i foud i ti image altoug eflage tut urace may be worn down pat te udercu uder te axial load.Suspected Cuses: n a trut loaded CRB itega rig flage wit udecut ae ubect to overload crackig epecaly iradia load i oo low to prevent oler tit xal crackig o ig occur ecodarly Rg crackig may occr alo if te axial loadcaue eavy flage galing wit roller kewig. owever eparator ad roller damage ould te be vible

TPle No 15Archve No: 23c

Imge ype l igt macroScer 3 mm m ico: ± 2%,oter + 1%, 5%Component CRB; IR tool teel runSpeed: 3. Mdod: 1.2 GPaurcton: yntetic polyeer oil 2CFure Code .221 . xial croectio crack in rgFlure Code .222 Bulk faigue crackFlure Code : -Flure Code

ESCRTONSFlure Descrpton: Bending faigue crackwa iitiaed at te urace of te oil lot located in te R bore Fuer cracking wa itiated at te ol oelot cornerEventually e IR diitegatedImge Descrpon: mage te fractured cro ecion of an IR. Flange are at image E ad W; te ring body at image ceter;te oil lot labeled at image S e roller pat ad trut urface are a cete oil ole labeled conec te rolle patundercut ad oil lot Fatigue crack wa initiated at uletered arow. Furer crackng extend from oil olelot coer arow Suspected Cuses: Hig peed CRB are ubject to ig cetrfugal oop tee. Oil lot ad oil ole may ave arp edge ormacining mark. Bendig fatigue ca iiiae at te oil lot were te cro econ of te ig i weakeed Furer cracking a oilolelot ieectio i promoed by arp edge ool eel beaig rig are epecially cack eiive.

325



Falre Atlas for Hertz Contact Machne Elements

TPlae No: 15 5

Archve No: 7-61Iage type: light macroScalebar = 1 mm (micos: ± 2%,others %, 5%Copoet: DGBB R unSpeed:Load:Lubrcato:Falure Code .22 .1 Aial cross sectioncrack n rigFalure Code .22.2 Bulk fatige crackFalure Code : -

Faure Code

ESCRPTONS

Faiue Code: 0022011Faiue Code: 0022012

Faure Descrpto Fatige ractred cross sectio of IR with crack origiang at bore om ecessve hoo stress acting on amino srface imerfectio. This is a gross failue.Iage Descrpto: Aialradial fatigue crack roagating throgh rig f rom a initiation oint (arow at the bore and etending toa arc cone ctig the seal g rooves triatios, first arallel to the bore ad the arcing indicate fatige. The ractue surface of theremaiing a of the cross section is coarse dicating rad overstress crackingSuspeced Causes: Ecessive hoo sess, as from oo great an iteerece ft betwee IR ad sha, combied wih cycc cotactstressig, may intiate blk crackig. Hoo stesses are greatest at he bore. A surface imerectio may iitate cracking at that suace

TPate No: 15 6Archve No: -6&65Iage type: a view b light macroScaleba a 1 b 1 mm (mcros ±2%, others 1%

5%Copoet: DGBB OR, runSpeed:Load:Lubrcao:Faure Code 22.1.2 Circumerential crackFaure Code 222 Buk fatigue crackFaure Code : 1 .2 cratch, ool mark, scffmarkFaure Code -

ESCRPONSFaure Descpto: Circmfeetial bulk fatige ractre of a ring,conectig the sa-ring goove with the ball groove A sharcorer or too mar i he sa-rng groove may have initiated hecack. This is a gross failure.

age Descpo: (a OR was ct i half by aialradial ct foreamiatio Circmerentia fracture has searated the rg,conectng a cone o the sa-ring groove wih the bal ath(b Fractre sace shows arced stiations of crack oagatioarod the itiato oit at the sa rg groove cornerSuspected Causes: a rg grooves rovided o receve rgslocatig the bearg aialy, case edced cross sectio f theyhave shar corers, damaged sraces or grinding burs,crcumfereial blk atige cacks can iitiate across thesereduced sections.

326

a

b



Faiue Code 2212Failue Code 2213

Chapter Bulk Cracking Fracture Permanent Defrmatin

TPt No 15 7Archv No: 762&63mg typ: a view b: ligt macroScbr a 1 b: 1 mm (micros 2%oters + 1 % 5%Componnt: DGBB IR rSpd:od:ubrcton:Fur Cod 22.1 .2 Circmferetal crackFur Cod 231 Plastic rolldown of contact atFur Cod : 16.2.3 Incient sall ing, single sallFur Cod

ESCRPTONS

Fur Dscrpton: Pastic olldown occrred in te groovede to ecessive load. A iciiet sall is folowed bycircmferentia crackig Tis is a gross failre.mg Dscrpton: (a Plastcaly worked (battered groovesrace A ccmferetial fractre searates te two rngalves (Black enmarks i bore register te aves Tere isa dee goge from a fragmet on te groove srface (at SW.Te iitiating sall is not sow (b Fractre sace neariitiating sa (Sallow crates are ot of focs abot 1image widt to eiter sde of image centerSuspctd Cuss: Long-term igload overollg mayrodce lastc root reslting i comressive stresses i te contact srface. Balancing tensile stresses aise elsewerei te cross sectio A sall relieves te comressive stess ata oit tensile stress acting from te sall bottom and aided

by cotied overrollig may drive a circmferentia crack.(Cross-section cacks ae more commo.

TPt No: 15 .8Achv No: 7-78Img typ: ligt microgram of section Nital etcScbr 2 mm (micros 2% oters +1% 5%Componnt: CRB R indcton adened Spd:odubrcton:Flur Cod 221 .3 Ro l ing elemet (ball roller crackFlur Cod 7.52 Heat treat crackFur Cod -Flur Cod

ESCRPTONSFur Dscrpton: Twisted cracks in core of an indction ardeedsmal rolle Cracks do not emerge to te sace. Te ardenedcoe of te roller is in ig tesie resdal stress de to eatteatment Cracks may form before nig ador oagate derig cyclic contact loadig Te roler is likely to factre on conied ning.

b

mg Dscrpton: Etced cross section of a roller sows idction ardened case as ligt gray and nardeed core as darkergray. Te S-saed black lie wit a sidebrac is te crack i te core.Suspctd Cuss: Small rollig elemet wit dee ndctio ardened case contains ig comressive case stress and igtesie core stress de to volme growt i e martesitic case Sontaeos ea treat cracks may eist in te core. Cracks maynitiate or grow in e ig tesile stress evironme of te core de to te rotating stress field imosed by cotact loading.

327



Failre Atlas for Hertz Contact Machine Elements

TPate N: 15 9Arche N: 07480&81age type: a: view, b: light microgramcaebar a 10 b: 1 mm (micros 20%,othes 1 00%, 0%)Cpe: DGBB B, runpeedad:ubrcat:Faure Cde 002201 .3 Ro ll ing element (ball roler) crackFaure Cde 2 00222 Bul k fatigue crackFaure Cde : -Faure Cde

ESCRPTONS

Faure Descrpt Spiral fracure o a ba in fatigue undercontact loading, from materia defec beow the surface Highheat treat stesses may contrbute to ths gross failureage Descpt (a): Mating fractue surfaces on twohalves o a fractured ball Radial steps on the two halvesmatch. The falure origin is he small circular area with anirreguar fracture suace close beow the bal suace (arrow)Cacks have popagated in both drecions around theperiphery and have met in a sep (b) aiure orign on Wbalhalf Ball surface is at N and is chpped. A dark patch isvisble at he crack origin, followed by dark/light stiations ofatigue popagationuspeced Causes: Water quenched balls may containsubstantial heat treat stresses If a materal mperection ispesent and contac loads are heavy, bulk fatigue crackng

may result.

328

Faiue Code 2213

a

b





Failur Atlas for Hrtz Contact Machin Elmnts

TPlate No: 1 5 1 Archive No 074-5Image type: viwScalebar 1 0 mm (micros: 20%, otrs 0 0 %, 50 %)Compoe CRB R rSpeed:Loadubcato:Faure Code 0022.01. Roll i g lmnt (bll roll crckFaure Code 2 00222 Blk figu crckFaure Code 3: 00.09.2 Glling from forcibl ssmbly ormoutgFaue Code

ESCRPTONS

Faiue Code: 0022013

Faiure Descrpto: Axl bk ftgu cck n rollr OD folowing xil gling stk inflictd i ssmbly or motng Throllr is likly o frctr o spll cotid runing.mage Descripto: Cylndricl rolr suc of vrying h of gry du to mgntic pic ispction. At rolr cnrli s ight gry xil gllig mrk in th cntr of th W rollr hlf. A blck, slightly curvd l followig th glling mrk to th S is tmgtic prticl ind icton of bl crckSuspected Causes: Gllig d to mountg dmg crts igh locl rsdul strsss nd surc dmg Mos commonly,such dfct wil spll i runig Howvr if rolr cotns high tsi rsidul strsss (possibly fom th qch, thn blkftigu crcking my occr

TPate No: 1 5 2Archve No: 0261 2& 9Image type: b: l ight mcoScaebar : 60 b: 0 mm (micros 20%, otrs: 100%, 50%)

Compoet: CRB (multirow; R & G rnSpeed:Loadubricato: mirl oil mist ? ocFaure Code 002201 . Ro l ing lmt (bll roll crckFaure Code 2 00222 Blk ftig crckFaure Code : 00 6. 1 2 Spll fom subsufc dfctFaure Code 008.02.2 Svr or dvncd dtg

ESCRPTONSFalure Descripio: Rollrs with bo ccommoding pi-typ sprtor.Cosssction crcking n ftig is probbly iittd from mchigdfct or dcrburizto t th bor whch is s bjctd to cyclic tsistrss in bnding Th cck ptrts to th oling srfc; it splls,cs xtnsiv dbris whic r rolld ovr d vnuly t rolr

splits. Tis is gross filu.mage Descrpio: ( I N img hl, ow of rollrs is hld btwtwo rings of th sprtor by pins through th bor long ch rollr xisThr rollrs to W intct; th nxt rolr is rctrd, th o iscrckd d splld. s of th bok roll r t S (b Four crckd,splld d chppd rolrs hld in th sprtor.Suspected Causes: Rollrs with bor or sptor pi r crckpronTh bor is slly in th smchid codiion Ufvorb rsdulstsss my xst. Bnding undr cyclic stssing tnds to initit crosssctio cckng, wih subsqunt spllig. Ths rollrs r cbrizd,wih bors sly mskd from crburizing tmospr Incomptmskig my cus ptchy crbrzing rsltng in high locl rsidulstrsss.

330

a

b





Falure Atlas for Hertz Contact Macne Elements

TPat No: 1 5 1 4Archv No: 08007mag tp: l i aroScaa 30 (iros ± 20%, oters 1 00%, 50%)Componnt SG; W i ardess, rSpd:oad:urcaton:Falur Cod 0022 01 4 Gear toot rak o r fratreFalur Cod 00222 Bl k atie akFaur Cod 3: -Falur Cod S s ATES 1517 ad 15.18

ESCRPONS

Faiue Code: 0022014

Faur Dscpton: Fratured seet o a toot fro bulk fatiue rak wi as popaated aross te setio Fatiestriatios are visble Tis is a ross failre. See late 15.18 for a overstress rak ad ae 1517 for a fate rak wit ostiatiosImag Dscpton: Seet of a too wit aifiialy ut surfae averted e otat srfae is at iae S followed by tebuled fratre srfae toward iae N e arrow idiates rak iitiatio Elipti fatiue stiatios exted ove W, N ad Eborder aeas of te fratue Tey are ost learly see ear arrow B Te rare sufae is soot ot frous Tis is typal offg raki , espeially i ard aterialsSuspctd Causs: Too fatie raki der ota loadi ay iitiate fo a srfae or subsrfae defet ad radallyexted to sever e toot

332



Faiure Code 0022014 Chapter Bulk Cracking Fracture Permanent Deformation

TPt No: 55Archv No - c&d&Img typ: b: mco c: ligt mtllogm Nitl tcSclbr , b: mm c: m (cos: %,os: + %, 5%Compot: BG W ig dss nSpd:od 5 Gubrcto: syc polys oil 6°Fur Cod G toot cck o fctuFur Cod 2 Rbbig cckFur Cod 3 Blk ftigu cckFur Cod 6 W uintndd suc contct

ESCRPONS

Fur Dscrpto A cck popgtd toug t bvlg oot oot om iitito t t bck of t g diskwic nintntioly bbd ginst sttioy p.Rbbig cd plstic woking ovtig d cckiition d popgtd toug t toot by igdistgtig t g. Tis is goss fiuImg Dscrpto () Fctd g disk toot fc s iNE qudt folowd by cck sucs A bbing cckittd t ow (s viw (b)) popgtd in ftigutog uc of t dsk d illy fctd t disk iovlod (b) G disk bottom suc (t ow of ())bbd t t bckt cck iittd t ow.(c) Etcd scon oug ubbd (bckt) t wokdti pps ligt t tmpd zo dk. T ccksts t ow.Suspctd Cuss: bck c of g diskunintntioly ubbd gist sttioy compotcting g t plsic woking nd vully ubbigcck' fo wic igu dov cck in dp towd tt. Evtuly t wkd g dsk fctud t ootoo dius

b

c

333





Faiue Code 00220141Faiue Code 00220142

TPate No: 1 1 8Arcve No: 080106Image ype: igt macroScaebar 40 mm (micros 20%oters 100% 0%Component SG W, ig ardness, rSpeed:Load:Lubrcaon:Falure Code 00.22 01 41 Toot root fractureFalure Code 2 00.221 Overstress crackFalure Code 3: Faure Code S ATES 1.14 and 11

ESCRPTONS

Chapter Bulk Cracking racture Permanent Deformation

Faure Descrpton: Overload fracture of a gear oot wi sigs of bk plastic ow during fractre Tis is a gross falre Seelates 14 ad 117 or fatge ractre of teetImage Descrpton: Te ceer toot of te gea segment sow is broken at te roo Fractre bega a W flank of te too witibros uniform textre. About midway trog te factue, a "um begins as materia pastically bent and was seared. Tis mp ad te absence of fatge striations disting ses overstess fractureSuspeced Causes: Ovestess ractre fom accidental overload or folowing a severe materal defect occurs in oe or a few loadcycles

335



Failur Atlas for Hrtz Contact Macin lmnts

TPate No 5 . 9

Acve No 002-004a&Image type a view, b ight maroScaeba a 40 b 2 mm (miros + 20%othes + 00% 50%)Component BG high hardess uSpeed 06 m/seLoad 0.5 GaLubcaton sythet poyeste oil 76°CFaue Code 00.22.0 .42 Tooth oner ratureFaue Code 2 00.06.2 nlusion stringerFaue Code 3: -Faue Code

ESCRPONSFaue Descpton

Two oseutve gear teeth are atued atigue aross the smaldiameter edge Both teeth were oud tootai arge (2 mm log aumia inlusio stiges n the orematerial rom whih the rature is seen to initiate The gear hasaied.mage Descpton (a: Ente gear with two teeth marked byarows having ratures at smaldiameter edges under arrows(b rature surae o one tooth showng rak sreading omlog onmetalli stringer idiated by oposg arrows.Suspected Causes Large iusion striges are severe stressonentrators whih may iitiate atigue ailure The nlusio ithis gear was so dee beeath the surae that it initiated be ndingatigue and not otat atigue.

336

Faue Code 0022012

a

b



Failue Code: 22142 Chapte Bulk Cacking actue, Pemanent Defomation

TPlate No 1520

Archive No: 080-109mage type: l ight mcoScalebar 20 mm (mcros 20%,ohers: 00%, 50%)Component: BG P, high hrdness & CB rnSpeed:oad:brcation:Faie Code 00.220 2 ooth corer fcureFaie Code 2 00.222 Bul ftige ccFailre Code 3: 00.09 Geometry ssembly o mountngdefectFare Code 0022 Ovestess cc

ESCRPTONSFaire Descipton: igue rctre of the coner ofsevel teeth i spirl eve ger due o mislignedmesh cusng overodig o ht core Themislignment ests from imp roper mou tiggeometry Other eeth e then broe n impct This s gross ilemage Descrpton: Sp bevel piion is in imge center; suppoing CB t N Cornes o the lrge-dimete end of ll visibeger teeth re broe off in digonl le from (or ner) roo leve (t the ger fce) to the tooth tip (further bord) thiscsehdeed ger, he cse shows fge stitios the core is woody frctreSspected Cases Improper elve positon of the wheel nd piion, de, fo exmple to excess looseess n the spportberings or wrog posito djustment eds to misliged mesh which my plce most of the tooth lod t oe corer o themesh. Ftige crcig of severl teeth my result, wh the othes hen broen by mpct

T

Pate No: 15 .21Archve No: 099-11mage type: viewScaleba 60 mm (mcros: ± 20%, others 1 00% 50%)Component: HG P, medium hrd rnSpeed:Load:Lbricaton:Fare Code 0022.01 .42 Tooh coer frctureFaire Code 2 26 Suppo berng dmge (of ger cm)Faire Code 3: -Faie Code

ESCRPTONSFailre Descrption: Tooth corers broen wy in three consecutiveicidents de to misocion o piio resultig rom sppo beigfilure (ot show) he lod ws shifted n ech cse to tooth sectorwhich iled to suppor it This is gross filremage Description: A piio is viewed o OD Tooth corners fcingimge W wee broen wy The pio the shifted to imge W dother legth o tooth tp broe wy, extedg from the rst frctureo roghly the ger cente ple. After secod shft third row ofrctres occured, now extedg to the E hlf of the fce width.Sspected Cases: Goss suppoberg filre ws observed to hvedisocted the ger mesh, csing locl overod i repeted psses

337





aiue Code 221 Chpter Bulk Crcking, Frcture Permnent Deformtion

TPae No 1524

Archve No 99-138&139mage type a, b: lght acoScaebar a 25, b 1 ( icros 2%others: + 1 %, 5%)Componen a: HG, eiu har b BG, high haress ruSpeedoadubrcatonFaure Code 22144 Tooh tip chippgFaure Code 2 Faure Code 3: Faure Code

ESCRTONSFalure Descrpon Appearace coparison of tooth tp

chippig betwee eiuhar an hgh harness (caseharee) gear (a) Meiu-har gear with tooth ipchippe probably fro ege contact (b) Case harenegear with cracks in tooth tips a -cotac possibly ueto geoetry eror faiig at case/core iterface n bothgears progessive failure is ikelymage Descrpton (a): Gear is viewe oblquely wth thethree tooth corners (i center) chippe off at the tip.Fracture suaces ae coarse in euhar aterial. (b):Gear s viewe on OD. Of the three tooth tips fuly showthe two towar age N show cracks a soe spalligon the contact surface exteig onto the tooth OD.Proxity to the ooth tp suggess that the failu re i s at thecase/core teface

a

b

Suspeced Causes Tooth tip oveoa fro geoetry error or passage of ha cotainants ay cobne wih aterial weakess(as in he case haree gear where case/core ierface appears weak) o cause tooth tip chippig.

TPate No 1525Archve No 811mage ype l ight acroScaebar 4 (icros 2%, othes 1 %, 5%)Component SG , high harness ruSpeedoadubrcatonFalure Code .22144 Tooth ip chippigFalure Code 2 .113 Tooth spall ig

Falure Code 3: .1 1 . 1 3 Subcasefatgue spalFaure Code -

ESCRTONSFaure Descrpton Poios of tooth tips are chppe offfolowing extensive spaling peetratg to the case/corenterace I this hghharness gear the spaling has ea o blkatigue fracure. Thi s is a gross faluremage Descrpton Three teeth at age N have ost uch of hecotac surace At N-ost ooh, spals have reache the case/core nteface The next wo teeth to S are heaviy spale a chps have fracure out of the tooth tips.Suspeced Causes Sevee spalln g, as ro overloa, possibly co bine with i sufciet case epth have cause su bcasespallig (also referre o as case crushg) i his carburize gear Subsequent bul fatige crackig has prouce chipping oftooth tips

339




Plate No: 15.26

Archive No: 01459Image type: viewScalebar = 15 mm (micros 20% oters + 100%, 50%)Component TRB; R, caburzed runSpeed:oad:ubrication: gease ? Falure Code 0022.1 verstress crackFalure Code : 214 Housing worFailure Code 00.23.1 Plasc rolldown of coac patFailure Code 4

Falre Code: 00221Falre Code: 00222

Faiure Descrpon: Radial/axial overstress crack across R (cup) secton as resuled from plastic rolldow of te cup rollertrack a ousing won oversie by te cup turing in a loose seat Tis is a gross failure

Image Descripon: R (cup) viewed from D sows axia/adial fracture wit suraces widely separaed up D fiisig liesare worn off. ous ig bore ( ot sow) was severely wornSuspected Causes: Te bearing was used in a weel ub and te ousg to R D fit was loose Te R tured and wore teousig bore Subsequent rolldow of te roller pa stetced te cotact pa circumferenially causig incr eased residualcompressve stress i te cotact pat case, ad inceased core tension. Evetually, te coe ruptured, causng crosssectiofracture. ase stress relief opened te fracture

Plate No: 5.27Achive No: 00200a&bImage type: a view, b lgt macroScalebar a 0, b 5 mm (micros: 20%, otes +100% 50%)Component: B W, ig adness ruSpeed 9 m/sec

oad: 0.6 Paubication: sytetic polyester oi, 76Falure Code 00222 Bu lk fatigu e crackFalure Code : Failure Code Failure Code S s PATE 5 0

Falure Description: Radial ad circumfereial disk fracture of a bevegear s fom fatigue origiating at a sarp macing discontiuitySee PATE 510 fo originating defect Tis is a gross failure.Image Descripton: (a) Saft wit two itegral geas, of wic telarge to image S s a bevel gear Tis as fracured at tee pointsradally across te teet and aroud 360 of arc in e disk Arowspoint to te fracture origi, sow in detai i (b) An edge eft imaciing acted as a stress raiser. (See defect in late 5.10) romtis origi, a striated fatigue crack exteded E across e disk tote toot root, e ndn g i overload fracture.Suspeced Causes: Te igly loaded bevel gear rg undergoes igalternatg beding stresses. Te (offspecificatio) macinig marksacting as stress raisers precipitated bedg fatigue

a

b



Falre Code 00222

Plte No: 152

Archve No: 002-024bImge type: lgt macoScebr 2 mm (micros: 20%,oters + 1 00%, 50%)Component: ABB; B, tool steel runSpeed 17 MdLod 1.4 ariction: syntetc poyester oil, 176°Filre Code 0022.2 Bu k atigue crackFilre Code : 0004.2 Formg seam

Capter Bulk Cracking, racture, Permanent Deformation

Filre Code 00.61.12 Spall rom subsurace defectFilre Code 4 00.17.2 Localized surface dsress (aloat defec)S s PLAES 523 ad 524

Fre escription: Bulk fatigue crack in ball, resultig ina spall ad surroudig alo of suace distress durigconinued rung. Metallograpy as foud a formng seam wic originated te crack. See also Plates 523 and 524 fo materialdefects i tis bal Te ball as faiedImge escription: At image cente s a circular spall craer exfoliated from a straigtie bulk crack (along arrows. Burnisigmarks around crater edge are from overrollg of te edgeSspected Cses: Formig seam and oer material sructure defecs in ball ave originated a radial fatigue crack wicsubsequey spalled out

Plte No: 15.29Archive No: 00511Imge type: ligt metallogram ita ec

Scler 250 m (micros 20%oers + 00% 50%)Component: M, case ardeed uSpeedLod: 2.1 Pariction: Diesel ue ? Flre Code 00222 Buk aigue crackFilre Code 0007502 eat treat crackFilre Code 0007.2 ffspecificaton maesiteplatelet sizeFilre Code 4

Filre escrpon At te edge of te cam obe twolarge cracks in te case are atribued to defects of teeat reated strucure, and possi ble tegranu lar eat reatcracks wc ave propagated i fatigue Te cam asfailed.Imge escripton: Te image is a etced metallograpic cross section of a cam lobe, incudig sideface at W image edge adcontact suace near image edge Te core trasitio zone (dark motted area) is in te SE corner Te dark area at and Wedges is mountg material Two twisting (dark) bulk cracks exted rom te sideface n EE drectio into case but do not reaccontac surace. Te igy tortuous crack pat i ndi cates i nergranu lar crack.Sspected Cses: A eat treatment error led to a coarse structure after eat reatmet wit weakened intergranuar bod sl tergranuar eat treat cracks may ave bee iiated, and were exteded by itergranua r fatigue cracks ( rare cotact devices)Te origi of te cracks at te sidewall suggests edge-loading ad weakened (peraps decarburized) sidewall surace



ailur Atlas for Hrtz Contact Machin Elmnts

Pate No: 15.30

Achve No: 002007gImage type: light metalogram, Zephiran etchScaleba = 200 m (micros 20%, oters + 100% 50%)Componen ACBB B tool steel runSpeed 1.7 MdNLoad: 1.4 GPaubication: sythetic polyester oil , 176°CFaiue Code 00222 B ul k fatig ue crackFalue Code : 0007502 Heat treat crackFailue Code 000751 Crack with oxidzed surfaceFailue Code 4 s PLAT 617

Failue Desciption A open crack, probaby formed during heat treatmet, rus from the ball

surace toward center Closed bulk fatigue cracks have exteded the crack front durng runig.Heat treat crackig creates a severe deect which precipitates both spallig ad bulk fatiguecrackig See Pate 6.17 for surface view and crack surface appearance.Image Descipton: Te etched, mottled metalographic sectio is finestrucured steel. N imageedge is mouing material Wide NS crack between opposig arrows s a heat reat crackBranchig cracks at arrows are bul k fatigue cracks which have propagated d uring ru igSuspected Causes: The oxidized surface of the primary crack suggests causation by forgig oheat treatmet The touous course o f the cack (see Plate 617) suggests a heat treat crack.he severe defect represented by the h eat treat crack i itated the buk fatigue cracks showhere

Pate No 153Achive No: 003001

Image type light macroScaleba 10 mm (micros 20%others + 00%, 50%)Component: ACBB; IR, ruSpeed 11 MdNoad: 9 GPaubication: synthetic polyester oil, 1Failue Code 00222 Bul k fatig ue crackFaiue Code : 00.08.2 Rehardened gridigburFalue Code 00.16.112 Spa fromsub suace defecFailue Code 4 00602.5 Advaced spalig

Failue Desciption: Crosssectioal fatigue

Falre Code 00222

crack i a ACBB (split) IR, found to have originated from a gridig burn (FC 00082) in he bore, hrough the actio of highcenrifuga ho op stresses in t he rig The spall has propagated i n the rolli g d irectio from the crack The bearng has failedImage Descption: Oe o two parts of a split errig from a ACBB with land (dark band) bodering ball groove on image Nand splitface at S A black axial crack crosses he eire rig of the image width rom E edge Extensive spal craterig extendsfrom crack toward W (n rolli g di rection) width the spa l reaches a spltface edge Reported g ind ig burn is not shownSuspected Causes: Grin ding wit h excessive pressure overheats materia ad causes rehardened gri ding bu r at he su race. H ighresidual stresses and brittleness of utempered maensite may serve as a i itiatig defect for bul k fatigue cracking, which hein itiates spalli ng






Pat N 1.34

Archiv N: 074-34Imag ty: viewScabar 40 mm (m icros ± 20%, others: + 100%, 0%)mnnt CB O (Sendzimirmill bearng), ruSd:ad:ubrcatin: meral oil mist, ? Failur d 00.22.2 Bulk fatigue crackFailur d 00.16 Spallig (ertzian contact fatigue)Falur d 00.13.2.1 oling suace galigailur d 4 -

Faiur Dscrtn: Gross materal emoval to about mm depth, fomcotacting OD o a Sedzimi r mi l bearig apparetly in itiated as cotactspallig. The lobed crack popagatio ad uniformwidt flat bad at spallbottom are ot explained, i te absece of faiure h istory from the m illTis is a gross aiure.Imag Dsctn: Te shot cydical pat sown is the tickwalled Oof a CB wit the OD used as a roller supportig a c uster roll n a sheetmi l Te center and facig end o te ring ae mssng a deep layer ofmateria removed by surfaceparallel cracks runig abou mm below teorigial suface. The ceter sows a smoot lat bad. Te sides of thespall ae lobed Deep axial galig marks are on te unspalled ODSusctd auss: Sendzimir mills are cluster mills wth two smaldiamete work rols supported by layers o backup ols, o which teoutermost cosists of CBs stacked o long safts. ollig foces aregreat contamination is possible ad tempeatures may be hig A specficaalysis of the pecul iar ailu re appearace equires detailed machi e failure h istory which is lacking

Plat N 13Archv N: 08114Imag ty: viewScalbar = 40 mm (micros: 20%, oters: + 100%, 0%)mnnt: SB; I runSd:ad:ubricatnFaiu d 00.22.2 Bulk fatigue crackFailu d : 00.19.2.1 Hot plastic flow wtout weldg(rolout)Failur d 00.19.3 Scale ormation

Faiu d 4 22.9 Geomety or assembly deect in shat

Faiur Dscritn: A improper taper angle on the bearg

Faire Code: 00222

seat of the shaft as suppoed onl one rig alf The other alf ailed by ccumferential cackig n bendng fatigue causingmassive overheating plastic rolout ad scalig. This is a gross failureImag Dscritin: A fracture surface rom cicumferetial cracking bouds te rig at image N. e adjacet roller pat isseverely oled out, and the racture suface is battered. The N rig hal is scaled. Saft contact (cicumerentia wear marks) isvisble in the S half of te bore. The N af of the bore is scaled but uwor; it probably ad o or tte saft cotact Tissuggests an agle error in te saf seat.Susctd auss Severe angle eror i a tapered saft seat creates suppor oly under oe rig hal (te largebore ed in tiscase). The other ing alf s cantievered ad undergoes sevee bendig atigue stressig Circumeretial fatgue crackig mayresult As his crack pogresses normal bearig geomety is destroyed, parts (such as a separato) break, overeatng and plasticflow occur.



Falre Code: 00223 Chapter Bul Cracking, racture, Permanent Deformation

Pate : 1536

Acive 018-1Image type: l g t macro o cut ringScaeba = 10 mm (micros 20%oers 00% 50%)Cmpnent: SRB IR, runSpee:a:ubicatin:Faiue Ce 00223 Rubbing crackFaiue Ce : 001212 Advaced mild wear of fitsuaceFaue Ce 229 Geomery or assemby deecti saftFailue Ce 4 -

Faiue Descptn: Multipe, geeally axially runing ie ubbig cracks are visible i te IR bore, ear te sideface.Circumferential wea maks are crossing te cracks. Te rig as otated o e saft, creating severe loca eating i e bandwere te cracks arose. Te rg is l ikely to crack troug if it is mou ed wit a interference fitmage Descpn: R cut to expose te bore is viewed o te bore Te corner radius is ear e N image edge, a sectio plaeis ea r te E edge A band S of te coer adius sows (dark) circumferential wear marks and m ultiple dark axia crack inesWear markings (dark inerrupted crcumferential lies) esewere in e bore are less pronouncedSuspecte Causes: Itererence fi betwee IR ad saft was isuficiet for te loadg ad sevee slidig occurred Wear marksresulted I te band near te corner radiu s ( presumably wit igter fi ta elsewee) eatg was excessive and tema adstucture trasformaion stress caused cackig Suc cacks are typcaly axial in adal fi suaces de to te iteraction ofrubbing-iduced stresses wit mecaca (oop ad/or coact) stesses.

Plate : 53Acive : 093-018aImage type: l igt macroScaeba 10 mm (micros 20%oters +100% 50%)Cmpnen DGBB; IR (segment) uSpee:La:Lubicatin:Falue Ce 00223 Rubbg crackFalue Ce 00131 Fi surface gallingFailue Ce 21 Housing msmoutedFailue Ce 4 002201 Axial cross sectiocrack rig

Falue Desciptn Rubbig cracks and galling o te sideface of an IR, fom unitended rbbng agaist te statioary end coveattaced to te ousig leading to materia trasfer i unlubricated slidig Oveeating of suface ad cacks rom termalstresses o stresses iduced by sructural tansormation. Heat imbalance failue may be in pogress Te ring is fractured by axial/radial crack emanatg from a rubber crack. Tis is a gross falre.Image Desciptin: Te R is viewed o te sideface Tee are circumferential ga lli g marks ( lig ad dark, iregu larly boudedstreaks) ad dark ie adial rubbing cracks Te E conour o te rig is an axial/radial fractureSuspecte Causes: Mslocatio of te saft assembly i te osig, o of te bearing on e saft, or of te ed cover in eosing, as poduced uiteded rubbg bewee e statioary ed cove ad te otatig beaig IR edface. Gallig andsevere loca overeatg caused suficiet termal sress o stucral trasformatio stess to initiae cacks. One as peetratedacross te ring ad broken it

5




Pate : 1538

Achive : 001-0Image te: color macro [SEE I MG N PPENDX]Scaea = 6 mm micos ±20%, otes +100% 50%Cmnent: CRB R, ruSeed: 00 KdNad: 1.2 GPauicatn: mineral oi 0°CFalue Cde 0022.3 Rbg crackFalue Cde 0013.21.2 Conact galling rom high acceleratonFalue Cde 00232.14 Wear rack at cotact edgeFalue Cde 4 11 Friction oymer, oil lubrication

Fare Code: 00223Falre Code: 002311

[ mg App]

Failue Descitin: contact srace o IR are several aia/radial cracks itiated rom an etensive galling streak ear thecotact ceter so, wear bands aear ear ot roller ends In a ig -seed CRB nnerrig acceeratiocased gallig mayinjre te ceriugally stessed D to case cackng Wea streaks may indcate oller skew Frco olymer idicaes ighemeratue Continued rnni ng is iely o case rg ractureImage Descitin Ceter orto o te mage is a CRB IR rolle ath Two iterrted lght brown bands ear N edge o rollingtrack are wear bads wit rictio olymer Two iterruted bads with dark bown edgig near te rolig track cene are wearbads wth galed metal whiteadbrow atcy deost) along teir cenelne Dar and ligt, rregular aial ies across thegallng bads and beyond ae bulk cracks enetratig adiallySusected Causes: Very high seed bearing I R, esecially CRB I R, are sbect to ig ceriugal hoo sress Ro lle slidn g romhigh acceleration skewng, or both) may cause wear, and i severe, gallig, wc is a severe tractive stress in the srace Tus,he damage doe o s urace inegrty by galling, and te centriuga oo stess ca combi e to orm adially goi ng aial cacks,ad eventaly crossseco acue

Plate : 1539

Achive : 001-4Image te: i ght macro sectioScalea = 1 mm micros: ± 20%,oers + 100%, 50%Cmnent: CBB IR, rnSeed: 11 MdNLad: 1.4 GPauicatin: syntetc olyester oi l 120°CFalue Cde 00.2311 Cotact ahrodown in bearingFalue Cde Falue Cde Faue Cde 4 S s PLT 10.5

Faue Descitn: verrolig o he contact ath at etreme essues causes lasc low in Hertzian dmensios I te cotacts wel centered, he rest is roile dstortion and residual stresses n the subsrace material I the cotact eteds to the trackedge as shown) a i or idge orms at te edge eraio uder a load suicien to cause lasic rodown destroys geomeryad leads to early saligImage Desctn: Te image sows a cross section o an CBB inerg aganst a black backgound t image is te edge othe ball at te straigh lie rom center to W s a land Te edge between track and and which sold be ounded, so ws arotrusio above the land caused by lastic low o material rom uder te ball atSusected Causes: In a ball earng, cotact overridng te track edge results rom (1) sevee overload (2 isuicien land eightor te oad c ondition or (3) ecessvely tight conormity as bilt or de to lastic roll dow I any o hese cases lastc rolldowoccrs as a resul o vey ig ertzian ressres Pae 10.5 shows rolledin lines on oe o the matg bals



Failre Code: 002312 haper Bulk racking Fracure Penanen Defonaion

Pae N: 15.40

Achve N: 099131Image tye l ig macroScaeba 30 mm micros 20%,otes + 100%, 50%)Cmet SG; , medi m ard, uSeedadubicati:Falue Cde 00231.2 Gear oo cotact rolldowFalue Cde : Failue Cde Failue Cde 4 -

Failue esciti: cessve cotact ressre medim-ard gear causes lastic ow i te cotact surace Pressue wasevely distibted to e cotac edge, ad lis omed rorudg ast te oot ace ad te toot i Geomety was lost Gear isoisy ad if flow rogresses may sufer too racureImage esciti: Side view of gear Toot contact suraces facig image form lis rotrudig ast e sideace Black sreako sideface is at mar)Susected Causes: Ecessve cotact ressure odces cotied lasc low o srface maerial a medumard materia,suiciet asticty is availabe to odce sbstatial gross deformatio beore racte

Pate N 15.41Acive N 080-126Image ye l g t macroScaeba = 0 mm micros 20%, otes +100%, 50%)Cme SG G, g adess, ru

SeedLad:Lubicati:Falue Cde 00.23.1.2 Gear toot cotact rolldownFalue Cde : 00.071.1 Isficet bulk adessFalue Cde Falue Cde 4 -

Faue esci: veroaded ee o isufficietlyardeed gear ave lasicay deormed by rolig dow ecoac srace ad erdig materal at te toot tis adeds Te suicetly ardeed gea s uab le to cary tedesign load Plastic defomation destroys te geomery ad may be oowed by gal ig sall g or oot racture as ossiblefrte ailues

Image esc: Gear segmet ree teet) is viewed from gear face Te Eacg oot lanks are more-or-less u cagedTe facig oaded) toot flaks ae ollowed out ad material is etuded form g etesios 'lis) at te toot tis ad al soa te toot-ed ed ges facig te viewer

-

Suseced Causes: uardeed or insufciely ardeed gears, eavy continous or mac oading may roll or amme o tetoot sufaces I roerly ardeed gardess gears, too fractue is more lkely)



GUIDIN-COMONN F lUR 16Failure Code 01

General Description

Ts chapt covs lus o separators and guideringscomponnts uniqu to ollin bansSpaatos a also known as cages o retainers, and a th componnts placd btwn th ins to hod and spac th o mnts. Guidins a in-shapd componnts (oosly ittd to acontact componnt (in Thy a usd n som (multiow oll bains to povid axial uidanc

to ol nds n th absnc o a ixd an and (in som cass to povid spaato uidanc.

16.1 SEPARATOR FALURE FALURE CODE: 01.1A spaato consists typicaly o on o mo rings, som o al with pockets o th olin mnts.

ndividual bars (cossbas attachd to th spaato ins may spaat th olin mnts instado pockts machind into a spaato in. th is mo than on spaato in thy (as wl asany cossbas a astnd toth by wdin ivts pons o bolts.

Spaatos hav many aiu mods in common with Ht contact componnts and oths which a unqu to thm. n this na dsciption o th aiu cass nomenclature and failure process a d back to th ditions o th cospondin contact componnt aiu mod whv possib with dintiatin atus ivn wh thy xist. Distinctive appearance, causesand eects bin vy dint o spaatos a naly tatd without back-nc.

Spaatos may b mad o (mosty nhadnd stl o a vaity o oth mtas incudn powd mtas Pastic matias (poyms o composits o polyms and nocin ibs a also usd

Spaatos (oth than thos consistin o undsiz oin mnts hav sidin contacts onyA spaatos hav such contacts with th olin mnts Som spaato dsins aso hav contacts with uidin suacs on th Ht contact ins o on uidins nusua spaatos may consisto individual inserts placd btwn adjacnt olin lmnts and unattachd to ach oth o tospaato ins ndsi os o bas can b usd as spaato nsts

Som multiow bains hav mo than on spaato

Separator Bulk Discontinuity Failure Failure Code:

16 Defntonh tm "spaato buk discontinuity aiu" is usd as th nic dsination o al ailus

invovin spaation o voids in spaatos o mtin and disintation o spaato matia. t incuds th oowin ailu mods:

Melting o burning (in polym spaatos Casting o molding defect;3 Weld failure4. Cracking andacture (spaato body5 Fastener failure (ivts pons bots

6112 NomenlatreBulk discontinuity aius a commoy dsinatd by thi spciic ailu mods as istd in

Dinition abov



ailure Ala for Herz Conac Machine Elemen

5

16113 Falr Procss

Meing ous n themopast mateas when the sepaato s opeated at exessve tempeatue. tan ane om patal metn, wth esutn dstotons o the sepaato, to nea-total dsnteatonBrning, whh epesents a hema deomposton due to exessve tempeatue, ous n polymes that do not met st

Cracking oacre s a ommon aue mode o sepaatos These ae eneally slende, suptuedshapes subjet to substantal stesses n bendn, toson and tenson Many metal sepaatos aeold-stamped om sheet, wth oppotunity o shap ones, sathes, wok hadenn and moakn dun manuatue Most sepaato akn s due to oveload o atue Chemay pomoted akn ous n polyme sepaatos, opeatn n aessve atmosphees Chemaly pomoted akn s aso known to ou n metas as a esut o eetoplatn deets Manuatun maoaks may ou n the abaton o stamped sepaatos o dun the "osue" o sepaatosaound oln elements n assemby (stamped sepaatos n tape ole beans, etane-tandesns n maned aat bean sepaatos See asener faire beow o aks n ponassembed stamped sepaatos

We faire ous n sepaatos weded om sepaate pats Spot wedn n eu o vetn sommon o ht sheet stee sepaatos some heave stamped sepaatos have ne-welded onstu ton Weds may ak om tense o shea oveloadn o atue, whh ae possby aded by esdua stesses, weaknesses o btteness n the wed Wedn aks may aso be manuat- n deets

·

Casing o moing deets o manuatue ou n sandast, entualy ast o deast metasepaatos and n molded past sepaatos Common deets nude vois, seams, srcre efecs,ner and incompee boning at nteaes whee met ows meet, suh as n neton modn.

asener faire (deomaton, akn o atue ous n veted, ponassembled o boltedsepaatos he alue o a astene may lead to weakein o dsassemby o the sepaato o losso sepaato eomety (wth subsequent ubbn on movn pats and possbly eventua atueo the sepaato body

1611 Dstnctv ApparancSepaato buk dsontnutes, seable, ae eadly eoned vsualy Dulty may ase

wth moaks o the akn o astenes n oneaed aeas Cak-evealn tehques, suhas de-penetant nspeton, ae avaabe Knowlede o the ponts n the sepaato desn whee manuatun stesses ae kely to ead to aks may depend on expeene wth alues o aven desn Desn eatues wth a hstoy o vuneabty ae lsted below.

16115 Cass

Sepaato buk dsontnuty may ase om manuatue (o desn o om seve.

Manufacuring and Deign Caue

Sharp eges n stamped sepaatos tend to wok-haden and a Sharp bens n etan pons and tans may ak dun o ate the bendn opeaton3. Rive heas and neks may be maomed, o ak n omn o seve.4 Large, hin wae san casings o mahned sepaatos may ontan vods o nusons5 Inerfaces n njeton modns, whee met matea on om two detons must bond,

may eman wea6. Wes n both steel and plast sepaatos may be nompetely used, ontan esdua stesses,

nusons, be btte o moaked.



Chapter Guiding-Component Failure

Servie Causes

Operation at excessive empeue as a resut of bearing heat imbalance faiure (FC 00.9) or insufficient separator cooing may cause melting or chemical decomposition (aso galing seeC 04)

2 Excessive separator roling element (or ring) foces may cause cracking or fracture of separator body fasteners or weds They can also cause overheating (see above) permanent deformation wear or galing (see FC 012 C 0113 and FC 04 ater in this chapter) Separators transmit forces to roing eements whie maintaining their reative position Ring and riding separatorsaso transmit forces to the rings When these forces exceed design eves buk permanentdeformation (see C 02) or buk discontinuity may resut

Causes for abnormal evels of separator roling element forces (in ring and riding separatorsaso ring forces) incude conditions that necessitate increasing sliding between roing eementsand rings namely

Mislignmen between bearing rngs; Axil bearing lods in excess of design eves; Dimee sorting eo among roing eements; Skewing of rolers in excess of design eves;• Off-specification (insufficient) pocke clence between separator and roing eement

Another set of causes for abnorma separator roling eement forces is represented by anycondition that increases friction between separator roing elements and rings notablyimpied luicion.

neil foces on the separator may cause cracking or fracture High-speed operaton imposescentrifuga hoop stresses on the separator body which act simiary to the roing element forcesdescribed under 2 Additionaly igh speed on an unbaanced separator displaces it from thecentered position or causes instabiity in separator motion wich increases roling element(and ring) forces This may reate untended contacts (between separator and a ring) withcorresponding forces

4 Geomey eos of the separator may cause cracking or fracture Distortions may cause roerskewing madistribution of contact oads or unbaance Excess cearance may alow the separator

to make unintended contacts Roing element riding separators can become and riding andseparator eements may be caught under a roing eleent wedge in the Hertz contact andcause catastrophic fractures

5 Chemicl ck (see C 0.15) can weaken a metal separator and promote cracking under stress.Chemica attack on a pastic separator (from atmosphere or incompatibe lubricant) can cause

embrittement and cracking

111 Effets of Separator Blk DsontnSeparator discontinuity eventually leads to gross machine eement faiure.

Separator Permanent Bulk Deformaton Failure Code:

1121 DefntonPermanent buk shape or sie changes of separators fa n this faiure cass (as distinct from wear

or galling which change oca microgeometry)

1122 NomenatreCommony used designations are ending disoion wising, and seching of the separator

5



Failure Atlas or Hertz Contat Maine Elements

16123 Falre Proess

• Imposed buk stresses xcng h lsc cus pnn buk psc oon n(l) spos

• Bulk oon y b cus by unlv residua stresses• In plsc spos chemica nuncs y cus buk oon.• Softening o spo usuly u o bng ovhng (C 009) y cus p

nn oon un ocs ohws w suppo

1612 Dstntve AppearanePn buk oon y b c n h assembed bng

• By c vsu vnc o sshpnnss (xp ou o ounnss);• By sgns o w unnn conc sucs o unvn w nn conc sucs

(s C 03);• By sun o xcssv o unvn spo loosnss ( xl o ccunl (n

h pock)).

Note: oboscopc obsvon o spo oon n h unnng chn y pov ncons o pn buk oon

5

Pnn bulk oon y b c n h spo removed o h bg bynson sun n by sgns o w s scb bov.

16125 Casesh o h olowng cuss y bng bou pnn buk oon

Any o h imposed stresses ls s cuss o cckng o cu un C 011su stresses cus by ny o h olowg:

• Cod forming, ncung spng wng ollng s nuctung opons• Forging, casting o moding opons no cvly sss lv• Bulk o suc heat treatment o hnng o png o l spos• Assemb of separator o s ps by vng pongcosu o wng snppng ov olng

lns ng o boy closu by co oon.

16126 Effets of Separator Permanent Blk Deformation

• Unnn chngs n spo clncs;• Dsoon o concs wh olng lns n o ngs;• Incs w concs;• W unnn locons;• W o gng o olng lns n/ o gs;• npn o spo n olng conc wh ' csophc lu o h bng

Separator Wear Failure Coe

16131 DefntonMid wear o spo s n s un u co C 00 o w o conc coponns

Surface distress, bng o o tgu l o roing conc s no lu o o spos.Gaing, coon lu o o spos s scb un C 01.14 Separator gaing



Chapter Guiding-Cmpnent Failure

NomenatreNomencaue o sepaao wea s he same as gven o conac componens unde FC

Falre Proessaue modes o sepaao wea ae he same as gven o He conac componens unde C

Because sepaao conacs ae amos aways simpl sliding conacs wea s a pedomnan aiue mode Accoding o he types o conac in he sepaao he oowng wea ocaons can be dstingushed

Pockt wa beween he ong eemen and s conanng sepaao poce Moe specicay

• ockt bo wa beween he oing suace o he oe (any suace o he ba) and he maing suace o he sepaao

• ockt bottom o nding wa beween oe endaces and mang sepaao suaces n he poce o on a sepaabe ending

Guidland wea beween a cyindica suace o he sepaao (boe o OD) and a He conac ng o gudeng suace

3 Wa o unintndd contact, when he sepaao conacs anohe componen a an unnended ocaion due o sepaao dspacemen o deomaion

Composes (such as be einoced pasic sepaaos o soidubcan ed mea sepaaos)can sue especiay damaging wea i he pasic o sod ubican aye weas hough o he

eiocing maea This einocing maea s hade; i s geneay no seeced o boogicacapabiies; and may poude as jagged pons o edges Sepaao wea can hen give ise o

wea o he maing conac componen

Dstntve A ppearaneSepaao maea is amos aways soe han he maing conac componen The wea sca on

he sepaao s expeced o be deepe ha on he He conac componen wheneve hey conacaong sufacs Conacs aong dgs ae possbe howeve and hen wea scaches on he Hecomponen may be moe ponounced han he wea o e sepaao edge had conaminan

paces ae embedded n a so sepaao hen he mang suace on he He conac componen may be seveey won

As descbed unde C , wea on a sepaao suace typicay consss o "nemaic wea mas in he om o cicumfntial scaches indicang he siding decon Typca wea paens indicave o opeang condions ae ised beow (on he assumpion ha he decon o beaing

oaon does no evese)

Pcket Wear

• On-sidd pockt bo wa on on o bac o he poce bu no boh indcaes noma adia poce ceaance and wea unde he oing eemen/ sepaao oad

• Onsidd pockt nd wa ndicaes noma axia poce ceaance and wea unde axa oad• Twosidd pockt bo wa indicaes ow ada poce ceaance• Twosidd pockt nd wa indicaes ow axa poce ceaance• Edg wa indcaes geomey eo o he sepaao (incudng geomery change by bu deoma

on o suace wea)• Coss-con wa n a oe sepaao poce indcaes sewg o he oe

5




uideland Wear

ven wea aund the cicumeence indicates tating sepaat ading w and ceaance Uneven wea aund the cicumeence indicates ne-sided sepaat ading sepaat

unbaance Uneven wea (ne and me than the the) indicates sepaat misaigment ocalized guideland wea indicates gemetic disttin the sepaat.

Wear at Unintended Contacts

his wea type indicates excess sepaat seness (incuding inceased seness m wea)sepaat gemety e high distting ces n the sepaat

Note: Retang tang wea n sepaats equipped with e ba etaining tangs indicates excesssepaat ceaance -speciicatin tangs

5

Cases

Contamination Sid cntaminant in ubicant the chambe apidy weas the siding cntacts the sepaat.

nadequate lubication Sepaat cntacts ae the beaings mst vuneabe cntacts unde nap ppiatey seected ubicant insuicient quantity ubicant

O-speccation sepaato cleaance Lw e pcet ( guideand) ceaance ceates highsepaat cntact pessues and apid wea.

Sepaato geomet eo may cause edge cntact (nt eiaby ubicatabe ) uneven distibutin ing eement ads n sepaat cntact at unntended catins

Rolling element soting eo causes dieentias in ing eement epicycic biting speeds

necessitating ing eement siding which equies high diving ces m the sepaat Beaing misalignment causes cycicay vaying ing eement epicycic speeds necessitating

ing eement siding whch equies high sepaat diving ces nsucient (munted) beaing cleaance causes 360° ad ne beaing and accumuating phase

es between ing eements necessitatg ing eement siding which equies high sepaa t diving ces

Beaing axial load (n excess speciicatin) High axia ad causes 360° ad ne in beaingand accumuating phase es between ing eements necessitating siding which equies hgh sepaat ces

ffets of eparator Wear

Run-in by se-imiting mid wea can pduce impved suace sh especiay in age beaings and in designs whee cined edges must cntact ing eements.

dge contacts may m as a esut wea impaiing ubicatin and acceeating wea causing gaing

Sepaato geomet may be impaied eadng t secnday aiues (sepaat unbaance entap ment unde ing eement)

Stuctual stength of sepaato is eventuay st due t wea causing actue

Depending n sepaat design cnsideabe mid wea ay be acceptabe withut impaiingsevice Machned meta and mded pastic sepaats teate appeciabe wea wing t thei heavy sectins Stamped sheet meta sepaats especiay thse cntacting ing eements angcined edges teate ny minima wea



Chaptr Guiding-Componnt Failur

Separator Galling Failure Coe

16141 DefntonGalng n sepaatos s dened as unde C 0013 o galng n ontat omponents Gang n

separators s dstngushed om md wea a ommon alure mode o sepaators desed underC 0113

16142 NomenlatreSee C 003: Galling in cntact cmpnent, or nomenature

16143 Fare Proesss desred under FC 0013, ths aure mode onssts o the transer o surae materal etween

separate loatons on the ontatng suraes y ton wedng o ontatng aspertes and thersuseuent sepaaton aong a plane other than the weld nterae

sepaato gas aganst ontat omponents whh are o deent materal (derent ompostonand or hadness) and thus transers oregn matera (mld stee yelow meta et) onto the (hadsteel) ontat omponent

Separator ontats are hghy ulnerale to galng eause (a) moton n them s imple liding,so that an aspety ontat s not nterupted y surae lto as n a rolng ontat; () sepaatos hae ompex shapes nludng shap edges; () meta separatos are made o reately sot metas; and (d) sepaatos are manuatued y methods nudng stampng mlng and turnng none o whh produe as ne a suae nsh as that on ontat omponents o rolng eangs

he ores atng on separators are wdely aae and the ontro s more poemat than that o the Het ontat ores; galng s oten the esut o unantpated oe exursons

Miscllanous Nots on th Failur Procss

• lthough t s more ommon o the (soter) separato matera to transer onto the ontatomponents evee tanser o hard steel onto sepaatos has aso een osered

• Separators made o pasts do not usualy suer galn aure Howee some thermopast materas are apae o transer to the matng ontat surae and ths transer may e onsderedgang Untended tanser o past sepaator matera to a ontat part may ause nose

nauraes and oeheatng n addton to pang arge oes on the separator• Separators n ontat wth rolng eements made o eams are muh ess key to sue

gang than wth stee olng eements onetheless separato matea an transer onto eram rolng eements and ths tanse may e onsdered galng

• Beangs opeatng n yogen luds may e eupped wth separatos made o eored telon Contoled tanser o teon to the olng suraes s a desgn reurement amed atsuppyg dry uaton and therey mpong the untong o suh earngs hs nten

tonal tanser s not onsdeed to e a alue

16144 Dstntve Appearanehe appeaane o galng n a separator s smar to that desred o ontat omponents under

C 0013 wth the oowng spea eatues:

• Galled mateial wea at one n the sldng separato ontat thereore wear maks wl appearon t

55




5

• Dissimir mteri may appa on th gald suac, spaato and Ht contact componnt

matals a vsuay dnt (xamp a bass spaato aganst stl ong lmnts)

1615 CasesTh common causs o gallng lstd und C 0013 also appy to spaato contactsCauss spcc to spaato gang ncud th load-ncasng condtons lstd und C 0113

and addtonaly th ollowng:

• Overheting o th spaato contact, pcptatng th oss o lubcaton and acltaton o wdng postuatd n Blos lash tmpatu thoy [14]

• Loss o cernce n th spaato contact du to domaton, contamnaton, ntapmnt o thspaato und olng mnts, tc

1616 ffets of Separator GallngSpaato galng may b astd (heed) th pcptatng condton s alvatd bo mata tans has dstoyd sgncant aas o contact ntac

Unss th s n th svty o opatng condtons to pmt hang, spaato gang typcaly lads to th olowng alu mods

• Bering noise nd vibrtion may b causd by th mata tansd though galng• Het imbnce iure (C 0019)• Seprtor cture (C 0111)• Seizure o th bang (C 0013) possbly wth bul cacng o actu (C 0022)

Sepaato Coosion Failue Code

16151 DefntonChmcal attac causng alu n a spaato s dsgnatd n ths Atas as seprtor corrosion.

Ts s anaogous to th dnton o cooson o Ht contact componnts und C 0020 Thdamag catgos dstngushd om cooson und C 0020 (ttng C (0015) pttng as acastng dct (C 0005) tmp coong and cton polym dposton (C 0019)) must aso bdstngushd om cooson whn thy occu n a spaato, although ttng s not a yspaato alu

16152 NomenlatreTh nomnclatu o subclasss o cooson (cooson stag, cooson pttng, ntganua

cooson), ctd und C 0020 qually appls to metic spaatos In nonous spaatos, th

stanng s otn dsgnatd dscooatonChmcal attac on plastc spaatos ncud dimension chnge (swng) du to humdty and

embrittement

16153 Falre ProessS C 0020 o a gna dscpton o alus by chmca attac

Metal Separators. Spaatos mad o stee cood und condtons and by mchansms sma to stl contact componnts

Bcaus o th ough suacs and low hadnss o stl spaatos, thy a ly to b mosnstv to cooson than th suacs o contact componnts



Chapter Guiding-Cmpnent Failure

Spaatos ad of ello meal (bo bass) cood by lctochcay ancd cooson

n th psnc of st coponnts and an ctoyt Ese ase synthtc ubcants of so fouatons a aggssv to ylow tal Yow tal ust b xcudd fo systs usngsuch st ubcants

Aluminum allo spaatos f usd a potctd by an anodng sufac tatnt Ths ay ay wa away and th xposd ta fos an ctoytc coup wth st that can pcptatcooson of th alunu aoy ladng to cacng

Plastic Separatrs Chca attac on pastc spaatos can assu any fos dpndng on ata and attacg chca Th ost coon a

• Dimensional change in nlon du to chang absobd wat contnt (not stctly a chca acton but ncudd h as bg th ffct of an nvonntal chca)

• Emilemen of plasic du to ncopatb ubcants o aggssv atosph. Whn btt

nt occus co o acocacs a y to sult und dflctons othws ady toatd by th ata.

Dstntve Appearane

• Spaatos ad of seel show cooson sa to st contact coponnts xcpt fo thappaanc dffncs du to dssla ogal sufac fshs

Spaatos ad of ello meal (bass bo) usuay show bown o bacsh stans undchca attac

• Spaatos of aluminum allo show a dsupton of th anodd coatng possbly wth cacng.• Plasic spaatos whn bttd tnd to show dscooaton possbly cacng

CasesTh causs of spaato cooson a sa to thos std und C 000 fo contact coponnts

Effets of Separator Corroson

Metal Separatrs. Th cooson poduct on seel spaato sufacs s abasv Whn won off by contact wth th olng lnts t contanats th ubcant and causs wa of contactcoponnts of th spaato and of gudng o sas (f psnt).

Spaato cooson ay chang spaato caanc. Spaato cooson ay wan th spaato(spcay a thn stapd sht ta spaato) and cacng ay sult.

Cooson of any pat n th chab contang th spaato tnds to anc cooson of oth

coponnts n th chab. Cooson of contact coponnts ay sult

Plastic Separatrs. bttnt of pastc spaatos poducs substantal wanng and typcally ads to cacng spcaly as pastc spaatos a oftn dsgnd utng th gat toanc

fo dflcton uch of wch ay b ost du to bttnt

Separator Heat Imbalance Failure Failure ode:

Hat balanc fau of contact coponnts gnaly nvolvs spaato ntacton that s ths coponnts coopat to gnat th xcss hat o a dscpton of hat baanc falus C 009

5




Separator Spallng Failure Code

On a occasons spang s sn n conact wn a (macnd mta) spaao pockand a olng mnt s conac agu alu ass om patd applcaon o nomal contac

pssu as olng mn (usualy a al) s pssd agans t spaato pock o uponcangs n ong lmnt otal spd (g wn t oad on s ntd and lt) o upon

msalgmnt o ang S C 006 o a dscpton o spalng

162 GUDERNG FALURE FALURE CODE: 012

5

s scton covs aus o guideings n ong angs Gudngs a sepaate ngs oosy td to on o t H contac ngs o t ang y sv to gud ot componntsGudgs sv two dstnc unctons as dscd ow In som dsgns gudng pomsoy on o uncons n ots t poms ot

Sepaato guideings patcpat n t postonng ( cnng) o spaatos Suc gudngs avconomng (non-Han) sdng contac wt spaatos

Rolle guideings a usd o povd a ac o axal gudanc o olls n dsgns w ntgal langs a no povdd at al qud o-nd conact ponts

Examps

1 Comnd spaato- and ol-gudngs a usd n som dsgns o spcal ol angsy a usualy oosly ttd ov a cnt and o t ng and p cnt spaao(s) w t OD w axay gudng t os wt t sdacs y atu sldng contac wt t spaao o and sdng ong conact wt t ol ndacs y a commoy mad o cast on powd mtal o plasc

2 In som sng-ow cylndcal ol angs ngal langs a suppmntd y oos nd ngs wt an Lsapd coss scton wc gud ol nds s aangmnt pmtsaxa mountng wt o ang ngs mountd on sat o n ousg o nston o oto

3. In som dsgns o mulow cyndca o angs spacng ngs twn ows gud olls axally w t sdacs and also cn t spaatos wt t OD Suc ngs a mad o matas smla o Ht contac ngsos otn adnd st

Gudngs av sma au mods as t angs o H contact ngs I gudng s mad o plastc t au mods o pastc spaatos may aso occu

1621 Definition alu mods std n a 61 a dnd y nc to au cods o contact compo

nns o spaatos

1622 NomenclatureNomnclau o au mods s sam as o t cospondng alu cods covng Ht

conact componnts o spaaos

1623 Failure Processau pocsss a t sam as o cospondng alu cods covng Ht conact

componnts o spaatos Bcaus som gudngs a o n scon cackng o actu ogudngs s not uncommon



Chpter Guiding-Component ilure

T ORREONDENE O UIDERIN ILURE ODE

CF C F C

0 .2. 1 Guidering manufacturing deect 00.0080 .2.2 Guideri ng buk dicontinuity failure 00.22

0.2.302.

01.2.

01 .26

01.2.701.2.8

Gudering buk permanent defomationGudering wear

Guiderng heat imbaance ailue

Guidering galling

Guiderng dentngGuiderng coroion

162 Dstnctve Appearance

0 1 . 1 10 1 . 1 20 0 . 1 20 . 30 0 1 90 1 1 60 0 1 30 1 1 0 0 . 1 800.20

0 1 . 1

Guierg of shcal oll bans are ypially rig of rapeoial ro eio (yiria bore a a age i efae) i lie o e ierrig la alog eir lie o eeparaor aog eir a uergo opou roligI iig agai roler e o eiriefae. Wa oralln ay appear o ay of ee urfae Bore a ar il be irufereial a i a eparaor. Siefae il o epiyli ar a i e oa beee a roler ea e flage of a bearg rig.

Guierg of clndcal oll bans ay ave reagular or Lape ro eio. ape

guierig of ige-ro yliria ave a ie urfae iee for oa i roler e paig rig of oe uiro yirial e or e bore urfae erve o guie a eparaora ie urfae guie roler e. Faiure of e ype appearig o bearig rig fage are eeo e roer-oa urfae. Separaor uppor urfae o irufereia arig.

1625 Causes

Seprtor Guide Surfce ilures

Manufacun dfcs: aig error geoery error (epeialy oe of iefae age) iorrelearae beee guierig I a ierrig a or beee guierig a eparaoror iorre urfae fi.

xcssv sldn sd ov h nnn (eeive learae beee guierig a ierig la; geoery error eaig o ig roler e loa fro roler ro oaig boh iefae )

Conamnan igre io e guierg/ a or guierig/ eparaor ierfae gap Hh oll conac load Hh saao adal loads fro arge ifferee i epiyi roler pee Inadqua lubcaon Chmcal aack

Roller Guide Surfce ilures. ailure ay arie fro ay of e aue of roler e/ fageoa faiure We e guierig alo arrie a eparaor guiig urfae e o e of faiureaue ay iera

5




30

Because guidergs are separate parts misaigmet betwee the roer-ed guide surface o theguiderig ad the rig carryig the rollig track may arise i moutig or i service. This sourceof misaig nmet may cause failures i the roer ed cotacts for exampe, roler skew ad edgecotact with resutig wear ad galig.

16.2.6 Effects of Guidering Failure

• The efects of separator gu ide surface faiure are simiar to those of separator failure• The effects of roller guide surface failure are simiar to those of the faiure of itegra fages o

Hertz cotact rgs



Chaper Guiding-Componen Failure


0 1 1 0

0 1 . 1 1 . 2

0 1 1 .

0 . 1 1 .

0 . 1 6

0 1 1 2

0 1 . 1 3

0 1 . 1 3 1

0 1 . 1 3 . . 2

0 . 1 3 . 1 . 3

0 . 1 3 . 1 .

01 . 13 .2 .2

0 1 . 1 3 . 3

0 1

0 1 . 1

0 1 . 1 . 2

0 1 . 1 6

0 1 . 7

P

16 .16.23

7.2012201 3 1 0 3 1 6266.298.

16

16 .6

16.2

16 .61 6 . 01 6 . 1 216.33

7 . 1

16 .716 .816.91 6 1 1 6 . 1 616.30

6 . 1 01 8 . 9

7.21

7.2016.26

1 6 1 11 8 . 1 9

13 .1 6 . 1 21 6 . 1 36.2628

1 6 . 1 3

13 .16.2163

1 8 . 1 9

1 6 . 1 1

1627




PLATESPate No 161Archive No 087011Image tpe: lgt macroScalebar 0 mm (mcros 20%, oters 100% 50%Componen DGBB; B&G riveted macned separator, ruSpeed:Load:Lubricaion:Falure Code 010 Separao manfactrg geomery defectFailure Code 0012322 Scratc marks kiematic wear marksi rollig srfaceFailure Code Failure Code 4

Failure escription: Mis-registry o riveted separato alves ascased mislocaio of ball pocke alves wit sarp edge at edvdig plane Duing a dynamc est rn te bearing did otrotate freely Te balls were scratced e bearg is otserviceable

Faile Code: 00Faile Code 0

Image escription: A two-pa maced riveted separator is viewed oblqely on te sdeace e pocket aves are not poperlyaliged by te rivets A step exists betwee e alves at te arrows (abeled "msagnmet e ball at image E sows manyfaint cicumfeential wea marks rom separator contact i a tigt pockeSuspected Causes: rror xurng for drillng of rivet oles may resul i ms-registry of separator alves If extreme, te ballsjam i some of te pockets and te bearig wi ll not tur In lesser cases, a sarp edge a pocket scraces te ball eseparator wears prematurely

Plate No: 162Archive No: 03-003mage tpe: igt macroScalebar 2 mm (mcros ±20%, oters 100%, 50%Component: ACBB&G (porous nyo separator, rnSpeed: 600 Kdoad:ubrcation: miera ol impregated separatorFailure Code 011 Separator meltig (polymerFailure Code : 00922 Ho plastic flow wit bulk wedingFailure Code Failure Code 4

Failure escrpton Meting of poros nylo separator maeria from g-speedfricto at a bal l/pocket cotact e bal l pocke t was el ogated by about 1/2 of tebal di amete trog mel tg and extrsion of sofeed ylo e two ballssown were melt-boded to te retainer and te retainer was bonded to te IRpo stoppg e steel compoents were ot damaged s s a gross eaimbalace failureImage escipion Vew o retainer OD wit two (glossy black-appeaig balls i pockets Glossy black IR is visible troug te alf of te grealy elongated pocket at mage Patces of nylo adere to te ball surace in pocket Muc fbros-appearinglgt ad dak ylon material from pocket was trow ot onto te separator OD and oto te bal at mage SSuspeced Causes Operation at excessive speed created a imbalance betwee te eat generaed te ball/reaier cotacts adte eat removal e nyo overeated meted, darkeed ad was extrded e cooling yon boded te bals to te R



Failure Code: 0111 Chapter Guiding-Component Failure

Plae N 163

Archive N: 03106Image ype: vieScalea 20 mm (micros 20% others: + 100%50%)Cmpnen BB (maximm compement) G (stampedseparator) rnSpeed:ad:uicanFalue Cde 0112 Separator fractre c rackingFalue Cde : Falue Cde Falue Cde 4 -

Faiure Descpn To halves o stamped 'ibbon typebal bearng sepaator are shon ith riveted staves Onehalf is fragmented across the ivet hoes ad may staves are missig hee is fatige cracking of eak cross sections ithrectanglar sharpcoered rivet hoes, probaby rom bearig misaligment This is a gross failre.mage Descpn: Vie of the ballcontac side of both sideals of a maximmcomplement ball bearng separator, ith a fecrossbars (staves) remainig riveted to each sderig Fatge fractre of oe siderig occrred across rivehoes of rectagashape ith sharp cores, hich receive stave prongs servig as rivets.Suspeced Causes: Riveted ball bearig separators may break i beding fatge f exposed to excessive ball/separator forcesmostly hrogh misaligment of the bearig ailing lbicaio may conribte to the high separator forces.



Failue Atla fo Hetz ontact Machine Element

Pate No 16

Arche No: 002026a&bImage type: a, b viwScalear a: 5, b 30 mmmicros 20%, othrs 100%, 50%Compoet: ACBB; G&OR ruSpeed: 17 MdLoad 2.6 GaLuicatio: synthtic poys oil, 176°Calure Code 01.11.2 Sparator acturcrackigalure Code : 0016.02.3 Spalling atcotact dg rom thrust loadFailure Code 00.16.025 Advacdspalig

Failure Code 4 01.10 Sparatormanuacturig gomtry dfct

Faiure escriptio: Extnsiv spallng onOR nar goov dg, und havy thrustoad ad high spd. As a scondaryfailur th sparator brok ito two rigshapd halvs by fracturig ach crossbara sharp dgs o th bal raiig tagsImage escriptio: a) An OR is at magctr, with two halvs of th boknsparator on ihr sid. All sparatorcrossbars ar brok. h OR bal groovshows lag spall catr aa a imag ,

xdig to Sacig groov dg b)Sparato with two brokn halvs isshown rplacd i aignmt All cracks

lure Code: 011

a

wr iitiatd at cornrs whr ballrtaning tags conct to crossbars. wo broknoff tainig tags ar at imag S.Suspeced Causes: h barig opratd at xtrm spd and load in a tst, rsulting i massiv spallg. arg spaator forcsrsultd from this failur, causing fractur of ach ba pockt crossbar a th stss-coctratio of th sharp) cornr btwrtainig tags and crossbas.



Filue Code 2

Pte N: 165Arive N 087002Imge ype: viewSlebr 15 mm ( micros: +20%, others +100%50%)Cmpnent: ACBB (with machned bronze searator)unrnSpeed:d:brtn:Fire Cde 01.11.2 Searator fracture crackigFire Cde : 01.11.4 Searator castng or moldigdeectFire Cde -Fire Cde 4

Flure Desriptin: The manufacturig crack across thesideace of the oneiece machine d bronze searato hasrobably resulted from casting stress. This is a gossfailreImge Desriptin: ACBB viewed on sideface. Themachined seaator is the gray center ring between lghtgray IR ad R Show at the arow is a jagged crosssection crack i the searator robably extendng to the ball ocket

Chapter Guiding-Component Failure

Sspeted Cses: Machied bronze searators are generally made rom centrigally cast broze tbing A castig deect cacreate a weak cross section ad/or high residal stresses whch recitate a crack Cracking has robably occrred after bearingassembly and d uin g storage; otherwise it is l ikely to have escaed detectio

5




DAAPat o: 166Arcv o: 002020a&c&eImag typ: a: vew b ght mcogram, c: metallogramScabar a: 100 b: 0 mm c 200 �m (mcros: 20%othes: + 100%, 0%)Coponnt: CRB IR&OR&R&G (slverplated steel separator) runSpd: 06 MdN

DESRONS

Failure Code

Load: 09 GPaLubricaion: synthec polyester ol, 162C

Faiu Cod 01.11.2 Separator fracture, crackngFaiu Cod 0 11. Separator rve, prong tang or boltfareFaur Cod 0112 Separato pastc defomatonFailu Cod 00124 Wear of gudng-component suppotsuface

Faiur Dscrption Rolle retanng tangs n the separaor were mpoperly staked n assembly. he separator sufeed bulkdeormaton (crossbars ae bent, sderals dshed) Wea occurred on the separator surface guded on the OR. he separaor ralshave fracued he separaor contacted the nnerrng unntentonally and the IR wore. he beang has faed.Iag Dscrpon: (a): Vew of dsassembed bearng. At mage NW IR wth wear tacks rom separaor contact at arows Atmage NE: sepaator wth cracks through sderals at arrows Wear nes on sderal OD (near arrow). (b): Cross-secton ofseparator. wo oller retanng tangs' at bowed cossbar at B dshed sderal at materal worn of at (c): he secton

shows crack (arrows) through he sderal/crossbar blend radus.Suspctd Causs: he rollers ae etaned n hs separato by stakng (plastcally defomng) the two tangs on each cossba IDPoor support n the stakng too has bent the cossbars whch n un dshed the sderals. he sepaator s guded on the ORlands he deomaton resuled n poor contac geomery and wore he separato at the OR gude surface Unntended IR/sepaatorcontact wore the IR Hgh forces cracked the separator

a

c

b



Falure Code

DAAPat o:

16.7Archiv o: 018-629Imag yp: ligt macroScabar 3 mm (cros: ±20%, oters: +100% 50%)Componnt: ACBBB & G (Soel separato), unSpd:LoadLubrcation syntetic poyeste oil, Faiur Cod 01.11.2 Separator facture, crackigFaiur Cod 01.3.1 Separator pocke worFaiur Cod Faiur Cod

DESOSFailu Dscrpon: Total fracture of sepaator siderails at eir

miiu ickess in te ball pocket, preceded by eavy balpocket cotact wea ailre is attributed to excessive ballseparaor forces, probably ro a saiged bearig Tis is agoss failure.

hapter 6 Guiding-mpnent Failure

Imag Dscption Obique view of a seget of macied S-moel ACBB separato on sdeface Total actue of bot sideailsoccurred across e bal pocket at image ceer Te tensie facture appears woody. ee is a lusrous, daedged wite weapatc N of te fractre, coverig oe-al e pocet wd ear IDSuspcd Causs Strogly vaiable ball coact agles arose operation uder eavy, exceric axial oad. Tey caused e lageorbiting veociy dfferences among te balls, placg excessve tesie sresses o te separaor wic factued at its weakescross secon Hig ballseparator coact pressures are idicated by eavy pocket wear.

DAAPat o: 16.8Archv o: 004

Imag typ: coor view [S IMAG IN APPNDIX.]Scaba m (mcros: 20%, otes: +100%, 50%)Componnt: DGBB; G (poyiid separator) runSpd: 12 MdNLoad:Lubrcation Ga-l-WSe soid, grapite weave, 300°CFaiu Cod 01.11.2 Separator factue, crackigFaiu Cod 01.13.1 Separator pocket worFaiu Cod

Failu Cod - PAT: 16.9

.DESOS

[ mg App]

Failur Dscripton Wear o separato pocket wit evetua breakout of a crossbar Siderails ave wor, wit deormatio ea te

acure OD as worn agaist te guide surace Te sef-lubrcatig, gapte fiber reiorced poyimid polyer separator wastested at ig teperature ad speed, resultg i tis failre mode. See Plate 169 for aoer failre iage of te same beargtypeImag Dscrpon: View o separato OD. Dark ad siy sraios on OD sow OD wear o te siny bads Two ball-pockets atiage ceter are coected roug wear ad fracture of crossba Te sideails adjace to te missig crossbar are distoedSuspctd Causs: Tis is a expermeal sepaator for a dry lubrcated gspeed, gemperatue applicaon, usg grapitefiber 3D weave reiorcing for te polyiid poyer separator caryig a solid lubricat e separator aied durg exploration oflimig falre modes I tis case tese odes are excessive ballpocket orces resulig in wear ad fracure Te sepaator island-guided ad sows wear o te contacting OD




DAAPat o: 169

Arciv o: 0042ag yp: ligt macroScabar 4 mm (micros ±20%, oters + 100%,50%)Coponn: BB (assemly); SiN B, polymer G, rSpd 12 MdNLoad:Lubrication: GalWSe sold grapite weave, MoS, 300CFaur Cod 0112 Separato racre, crackigFaur Cod 03.1 Separator pocket worFaur Cod 13 Soid or gas lricat ailreFaiur Cod PLAT 168

DESRONSFaiur Dscripon: Two al pockets separator arecoected y fractre of crossar. Pocket wear occrred.Wear marks are o te separator ID. Ball sraces are

Failure Code

partly coated wit soid lrcat ad separator ders Te earig as slico itride alls ad a reforced polymer separatoMoS s spteed o rigs ad alls ad is a powde ller i te separator Te earg was esed at g load ad speed, witotexteal licatio, resltig i tis aile modeIag Dscrpon: Bearg assemly wt oe IR al emoved s viewed o ore. Hosig wt ctot N of sepaator osceste OR Two separator pockets ae coected y fractre of te cossar, ad wor ope. Sepaator ID sows axial wear stripes(possily related to separator wirl). Balls sow a peppered sface, od to est rom deposis of separator ad lricatmateriaSuspctd Causs: Tis is a experimetal earig wit grapite e reiforced polymer separato carryg solid ricat, for adry ricated ig-speed igtemperatre applicatio Te separato ailed i a test for te explorato of limitig falre modesI tis test excessive al/pocket orces eslted i wear ad factre. See also Plate 168

DAAPat o: 1610Arciv o: 01431Iag typ: viewScabar 20 mm (micros 20%oers + 1 00% 50%)Coponnt: TRB; G (stamped steel separator),rSpd:Load:Lubrication:Faiur Cod 01.11.2 Separator fractre, crackigFaiur Cod 01.131.2 Separator crossar wo, ot pocke sidesFaur Cod 01.12 Separao plasic deformatio

Faiur Cod 0019 Heat maace failre

DESRONSFaur Dscription: Fractred stamped stee roller separator, followg eavy wear o crossars o o sides of pocketsLrcatio was iadeqate rolles exeted grea rictio orces o te separaor Tese wore te cotacs, plasically extrded temeta past te edges i e pocket corers ad evetally fraced te siderails edg fatige. Heat imaace o te earigis cojeced is is a gross failreIag Dscrpton: A stack o roke separator segmets is sow Ligt gray wear aeas appear aog te ID edge o allcrossas. Sepaator materal is plascally flow a te coers of two pockets at image . ractre sraces of te siderails areplastically atteedSuspctd Causs: Te earig was oserved to ave iadeqate licato, podcig excessive sepaator/roller forces ad wear.Te sepaato ecomes looser ad drops dow i te eaig, re icreasig oler forces. Te sepaator edg stress may eso large tat edig fatige of te rails eslts Te separator may ecome trapped etwee a roller ad te OR (Tere is odiect evidece i is image)



Failure Code

DAAPate o 16.11Acive o: 027-257Iage type: clor view [SE IMAG IN APPNDIX.]Scaear 0 (icros 20% others +100% 50%)Copoet: ACBB G (pheolic onepiece separator) ruSpeed:LoadLicatio: grease, Faire Code 011.2 Separator fracture, crackigFaire Code 013.2.2 Land gided separator, guide sace wor, localFaire Code 01.6 Sepaator heat ibalance failreFaire Code

DESRONS

Chapter 16: Guiding-Component Failure

[ mg App]

Faire Descripto: ragented pheoc plastic onepiece landridig sepaator with OD wea over one area and ID wear over

another area o the circuferece The separator, likely to have bee ubalanced, ran progressively ore exceticaly andevetally fractured due to copetig guidig forces fro bals ad lad Darkening i one pocet indicates high teperature deto large frction orceIage Descriptio: Three fagets of the broke separator ae at iage NW N and S. xtree NW and N pockets show adar spot, probably fro overheatg The suaces on the OD of the N fraget and on the ID of the S fraget ae ablated bywearSspected Cases adgded plastic sepaators are used n highspeed angular contact ball bearings especialy low noiseappicatios If separato orces are not syetrical (dyaic ubalace, iaccrate pocket geoetry, heavy cobined bearigload) then the sepaator orces at the gdeads rise resultng i wear and distoro. The separato ay ake uiteded cotacto the opposte rig and acceerating wea. Hoop stresses ay case fracture.

DAAPate o: 162Arcive o 087017

Iage type vewScalear 15 (icros: 20% others: +100% 50%)Copoet: DGBB (asseby) (2) runSpeed:oad:ricatio:Fare Code 0.112 Separator fracture cackingFare Code 01.133 Separator wear fro niteded cotactFare Code 01.12 Separator plastic deforatioFare Code

DESRONSFalre Descriptio: Disitegrated ribbotype riveted stapedsteel ball bearing separators. The separator OD was stretched andtouched the OR land nitentioaly. Separator wea occurred atthe OR contac The falre s attributed to isaligned operatiocreatig excessive ball/sepaator forces stretchng the separator,casig nintended contact and bendig fatge fracture his isa gross failure.Iage Descriptio: wo DGBB viewed o sideface. The separators are defoed ad fractued in both The separator edge touchesthe OR land ID at i both bearings and is wor irreglary The separator is fractred at S (in the bearg at iage W) Thesepaator is fractured at W and S (in the bearing at age E).Sspected Cases: Heavily saligned operation of DGBB results in cssconer loadig" o the bals by a high overurnigoent Contact agles ad ball orbital speeds vary drasticay around the crcuference placing excessive hoop stresses o theseparator. The separator stretches toches the OR or IR land, creatig additioal forces vetally, atigue facture occurs




DAAPat o: 1613

Archiv o: 014-49ag yp viewScabar 20 mm (micos ±20% oters +100%, 50%)Coponnt: RB IR&R&G (stamped stee separato) ruSpd:Load:LubricaionFailur Cod 0111.2 Separaor fracture, cracgFailur Cod 013.3 Separator wear from uteded cotactFailur Cod 0114 Separator gallingFailur Cod 219 Geometry or assembly defec ousg

DESONSFaiur Dscription: Gross wear gallig ad evetual fractre

on (smalend) sideface of separato, restig from uintendedcotact wit osing ed-cap Hig rictio geeatio ad gemperatres prevailed durig rning is is a gross defectresultg in gross are

Failure Code Falure Code

Iag Dscription: e RB lrolleseparator assembly is viewed obiquely o its small edface e separator siderail isseverely worn battered ad galled o its etire ccumerence At image N total separator facture occurred At image SW, partialacure o smal-ed sdeail is visble Roers ave alle o e separato at mage Suspctd Causs: A desig error o te ousig edcap faied to alow clearance o a separato normally protrdg above eIR (cone) sideface Rubbing cotact between separator ad ed-cap produced gross wear oveeatig ad facture

DAAPat o: 16.14Archiv o: 093-201Iag yp: igt macro

Scabar

10 mm (micos: 20% oers 100% 50%Coponnt: CRB G (cast broe separator), unruSpd:Load:Lubrication:Failur Cod 0114 Sepaator castig or m dig defectFailur Cod Failur Cod Failur Cod

DESONSFaiur Dscription: Repared" macro-porosity in te separatorcrossbars was due to casig defect A atempt was made to repaire porosity by filling te pores wit weld mateial Porosity weaeste cross section ad, i exposed o worg sraces, may lead to

galig Weld repair is generally unsatisfactory de to poor bodigad ig residal stresses is is an unacceptable separao blaag Dscripion: CRB sepaator wit oe integaly cast siderailad crossbars s viewed o ts ID Milled recesses are o eaccrossbar Of te tee crossbars sown tose at mage N ad Ssow large rregularly saped pits from maco-porosity filed witarc-weld material (ece te ipped surface)Suspctd Causs: Sand casting of arge broze components ofcomplex sape suc as tis separator is a difficlt process Cleaingof gas duing md fillg may fail leaving bubbles entrapped wiccreate macroporosity As a salvage operatio tugsteiergas(IG) ac weldig is at times attempted to i te pores



Falure Code Falure Code

DAAPat o: 615

Archiv o: 087045Iag typ: ligt crograScalba 1 cros 20% oters 100% 50%)Coponnt: DGBB; G glass ibernylon separaor rnSpd:oad:Lubicaton:Faur Cod 014 Separator castng or olding defecFaur Cod 0131 Separator pocket wornFaiur Cod Faiur Cod

DESRONSFaiu Dscrpton: In a gassbe reinforced nylon balbeaing separaor bal pocket, protruding glass fibers weeuncovered fo te nylon arx by a olding erro and bywea in service Suc fibers scrac bas, break of and cause

Chptr 16 Guiding-Cmpnnt Filur

indentations n roling suraces. Te bearing rns wit g torque and noise and it ay spall peaturelyIag Dscrpton: NW iage quadant sows a quaer-cicle fo a ball pocket wit dak background. igt gray ateia is areinorced nylon separator Glass fbers protude nto e bal pocket.Suspctd Causs: Glass-fiber reinorced nylon sepaators are used n aerospace insruen and oer bal bearings. Wenpropery ade, an uninterupted nylon contact surface s pesented to e balls If te separaor was iproperly olded or afteeavy wear gass bers ay becoe exposed scratc balls beak off and dent roling contacts

DAAPat o: 1616Archiv o: 01860Iag typ: ligt acroScabar 3 icros: ±20% otes +100%50%)Coponnt: ACBBB B & G silver plated seel separatorrunSpd:Load:Lubrcation: syntetic polyeste oil, Faiur Cod 01116 Separator plating defectFailur Cod 01131 Separator pocke wornFailu Cod Failur Cod

DESRONSFalur Dscrption: Silver pated seel separaor ofACBB wt blisered plating in ball pockets Te plating

s elevated above srrounding surace and wearsPocke galing o separaion of plating lakes is likelyupon contnued unnng lakes ay indent te roling sufacesIag Dscrpton: Macined silver plaed stee ACBB sepaator is viewed on ODTe ball pocke acing iage S sows wocrescent saped roug-edged dark areas were siver plaing as blistered up above te surronding surace and is worn Te ballis visibe furter S n a droppeddown position relaive to its operating postionSuspctd Causs: Silver platng o seel separators reqires a tin copper under-plating or good adesion Ts was ound to beissing in te present case peritting e blisterng Wear o e elevated, poorly supported siver plate as occred at te ballcontact.




DAAPlat o 16.7

Arciv o 0144Imag typ: ligt macroScabar 10 mm (micros 20% oers +100%50%Componnt: TB I&&G (stamped steel separator)ununSpdLoad:LubricaonFalur Cod 01.12 Separaor plastic deformatioFalur Cod 00.09 Geomery assembly or moutingdefectFaiur Cod -Faiur Cod

DESRONS

Falure Code

Failu Dscrpton: Siderail of stamped steel separator at large-ed of TB l (coe) is stove in from dropping o te l/rollerassembly durig montig Te deormatio results in mislocation of te crossbar insuffciet oller pocket looseess ecesswear and possbly eat imbalance failureImag Dscrpon: TB l/roler/separator assembly is viewed fom (large) sideace Between wo rollers at image N cete tecircuar sape of te sepaator sderai is bent nwardSuspctd Causs: Accidetal dropping of an assembly is likely to case brnel damage between e rolles and IR n tis caseseparator deformaio as reslted because impact was o te separator edge

DAAPat o: 1618Aciv o: 01448Imag yp: viewScaba 10 mm (micros 20% oters: +100% 50%Componnt: TB I&&G (stamped steel separator) unruSpdLoad:ubricaion:Failur Cod 0112 Separator plastic deformationFaur Cod 00.09 Scorig rom orcible assembly ormonting (o gallig)Faiur Cod Faiur Cod

DESRONSFaiur Dscpton: Severe sarp indetatios in te (smalled) sideface of e separaor from drift' sed to mout te onto a tigt seat Te separator sufered overal

deformation ad local bending of siderail to roller pocketscausig local rubbing Te bearing is ikely to ru wit igfrictio and overeat e separator may break at icks fromormal roller orcesImag Dscription: An l/rolle/separator assembly is viewed oblqely from small-ed Numerous sarp icks acoss teseparato sideface from a sapedged drivig tool (drift') At tree rollers in SW quadrat te rail is bet i toward rolersSuspctd Causs: Mouting o iteerece-fitted l (cone) requres a ubular driver contactig e sideface Use of a driftdamages te separato ad by drving trog te separato ad ollers to te trust flage may case role-ed and/or flagedamage



Falure Code 3

DAAPlate No: 1619

Archive No: 10300 &002Image type: a: view, b: lght macroScaleba a: 3 b: 2 mm (micros: 20%othes: +100% 0%)Componen ACBB G (poros polyimide separator),ruSpeedLoad:Lubrcaon sythetic hydrocarbon impregatedseparator, 2°Falure Code 01131 Separator pocket wornFailure Code Failue Code Failue Code

DESRONS

Chapter 16 Guiding-Component Failure

a b

Falure Description: (a): 360 circumferentia wear i the sepaator pockets due to dyamc istability causing high-speed whir othe sepaator i a highspeed gyro spin-axis bearig. (b) Pocket wea, cefy at eading ad traing cotact points o the balls nthe pockets of a separator in stable opeatio. Separator whirl is a uacceptabe gyro bearg operag mode.Image Descpion (a) Onepiece separator wth cyldrical pockets s viewed oblquely o sideface. Dark circle of wear exeds360 aroud pockets, as the result o separator whrl (b) Similar sepaator, partial vew on OD A elogaed but ocaed dakcontac area is visibe at N in the pocket a mage N, and at S in the pocket at image S. A fait cotact mark extendscircmferetally in both pockets This separator has operated without whirlSuspected Causes: Porous, oi impregnated polyimide separators are sed in gyro spinaxis bearigs. They are lad gided, wihclearace to permt ree motio Normally, separators run excentricay bt stably xcitaton by frictio forces ca lead to a whirligmotio consumg energy, increasing separaor foces ad wear and degradig the reired smooth, constanttorqe opeaion.

DAAPate No: 16.20Archive No: 002-002Image ype: ligh micogramScalebar 2 mm (micros ±20% others + 00%0%Component: ACBB G (silver plated stee separator), runSpeed: 1.7 MdNLoad 14 GPaLubicaon: syntheic polyester ol 176Falure Code 0131 Separator pocke worFalure Code Failure Code -Failure Code -

DESRONS

Failure Descrpton: ve-spaced impac wear' i the silverplatig of a separator pocket, aong with norma polishingwear i the slver plate. I highspeed aerospace bearigs,ballsepaator cotact nde D conditions was observedto cause peodic wea marks attributed to intermittet ballimpact o the platg. The ormal wear area is adjacet. he beaing has ot faed.Image Descipon Bal pocket surface o (sectoed) separator. Sldig direction is S to N. Separao etaiig prog s at mageN Dark-appeaing poished ball cotac pach is i S image half. Arrows idicate lightdak NS gers" worn silver platg bympact wea'Suspected Causes: Noma (smooth) plating wea is expected i a separator pocket Data ae limited cocering peodc impactseparator wear attrbuted to iermittet lbrcated bal coact The kiematics of the periodic wear markig are ot clearyuderstood.




DAAPate No: 16.21

Arhive No: 087-111Image ype: ight macroSaebar 5 mm (micros 20%, others + 100%, 50%)Component: DGBB B&G (samped steel separator), ruSpeed:oad:ubrationFaiue Code 01.131 eparator pocket wornFaiue Code 00.12321 mooh rollng sace wear (fiishmarks removed)Falure Code 00.17.1.2 Microspallig (advanced sace distress)Falure Code 00.16.02.4 Icipiet spalling multiple spalls

DESRONSFaure Desripton: Conceric wear scraches in a separaor balpocke cocetrated ear he separaor ID Mate, wor ball srfacewith iear bads of srface distress microspalls and icipietmacroscopic spaig he failure appearace suggests solidcotamiatio The bearing rns noisiy has lost accuracy ad islikely to ail from early spallingImage Desription: I N image half is a bal with uiformly matteworn sace Linear narrow bands of microspalls extend from Npoe southward, ad in E quadrat of ball image. A ball cener and

Falure Code 3

in E quadrant some macro spall craters are developng The no-ccular ball conor is an imaging aifact. n the image half ishe ball pocket of a stamped ribbon separator, with ligh ad dark cocetric wear scraches near both edges strongest near N(ID) edgeSuspeed Causes Geeralied wear o ball and retaier suggests ne soid contamiat i he ubricant. Overrolling o the ballsurface damaged by wear produces sace disress microspallig and evetaly macroscopc spalls.

DAAPlae No: 1622Arhve No: 027-18Image type clor vew [EE IMAGE IN APPENDIX]Salebar 10 mm (micros: 20% others: +100% 50%)Component: DGBB; B & G (samped steel separator) rnSpeed:oad:ubiaon grease, Faure Code 01131 eparator pocket wornFaure Code 001 91.1 Generalied emper colorsFaiure Code 12502 evere grease contamiationFaiure Code PATE 3.1

DESRONS

[ mg App]

Failue Despton: Temper clor on separator and ball. rom Plate , the exposure temperaure was approximately 210°C. Thebal shows scratch marks from abrasve wear by a contamiat (covered by temper clor) resh heavy scratch marks are i heseparator pockets evere grease coamiation by abrasive sods is suspected. Bearing is nosy, may ru ho.mage Desripion DGBB ribbo separao half is viewed on the iside face. Oe ball is show Boh compoets show browtemper clor The bal shows radom wear marks nder the emper clor The separaor bal pockets show fresh, meal-coloredconcetric wear marks (arrows).Suspeted Causes evere coamiatio of lubrican wih cotamiat (probably extraeous abrasive) causes abrasion beweeballs ad separator ball pockets. Cocentrc scratch marks in the separaor pocket are he result. crach marks on he ball mayo be concentric if the ball has indexed Overheaing of the bearng resuts from high fricto i the presece of a conaminat



Failure Code 3. Chapter 16 uidingComponent Faiure

DAAPate No: 1623

rchve No: 087006Image tye: ligt macroScalebar 10 mm (micos 20%,othes + 100%, 50%)omonent: ACBB G (macied rozeseparator), ruSeed:oad:ubicaton:Faure ode 0131 Sepaator pocketwoFaure ode 010 Separato mauactrig geometry deectFaure ode 111 rictio polymer, oi luricatioFaiure ode

DESRONSFaiure Descriion: 360° crcumeetal wear ad i al all pockets of a machied roe sepaato, dicatig isufcie pocketcleaace due to dimesioal error i mauacture Beag is likely to u at excessive temperate leadig o eat imalace faiureDecomposed ol coaig (ricto polymer) o ocoacig retaier surfaces idicates igemperatre operatomage Descrition: A segmet of a macied roze separator a as all pockes cylidrical a OD ad sperical a ID to retaials Dark coatig (possily fictio polymer) is o te saces, except i a 360 crcumfereial shiy wear ad (arows) i tecyldrical part of te pockes, ad a few wea patches i te sperca part of the pocketsSuseced auses Normally dmesioed all pockets sow wear marks ear frot ad rear ceter, were all forces producecoac uder load A pocket wth isciet cearace rs over ere circumfeece Cotact i sperical reaiig par ofpockets does ot appear excessive

DAAPae No: 1624

rchve No: 002-012c&dImage tye: a: ligt mcrogram : SEMScaebar a 1 mm 20 Jm (micros: ±20%, oters + 100%,50%)omonent: ACBB G (siver plated steel separator), uSeed: 05 MdNoad: 22 GPaubricaon sythetic polyester oil, 3Falure ode 01131 Sepaator pocket worFalure ode 011 6 Sepaator paig defectFaure ode 113 Solid cotamiat i oFaure ode -

DESRONSFaiue Descrition Sepaator all pockets damaged y (1) emedded

solid cotamiat, (2) wear, ad (3) rregar platig (odes) ecotamiaed pockets were foud to damage alls ad hece racese iregular platig wears premaurely Bal surace damage is expecedto result, ad earg falure may olowImage Descition (a) Sectioed separator pocket is show, exposgal cotact surace he dark EW ad ear te pocket ceerlie isthe all cotac pat Iside ad to N o this ad te may smallgraiy potrsios are patig odules' Arows sow emedded metalcotamia () Edge o the all cotac path (laeled) rus EW ustS of mage ceter, wth the smoot srace of te ad to te Sxtraeous metal flakes are olled i at te arrows is a platig oduleSusected auses: he platig odularity is due to a processigdeficiecy he emedded metal flakes come rom exraeouscotamiaio e coama as ee oserved to damage alls

a

b




DAAPate No: 16.25Archve No: 02-256Image tye: clor view [SEE MAGE IN APENDIX]Scaebar 20 mm (mcros 20% oers +100% 50%Comonen: DGBB (cartridge; IR&G (stamped stee runSeed:Load:Lubrication grease ? Faiure Cde 01.131 Sepaator pocket wornFailure Cde 01133 Separator wear from unntended contactFailure Cde 00124 Wea o guidingcomponent suppo suaceFailure Cde 0141 Separator pocke galed

DSRONS

Falure Code 3Falure Code 3

[ mg A}

Failure escritin: e ball pockets are worn and galled Wear and cipping (F 011.2 occurred on separator ID in unintended

contact wit IR land, wic is also wo e circular sape of te separator is distored ( 01.12. Hig separator/ball focescaused pocket wear, increased separator looseness and unintended contact wit te IR land e separator was empoariy caugtbetween ball and groove edge causing greater forces, pocket gallig, cipping and distoed sapeImage escritin: At image W is te IR, wit dased dark wear maks on ands and a dark contact band in te groove. eseparator alf at image E as lost its circular sape e W-most pocket s cipped at e ID. Al pockets are worn Galled patcesin te S-most pocket n two pockets to its E, and n one o its WSusected Causes: e separator may ave been distored i assembly or lubrication may ave failed causing ig separator/ballforces esulting n complex wea galling and distorion Erratic orbital separator motions may occur causing e dased marks onte R. atridgetype (wide DGBB ae grease lubricated Bearing may ave been run past functional grease life, precipitatinglubrcant faiure

DAAPate N 1626Archive N: 003007

Image tye: lgt macoScalebar = 4 mm (micros ±20%, otes +100%,50%Comonen: RB G (macined brone separaor, runSeed: 22 MdNLoad:Lubricaon: syntetic polyester o ? Failure Cde 01.131.1 Sepaator crossbar worn,one pocket sideFailure Code 01.131.4 Rolle separator pocketbottom wornFaiue Cde 01112 Sepaator fracture cackngFalure Cde

DSRONSFailue escritn: Wear o separator crossba andsiderals. Plating on te crossbar is won troug. eplating peeed and te crossbar probably cracked troug. Roller forces rom a skewed roler produced dogbone" wear pattern.e bearing is likey to fal soon due to separator fractue.Image escron Oblique view of separao pocket from OD e siderails are at E and W e rolle contact face of te crossbaris at S center, wi retainng tangs at S A second crossbar is out-o-focus a N image edge Sarp wear marks (gouges are atbot corner radi of te crossbar A dogbone-saped dar wear scar is in te crossbar sideface, wt pating worn troug(dark. A jagged da crack ine appears near te W coner. e edge of te plating is ifted a te cackSusected Causes: Hig-speed RB at times suffe severe roller/separaor oading wen rollers skew (example: om unbalance.oads between roler end and siderail cause oler end and separator wear (see te arp cut into corne radius. Load on tecossbar from roller edge contact (skewed roller causes dogbone wear pattern and, secondarily cracking



Failure Code 3Failure Code 3

DAAPate No: 16.27

Archve No: 003003Image tye: ligt macroScalebar = 4 mm (micros 20%, otrs 100%, 50%)Comonent: ABB B&G (silvr platd stl sparator) rSeed: 2 MdNLoad:Lubicaton: syttic polystr oil 120°Faiure Code 011311 Spaator crossbar wor, opockt sidFaiure Code 0117 Sparator contact spaligFaiure Code Faiure Code

DESRONSFaure escriton:

War troug t sivr plat of asparator pockt Spallng in t udrlying st sparatormatrial s uusal failr mod is attibtd to ig bal

Chater 16 Guiding-Comonent ailure

cotact loads rom baing misalignmt udr vry good lbricatio of t sparaor ball contact, wic limitd war adprvtd gallng, alowing t cotact load to prodc a spall Barig faid by sparator ractr itiatd at aotr spall (otsow)Image escrition: Vw is on sparator OD, wit balls droppd blow normal posio by rmoval o t I pockt towardimag S sows igt csct-sapd ball contact wit silvr plat ovr 10° agl. At t pockt ctr, a dark, fatrd lipsas worn trog to stl. cnral aa of t llips sows t factu surfac of a spall cratr A addtional small spot ofsilvr pat rmoval s 4 from W imag dg in t sam pocktSusected Causes: Misalgmt o barig was obsrvd ading to svr anglar vocity and pas diffrncs amog ballsand vry ig bal cotact forcs on t sparato War, gallng, possiby at imbaac woud b xpctd Spallig of mdimard stl sparator is uusal and idicats xcllnt coolig ad lubricatio of t contacs

DAAPate No: 162Archve No: 01-2Image tye: ligt macroScaeba 10 mm (micros 20%,otrs: 100% 50%)Comonent: SB G (macnd brosparator) rnSeed:Load:Lubcation:Faure Code 011321 Lad giddspaator, guid sac wo, gralFaiue Code 0113.3 Sparator war fromnintndd cotact

Failure Code -Failure Code

DESRONSFaure escrition: Macid bro ad-gdd SB sparator wit cntr rng and catilvrd progs is won avily ocntr rig guid srac contactig I ctr flang OD. rsulng adial displacmt as causd I contact at ID of tprogs, and war Sparator fractr o baing sir is likyImage escrition O-af of a wo-par macnd bron SB sparaor s sown, wt ct ing facing to imag S andprongs o N. sdfac at t S mad cotact wit t ot sparator al and sows slgt polisig nar t D. adjactcylindrical ID was origially at t prog ID lvl; now it is avly worn down prong ID sows dark war pattrn.orrspodig wa of t prong sids cotactig t rollrs is not visibl i tis imagSuseced Causes: Inadat lbicato probably wit contaminatd ubicat possibly combid wt og I ctr flagOD sufac, can cas avy war. sparator will drop down o t rollrs as t rollr contact suracs wa, vntallycontacting t D rolr pat at t prong ID, casig war



ailure Atlas for Hertz Contact Machine lements

DAAPate No: 16.29

Archive No: 087-010mage type: viewScalebar = 5 mm micros: 20%others: +00%, 50%)Compoet: BB maximm complement);G 2-piece separator), runSpeed:LoadLubricatioFaure Code 013.3 Separator wear fromunintended contactFaiure Code 01.11.2 Separator fracture, crackingFaiure Code 20.01.2.1 ouling o monting partby other moving part

Faiure Code

DESRONSFaiure escriptio Separator sideface and rivet head wearfrom unintended contact wth stationary mounting parhree cracks run across he thn cross sections over theball pockets his is a gross failreImage escriptio: Maximum compement ball beaingwith machined, riveted two-piece sepaator is viewed onsideface. he dark gray separator sideface including iveheads) shows deep wear with plastcally flown edges. heworn areas are of ighter clor. Black agged cross-section cracks are at the arows

Falure Code 33Falure Code

Suspeced Causes: Incorect dimensioning of housing o end-cap alowed contact of the separator sideface with a stationary part.In most ball bearings the separator is wholy contained in the OR outlne, bt not in this design) eavy wear and large ball/separator forces resulted which have ultmately led to cosssection crackng nder the hoop stresses

DAAPate No: 6.30Archive No: 093-1312Image ype: light macroScalebar 40 mm mcros 20%,others: +100%, 50%)Compoet CRB;G 2-piece machined bronze separator), runSpeed:Load:Lubricao: oil, ? Faiure Code 01.141 Separator pocket galedFaiure Code 01.131 Separator pocket worn

Failure Code Falure Code -

DESRONSFaiure escrpto: xtensive gallng and wear) ofseparator prong/roler contact suface, pobably nitiated by solid conaminant. Galng of this severity causes a large volme ofdebris, adding to the contamination. his may precpitate contined wear, galling, heat imbalance faire and seiureImage escriptio: he machined brone separator consists o a siderail wth intega pongs and a sepaate closing ng notshown) attached by rvets passing hrough the prongs. he image views the separaor fom the OD. he enre prong srfacemarked is coveed with cicmferential steaks o lightappearing gaed metal on a dark background of the origina materia hetransferred metal is hgher than the origina suface and s polshed by wear aganst the rollersSuspected Causes: his very arge multirow CRB worked in a steel rollng mill in a severely contaminated environment both waterand soids) Galing at highspeed siding contacs between the separaor and rollers can result and s progressive, sincecontamination contines and water degrades he oil mist ubrication.



Faiure Code Failure Code

DAAPate No 1631Archie No 027-209Image type lr iew [S IMAG IN APPNDIX]Scaebar 15 mm (mirs 20% hers +00% 50%)Compoet DGBB B & G (samed seel searar) rSpeedLoadLubrcatio grease, Failure Code 01.15 Seaar rrsinFailure Code 00.20.01 Geealized rrsiFailure Code 12. Waer in greaseFalure Code

DESRONS

Chapter 1: GuidingComponent Failure

[ mg App

Falure escrpto Generalized rrsn f aessble sufaes n bals ad searar Rieed searar i srfaes are n

rrded. his degree f rrsin ases frii and wear nnued runig, rrded rllig saes are liely sall.Waer (seawaer) in he grease is he ms ikely sure f rrsi.Image escrpto ne half f rieed ribb' searar disassembed, is ewed n ball a saes Pke suraes areered wh brw rsn. hree balls are als rrsi-ered he searar f saes wh rie hles shw a few saisnly, where waer seeed i he grease ak may shw he resee f waer (C 12.4)Suspected Causes he bearig was eraed shibard eirnme and may hae been exsed seawaer sray r mis.Grease namiaed wih seawaer is a seere rrding lee

DAAPlate No 1632Arche No 027142Image type lr ew [S IMAG IN APPNDIX]Scalebar 10 mm (mirs 20% hers +00% 50%)Compoet ACBB; G (hel searar) (2), ru

SpeedLoadLubricato gease Falure Code 0116 Searar hea mbalane fareFalure Code Faure Code -Faure Code -

DESRONS

[ mg App

Faure escriptio Cmarsn f asmanufared ad erheaed henli las searars fr ACBB erheaing rdeshemia demsii he las reealed by dislrai. Demsin auses he lasi lse srengh and i aybeme brile Searar raure may resl.Image escrpto w heni lasi ACBB searars are iewed blqely n D he searar a W s f he asmaufaured a lr. In he searar a lr has haged greenish-blak frm exsure exessie emerare.Regiin f he lr hange reqires a baselie f as-mafaured lrSuspected Causes Plasi searar maerials are sensie eleaed emerare Differe asis may el (hermlasimaerials) r hemially demse (hermseig maerals) a exesse emeraure. mbrilemen and lss f ensile sreghends ur as a resl f hemial hages ee i he absee f melig n bh lasses lasis.




DAAPte No: 1633Arhive No: 07-14Ige type: lr ve [S IMAG N APPNDSebr 15 mm (mir +0%, ther +100% 50%Coponent: DGBB; G (tampe ibbn' eparat, runSpeed:od:ubrtion: greae ? Fiure Code 0116 Separatr heat imbalane falreFiure Code 001911 Genealze temper lrFiure Code 011 Separat plati efrmatinFiure Code PLA: 13.1

DESRONS

Falure Code

[ g App]

Flure esripton: Dak brn tempe n the enire epara ae, frm taine verheating f the bearing FmPlate 131, he temper l r rrepn apprxmatey 30°C veheating temperatre Whie a high temperatre the eparati eakene an trethe hi may aue ntat th ing lan, eging an eizreIge esrpton: Onehalf f a tpar, rivee ibbn-type tampe ball bearng epaatr remve fm bearng, i vieen the fae Clr f the entire viible uae i ak brn niative f expre t high temperatue (temper lr he ballpket ae platally engate frm their riginal emirlar hape (ee S-fang pketSuspeted Cuses: Inaequate lubriatin, velaing r lak f interna lene are lkey t verheat the bearing If tainetemper lring may relt

DAAPle No: 1634Arhive No: 00-014b&Imge type: a, b light marSlebr a 0, b 10 mm (mir ± 0%

ther: +100%, 50%Coponent: ACBB G (ilver plate teeleparatr, runSpeed: 17 MNod: 15 GPaubriion: ynthet pyeter il 176°CFure Code 0116 Separatr hea imbaanefailreFure Code 01141 Separat pket galleFiure Code 115 Carbnize il eptFiure Code PA 134

DESRONSFilure esrpon: Bearing ha uffere heat imbalane ailure, reulting

in galling an ht plati fl in the eparatr pket a arbnizebriant ept n the epaatr an xiatin f the ilver plating hi a g failre See al Plate 34 fr amage t the ballIge esrpon: (a: Separatr i vee n it OD he entire viibleurae i arkene an pathy here the ilver plate ha xize anpeele ff an here arbnize il a epite he pket ege arepeene (ar (b Setin exping the pket urae, ith heavyabnize il epi (bak faking epit veing gale tranferemateial he ege at the arr an the light-lre material W f thearr i galle tranferre mealSuspeted Cuses: Mnting err a berve n he beaing, leaing IR rtain n the haf, high veheating an erutin f ballepaatr an lbriant

b



INTEGRAL CLOSURE

FALURE 17Faiure Code 02

Genera Description

Inegra cosures are par o some roing bearngs, nended o keep ubrican in he bearng and Ior keep conaminans ou Typicay, hey are irmy aached o one o he bearng rngs, whie heoher ring roaes pas edge or ip o he cosure The wo main ypes o negra cosures are sealsand shields.

Seals, ha is, rubbng seas, have a (exibe ip n siding conac wh a surace o he reaiveymoving par hese seas ypcay consis o he oowing

A seal contact surface provided on one o he bearing rngs and consising o a cyndrca, cocaor oroida, mosy ground or poished, surace or he exbe sea ip o side over

A seal body made o an easomer, and comprsing (a one or more lips ha sde over he seaconac surace under some pressure, and (b a a, rngshaped body, oen reorced wih amea nser, wih an edge ha is snapped, saked or crimped no a recess n he bearng rng,ormng a saonary seang nerace wih ha rng. Sea bodies are oen designed wih sharpedges on he ps o ensure igh conac wh ow ricon. A common mehod o producnghese sharp edges s tear-trimming whch a hn shee o easomer is aowed o prorudeino a gap n he mod and is subsequeny removed by earing over a sharp mea edge

Shields are smpe gap seas, wh a narrow space beween he reavey movng suraces Thesesheds are generay made o shee mea or shee pasc hey are aached o one rng as is a seaand have an edge ormng a narrow bu e gap agans a roaing surace o he oher rng Nonconac sieds are no eakree cosures. hey serve wo purposes

Proec he insde o he bearng rom accidena ingres� o szeabe oreign bodes2. Lmi egress o grease

Rotating ingers are (roang sheds aached o he nerrng o he bearng and paced ousdea (saonary shied or sea o expe impngng sod conaminans

Note on mage Material Limitation: Phoographc images o aied negra seas are no avaiabe or

his Aas As a subsue, a Pae wih setches o seas usraes he dsincive appearance o someaiure modes. Chaper 9 Mouning par aures,' comprses some images o aed external seasThe aiure modes o exerna and negra seas are simar, hereore some gudance as o heappearance o inegra sea aures may be obained rom Chaper 9.

7 Deiniionhe aure modes in abe . appy o negra cosures

7 NomenclatureThe designaons used n hs Aas are common in bearng ecnoogy




Table 1 7. AILUE MODES O IEGAL LOSUES

Failure desciption Failue CodeRg f Pre-service defect (seal) 0 2 Wear (sea) 022Torn ip (seal) 023Leakage (seal) 024Chemical attack (seal) 025

N- h f Pre-service deect (sield) 022Wear (sield) 0222Leakage (sield) 0223Cemical attack (sield) 0224

17.3 RUBBN SEAL FALURES FALURE CODE: 021

7.3 Failure Process

111 Preservice Defects of Seals Failure Code: 0211

. Geometry defects o he sea

Dstorton o mea pars Moldng error n easomer Defect n teartrm o easomer.

2 Mcrogeometry errors o sea conac surace (excenrciy, waviness, rough surace nish3 Elastomer ntegrty defects (ears, gaps4. Elastomer materal defects (ospecicaion composon, embremen, ackness, gh rcon

coecien, ow wear resisance

112 Wear of Seals . Failure Code: 0212Boh he sea conac surace and he sea ip may wear, n eher he wobody (adhesve or hree

body (abrasve wear mode. Sea lps are paricuary sensve o wear aiure as heir precise geomerys decisve or eecve seang acon whou excessve rcon.

Note: Some sea ps are designed or conroed wear during runn o provide a conac band o suiabewidh or he suppor o he sea ip pressure.

11 To Seal Lip Failure Code: 021Easomeric sea ips are rage Ia damage (e.g., during earrimmng, abrasion or momenary

adheson o he conac surace may sar a ear n he ip edge which progresses during operaonA ear may eak and may evenuay separae a piece o he ip eaving a gap.

114 Seal Leakage Failure Code: 0214Leakage pas a sea may occur whenever he conac beween sea body and bearng ring (a he

nsaaon nerace or n he sea conac s inadequae Leakage ncudes wo aure modes

• Leakage o contamnant ino he bearing Leakage o lubrcant ou o he bearng



Chaptr 1: Intgral Closur ailur

Souces o ekge e

• Uiended openings;• nsuicien lip pressure• Pressure derential coss he se• "Screw pump eect whee ishing mks on he conc suce hve scew-ed ype

"ed moving ubicn o conminn xiy unde he se.

115 Chmical Attack on Sal Failur Cod 0215The esomeic se body is subec o chemic ck by ubicn o mosphee especiy

when opeed ho. The esome my embie o become cky, cusing he ip o sick o heconc suce nd o e

The me se conc suce my coode esuing in highe icion nd in bsive coosionpoducs in he se gp h my cuse we o se o conc suce See C 00.20 nd C 01.15

o souces o chemic ck on he conc suce

73 Distinctive AppearanceGeometry errors and distortion (C 021) my be obseved s ieguiies in he se conc.

Lekge my be n indicion o geomey eo, o be conimed by dimension mesuemen.Wear (C 02) my eve visibe we mks on he se body o poish he se conc suce

Lip we o mgniude suicien o cuse ekge o high icion my be discebe by inspeciono he ip edges unde mgniicion.

The torn lip (C 02.3) o conc se is bes obseved on he dismouned seLeaage (C 02.4) o ubicn ou o he being is mniesed s beds o gese ouside he se

( he inseion inece o he se gp. Gee ekge cuses gese o be ung wy by oingps Lekge o conminn ino he being is usuy deeced e emov o he se SeeC nd C 2 o dignosis o ubicn conminion

Chemical attac (C 0215) on me se ps is ecognizbe s us Chemic ck on esomesnd psics is geney no mophoogicy discenibe excep s oows:

• Embrittlement my esu in visibe ccking• Taciness o esomes my be e by ouch.

733 CausesPreservice defects (C 021) cn occu n he mnucue o he se o he shng o he se

conc suce. Inseion o hese ino beg ng my ed o disoion o ck o igh i

pemig ekge.Wear (C 022) is commony due o he oowing cuses

• Se geometry eo cusing excessive se pessue• Impope surface nish o conc suce Rough suces, bu so eivey smooh unpoished

gound suces wch hve shp-edged speiies pomoe we• Deecive elastomer mei wih ow we esisnce• Lck o lubrication. A conc se equies h im o oi (om he oing being gese o

void we.

A torn lip (C 023) my ise om

• Manufacturing deec• acy esome dheing o conc suce• Indeque se ip lubrication



Falure Atlas for Hertz Contact Machne Elements

Leaage n the movng nterface (FC 024 beween ip and conac suface may be caused by

• Manufacturng defec in sea o conac suface• Defecive nstallaton of sea• Wear• Torn sea ip• Excessive grease chage o unsuiabe gease in he beaing• Overheatng of he beaing• Beaing msalgnment.

Leaage at the statonary nterface (FC 024 whee he sea body is mouned ino he beaing ingmay esu fom

• Manufacturng defec in sea o beaing ing•

Defecive nstallaton of he sea• Excessive grease chage o unsuiabe gease in he beaing• Overheatng of he beaing• Pressure derental acoss he sea (in pumps o in chambes n which cosed ai voumes chge

empeaue

Chemcal attac (C 0 2 is caused by aggessive ubican o amosphee

174 NON-CONTACT SHIELD FAILURES FAILURE CODE: 02.2

7 Failure Process

1.4.1.1 Pre-servce Defects n Shelds Falure Code 02.21

• Geomet eos of he shied he hoding goove o he maing suface foming he gap mayincease eakage o cause ubbing

• Installaton defecs may cause eakage a he insaaion ineface o diso he shed andcause ubbing

1.4.1.2 Wear of Shelds Falure Code 02.22Nonconac shieds wea in wo cicumsances:

• Unntended contact wih movg ing due o defomaion o geomey eo• Contamnaton wih abasive maeia ha enes he shied gap

In eihe case he shied as we as he maing suface may wea

Note A aey used shied design equies iniia shied wea o fom he shied gap

1.1. Leakage at Shelds Falure Code 02.2Nonconac shieds ae no eakfee in noma opeaion Excessve leaage (conaminan ingess

o ubican egess may have he causes ised in secion 743

1.4.1.4 Chemcal Attack on Shelds Falure Code 02.24See C 0020 and FC 0 fo souces of chemica aack



Chapter 1 ntegral Closure Failure

7 istinctive Appearance

Geometry errors and distortion (C 02 .2) may be observed as irregularities in the seld gap Leakagemay be an indication of geometry error, to be confirmed by dimensiona measurementWear (C 0222) may leave visible wear marks on the shield body, or on the unintentonally)

contacted surface of the ring across the shied gap.Leakage (C 0223) of ubricant out of, or contaminant into the bearing is manifested the same as

for seals see Section .3.2).Chemical attack (C 02.24) on meta shield parts is recognizabe as rust

17.4.3 Causes

Preservice defect (C 02.2 ) See C 02.Wear (C 02.22) is due to geometry error in shied or bearing rings

Leakage (C 02.23) in excess of permissibe evel may result from

Geometry error wide gap); Excessive grease charge for the design); Excessive contaminant outside the shield; Overheating of the bearing; Excessive vibration of the bearing causing grease to slump.

Note: A non-contact shied is suitable for use if it is intended to bleed off a pressure differentia acrossthe closure.

Chemical attack (C 02.24) is caused by aggressive lubricant and/ or atmosphere

7 Effects of Integral Closure FailureTs section covers both rubbing seals d seldsLoss of lubricant may resut in the folowing faiures:

Insucient lubricant remaiing in bearing, with resulting failure from inadequate ubrication; Lubricant contamination of parts outside the bearing

Contaminant ingress nto bearng may cause failures of the lubricant or of bearng componentsExcess heat generation may occur the bearg due to seal friction



Failur Atlas for rtz Contact Machin lmnts


P N

02

0 2 2

0 2 3 0

0 2 9



Failue Code

PLATESDAAPate No: 17.1Archive No: 1171 &&5Iage type: a c dawgScaear -

Copoet BB S (modd tgral lastomr sal)Speed:LoadLrcatio:Faire Code 011 Ruig sal warFaire Code 01 or rug sal lipFaire Code 019 Gomtry or assmly dfct i

ruig saFaire Code 01 Ruig sal dfct PLAES: 191 ad 1913

DESRONSFaire esciptio: Sktchs (a) throgh (c) show crosssctios of itgral rg arig sals sal ip war (F011) ; 8: tor sal lip (F 0.1) dformd sal gomry(F 0.19). Othr failr mods (ot show) ar coutacwar (F 013) ad chmical atack (F 015) Sal lakag(F 0014) from ay of th aov failurs may slt iarig failu Excss hat gratio may caus hatimalac failur (F 0019).Ige escrptio: (a): Atomotv whl sal with mtalcasig (whit) ad lastomr ody (lack). ip wor dow to

li () Sal fo pillow locks. Radal tar i ip to li B(c) Moldd r all arig sal with stl isr (whit)Is t dow to li prvtig tight salig a ORisio ot show outfac o shaft may show warad hmical attack may cas tackiss or rittlssSspected Cases: Sal failurs may du to maufactrigdfcs sto rors, damag i arig moutg,usuital coutfac (rough otofroud) shaftmisaligmt (F 011, 0.1 013 019), xcssmpratu or spd icompatiiity or iadquacy oflurca (F 011 or 015) or cotamia igrss(F 0.11, 01, 013). Ay of ths may cas lakag(F 0.14). PAES 19.1 ad 1913 show x salfailur.

Chpter 1 Integrl Closure Filure

w



UBRANT fALURE 18Failure Code 1113

General DescripionLbicants coveed n ths Atas a nto thee casses

. Oil (FC 1) In this cass a a (oganic) d bicants whose heoogica popetes (nceaseo viscosity with pesse) pemt EHD ims n Het contacts

2. Grease (C 2). his cass o bcants consists o ois bended wth thickenes oming semsod ges that can be packed aond moving components and can be channeed by thei moton.

3. Other lubricants (C 13). A bicants that ae nethe os no geases a n ths cass. t ncdessoid bcant componds and coatings, patcate (powde) bcants, eactve gases and

ds withot the abiity to om EHD ms, and neactve o eactive vapos which ombcant ims by condensation o chemca eaction wth the contact saces. Aso ncdedae soid ge entapped ois which ae moded aond movng pats bt do not channe.

Many bicant aies ae chemca in nate (decomposition, oxidation, o depeton o bondaybcatng additives) and ae not dscenbe by mophoogica examnation. hese aies ae notcassied in ths Atas. When they occ, they ae meey desgnated C 1 Oi ae, and kewiseo the othe bicant casses.

Lbicants, nike a othe pats o the Het contact machine eements, ae otiney epenishedo epaced in sevice. A niqe "ae" pocess estng om these pactices is ntodction othe wong bcant (a bicant othe than the one specied) This can ead to ae thoghtwo pocesses

. Use o a bicant wth the wong rheology o chemistry, o se o an mpope quantity obicant may est in any o the ae modes heeate descbed.

2. Admxte o a derent class o bicant to a sppy aeady pesent may est in chemicao physca eaction podcing an nsevceabe mixte

181 OI FAIURE FAIURE CODE: 11

DefiniionAny deect o, o damage to, the seection, qaity, o qantty o the oi bcant to a Het

contact machine eement s designated an o aie in this Atas.

NomenclareA ae designatons ae conventiona except "cton poyme," which designates a (cooed)

had coatng omed om the bcant on the contact path o a component. Ths deposit is asocaed "depost," "acqe," "sace dscooation" o othe nonspecc desgnations.

83 Failure Process

Two majo pocesses o o bication ae n Het contact machine eements ae distingshed

. Contact lubrication failure The qantity, viscosty o bonday bcating abity o the bicantin the contact inteace is not adeqate, esting n one o moe o the oowing



Failue Atlas fo Hetz Contact Machine lements

• Friction s excessve•

Wear, allin o contact fatiue faues occu pematue• Contaminant n te ubcant poduces dents and teebod wea• Wate o aggessve decomposton poducts of te ol cause corrosion

2 Coolin failure e eat emova toug mpngement of bulk o on wokng sufaces snsuffcent and oveeatng esults Ts ma n tun bng about contact ubcaton faueo dect ead to eat mbalce faue

Te system povdng o ubcaton stongl influences te ole lubcation plas n coolngte Het macne element Lubcaton b dp feed o b an mpegnated lubcant esevo(nstument beangs) povdes tte coong capact Mst lubcaton povdes coolng b teentaning gas steam, wc s effectve n steadstate condtons but as tte onste eatcapact to quenc (counteact) eat excusons (suc as n galng) Bulk o lubcatng sstemsae effectve coong means e capablt nceases n te ode sump, splas, cculatng

and et (o nace) lubcatone folowng sectons descbe canges n te o ubcant wc ae dagnostc of, and conducve

to, falue of te macne element toug nadequate lubcant pefomance

1814 Friction Polymer Failure Code: 11.1

DefiniinA iction polymer s a tn, sold, adeent coatng deposted fom te lubcant onto a contact

suface t s nsoube n commo used sovents

Failure Prcess

Unde condtons of eevated tempeate (and peaps, sldng), contact sufaces ma, aftesubstantal uing tme, become coated wt a tanslucent flm of oganc mateal deposted outof te lubcant e lteatue suggests tat tese coatngs ae pomes fomed fom te lubcantn te gpessue, g sea envoent of te Hetan contact (ence fcton pomes)Te stee contact suface mateal s beeved to act as a catast and to contbute on to tecompounds fomed

3 Disincive Appearancee fcton pome appeas as a coloed coatng on te contact sufaces only. (Tempe colo

(C 009) s not lmted to contact sufaces ) Te fcton polme s geneal tanspaent o tansucent finisng maks can be seen toug t t often foms ccumfeenta bands sepaated b gaps

wc ae of metal colo Due to eav sldng, te fcton pome s genea won awa fomfange contacts but ma pesst n olng contactsWen tn, te fcton polme s gt elow n coo tcke coatngs can be bown, edds

o geesA fcton pome s dstngused fom temper clor (C 009) b two caactestcs:

It s lmted to contact aeas2 Wen quckl wped wt a cotton swab dpped n dute (:0) HC (docloc acd) n

wate, t emans unaffected empe colo s dssoved, eavng bae meta

A fcton polme s dstngused fom dried-on rease b beng nsoube n te commonl usedsovents Dedon gease usual can be emoved (atoug often wt dffcult) b sutable solventsandI o detegents



haper 18 Lubrican Failure

A ction polyme is dstnguished om rus by coo (usually lghte and by ts pacement n

ccumeental bands n the contact aea ony Contact cooson is n patches (oten at olling eementspacing genea cooson is not conined to contact suaces.

.. Caeicton polyme omaton is pomoted by hgh contact tempeatue and (pobably by hgh

contact pessues and shea ates. Roughness o the contact suaces, the pesence o yellow-metabeaing sepaatos and the chemsty o the ubicant have al been suspected o havng an inuenceon icton poyme omaton.

hee is little data concenng specic lubcant chemsty inuences on icton polyme omationHydocabon and polyeste ols, the most commonly used, ae known to om icton polymes

Effec of Fricion olymerA icton poyme is usuay not detmenta to unctioning (wth the eception o instument

beangs in which t depletes an aleady mnima lubicant supply, but has been used as an ndicatoo sevee opeating conditons, especialy oveheatng

1815 Water in Oil

.. Definiion

Faiure Code: 112

Waer in Oil s the pesence o liquid wate n a (non-watemscbe oil.

. Failre roce

Conventional ubicating oils do not eely m with wate. Howeve, smal quantties o watecan be absobed om humd atmosphee o dectly mied nto the o, whee they ae emusiedLage quanttes may be pesent as doplets o as ee (sepaated wate.

Wate-based hydaulic uids ae used as ubcants o some Het contact machne elements.Ths ailue mode does not appy to them

3 Diincive Appearance

Smal quanttes o wate ae no visible n o. Laboatoy evaluaton is necessay2 Somewhat lage quantties o wate can gve the ol a loudy o mily (non-tanspaent appea

ance. Even lage quantites o wate may appea as suspended droples visible n tsmitted ght4 Lage volumes o wate sepaate om most ols and om a dstct layer i the ud is allowed

to stand

Cae

. Oil contaminated wth wate as supplied to the chambe.2 Wate ngess ast the chambe seal due to

• cleanng o machney• envonmenta eposue (condensation, ain, snow, oodng• pocess wate

. Leakage o wate into (cicuatng o in an ol/wate heat echange





Chapter 18 Lubricant Failure

Examination b ouch Sold conamnns o hard maras may caus h o o gritty whn

rubbd bwn h ngrps Ths occurs h parcls ar no oo n and h conamnaon sdsrbud hroughou h ol

Viewing Under Low Magnification ndr 030 powr magnicaon o o pacd on a glasssd, argr sold conanan parcs ar ndvdualy vsb

• Metal particles usually glr n rlcd gh• Machining chips or shavngs may b dsngushd rom n lamnar wear parcs by shap• Spalling dbrs ar blocky and hav racur suracs ulss xnsvy rold ovr)

Steel particles on appar slvry, whl brass and bronze parcs appar goldn Howvr,nrrnc colors or vwng ough a ayr o coord ol can chang h hus

Accuray sphrca parcs hav bn dcd n spalng alur by scanng cron mcros

copyCeramic (abrasv) parcls usualy do no gr and hav sharp racur dgs brglass parcs

rom rnorcd rolng barng sparaors) ar brs wh racurd ndsOrganic parcls may b brs x) or war dbrs rom pasc or lasomr componns)

Examination of Filter or Magnetic Drainplug Ol crcuaons ar on quppd wh lrs osumps may aur magnc dranplugs A lr colcs sold conamnans n xcss o s pors lr rsdu or h mass adhrng o a magnc dranpug can b washd and xamndundr magcaon Crra ar smlar o hos or ol xamnaon

Causes

• Chamber contamination l bhnd rom manuacur or assmbly Th conamnan can b common dus, casng sand, polshng compound, pan rsdu or chps o any o h maralsusd n h assmbly

• Oil contamination prsn n h ol as suppd o h chambr Ths conamnaon can varygray, comng rom mproprly cland conanrs, workpac dr, admxur o od lubrcan,a conamnad ol crcuang sysm, c Any mal or cramc parc may b ound Organcbrs rom wprs) ar also common

• Wear particles or spalling debris rom any o h workng componns Ts s mos on srom h Hr conac componns In h cas o barngs, sparaor maral may provddbrs Lubrcaon sysms common o svra machn lmns xampl: barngs and garsor psons) carry dbrs bwn h mns

• Process material particles n any machnry procssng dusy mara or surrs or makng chps

Th parcls can b mal, cramc or organc• Atmospheric dust carrd drcly no h chambr pas h sals Ts dus s gnray cramc

(sand or clay)• Combustion products (soot) n h crculang o o nrna combuson ngns

Effecs of Solid Conaminan in OilHard conamnans, down o mcromr parcl s, ar abrasv o h workng componns

S C 002 or war o conac componns, C 03 or spraor war, C 024 or gudrngwar and C 0222 or sal war

Sold conamnans whhr hard or so) may produc dns n Hr componns S C 008Dns ar major spalng causs




ontamnant in the oi may case noise and vibaton n the machine eement

In cicatng bcaton, sod contamination may cog fites and ets and may intefee wthheat tansfe by encstng heat exchanges

181.7 Dicolored Oil

7 Definiion

Failure Code 114

Disclred il is oi of a coo dffeent fom the nsed oi of the same type (especiay whenvewed n tansmitted ight

7 Failue Pocesshemica changes n the o may case it to discoo O dscooation may aso be cased by wate

o soid contamination Ths faie mode is defned to cove chemicl dscooation o discooaton byan known soceIn epenishing o epacng the oi sppy the machine, nadvetent seection of the wrng il

may occThe dmixure of oi of a dffeent type to an existg sppy may ceate a bend of nexpected

popeties If the casses ae incmpile, a chemica eaction may occ, podcing an nseviceabefd Replcemen of the oi sppy with one of diffeent specifcation may podce any of the faemodes heeafte isted

73 Disincive Appeaancehemcay decmpsed oi may dffe in coo o tanscency fom nsed oi n vtay any way

(incdng none ompason wth nsed o and knowedge of the appeaance of decompositon

(oxdaton podcts of the oi n se ae necessay fo dagnoss• A common discooation in ea os s drkening.• O contaig sma amonts of finey dispesed wate is milky. See 2• Sod contaminated oi s often pque and/ o dakened See 3

The wrng il o a mxte of two dffeent os may podce nexpected appeaance (coo,vscosty, odo, etc

7 Causesases of chemica decompostion

• Overheing Many ois oxdize at eevated tempeate

ote Antoxdant additives ae commoy povided to etad o oxidaton

• Ingress f recive chemicls.• Expsure incmpile mels etain synthetc o fomatons eact with yeowmeta compo

nents

ases of contamination ae sted nde 2 and 3

7 Effecs of Discoloed Oilhemca discooaton of o s sed as a waning symptom of chemca change Its potentia fo

hamf effects can be dentifed by chemica anaysis oy



Chater 18: Lbricant Failre

182 GREASE FAILURE FAILURE CODE: 12

General Descritiono mos Hez conac macne eemens grease s suppe n e om o a pack e gease may

be packe no e macine eemen (rong beang w inega cosues or no e camber aassemby. may be njece peroicay oug a cae uing sevice. e gease suppie byany o ese meos is geneay inene o be chaeled by e moving pas o e macineeemen so a e bu grease is orme no a pack surounng e macne eemen bu evoume swep ou by e moving pas s us e ee o buk grease. A in aye o oi conaigsome proporon o ckene coves e conac suaces an s repense by e movng parswiping es grease rom e pack's woking was wic ey conac uring opeaon. sbeieve a e gease wpe o by a moving pa s rcer n oi an e buk grease an ae ckene srucue s paiay broken own. n a norma gease pack o is repese a eworkng wa by capiary acon om e buk o e pack.

DefintonAny eec o or amage o e seecon quay or quaniy o e grease ubican o a Hez

conac macne eemen is esignae a grease aue n s Aas

NomenclatureA aiure esgnaions are conveniona excep "icio polymer wc esgnaes a (coore

a coang ome rom e ubcan on e conac pa o a componen. s epos is asocae eposi acque suace scooraion or oer nonspecic esgnaons.

3 Failure ProcessConac componens ubrcae wi gease aas o ose ubicae w oroug inae

quae conac ubrcaon or mbaance beween ea geneaion an ea eova. Copare woi ubicaon especay one using subsana voumes o oi o was e componens a geasepack removes minima ea. Accoingy ea imbaance aiues ue o gease ubcan mauncionare e esu o excess ea generaion no o euce ea emova by e grease.

n e oowng secions eicences in e grease pack o e Herz conac macne eemen aeescbe. oug ese eicencies e macne eemens ubrcaon is mpae an evenaye macne eemen ais. n e pesen secion ese moes o ubricaon aiue ae enumeae.

Grease ubrcaon may a uner e oowng coniions

• e oi suppy o e conacs becomes insuicen as a resu o depleio of oil a e working

wa o e grease pack.• Coamiaio increases cion osses an ipees capary oi movemen in e gease.• Poor chaelig o e grease causes is ee surace o ecee ou o conac wi e moving pas.• Excessive camber emperaure reuces o viscosiy.• Severy o coac codiio (suc as oca empeaue o sea rae amages e gease.

Effects of Grease Failuree aiure o a Hez conac macne eemen may ake pace by one o e gease aiue pocesses

escibe beow.Ieecive lubricaio wc as o pove oi e quaniy requre bu is sabe ove e sor

em may cause one o moe o e oowing aiures o e working componens




Wear of cotact compoet (FC 00.12), guiigcompoet (FC 01.13 o FC 0123) o seal

(FC 0212) Spalling (FC 0016). Galling of cotact compoet (FC 00.13), o guiig compoet (FC 0114 o FC 0124).

Cyclic grease failure aises if the oil o the cotact sufaces s eplete o cotamiate ueopeatg cotios that ae magally too seee fo the gease. ski of gease mmeiatelyaacet to the wokg wal ies out a fails to poe suffciet ol epleishmet The ubicatioeffectieess is impaie. The tempeatue of the mache eemet ises, causig the gease pack tosofte a sump. Ths iects ew gease amog the moig pts The excess slumpe gease sexpele by the moig pats a a fesh, ot oiepete wokig suface is eestablishe, poigsuffciet o epleishmet uti the cycle epeats The epeate cycles of gease amage a impaielubicatio eetually amage eough gease to peet estoatio of omal lubcatio befoeheat mbaace faiue sets i The machie eemet fas by eesibe gease faiue see beow).

Irreversible failure of ubcatio aises fom a ustabe cease of opeatig tempeaue a heatimbaace faiue. This pocess takes place f the opeatg cotios ae too seee fo the ecoeyof the gease pack escbe the peceig paagaph The faue moe chaactestc of thispocess is heat imbalance failure (FC 0019).

If the gease failue is ey gaua, failue moes iste ue effectie ubcato may aisefist a temate seceabiliy of the mache elemet

18.2.5 Gra Quantity Dfct Faiur Cod: 10

151 Definitin gease quatiy efect is efie as a excess o shotfa of gease chage i the chambe o

seale beaig).

It is commo pactice to specfy a pecetage age of the chambe o beag) olume as theequie gease chage.

1.5. NmencltreThe esigaio gease quatty efect is ucommo. Specifc eatios ae calle oegeas

ig o excess gease a uegeasig o isuffiet geaseThe tems slumpe gease pack a chanele gease pack ae commoy use to escbe

the coitio of a gease pack which the gease has o has ot softee

15.3 Fire Pcess stabe chaee gease pack is cotiget upo the ight olume of gease i the chambe. If

the gease chage is i eo, oe of the cosequeces escibe below may esue.

Excessive grease tes to slump back ito the oume swept out by mog pats, is thow cleatime a time agai chue), ut eeualy it s puge fom the icity, o softee. Softegacceleates the chug a eetualy eas to liquefaction, at which pot the pack colapses ais ofte expele fom the chambe, leag a shotfall of gease.

Insucient grease oes ot last as log i seice as the specfie pack a whe exhauste c leato faiue Seee isuffcecy may peet pope chelg fom the outset; the gease is owcea of e moig pats a emas too emote to esuppy the cotact sufaces wi lubict.

15.4 Distinctive AppernceIf the chambe s accessibe, the the gease emag at the time of examatio ca be estmate

o weghe



Caper 1 Lubrican Failure

Noe: Excessve gease tends to puge he amount found upon opening the chambe may be low, though

the failue was itated by excessive gease

Ecssv gras may be dentified as folows:

ease may be softened, lquefied ease may have slmpd into the path of movng components ease may be dscolord fom oveheatng

nscnt gras appeas as folows:

ease pack may be ot of contact wth moving pats ease may be dscolord fom oveheating

18.2.55 CsesEcssv gras may be the esult of the foowing causes

nitia ovegeasing Regeasng wth moe gease o moe fequently than specifed eakage of o into the gease, fom adjacent, inadequately sealed chambe

Noe: f ol leaks into the gease pack, t w both incease the total gease volume ad soften the gease(see FC 12)

nscnt gras may esult fom the folowng causes:

nitial undegeasing Regeasing wth ess gease o ess fequently than specifed oss of gease by leakage fom the chambe

18256 Effects f Grese Qntity DefectEcss gease may cause:

Excessive fictional losses Oveheating and heat imbaance failue (FC 0019) Softening o iquefaction of the gease wth subsequent loss of gease

nscnt gease may cause: nadequate ubcation with wea (FC 0012), galing (FC 0013), o heat imbalance failue

(FC 009) Dying out, discoloation and decomposition of gease

826 Softnd or Liqufid Gra Faiur Cod: 2

182.6.1 Definitinease wth a consstency that s modeately lowe than when unused s defned as softnd ease

of consistency so ow as to be a thick fluid is defined as ld.





Chapte 1: Lubcant Failue

Nte A sma failue may occu geag compsg a otatg iteal gea

• lvad prang mpraur softes gease ad may pecptate quefacto diectly o viachuig

• ss prang spd. ease lubcated applicatos have stct speed lmts Exceedg thespeed acceptable fo a gve gease paces geate mechaical ad thema stesses o the geasetha t ca eady suppot; these stesses ted to softe the gease

18265 Eects Grese Stening nd LiqectinSfnng of the gease pack, uess evesed upo coolg, is a selfaggavatig faiue, leadig

to gease loss Mache elemet faue ca be avoided by pugg ad eplacemet of the damagedgease, oly if the cotact sufaces ae ot yet damaged ad f the opeatig coditos causg thegease softeg have bee emeded

Lqufan of gease geealy poduces iadequate ubcato shot ode, leadg to machieeemet faue

1827 Carbonized Grease Failure Code: 122

18.2.7.1 Deinitinarnzd gease s gease cotag sod cabo patcles asig fom gease decomposto

18272 Fire PrcessExteme oveheatig of commo geases (especialy those wth soap thickees) decomposes gease

costtets to the poit whee fee cabo paticles fom hey may be fiely distbuted, butgeeally ae age eough to be gtty to the touch hey geeally become mxed wth emaig gease

Cabozed gease may eta some ubicatig abity fom the emaiig udecomposed mateal, but is geeally usuitabe fo sevce

Nte eases with clay (betoite) thckees exst etote does ot caboe, but the ogac oilcotet may etote gease, whe exposed to the gh tempeatues causg cabozatio of theoil, may poduce clumped clay patces which ca be abasve

182.7.3 Distinctive Appernce

Caboized gease cotas black paticles of cabo The ete gease pack may be dakeed bydistbuted cabo paticles Howeve, t is moe commo to fd cabozed gease adheg tosufaces of the wokg pats, o the ski of oveheated gease that may fom aog the wokgwal of the gease pack f the cabo s fiey dstbuted, t gves the gease a backsh hue, compaedto ts clo whe uused

Nte ease may show dak dscoloato fom causes othe tha caboiaio

f the thckee i a cabozed gease ca be dssolved, the ftato ay leave back cabodust o the fte pape Howeve, dak esidues may ase fom othe souces ad laboatoy methodsmay be eeded to diffeetate betwee them

·




f agglomeated cabon gans ae pesent, then dstinct black ganules can be seen in the gease

on a gass slide, unde the micoscope ttness can also be felt when ubbng the gease betweenthe fingetipsCabon gans ae of ounded shape and tend to agglomeate This may ad n dstngushing

them fom solid contamnant patices coveed with backsh o esidue, whch ae moe ikey to be angula, and aggomeate less

1827.4 Cuses

Rapid, exteme verheaing of gease in the pocess of a heat imbalance failue Sevee eplein of gease pack Remanng gease quanttes adheing to woking contact compo

nents ae nsufficient fo ubicaton; heat imbalance esults and the gease cabonzes

18275 Effects of Crbonized GreseCabozed gease has magna ubcatng abity (the oil eease abty s impaed), and ts

consstency s stffe than in the unused gease t s ulikely to pemit noma machne elementpefomance

1828 rcon Polymr

18281 DefinitionSame as unde FC 11.1 Ficton polyme n oi lubication

18.28.2 Filure rocess

alur Cod: 123

Fomaton of ficton poyme fom gease poceeds as fom oi (see FC 11.1). he fction poymeand any dedon gease esidue may both fom coatngs on the same sufaces eneally, ded-ongease can be washed off with sutabe solvents and detegents, wheeas fcton polyme is nsouben common sovents

18283 Distinctive AppernceSame as unde FC 11.1 Ficton polyme in oil lubcation

18.284 Cuses

Same as unde FC 111 Ficton polyme in oil lubcation

18.2.8.5 Effects of Friction oymerSame as unde FC 11.1 Ficton polyme in oi lubcation

1829 Watr n Gras

182.9.1 DefinitionSame as unde FC 112: Wate in oil

alur Cod: 124



Chapter 18: Lubriant Failure

18292 Filure ProcessWater can be incorporated into grease from the same sources as into oi (see FC 11.2) Due to pack

ormation, grease can entrap substantial quantities o water, either thoroughly bended with thegrease, held as drops or in sizeable pockets.

Water in grease has the same detrimental eects as in oi Additionay, some greases are washedout o the chamber by suicient water

Note: Water-toerant grease ormulations exist that resist washing out and hep to protect corrodibe partsrom smal amounts o water However, large amounts of water are detrimenta with any grease

Notes:

18293 istictive ApperceMmal amounts of water in grease are invisibe and require laboratory testingModes amounts o water can be present in two conditions:

• Bended into the grease, which gives the grease a whitish appearance (compared to the coloro unused grease).

• Present as droples which may be visible if a smear o grease is placed on a gass slide or a smalquantity of grease is squeezed at in a transparent pastic bag.

A lae cocerao o water is present as a ree phase in pockets of the grease pack or loose the chamber

8294 CusesSame as or water in oi See FC 11.2.

18295 Effects of Wter i Grese

• The same eects arise as or water in oil (see FC 112)• Grease may be sofeed with resuting sumping, iquefaction and loss o grease.• Grease may be ashed ou o the chamber with resulting loss of lubrication

0 Solid Contaminant in Grease Failure Code:

1821 efinitioGrease contamination is solid particulate matter bended ito, or present along with, grease in

the chamber Because grease can pack, contamination can be limited to ayers, or isoated voumes,or may extend through the entire grease quantity in the chamber.

18212 Fiure Processhe sources o solid contaminant in grease are the same as in oil (see FC 11.3).

1. Impropery prepared grease thickener may be a source o granules, which may produce noise(less often cks). Examples foow

2. Bentote thickener may contain, or agglomerate into, larger grains.3 Nitrite anti-oxidants added to some greases may orm crystalites larger than acceptabe for

quiet rung applications in bearings



Faiure Ata for Hertz Contact Machine Eement

1821.3 Distinctve Appernce

Observaton o contaminant in grease is eormed by means smilar to tat o contaminant in ol(see FC 113) Because grease orms packs, examinaton o secc layes s diagnostic:

1 Contamnant n te ayers immedatey adjacen to a movng comonent suggests artceremoval (wear salng) rom tat comonent. Identcaton o artce matera and comarsonwt comonent materia is dagnostc

2 Contaminant n te ouermos layers o te gease ack (acing seals) s indcatve o contamnationingress nto te camber.

3 Widely disribued contamnant may result om eter o te above condtions ate long runingor ndicate nita contamnaton o camber o grease suly.

18214 Cses

Causes o grease contamination ae smilar to tose o o contamnaton. See FC 113

18215 ffects f Slid Cntmintin f GreseA grease ack can nteact wt contaminaton n two dierent and oosng ways

Proecive eecs of grease agains componen damage by conaminan

Contaminant omed at te wokng suraces o exame by wea can be exeled nto te geaseack and eld tere reducing te damage t causes to te working suaces

te contamnant entes te camber troug a sea tat is it encounters te outsde o tegrease ack ten te ack acts as a barrer and can absob substantia contamnaton witoutemttg t to reac te workng suraces.

Labyrnt seals ae oten led wt grease o te urose o traing contaminant beoe tenters te camber roe

Damaging eecs of grease/conaminan combinaion

I too muc contamnant is incooated into te gease ten t wil be contnualy resented tote moving comonents and act as an abasve cause nos wear and nicks and i te contamnationis sucently sevee utmate aiue.

Hard contaminants down to mcrometer artcle sze are abrasve to te workng comonents.See FC 0012 or wear o contact comonents FC 03 o seaato wear FC 0124 or guiderngwear d FC 0222 or seal wea

Sod contaminants (weter ard o sot) may oduce dents n contact comonents. See FC 008Dents are major sang causes Contaminant ed onto te wokng suaces om te grease may

cause nose and vbation in te macne eement

18211 Greae Dried Ou or Dicolored

182111 Dried-ou Greae

1821111 Definitin

ailure Code 126

ailure Code 1261

Grease tat as ost some o its unused o content and tereby acqued a arder consstencytan wen unused is deined as dried ou

• rease dried ou in buk as lost ol trougout te volume o te gease ack.



Chapter 1: Lubricant Failure

• Grease wth dred skn shows a rie-out ayer aacent to a ree surace mosty the surace swept by a movng part).

121112 Filre PrcessGrease may ose some o its oi content ry out) through the processes escrbe beow

Bleedng

To be eectve as a ubrcant, grease must reease o to the moving suraces. Ths is known as"beeng he rate o beeing epens on grease composton, operatng temperature an mechanca actors, such as vbration an the shape, size, surace ish an spee o parts movng trought. Beeng is an nevitabe source o o oss rom grease, but may be suicenty ow to permtvery ong grease e

The ree surace o the grease pack swept by a movng part s especiay prone to ryng out, an

thus to eveopng a dred-out skn The moving part wipes o an some thckener) rom the workingwas o the grease pack. I the epetion o o is arge an repenishment rom the buk pack sow,a permanenty re -out skn can orm. In such a skn, capiary repeshment o oi s soweown, urther aggravatng the ryng out.

the grease an operating contions are we matche, capiary repenishment o the o preventsormation o a rie-out skin. The buk o the pack may eventuay ry out i oi epeton s severe.

Eaporaton

Evaporation, especiay at hgher temperatures or n vacuum, attacks a ree suraces. rapi, tmay ea to rie-out skns on these suraces; i sower, or the pack s churne, the entre buko the pack may ry out.

121113 Distictive ApperceDrie-out bulk grease may appear arker than norma an ee stier to the touch. Moerate

egrees o oi oss may not be etecte by these methos an require aboratory measurement openetraton or o content

Dre-out skn on grease, i pronounce, may be visbe as a ayer o change coor an etwth a probe, as a harer surace. moerate, mcro-penetrometer measurement or o contentetermnaton on a oca sampe may be requre or agnosis

12111.4 CsesCaplla ol loss can ea to rie-out grease uner these contons

•

Oerheatng causng reuce oi vscosity an aster capiary movement.• Hgh speed o movng suraces that crease the wping eect Tis may ea to re-out skn

i repenisent o o rom the buk pack ais to keep pace.• Excessive age o grease pack without repacement• Instablty o grease. Some greases spontaneousy bee oi uner gravity others o so in vibratory

envronment

Eaporaton o oi is ehance by these eects

Volatle components in the o.• Eevate temperature over extene tme.• Vacuum environment



Failure Atlas for ertz Contat Mahine Elements

Contamnaton by ne patces may ncease the olume of sold matte n the gease, thus educngthe pecentage of o Ths may lead to both the appeaance and pefomance of ded out gease,

een though no ol s ost.

1821115 Eets Dried-t GreseDed out gease s often the st symptom of the genec gease faue pocesses descbed unde

Secton 1823

8 Discolored Grease

182.1121 Deinitin

Faiure Code 6

Gease s dscooed f ts coo dffes fom that of the unused gease.

18.21122 Filre PressGease s a complex system and many causes of dscooaton affect t, among whch ae the fo-

owng

• Change n ol content• Water ngeston (at low leels• Sod contamnaton by fne patces• Chemcal change n o o thcene

n eplenshng o epacng the gease suppy n the machne, nadetent selecton of the rong grease may occu

The admxture of gease of a dffeent ype to an exstng pac may ceate a bend of unexpected

popetes. f the classes ae ncompatle, a chemca o physcal eacton may occu between baseos o thcenes, poducng an unseceable gease.The replacement of the gease pac wth one of dffeent specfcaton may poduce any of the

faue modes heen lsted.

1821123 Distintive ApperneChemcaly decomposed gease may dffe n colo o tansucency fom unused gease n tualy

any way (ncludng none Compason wth unused gease and nowledge of the appeace ofdecomposton (oxdaton poducts of the gease n use, ae necessay fo dagnoss

A common dscooaton n geases s darkenng, o dulng of the (atfcal coo added tounused gease

Gease contang small amounts of nely dspesed ater s my (see FC 24)

Sod contamnated gease s oten daened, gay o bown (see FC 125)The rong grease o a mxtue of two dffeent geases may poduce unexpected appeaance ( colo,

consstency, odo, etc.

1821124 CsesThe causes of gease dscooaton ae those of the pocesses of whch t s a symptom. Exam-

pes folowDred-out grease as descbed aboe.Water contamnaton. See FC 124Sold contamnaton See FC 125



Cptr 1 ubricnt Filur

Chemcal chanes n o or hckener brogh abo by one o he olowng cases

• Overhean Many greases oxdze a elevaed emperare

Not: Anoxdan addves are comonly provded o reard grease oxdaon.

• Inress of reacve chemcals.• Eposure o ncompable meals Ceran synhec grease ormlaons reac wh yelow mea

componens.• Lonerm nsably of formulaon Greases are complex maeras. Sably over he exreme

perods a mes many years) drng whch a greased and seaed Herz conac machne elemen(bearng) s expeced o ncon may be dcl o acheve especaly he operang condonsare severe

Admure or sbson o he ron rease A common sorce o nadveren mxng s regreasng

drng servce sng a grease dspenser charged wh he wrong grease.

1821125 Effect f Grese DsclrtnDscooraon s sed as a warnng sympom or grease alre by conamnaon chemca deco

poson or o oss.

Eecric Crrent Damage to Grease Faire Code

182121 DeftnEecrc crren damage o grease s dened as he damage o grease n a Herzan conac cased

by he passage o elecrc crren (spark)

182122 NmencltreAlernave desgnaons o elecrc crren damage are gven n he Nomenclare o FC 002

182123 Flre PrcessPassage o elecrc crren beween he sraces o a greasebrcaed Herzan conac (see

FC 002) prodces chemcal damage o he grease smar n nare o ha cased by severeoverheang. Becase a spark aecs only a sal any o grease a a me elecrc crren damageo grease ends o be ocalzed Smal volmes o severely damaged grease are ond n ndamaged

blk grease where hey are evenaly dspersed by movemen whn he grease pack

Not: Grease damage ro overheang by oher cases may be generazed he emperare o an enremachne elemen becomes excessve; may be ocalzed s de o galng even.

18212.4 Dstctve ApperceLocazed vomes o dscolored (FC 26) or carbonzed FC 25) grease dspersed n he grease

pack near he conac pah.Eecrc crren daage o conac componens FC 0021) s expeced o be observed along wh

he grease damage.



Failure tlas for Hertz Cotact Machie Elemets

182.125 CsesHg loca tempeatues caused y passage of cuent (spak) Posse electolytc effects in

some geases.

18.2126 Effecs f Elecric Crren Dmge Gresee effects ae te same as fo decomposed (FC 126) o caoized (FC 25) gease.

183 Filure of Other Lubrcnts

183.1 Definiin

Filure Code: 13

All ucants not defined as oi o gease ae ncluded in te defnton of 'ote uicants eyinclude te casses listed elow.

Sold lucants

• Lucant coatngs• Lucant compounds including,

solid compounds andad ogac gels wc contan entapped o

• Sacrcal components wt lucating aiity• Compostes of wc one element is a uicant.• Powder and smoke lucants.

2 apor phase lubrcants wic depost luicating layes n stu3 Lquds ote tan oganic ols (wate, cyo-uids, pocess fluds)

is section coves te faiues of tese numeous ucant classes

1832 NmenclreDue to te multtude of "ote lucant types, many desciptve tems ae used fo tei faiue

Fo sold lubrcant compacts, incudng te ad ges, faue modes suc as factue, cacking, wea,and meting ae ecogzed Powde, vapo and cyo-fluid uicants euie uue teminologydepending on tei specfc type

1833 Filre Prcess

133.1Failure of Solid Compacts, Coatigs, or Sacrificial CompoetsFailue of sod lucant compacts o coatngs may occu y many modes, suc as

1 Cackng, factue o sepaaton.2 Wea3 Cemca decomposition of te solid uicant.4 Inaity of te uicant to povide eued lucation, due to one of te followng causes

• Excessve load o speed• Offspecifcation opeating tempeatue.• Contamination• Dmensiona cange of luicant compact



Chapter 1: Lbriant Failre

13.32 Failre of Vapor Phase LbriantsVapor pha lubrcant function by ntractn with th ubrcatd urac n a way that crat

a continuouy rplnihd ayr o lubrcatn oid or liud Th lubricaton mthod can oprat by two ditnct proc

(a) Vpr ph dp whr th vapor ract with th ubricatd urac to orm a oliddpoit ayr.

(b) Vpr ph d whr a liud ubrcant ilm condn rom th vapor on th ubricatd urac.

Corrpondin to th proc, vapor pha ubrcaton may al by th ollown mod:

Th ubrcatin vapor do not rach th workn urac at a ucnt rat. Th may rutin aur o thr proc (a) or (b)

2 Th raction wth th ubricatd urac ruird n proc (a) ail to produc th rurdubrcatn ayr at th ruird rat or wth th rurd proprt

3 ntrrnc by an xtrnal ant, uch a xc hat, od, liud or aou contaminantobtruct craton or unctoin o th olid ubricatn ayr (a) or iud m (b) Th opratn condtion ar too vr or th ubrcatn ayr (a) or m (b) to prvnt alur.

I any o th lubrcation alur occur, th lubrcatd urac may undro on or mor oth typ o dama litd undr "C lur flur in 83 Md war o th contacturac (C 00232), urac ditr (C 007) or allin (C 0032) ar lky on th contacturac, a i parator war (C 03), aln (C 0) or ractur (FC 02) Hat mbalancailur o th barn (C 009) may occur.

1333 Failre of Lbrant Types Not Listed Abovealur o ubrcant typ not td abov (powdr, a, cryo-fluid, or tranr lm) ar dpndnt

on th pciic typ and mod o unctonin o th ubrcant.

18.3.4 Disincive Apperncetinctv apparanc o th ailur i dcrbd on th ndivdual Pat

1835 CusesCau o th aur ar dcrbd on th indivdual Pat.

1836 Effecs f Nnil, Nngrese Lubricn FilureEct o th aur ar dcrbd on th indivdual Pat.





Fiur Cd

6

6

P N

6

6

6

6

66

6

6

6

6



Filre Cde 111

PLATESDATAlate No: 181Achve No: 00615mae ye: igt microgramScaleba 100 m micros ± 20% oters 100%-50%)omonent: 0 sol id lbe f i lm); G runSeed:Load:Lbicaton: mea ol based gear oil Fale ode 11 Fictio polymer ol lbricatoFae ode 00.12322 Scratc marks kiematicwear marks in rollig suaceFaie ode Faie ode -

DESCRIPTONS

Chpter 1: Lbricnt Filre

Faile Descton: A gear toot operated i oil wit an at-wear additive wc forms visible patcy surface depositsScratcmarks pass rog te deposit patces Te fim persists in some scratces and meta is exposed elsewee. Te gear isoperable te patci ness of te deposit may li mit te abi lity of te additive o povide niform a-wear actio Imae Descition: e gay backgroud is gear sace materia sowing NS rng fiisig lines. Patces of black depositfilm are oriened alog tese isig lines NWSE uig sarp scracmarks mostly black) ae due o wear Te depost isinterrped by te scatces. Te back lm may be pressed into e scratc wle worn away otsde; elsewere e scatc asremoved te film foming a gay lne o black backgrodSsected ases: Atwear additives o may compostios are used n bricag cotact sraces Sc addiives may beelpful in ruing-n and n mitigating te coseqences of slidg i e conac suc as i gears Most addiives do ot ormilms visible uder low magificatio but some sc as tose containg grapite or molybdem disulide) may Incompleteness

of protective films exposes te surfaces o wea or gallig.

DATAlate No: 182Acve No: 103004&005Imae tye: a b cor microgram [SEE MAGE IN APPENDIX]Scaleba ab 40 m mcros 20% otes: + 100%, 50%)omonent: ACBB; OR ruSeed:Load:Lbcation: sytetic ydrocarbon impregated separated 25°CFae ode 111 Friction polymer oil lbicaoFae ode 00171.2 Microspall ig advanced su race d isress)Fae ode -

Faie ode -

DESCRIPTONS


Fae Descton: a) Frictio polyme formaio ot o te ti oi layer deposited at moning on e ball pats of a separatorless ACBB Tere s no repleismen of oil. I 'parced ED lubrication te flm progessively tins Te ricio polymeformatio rate creases rapidly wit decreasing ED i lm. No surface damage as occred yet. b): Simi la evets occurred as a) bt al f luid is los and srface dstress started. I ig speed BB a) can cange to b) vey rapidlyImae Descition: a): Mic rogapc view on OR ball g roove cotact track and adjacent bands ae i focus. Crossig te tackfrom image E to W (1) Narow mticolored band itereence colors) o riction polymer (2) metalli c co or i n contact tack (3)wde mlticolored bad of riction poymer b) Image as i a) (1) Cotact bad is gray wit black micospa craters (2) uifomdarker gray frcio polymer bad is to te W; (3) tier bad ot o focus is to te ESsected ases: Lubricat polymeriatio occrs gradally nder cotact stresses ad accelerates greatly wen EHD filmbecomes very t casg very ig film s earig rates Frictio polym er is swept ot of contac by ball spi n and deposted eadjacent band one side is favored by spin drection) Fer EHD film ining cases surace distress



Failure Atlas fr Hertz Cntat Mahine Elements

DATAPlate No: 8Archve No: 0069&40Image type: lig mrb: ligt mirgrmScaebar 20 12 mmmis 20% tes + 100%50%)omponent: 0; brit tmim TRB uSpeedLoadLubricaton mer ? cFalure ode 102 Severe iltmiFaue ode 115 Cbized il

depstFaure ode 11 Abrsivetm ilFalure ode 11 Seelmit i il

DESCRPTONSFalue Descpton Fltre is sw

Failure Code: 11.3.2

a b

rm ulrsi leig slvet used RB Bk kes e vsible pssibly rzed lu brit) sme ir d her meld bsives wee idetied. Ctmit tis mgitude uses detig d my use premture wer.Image Descpton ) Blk kes d pwder tmit TRB lleted m ltsi eig svet used emiti is sw gy kgud Whte pthes re light eleis b) Sme debrs s shw mgied. Blk kesppe t be deted rized l depsits. he mttled gy mss t mge NW is sme the tmt t idetiiblem ths mge.Suspected auses: Cried idtes ig tempeture t sme pit the lubrited hmer t eessrily i thserig) I tig piles ud re pr bby wer tres brsive miti hs gied ess t the hmer



ailure Code 115aiure Code 12

DATA

Plate No: 84chve No 08040Image type: viewScaear a: 20 10 mm mirs 20% hers 00%50%)ompoe ACBB a IR assemly & B & G sepaatr) rnSpee: 00 KdNoacao: i l ? cFare oe 115 Canized il depsteFalre oe 001921 H pas lw witt wedin grlt)Fale oe 0018 iel l gFale oe 4 0112 Separat ae raking

DESCRPTONSFae Descrpo: Vsile are ea imaane iarizai ateed ad rineled IR a pah and alsared separatr separat wear C 012); al rm

Chpter 1 Lubricnt ilure

b

-.

served misalged mnting ad perati at hgh speed ad aeleati. Ths is a grss aile.Image Descpo a): IR is vewed n O. Tere is an iregla irmeretia lak ad i he all pat tm. Te al pais plasally dermed ateed). innell maks a a spaing aise m eaig seie. ): Image N ken separa almaied metal) shws wea te pkets arws) Ne S a assemed eaig wih he sepaatr hal remved. Far S: aswth arized ak depsts and plasti dema.Sspecte ases: Oserved mting misaligment ased sevee mmet ladig te earg resltig high sepaates wea ad ae Te ea ig vereaed ad te a ized. Evetally earing seizre rin el ing and plas lwreslted

DATAPate No 185rchve No: 02129&10mage type a : l view [SE I MAGE IN APPENI X.]Scalear a 20 mm mirs 20% ters 00% 50%)ompoe 0 gease & GBB nrSpeeoacato: mieral il ased geaseFare oe 1200 Gease as-maatredFalre oe Falre oe Falre oe 4 -

See ls PLATES: 184 and 815

DESCRPTIONS

[See Image Aex]

Fae Descpto: Samples asmaatred greases a) in taine ) i taie ad arged it GBB May therrigial gease lrs ae made r is idiati mpsit Cl ad sisteny stiness) samples asmaatred grease are ered mpaative evalat grease paks mdied y seve ese ae t ailes. SeePLATES 814 ad 185 r mparis wt sed gease.Image Descrpto: a): Tree rad-ame geases ae paked shallw aiers as lr samples. These tree greases areeivalet in satisyig a spei ser sandard The r grease aged it a eaig may dier rm lk de ti layerdark akgr d etSspecte ases: hs Plate illsrates the lr aselie eeded r grease appearae evala. Ea gease sed ees isw aseline. The aity te grease harge mst e deemied y weghig The nditi te grease pak ate rnigdiers rm asaged de t aneling slmpig leati disrai wae slids arian Cr sisteyad pak dii aselies ae desrae




DATAPlate No: 18 .6Archve No: 087030mage ype: viewScalebar 1 0 mm (mirs ± 20%, thers 100% 50%)omponent 0 (grease) & RB runSpeed:oadubrcaton grease Falure ode 12.02 Gease pak eessiveFalure ode

Faure ode -Falure ode 4 -

DESCRIPTONSFaure Descrpton Grease was p umped th rug h a TRB m an

eessive rginal gease pak and appeared as a bead at the s lange side. This ill ustrates the hurnng (wrking) aneessve grease pak as it is red thrugh the mving parts the bearing. nless there is pen spae at the small lange side ths bearing the grease wil be red bak int the mvingparts wil liuey and be lst r ail.

Failre Code 122

Iage Descrpton: RB viewed n s lange sideae. Light lred grease appears in beads arund the IR ange OD mstheavily in the SW and NW image uadrants.Suspected auses: Bearings may be vergeased at instalatin r when regreasng a husng euipped with a regreasing itue.Gease mst have spae t be hanneled ut the vlume swep ut by the mving beaing pars t rm lsely nmingwals a eah side and supply lu brant by pkup rm these walls. ess gease s repeatedly pumped thru gh the beaing unti l tiueies and/r the bearing verheats.

DATA

Plate No: 8.Archve No: 06-001Image type: lr vew [S I MAG IN APP NDIX.]Scalebar 200 m m (mrs 20% thes 1 00% 50%)omponent: 0 (grease) & C (seal) unSpeedoad:ubrcaton grease

Faure ode 1 2.02 G rease pak eessiveFaure ode 25.1 Labyinth seal ailureFalure ode

Faure ode 4 -

DESCRPTONS

[See mage in Appendix]

Falure Descrpton Grease eruded m the regreasabe etenal labyrinth seal n a bearing pillw blk. he seal is kely

have been vergreased. Ths s nt a alure unless grease lss s ndative verheating in the labynth seal grease pak withesulting iueatin and runut the grease pak.Iage Descrpton: At image W is a splt pillwbk. An etenal labyinth seal husing is munted n the ae the blk itis llwed eastward by an epsed shat and then a geab. Just S the sea husing enterline is a regreasing nippe. A bead eruded gray grease uns ang the ntur the seal husing n the shat.Suspeced auses: abyinth seals are generally geaseilled t aid in ntaminant elusin. A egreasing nipple may be pvidedt epenish the grease hage. I eess grease is pumped in it will appea as a bead between the seal and the shat Overgreasingis u sual assue purgin g ntamin ated gease rm a seal. esh grease is p urged in peratin then verheating andli ueatin the grease i n the sea may have ured and seal ing i s lst.



Failue ode 121

DATAPa N: 18 8Arcv N: 03k120&k138Imag typ: lor w [SEE IMAGE IN APPENDIX.]Scabar b : 20 mm (mros ± 20% othrs: 100% 50%)mpnnt: 0 (grs) & SRB (montd) ruSpdLad:Lbrcan: mnrl ol bsd grs ? cFar d 1 2. 1 Sofd or lq d grsFalr d 1 2.0 Grs pk lowFalr d 1 2.00 Grs s-mufturdFalr d 4 -

DESCRPTONS

Chapter 1: ubricant ailure


Far Dscrptn: Sphrl rolr brg grs pk ftr rmol o hosg dor. () Norml pk grs ssntly

s mufturd (b) Dpltd pk of lqufd grs (th rst of th pk hs ru out). (b) s kly to fl mmtly du toloss of lbrtomag Dscrpn: () Sh wth brg st xtnds from mg W to SRB Th SRB sdf s ord by brkrdsmooth sm-sold grs h brg s n hosg (gry sdf wth montng hol t mg E). (b) SRB n housng wdon h sdf. h shft hs b r mod Th R bor s t mg r Roll r nd rng-sds r thn ly ord by brkrd grs All grs btwn h rolrs hs ru ot. Th grs s thk lqud.Sspctd ass: Grs lq ufs f (1 ) t s srly orhtd d/or (2) workd (kdd) byond th tolr of th grstyp. An ohtd grs pk softns nd slumps no h brng whr t s srly workd by t sprto d rollrssng furthr lqfto Lqufd grs s of xplld from th housng pst sls o ft srfs

DATAPlat N: 18 .Arcv N: 03-k135Imag typ: or w [SEE IMAGE IN APPENDIX]

Scalbar

30 mm (mros:

20% othrs 00% 50%)mpnnt 0 (grs) & M (housng) ruSpd:Lad:Lbrcatn: grs ? cFalr d 1 2 1 Softnd or lqfd grsFalr d 1 202 Grs pk xssFalr d

Falr d 4 -

DESCRPTIONS


Falr Dscrptn: A flow of grs s xtrdd ps th hosg/ndp ft trf nd s dpostd on th otsd f of tdp. Th grs pk s lkly to h bn xss sg hy pumpg to lquton of grs nd xtrusothrough th p ft gp. Th brng lbrton s mprd nd rly flur through ht mbln s lklyImag Dscrpn: h rulr bl/gry housg dp s hld wth four hx-hd srws. A flpld juto box s tthd t

th dp tr ol sprg s t mg N. A ppld r o drk gry-grn grs xtnds from N dp dg to th jobox Th grs flow mts from t ndp f tf t mg NSspctd ass: Or-lbrto of brg hmbrs (splly thos wth rlubrton tngs) s ommo flr us Anxss grs pk no b hnd ousd th olm swpt out by th mog brng ps d thrfor sotn uosly hrd t progrssly lqfs d s th ost through gps n th housng ssmbly.



Failure tlas for Hertz Contact Machine lements

DATAPlate N: 1 8 1 0Archve N 03-1 3Image type: lor w [SEE IMAGE IN APENDIX.]Scaleba 30 mm (mros ± 20%, otrs: + 1 00% 50%mpnent: 0 (gras & SRB ruSpeedLadLbrcatn: mral ol asd gas ?

Fae de 121 Softnd or lqufd grasFare de 1 25 3 Aras otamant gasFare de 12.5.2 Nonstl mtal otamat grasFare de 4 12.5.1 Sl ontaman gas

DESCRIPTONS

Faile Code 121Faile Code 12.3


Falre Descrptn: Gras was mpartd a gray or y sold otamnants A tn layr of lqufd gas s t arng, wt

t rmang pak lost Aras otamant as asd war, ratng non-stl mta partls from t sparator ad/or stlparls rom rollg lmts. Ts wr mxd nto t gras. T ang s lkly to fal arly du to (1 oss of lraton asa rslt of gras loss, and (2) war w possl sparator faurImage Descrptn Olu w of SRB o sdfa, n osg and on saft Barngrtanng saft ndplat s rmod nsmars of gras o parts o t roll ndfas ad ntrng spas Mu of t gras pak was osd o los Trmang gas s sm-lqd, mdm gray ad gtty to t fgrtp tst. A sprnklg of rdds aras dst not yt mxdnto gras s at mag SE o t osg sua Isolatd patls ar on t arg sdfa.Sspected ases: s arg oprad n a aras dst lad romnt (sakr sr w pntratd past t sal,was mxd wt t gras, and aradd t sldng (and possly rollng arng sufas, ratg utr otamao otrnnng as rsuld fom t m pard l rato War s lkly on sparator, ad p ossly o t rollg lmnts A aspals and war drs fom t sparator (onsl ad possy fom t rollg lmts (stl ar t gras

DATAPate N: 18 . 1 1

Archve N: 027-215&21&218Image type: a, , lor w [SEE IMAGE N APPENDIXScaeba a, , : 1 2 mm (mros 20% ots: + 100%, 50%mpnent DGBB I R, ruSpeed:Lad:Lbrcatn: mal ol asd gras ?

Fare de 12.3 Frton polymr gras lratoFare de 00.1 5.1 .2. 0.2 No mal frtng, arat rada ft, radal loadalre de 00.1 2.3. 2.1 .2 War tak off-tr onaalre de 4 00.1 2.3 2. 1 .1 War tak trd ontat

DESCRPTONS

[See Image in Appendix

Falre Descrptn: rto polymr fomd onat pat of t IRs (a ay trst load; (: modrat load wt trstomponnt ( lgt radal oad Indtal rttng as ourrd t or of (a War trak loaton as datd y frton

polymr, s offt (du to trust load n (a and ( and s sstally ntrd (rom radal load n (. s ar not falurs,t (a was ry aly loadd ad ra a latd tmpraturmage Descptn: Mltolord (row, gray, pp frton polymr oatngs ar sl n rular ads arond t IRdatg t onat pat. (a alf of t groo yg to mag W, s ord wt frto polymr. Fttng s s tor ( O wd ad of frto polymr s sl off ntr, toward mag W ( A arrow ad of frton polymr s argroo ntr flakd y two t rown lnsSspected ases Frton polym dlops Hrtz ontats y domposton of lat to orm an adrnt, ardoatg on stl srfa l s typally yow row, gray or purp Hg tmprau, low EHD fm tknss ad (somsldg ontrut Hgr sldng may war t polymr off ro polymr dos not dssol w dlut ydrolor adtat s ry appld (tmpr lor dos.



Failure Code: 12.3Failure Code: 125

DATAPae N 18 1Archve N 013&14Image ye: a b: clor view [SE IMAGE IN APPENDIX.Scaear a b 5 mm (m icros 0%, oters + 100%, 50%)mnen: DGBB; B, runSeed:Lad:Lrcan: grease, ? cFalre de .3 Friction polymer grease lubricatonFalre de 00.1 9.. Friction poymer on roll ing tackFalre de Falre de 4

See ls PATES 1 03 3 .1 6 and 1 538

DESCRPTONS

Chapter 1 Lubricat aiure


Fare Descrn: Mlticolored ines of a ard organic coatng on te ball sraces have formed as a reslt of greasepoymerization under contact stresses at relatively igh temperatre Friction poymer of tis magnitde is not a failure bt servesas a warning of hgh temperature in the bearing See si mi a fiction polymer coatngs on Pates 0.3, 1 3. 1 6 and 1 5.38Image Descrn: (a) Tree bas are at image NW SW and E The W and E balls show mltple familes of coaxial circarli nes of had brown, yellow and b lisblack coating te SW ba ll shows one famly of lines over te entire su face. Steel-cooredlnes sow whee te polymer was worn of (b): Tree balls are at W E and SE Finer, brown fricon polymer li ne familesappear on eac ball. Te irregular black dots on all balls are imaging aifactsSseced ases: Formaion of adhering friction polymer on rol ing contact suraces, from mi neral oil (and s ome ote oganic)u bricants ndicates elatively severe contact conditions , probab ly with some s lid ing he polymer coating is distngsa ble fromtemper color by the m omentary application of dted ydochl oric acid etcant, whic removes temper col o, but nt frictonpolymer.

DATAPlae N: 18 13

Archve N: 0-0&05&06Image ye: clor macro [SEE MAGE IN APENDIX]Scalear a b c 5 mm (micros ± 0%, oters + 1 00%, 50%)mnen: 0 grease rnSeedLadLrcan: mineral oi based grease, ? cFalre de 1.5 Solid contaminant in geaseFalre de 1. Carbonized greaseFalre de Falre de 4

DESCRPONS


Fare Descrn: Specimens of used grease are spread on a glass slide for visual examination. (a) Sows a smal volume ofblack contamnant parices and a p ossible darkeni ng of the grease. ( b) Shows severe blackenng of te grease (carbonizedgrease), and pariculate conamnant. (c): Distinct dark contaminant particles are visible in oterwse freshappearng grease lorevalation of grease reu ires fresgrease baseline .Image Descrn: (a) Unevenly spread brownish grease smear on gass slide In NW image adrant the clor is darker brownas if grease were decomposed. Black powder and granules mixed nto te gease represent solid contaminant (b): As (a), btmuc heavier black (carbonized) mass is in the grease. (c) eddis, fibrous grease smea, wth a few isolaed smal blackcontaminant particles. Fingertip es may feel grity in (a) m ore so in (b) No metalli c paices are seen.Sseced ases: Exenal conami nants and/o bearing wear may prodce particlate contaminaio n, w hic f very fne, darkensthe grease. Disco loration may be due to ig temperatre, wic if sevee, may lead o carboniation




DATA

Plate No: 18 . 14Achve No: 027-32mage type lor vew [SEE MAGE APPEDX.]Scaleba 8 mm (mros: 20%, oters 00%, 50%)omponent: 0 (grease) DGBB, rnSpeed:Load:Lbcaon: mineral oil based grease, ? c

Fae ode 1 25.02 Severe grease ontaminationFae ode 12.5.1 Steel ontaminant in greaseFae ode

Fae ode 4 -See ls PLATES: 185, 1813 and 18.15

DESCRTONS

Filre Code 12.5.2Filre Code 1262

[See Imae in Appendix]

Fae Descpton: Darkened (di solored) ontaminated gease is in D GBB origaly arged wit grease o 1 of Plate 1 8 5 (a).Clor turned from red to graybrown smoot pasty onsisteny to gritty Stee partiles are obseved in te grease speimenSepaator wear is suspeted Te bearng is l ikely to fal from inadeuate briationImage Descpton: In a D GBB, grease aderes to te OR land and te separator. Te pa of te pak loated at te O R appearssmoot bt gray te par on te separator s gritty and gray Fingeip feel o a grease speimen is gritty. Steel pailes may bevisible in te grease on a glass slide, wit a magniier. Upon separator disassembly, wear may be visible.Sspected ases: Separator wear, due to geometry erro strongly misaligned load or external ontamination, prodes fine steelpailes wi are mixed into te grease ey disolo it and ender it gitty. Heavily ontaminated gease ats as an abasive naddition to (or n eu of) beng a lbrant. See Plate 185 or es grease, and Paes 18.13 and 1815 for deomposed grease

DATAPlae No: 18 15Achve No: 027-131Image type lor view [SEE MAGE I APPEDX.

Scaleba 1 0 mm (miros 20% oters + 1 00%, 50%)omponen: 0 (grease) DGBB, rnSpeed:Load:bcaon: mineral oil based grease, ? c

Fae ode 12.6.2 Grease dsoloredFae ode 12.6.1 Grease dried outFale ode -Fale ode 4

See ls PLATES 185, 183 and 18.14

DESCRTONS

[See Imae in Appendix]

Fale Descpton: Darkened (disolored) and dried grease in a DGBB originaly arged wit grease o 1 . of Plate 1 8.5 (a).Clor turned from red to reddis-brown, smoot pasty onsisteny to granular. Remaini ng gease aderes to te separator Oterpas of te grease arge may ave been lost, eiter in servie or at seal emoval Te bearng is lkely to fail early frominadeuate lb riation d ue to extensve oi l loss from died greaseImage Descpton On te separator of a DGBB, globs of grease adere to reesses as between te poket and te iveted areaGrease aderes to te OR land. Te grease is m darkened and appears granular Fingertip examination o a speimen an beused to verify granlarty. nless substantia grease aderes to te removed seal te pak appears mu depleted.Sspeced ases: Opeation at elevated tempeatre is te most ommon ause of grease deompositon and dying ot.Unde rarging (i nsfiient grease) or overarging (grease pak i ueies and runs out o te bearng) are also possible auses.Contamnation may simulate grease deompostion by angng te grease or. See Plate 8.5 or fres grease, and Pates 1813and 8.14 for ontaminated grease



Failure Code: 127

DATAPte No 1 8 6Archve No 0870 through05mge type a c: vw b d ght crograScebr a c: 0 b d 1 cros: 0% othrs: + 1 00% 50%)omponen 0 gras) & DGBB rnSpee:

DESCRITONS

Chapt 1 Lubicant Fail

Lo:Lubricton: gras ? c

Flue oe 1 . lctrc cu rrt daag o grasFlue oe 1.6.1 Gras drd ouFlue oe 1 .6. Gras dscolordFlue oe 4 -

Fiure Descrpton: Elctrc currt passag throgh a grasd bal barg rsuld dcoposon cor and cosstncychag of th gras. Elcrc roso ay jct coaans nto th gras bt drc daag by crrt passag through thgras occrs arlr. Th gras s dtroratd. Th barng s kly to fal throgh lbrcaton aur ad/or roso cratrgmge Descrpion: a): Dryapparg gran lar gras adhrs o h sparator o a D GBB wh a ochandprog fasnd rbbosparator. c) a coguato blacknd th gras layr. b) Mcrogra of sparator prog a) half-oval lght clor araar ag cntr) ad surrodg sparator sufac. Gras adhrs n dry granls of lght and gray clor Dark backgroud s

th sparator d): Mcrogra o prog n c) gras adhrs thn sars of gray clor.Suspecte uses: lcrc currn passag through a barng ca occr wh a xcssv voltag dfrc arss across throlng contacts oft lcrcal achry). h fld gradt through h thn lbrcant ls s vry hgh sparkg rsuls adh gras dcoposs Daag o al sracs ctrc roson) s th nd rst

b

c

7




DATAPate No: 18 17Archve No 13001Image ype lght mcogramScaebar 0.9 051 mm maks (mcros ± 0% others 100% 50%)omponent: 0 RC tes g rod 15 tool steel rn agast 15 ballsSpee:Loa 334 GPaLbricaton: Tertary buyl pheyl phosphate vapor 371 c

Falre oe 3 1 Chemca s uace attack by vapor phase ub rcatFalre oe 000 CorrosonFalre oe 000.1 3 Contact corosoFalre oe 001.31 Smooh rolg suace wear (sh marks removed)See l PA 18. 18

DESCRPTONS

Failure Code: 131.1

Faire Descripion: he too steel RC test rg rod was rn at hgh emperaure der vapor phase lubrcato by a orgacphosphate (TBPP) whch reacts chemcaly (corrosvely) wth the too stee surace at the hgh temperatre ad stress codos ohe tes Und er the h gh stress the cotact path wdened rom 0. 51 mm to 0.9 mm d urng tesg hogh wear ad ro down.he al cotact pah was measred to have abou 8 mm ads (compared o a ball ads o �6 mm) wo bads o darkcoroded depost have ormed alog the contact path. he coroded bads appea to oow the pue rol g (Heahcote) band s nthe cotact path where sldg does not wear them away. Addtonaly one conact corroson mark has ormed whle thecograton was statoay.mage Description: he axs o the test rod rns W the cotact track NS Intal wdth o ao 0.5 mm and na wdth oa 09 mm ae marked he cotact pah s cocave ater rung reectg ght the cetal zone bt not ear the (thng ht) edges o the rack. Dak reglary textured coros on bads abot 0 .1 mm wde ru NS about 1/3 mage wdth om the ad W edges. Some corroson les exted outward rom he W band. xcept where coroded the track appears poshed. At theNS mdpont o the mage a ger-shaped coact corroso patch s vsble dark outle where a ball rested whe theco gurato was statonarySspecte ases: Vapor phase deposto provdes lubrcaton to the cotact surace by chemcal reacton between lubrcantvapor ad metal srace at elevated operatg temperatres (sally excess o those at whch the ld phase o the lbcat s

uctona) The resultg lub rcaton s essetally by sacrca dry lm The contact saces dergo ml d wea as he sacrcam wears away Where sldg s mnmal the lm may orm aster than wears o and vsble lm remas regos o hghersd g the lm weas as ast as t oms resltg n metalc su ace. The lu brca sed s sucetly aggressve to orm contaccorroson aroud a statoay ball coact.

af 09mm

ao 0 5 m m



Failue ode 1311

DATAlt No: 1818Archiv No: 123002&003Img ty: a: b: SMSclb a: b : 10 m (micros + 20%otrs: + 100% 50%)omot: 0 C tst rg ro T15 ool stlru agaist T15 ballsSLo: 334 GPabrco Trtiary byl pyl pospat vapor37CFir o 1311 Cmical surfac atac byvapor pas lbricatFilr o 00202 Corrosio pitigFilr o 00051 Micro-porosiy

Flr o 4 0006 IclsioSee ls PLAT 1817

DESCRPTONS

Chapter 18: Lubriant Failure

Fl Dscrio Corrosio pts form i roig srfac as a rsul of attac by cmicaly activ vaporpas lbricat. A small boy o matrial a Acotaig ig r prctags of tool stl alloyiglmts a lss iro ta t part sl forms aclsio itrsctg cotac srac (origicra) Possib microporosity i stl at B.Img Dscriio: (a) Mtallograpic scio of roligtrac. Stragt g rom imag NW o S is gbtw rolli g s urac a scio. Ara o N of gis polis cross sctio. iy isprs roucarbs of 12 m iamtr typical o tool st arsow as promit ligtrgray lmts i tsctio Mtal is mium gray. At A a wi ulsap arr gray zo abo ut 20 m wi at op ig xs from t cotact sac. Carbis arisprs i tis matrial lctro prob aalysissow igr Va, Mo a Cr a muc lowr tat part sl. A small p agg "ol i sctio at B appartly uc oct to t srfac is(possby) microporosiy. T marial o SW o sciog is moutig plastic (b) Hgr mag ificatosctio of sam trac sowig corrosio pitt bsrac Upitt ara at xtrm imag NW. swralog g (imag cr) corrosio pitg as

ptrat about 2 m p tacg mal a oosig carbisSsct ss: Vapor pas postio pr ovis l bricato to t cotact srac by cm ica ractio btw l bricatvapor a m tal s rac at opratig tmpraturs i xcss o tos at wic t li qu i pas o t bricat s opraioal. l bricat us s sffictly aggrssiv to form corroso pits t roll ig srac.



Failure Atlas for Hertz Contat Mahine Eleents

DAAPate No: 1 19Archve No: 004Image pe: clor viw [S IMG PPXScaebar 1 inch = 5.4 (icos + 0% ohrs + 1 00% 50%)ompoet: DGBB too stl sivrplatd sl cag; rnSpeed: 60 Kdoad nknownbrcato Tiary btyl phnyl phospha vapor °CFalre ode .1 Solid bricant dposit fro vapor phas lbricantFalre ode 01 .1 4. Land gi dd sparator gid srac galdFalre ode 01 1 Land gidd sparator gid sfac worn localFale ode 4 01 .1 1 Sparator crossbar worn both pockt sidsSee ls PL 1 0

DESCRIPTIONS

Falue Code: 13.1.2

[See Imge in Appendix

Fare Descrpto: Tst barng aft 1 hor rn n aircaft gas tbin ngin. ings and balls covd with solid lbricantdposit gnratd by vapor phas lbicant spplid as ist Sparator silvr plating worn throgh in pockts and along both railsn co ntact wth O lands. So lb ricant dpost on cag wh stl is xposd b not on silvr M ino r galing of xposd stl.h baing has not faild bt land gidd cag is at isk of galing air.Image Descrpto: Disassbld dpg roov bal baring with on-pic otrring and gidd sivr platd stl cag On bal both ring s and cag shown ings and b all s rfacs nifory covrd wth att rddish blac k dposi. Th dposit showsbrnishing fo ovrrolling in contac tracks. Whitish silv plat on cag worn throgh to darkr stl n pockts and along bothails. "Sard apparng lightr galng straks on darkr stl sac of ralSspected ases: Vapor phas dposition povids lbricaton to th contac sfac by chical raction btwn lbricantvapo and tal srfac at oprating tpras in xcss o hos a which h liqid phas o th lbicant is oprationalLbricaon occrs by way of th sacrifical srac dposit ford bwn lbrican and tool stl contact atria t thoprating tpratr of this tst th lbricant fod a hard strongly adhring coating on th ncoad rings and balls whichtolrats ovrrolling Th lbrication was fctiv in th roling contacts and th baring opratd witho fnctional failr throghth tst ot that lbricant dos not appar to ract wih slvr plat on cag and fos no cohrnt fil whr cag stl isxposd. Sold lbricaion o sliding contacts on sparator appars inffciv to prvnt waring off of th silvr and sbsqntgalling of th stl sbstrat.



Failure Code: 1313

DATA

te N: 180rchve N 13-005Imge tpe: SMScer 50 m (micrs ± 0%ters + 1 00% 50%)mpnent: DGBB I tl steel, runSpee: 1 Md:urctn: Tertiay buyl penylpspate vapr, 480CFlure e 1313 eeling depsitfrm vap pase lubricantFlure e 001 3 Wear in l ingsufaceFlure e

Flure e 4 See l PLAT: 18.19

DESCRPTONSFure Descrptn: Test bearing ball patswn after 9 urs f running in aircrafgas turbine engine Bal grve was intiallycvered wt slid lu brcant depsit frmvapr pase lubicant supped as mist Tedepsit is flaking f in streaks alng teball track ug running and increasing

hapr 18 ubrican Failur

trque ccurred srly befre tes terminatin Te bearng is faling m unbaanced frmatin and wea f slid lubricantdepsit at te test temperatue Since te depsit frms by inteactin te lubicant wit te surace mateial, remval f metalis taking place wit wear te depsitImge Descrptn:

Lw-magnificatn SM s ws ba track ling track runs SW Daker, mttled appearng gray suraceis sli d l ubricant depsit as frmed Bands lige gray are znes were te depsit is wrn One un interruped lig t gray bandwit sarp jagged edges u nni ng a ng te ll ig track appears wrn dwn t bare metal Drp-saped val bjects in S crne rmay be agg lmeratins f lbricant depsitSuspecte uses Vapr pase depsitin prvides lubicatin t te cntact surface by cemcal reactin between lbricantvapr and metal suace at g perating temperatures (us ually in excess f tse at wic te li quid pase f te l ubrcant isfunctinal) Lubrcatin ccurs by way f te sacrifical suace depsi frmed between lubrcant and tl steel cntact materal Atte perating tempeature f tis test e equ il br um between ub ricant depsit matin and wear brke dwn after 1 9 urs frun nin g, wear tracks develped and te frictn trque un derwent a step increase



MouNTING CoPONENT F AlLURE 19Failure ode: -6

Gn scptn

Nthr th dfiniton of mountng comonnts, nor th numraton of th falurs ams forcomltnss n ths Atas. Many mountng comonnts hav fctons unratd to th Htzcontact machn lmnt; many ar scazd dsgns fo on machin ty My faurs of thscomonnts as from causs, and hav ffcts, not drctly latd to th Htz contact machnlmnt. Dtad nformaton on falus of som gna-uos mountng comonnts such asshafts, s found n 10 and, for ga mountng comonnts, n 9.

9 DefinitionMountng comonnts for Hrtz contact machn mnts ncud

• Fitting components, havng fit ntrfacs wth th Htz contact machin mnt. hs ncud,among othrs: shafts, housngs, sacng rngs, mountng slvs, locknuts and ockwashs.

• Lubrication components, artcating n th ubcaton systm of th machin mnts. hsnclud, among othrs: xtrnal sals and lubrcant suly arts.

• For a ga or cam wth ntgra shaft, a support bearing s a mountng comonnt

Faurs of tting components fal nto four broad casss:

• Interface failures, whr th fit sufac wth th Hrtz contact machn mnt fas by war,galling, frttng, cooson or nicks

•

Bulk failures of cackng, fractu, or rmannt dformaton• Mounting failures, whr th mountng comonnt s mrorly mountd nto th machn orth Hrtz contact comonnt s mrorly mountd n (on th mountng comonnt

• Unrelated failures, that s, faurs ratd to th fncton of th at as a mountng comonnt.hs s a broad class that may ncud som faurs smar n mod to thos lstd abov

Falus of lubrication components fa into two boad cla�ss

• Seal failures, smlar n thr ffct to thos numratd undr FC 02 for ntgra bang sas, but comrsng a grat varty of falu mchansms as a sult of th gratr varty ofxtrna sa tys.

• Lubricant supply part failures, ncudng, among othrs, dfcts n ubrcant fow conto lmnts,such as ol jt ngs, gras valvs and ol mst nozzs.

Faurs of support bearings (f rolng bangs) ar covrd n th cdng chatrs of ths Atlas

92 Nomencatureh dsgnatons for falus of mountng comonnts follow thos of Htz contact machin

mnts wh alcabl. For faur mods unu to a mountng comonnt, ths Atlas dos notdfn nomnclatu.

93 Faiure ProceDu to th multlcty of comonnt and falur combnatons ossb fo mounting comonnts,

only th folowng bf commnts ar rovdd to aml th lst of mountng comonnt faucods n Chat 2.



Failure Atla fr Hertz Cntat Mahine Element

2

Crrepnding Failure Mde

Tabl 19. sts maor aur mods and faur cods o motng comonnts covrd n thsAtlas for whch a corrsondng aur mod xsts n Hrtz contact machn mnts.Any o th mountng comonnt aur mods std n on bock of Tab 9.1 corrsonds to

th Hrtz contact machn mnt falur lstd n th sam block. Faur codng o mountngsvs, nuts, lockwashrs (FC 4 s nsucnty dtad to tabulat corrsondng alur cods.Ths mnts may suffr crackng, fractur, rttng, war, gallng, corroson and msmountngalurs. Th corrsondng falur cods n Hrtz contact mac lmnts ar FC 00., C 00.15, FC 00, FC 00.3, FC 00.0 and FC 00.09, n th ordr std.

Mountingcomponentfaure code

Table MOUNTING COMPONENS CORRESPONDENCE OF FALRE CODES

CorespondingHetz eement

Mountng component faue desgnaton faue code

Housing cracked o fractued Shaft cracked o factued

Housing frettedShaft fetted

Space, shoulde fettedHousing gaedShaft galed

Housing wonShat worn

ousing defomedShat defomed

Msmounted ousingGeomety o assemby defect n housingMsmounted shatGeoetry o assemby defect n shaft

ousing cooded

Extena sea aiure

Nn-rrepnding Failure MdeMounted Looseness O-speccation (C 2003rronous t dmnsons shaft or housng, or ncorrct tghtng o tard mountng slvs

may rsult n osccaton mountd radal or axa loosnss of barngs. Incorrct sacng oshafts may rsut n osccaton backlash n gars.

Lubricant Leak om Housing or Covers (C 215Imrcs t, naduat gasktng, cracks n th housng or covrs, tc may rmt lubrcant to

sca from th chambr

Seal ailures (C 25Svral falur mods ar unu to xtrnal sals. Thy dr dndg on sal ty, as numr

atd blow.Labyrnth sals may a du to msalgmnt, unntndd contact causng rubbng of arts or

xcssvly larg gas. Lack of gras n crtan labyrnth sals causs lakag.



Chapter Munting Cmpnent Failure

Face seals, beng compex assembies, have many unique failure modes: misalgnmen, warpage

of rider, chppng of cabon, leakage of pison ring (if any), facue of belows, ecGae lip seas may, in addon o he failues lsed in FC 02, fal due o beakage of he garersping o defomaon of he shee mea casing.

Nte: lusaons of some exerna lp sea failues may serve o augmen he scarce mage maerialavaiable fo inegal rubbing seas (FC 02)

Failure of Specialize ouning Componens FC 20Ths Alas does no cover specialied mounng componens, for exampe, ampers for uahigh

speed urbine beaings, pins and bushings fo cam folowers o any of he special assembly elemensof ficon drives.

9.4 Ditinctive AppeaanceCoresponding failue modes (see Secion 19.3.1) of mouning componens ae sma in appeaanceo he respecive faue modes of Herz conac machine eemens, alowing for he fac ha housngsand shafs ae genealy made of diffeen (sofer) maeial and wh greaer surface oughness hanconac componens.

In he neface wh a hard see ring, a urned, sofer see shaf is lkey o suffer more wear, galling and eing damage han he hard ring. Convesey i is ess lkely o crack.

Cas ron housngs esis eing and galling bee han see bu wear readlyAumnum housngs wear and suffe plasic rollown Thei hermal expansion coefficen exceeds

ha of seel, which may cause loosening of fis.The appeaance of non-corresponing falue modes is descibed he Paes, o he (mied) exen

hey are lusaed. Refeence o [0] and, for gears, [9], or oher ieraure coverng he faiedcomponens is equred for deal

95 CaueMany falues of mouning componens have causes unreaed o he Hean macne eemen

These ae no covered in s Alas.The He conac machne eemen may cause faiure n e mouning componen by he ransmis

sion of forces, hea and relave moon. Deals folow.

Fitting CmpnentLoaded fing componens ansmi he forces beween conac componen and machine and may

suffe pemanen defomaion, cacking or fracue fom oveload n bending and shear, and (forgear shafs) in oson.

Fng componens suppong conac componens across inefaces may undergo relave moion in he neface and suffe wea, gaing o freing.

Msplaced mounng componens (mismouned n assemby or defomed o dspaced in sevice) may unenonaly conac moving pars, causing fouling of a suface, wih wea, gaing, heambalance faiure or rubbng cracks.

Lubricatin CmpnentExenal seals may fai as a esu of saignmen of he shaf suppo bearing, o suffer conamna

ion fom debis generaed in conac (or guiding) componen failue.Hea imbalance of a conac componen may overhea and fail (elasomeic) seal. Fouing by msplaced conac componens may fai a sea o oher lubricaon componen.

25



Failure Atla fr Hertz Cntat Mahine lement

96 Effect of Mounting Component Faiure

Tab 9.2 coas mounng componn aus wh alu mods sung om hm n hHz conac machn lmns An o h mounng componn alu mods sd n on bock ma caus an o h H conac componn alus lsd n h sam loc

Tab HERTZ MACHINE ELEMENT AURES CAUSED BY AURE O MOUNTNG COMPONENTS

Moutg Moutig compot Cotact Hrtz cotact mach mtcompot faur dsgato compot faur dsgato ( ordr offaur cass faur cass khood)

Faiue of speciaized Not coveedmounting components

ounted ooseness off-

specification

426

Housng cacked o factuedShaft cacked o factued

Housing fettedShaft fettedSpace shoude fetted

Housng gaedShaft gaed

Housing wonShaft won

Housng defomedShaft defomed

ismounted housingGeomety o assemby defectin housing

ismounted shaftGeomety o assemby defectn shaft

Lubicant eak fom housingo coves

Housing cooded

Extena sea faue

Sepaato faiue

SpaingHeat imbaance faiue

Buk cacking o factueGaing (fit suface)SpaingWea (fit suface)

Fettng (fit suface)Wea (fit suface)Gaing (ft suface)SpaingBuk cacking o factue

Gang (fit suace)SpaingWea (fit suface)Buk cacking o factue

Gaing (ft suface)FettngSpaingWea (fit suace)Buk cackng o factue

Pemanent defomationBuk cacking factue

ounting eoRubbing cacksHeat imbaance faiue

Buk cacking o factueWea fom foungSpaing

Oi ubication faiueGease ubication faiue

CoosonBuk cacking o factue

O ubicaton faiueGease ubcaton faiue





Failure Cde Plate N

7.7

27



Failure Atla fr Hertz Cntat Mahine lement

PLASDATAPlate No 191Arhve No 027-28Image type vewSaebar 0 mm (ms: + 20% thes + 100% 50%Component DGBB; OR Speed 25 KdNoad 2.4 Gabraton gease, 50CFaire Code 21 sg defmedFailre Code 005.1.2 aled fettng adal ft sfaeFalre Code Falre Code

DESCRPTONSFale esription Fettg s has fmed n a pedmfeetal patten n the OD f ths OR datng that sppr n

the hsg s neven, that s, the hsg be has meentalwavess The tepted lad sppt may lead t OR bendng fatgewth sssetn akg.Image esrpton Seveal meenta bads f fettng sn the OR OD shw a ped patte f feathey dak makgs.These deate the hgh pnts at whh ntat wth the hatteedbe f the hsng was mst tmate.Sspeted Cases Wavness the hsg be may eslt fm

Failure Code: 216

vbatns n the bg tl dng hsng be mahng. Gdg hatte the OR OD s anthe pssble se f pedettng maks Dfeentat eqes t tang

DATAPlate No 19.2Arhive No 0145Image ype lght maSaeba 10 mm (ms 20%,thes: + 1 00% 50%Component TRB M & OR SpeedLoadLbratonFare Code 21. Hsng defmedFare Code 2002.2 Mtg partked ggedFare Code

00.1012.2 Spalng at ntat edge, fm gemetry eFare Code 001802.2 Sevee advaned dentg

DESCRPTONSFaire esrpton The hsng has a lage nk at the beang seat, leadng t neven ng spp, lal velad and a agespall ass the ete le path ldg the edges The OR (p) lle path s veed wth age senday dents m spalldes Csn spts (FC 00.20 may als be pesent the le path. Gss fale thgh beag seze s lkely as thespall pgessesImage esrpton Oblqe vew nt the lle path a TRB OR (p'), whh s mted a hsg. At mage S, ente thehsng edge has tw deep nks wth a ased edge betwee them Detly N the ks, the le path s spalled ass ts lwdth (wde shallw spall) The emade f the e path shws may dents (and what appea t be s spts)Sspeted Cases The hsg s gged (wth a ased edge) ass the OR spp srfae, as the est f sevee abse nmntg, by mpat wth a shap tl The OR mted n the defmed hsng s deleted asng lal stess netatad ealy spallng. A ss-setn fate may fllw.

28



Faiue Code: 218Faiue Code: 221


DATAPlate No

93Arhve No 04-002Image type clor view [SEE IMAGE IN APPENDIX]Salebar 30 mm micros +20% oters: +100% 0%)Component B; M housg) rSpeedLoadLbratonFare Code 21.8 osig corrodedFare Code Falre Code Falre Code -

DESCRPTONS

[See Image in Appendx]

Falre esrpton Severe damage to the bearg sea i the boss o a gearbox This boss receives he bearig OR. e etire

boss is covered wit corrosio stai The bearig ad edcap fit surfaces ae deeply ptted. The bearig ft srface is suited forhe motig of a bearig, as poor OD spport will case bl crackig ad/or galigImage esrpton Oblqe view rom iside a gearbox, oto the edface of a cylidrical bossbeaig housig) i te gearboxwalaf of a secod boss s visible at image N) Al eemets sow are staied reddish brow by corrosio. Oe arrow ad wowide cyldrical ID srfaces ae machied ito the boss. Traversig he bore image from frot to back, oe sees he locatig flage,bearig sea ad reaig cap seat The beaig ad retaiig cap seats ae deeply pittedSspeted Cases The gearbox was exposed to a severe, log term corosive evirome while ope The ree srfaces,proteced by pait, corroded ligty he potected fit surfaces are corroded to uselessess.

DATAPlate No 19.4Arhve No 099145Image type: viewSaebar 30 mm micros 20% otes: +100% 0%)

Component G; M shaft) rSpeedLoadLbratonFalre Code 221 Shat cacked or brokeFare Code Fare Code -Falre Code -

DESCRPTONSFalre esrpton Example of bedig fatigue factre of aitegral gear saft with the fatigue crack itaed ear thesurace ad expadig thog coceric sriaios e cracksurface is a cross sectio of te saft his is a gross falre.Image esrpton View of cosssectio fracure of a saft At

image E is the fractre itiatio. Cocetric faige striatiosexted from this poit throg % of the shaft diameter Suddeovestress fracture broe the remaiig cross sectio omigradia steps as te shat separatedSspeted Cases Oveload o the shaft may ceate bedgfatigue Defects i the shaft materia are ikely cotribtors.

29




DATAPlate N 19.5Arhve N 099-146mage type viewSae bar 3 i. = 6 mmmicros: ± 20%,oters + 100% 50%Cmpnent G; M saft rSpeedadubratnFailure Cde 22 Saft cracked or brokealure Cde alure Cde Falure Cde

DESCRPTONS

Faiure Code: 22.

Faiure esrptn Example of torsioa fatigue failue i a itegra gear sat Te ractre srface is twisted ad makes aapproximate 45° age wit te axis Tis is a goss faiureImage esrptn Oblique view of te fractre srface of a gear saf. Te fracture suace at mage W is a twisted srface, atapproxmately 45 wt te saft axis Te fatigue iitiatio is ear te W image edge ad te striatios are cocetric arod testep at tat locatioSuspeted Causes Excessive trasmitted torqe possible combiatio wit a defec i te saft may iitiate torsioal fatiguefailue. Propagatio may be accelerated by orsioal vibratios i te system

30



Failure Code: 22.1

DATAPlate No 196Archve No 002-003a&fImage type a view b: SEMScaebar = a 30 mm b 200 m (micros: ± 20%,others + 100% 50%)Component BG; W & M rSpeed 91 m/secoad 06 GPaubrcaion: synthetic polyester oil 176°CFalue Code 1 221 Shaf cracked or brokenFalure Code 2 00084 Hydroge embrttleme crackgor flakgFailure Code 3 20.02 Corrosio of mounting paFaiure Code 4: -

DESCRIPTIONSFalure Descpton The integral hollow shaft of a bevel gearshows merous axal cracks across the screw threads Hydrogeembrittlement resulig from a plating opeation initiated thecracks Corrosio of the suaces ear and at he theads, rom aaggressive environmet, may coribte to the cracking Grossfailue is likely from cross sectio cackig o the shat.Image Descrpton (a) Side view of bevel gear wth integralhollow shaf There is a scew thread at the end remote from thegea. Small axial cracks appear across the hreads (whitelorescent dyepenetrat pots, arrows) Corosion pts ae onthe surface N o the heads (b) SEM of fracture surface alonghe axal cack shows the riangar thread coss sectio iductile, dmpled' factue For arrows show hydroge

embrittlement isheye'Suspeced Causes A epar operation involvig electroplating isknow o have bee perormed If properly doe, hydogeembittleme ca result which produces cracks durig rig.Corroson pitting dcates chemicaly aggressive evronmet,which may have contribted to the crackig

Chapter 9 Mounting Component Failure

a

b

431




DATAPate No 197Arhve No 049002Image type light mSaebar 20 mm ms ± 20% thes + 100% 50%)Component RB; M unl) nSpeedLoadLbratonFare Code 222 ht fettedFare Code 221 hft ked bkenFaire Code Fare Code -

DESCRTONSFailre esrpton xteme fetting nd "hippng f the

being set n the hlw shft f ppemhine sutin ll.

Faiure Coe: 222

The entie being set sufe is veed with sinled shpedged tespding seshell-fgment ppene.Dimensins e lst nd the junl is nt serviebeImage esrpton he being set ves mst f the imge At imge N is the pen jnl edfe with nw fee OD ndndeut fllwed t the by the being set extending t imge t the undet t the flge The beng set surfe isnifmly veed by shp-edged velpping tes The sue is d led s fm fettingSspeted Cases Lw junl wll thkness nd lw interfeene existed t the being ft Retive mtin used fettingDung extended petin the fetted se develped shllw ks fm bending f the thi shft. lt is netued tht thispess pdued the tes whih then wee veed by fettng sin pdt pdung the dk l his shftppene is vey nsl

DATAPlate No 98Ahve No 099-15

mage ype view 2)Salebar 40 mmmis 20%thes +100% 50%)Component M shft) unSpeedLoadLbriatonFalre Code 22.2 hft fettedFalre Code 22.3 hft glledFalre Code 22.4 hft wnFare Code -

DESCRTONSFare esrption he tpeed ge set is deeply fetted; theiginl sufe is emved lling nd sbseqent we hveed hee is n xi elevted ine s m split hb

uges e fm emvl tl he ge set dimensin islst nd the shft is nserviebleImage esrption)b) Views tted 80° the sme

tpeed ge set n shft with shldeimge ) nd thed imge N The set se is mpletely fetted ndglled he iginl se s emved Fetting snpdut ws lgely emved by fthe we he elevted xilline ne the W nt f the set nb) suggests tht thee a b

ws split hb in the ge The i guge mk ne thsline is fm tl sed t emve the fetted-n geSspeted Cases nsufiiently diven-up tpeed fit between ge nd sft pdes eltive mtin nd fettingledng tglling nd sbsequent we Jdging fm the xil line in the set the ge hs nt tned meely mved mispilly n theshft

432



Faiue Code 224

DATAPate No

199Arhive No 108006&002&003Image type a, b, c SMSaleba a 900, b: 250, c 40 m (micros ± 20%,others: +100% 50%)Component 0 (chain pin), medium hard, uSpee 200 cm/sLoa:Lbaton oe, ? ocFailre Coe 224 Shat worFailre Coe 223 Shat galledFaire Coe 222 Shat frettedFaire Coe

DSCRTONSFare esription: Conectg pi wea, galling and frettingi a roller chai under oscllating motion bewee pin andbushing during chai articulation This is a unlubrcatedcha with hardened bushings and medium hard pins Theetire pin contact suace is severely retted, and thee areccumferentia gallig and/or wea mars The chaindmesions are lost, he chain/sprocet aculaion becomesfaulty and the chain may eventually breaImage esrpton (a): Oblique view o the pin contactsurface Cicumfeential, terrupted gouge mars fromcombinaion of (observed) retting, wear and gallig (b):Gouges are visble in the SWN sliding direction, suggestgplastic flow, and gallig, olowed by wear (c) No-diectionaldepressions and debris from fretg and wearSspete

Cases: Roler type drive chains have ulubricatedor wealy ubicaed sliding contacts between p and bushig(and between bushing ad oller) The ormer cotacs areoscilaory The suace appeaaces show ae fomunlubricated tests, i which progressve wear and fretting wasobserved Macoscopc seizure did not occur, even though thesurface appearance suggests repeated gallg events Thegeometry is los


a

b

33




DATAPate No

190Archve No 001-31Image type vwScalebar = 2 mm (micros: ± 20% ors + 100% 0%)Component RB R (wit spacr) unrunSpeedLoadLbrcatonFalre Code 23 Spac, sould damagFalre Code 00.03 Pt o unfinsd araFalre Code Falre Code

DSCRPTNSFare Descripion Extnsiv at trat scal s on t OD

surfac of t spacr xtnson o a RB R. Tis OD surac isa fr surac and quird to b wtout scal. T prsnc ofscal may contamnat t lubrication sysm and/or producsrss concnrations wc may lad to cracing

Faiue Code 23Failue Code 2520

Image Descrption Sown is a combnation RB R and spac. T rol pat is at imag S t spacr xtnsion a imag NT OD surac of t spacr xtnsion is covrd wit patcs of blac scal arow points to a scal pacSspected Cases Inadquat clanup of surfac af at ratmnt (as by grinding or grt basing).

DATAPae No 19.1Archve No 09913mage ype viwScalebar 30 mm (micros 20% ors 00%0%)

Component M (gatr sa) mountdSpeedLoadbrcaonFare Code 2.20 Manufacturing or assmblydfct xtrnal conac salFalre Code Falre Code Falre Code

DSCRPTNSFare Descripion Indntd and bn sidfac of tstmtal casng in a gar typ (gartr-sping loadd)lip sal du to impropr tool us in mouning Tdistord cas may pvnt t sal fom sating poprly

in ousing or on saft and caus laag.Image Descrpton gartr sal assmbly is viwd on

t sidac. T OD and outboard pat of t visibsidfac ar st-mal casng. Sal lps ar at t ID. T sidac of casing s indntd by radial dgs at imag E andSE (arrows ) and bruisd at imag S and W (arows B)Sspeced Cases Impropr mounting tool us causd xcssv local forc on t s mtal sal casing dnting and bruisingt Excss infrnc btwn t casing OD and t ousing bor may pvn smoot assmbly and may bucl t casingwn it is forcd into plac

3



Failure Code: 25.22 Chapter 9 Mounting C01nponent Failure

DATAPlate No: 19.2

Archve No 099-15Image type ligh macroScalebar = 15 mm (micros: ± 20% others: +100%, 50%)Component G; M (garte seal) montedSpeedLoadLubicatonFailure Code 1 252 External elastomerc contact seal lip ornFaiure Code 2

Faue Code 3

Falure Code 4: -

DESCRPTIONSFaue Desciption: The seal lip is cut and folded in a gaer-ype (gater spring oaded) easomerc ip seal The seang abiliy is

los. The seal s not sevceabeImage Descripton The meal sea casng is he shaded gray circa band at the seal OD (image S), followed to he N by thedoble seal p At the NS image centerline the lips are radialy ct and olded towad he viewer Duing monng, these ipswere folded under and on, leaving an unsealed gapSuspected Causes Imprope ead chamer on the shaft or careess handling dring monting may ct a gaer seal lip. Whenpushed onto the shaft the c seal ip ods nder, and the ear engthens. he sea becomes nsable.

435




DATAPate No: 1913

Archive No 099154&155&56Image type: a, b, c ligh macoScalebar = a, c 15, b 30 mm(micos ±20% ohers +100% -50%)Component G; M (garer seal), uSpeedoadubricationFailure Code 252.5 Exernal coacseal chemcal/hea damageFailure Code Faiure Code ailure Code : -

DESCRIPTONSFaiure Descripion hree examples of

he effecs of deerioraio of elasomeicsea maeial by chemcal aack orovehea (a) Muliple radial cracking of

he elasome (b) Chippg o he seal ipedge (c): Blisering o he seal lip.Deeriorao o he elastome sireversible Seag abiliy s los orimpared depedig o the severy o

the damage.Image Descripion (a) Easomer lip seais vewed from he open side. Traversig

he image fom S o N one sees casgad wo elasome ips. Muipe dark

radia cracks are vsible acoss heeasomer maerial (arrows). Damage o he N edge of he lip. (Two wre sraps areo pa of he seal) (b) and (c) Seals arevewed o clsed (casg) side heN-facing edge of he lip is chipped a hearrow i (b), ad blsered a he arrows (c).Suspected Causes Excessive opeaig

emperaure unsuiable lubrican/easomer combiaton or aggressiveamosphere may deeriorae he elastomer.l may harden or embrile ad crack orchip Due o decomposiio of he

materia he lip may blser

36

Failure Code: 252.5

a

b

! I /

c



PPENDIES

37



EERENES

1. umn, H N, Wl, H : nteeting evice dmge in olling tye being" STLE ecil ubliction 4-671500 Pk Ridge, I. 195

2 Nibet, T. S, Mullett, G W Rolling being in evice" Hutchinon Behm, London. 1978 . Lundbeg, G, Plmgen, A Dynmic ccity o olling being" Aca Polyechnca Mech. Eng. Se.

Vol 1, No , Stockholm 1947 4 Tllin, T E. n cometing ilue mode in olling contct" ASLE Tn Vol. 10 196. 41849. 5 Littmn, W E., Moy, C A.: ometitive mode o ilue in olling contct tigue" SAE e

620A 196.6. Dwon, P. H. The itting o lubicted olling uce" Power Transmsson London 1961

7. Tllin, T E, Bile, G. H, Dll, H., Guton, G: Rolling being dmge tl" SF IndutieInc, ing o Pui, PA 197 4.8 AGMA Stndd No 11004: "Nomencltue o ge tooth ilue mode" Alexndi, VA 19809 Albn, L E: Sytemtic nlyi o ge ilue" ASM ntentionl, Metl Pk, OH. 1985

10 AM Meals Handbook 9th Edition, Vol. 11: Filue nlyi nd evention." ASM Intentionl, MetlPk, OH 1986 R I Widne "Rolling being ilue," . 490511; L E. Albn "Ge ilue," . 586601

11. AM Handbook, Vol. 18 "Fiction, Lubiction nd We Technology" ASM ntentionl, Metl Pk, OH, 1992. T A Hi: Fiction nd We o Rolling Element Being," . 499514.

12 Wuli, D. J.: How mechnicl comonent il" ASM Intentionl, Metl Pk, OH 19851 Engel, L., lgele, H.: An tl o metl dmge." PenticeHll Inc, Englewood Cli, N. 1981.14 Blok, Hmon Genel dicuion on lubiction" Poc. Int Mech. Eng, Vol 2., 222, London. 197.

15. Tllin, T. E: A uniied model o olling contct lie ediction." Tn ASME, JOLT Vol 104 1982 . 646.16. Vokm, A P Mteil eone to olling contct loding" Tn ASME, JOT Vol 10. 1985

5966.17 Mtin, J A, Bogee, S. F., nd Ebehdt, A D: Micotuctul ltetion o olling being teel

undegoing cyclic teing" Tn. ASME, J Basc En Vol 88. 1966 55556718 Wy, S. Pitting due to olling contct" J Appl Mech Vol. 2. 19 . A4919. Bowe, A F: "The inuence o cck ce iction nd ted uid on uce initited olling contct

tigue cck" Tn ASME, JOT Vol 110. 1988. 0471120 Bhgv, V., Hhn, G. T, nd Rubin, C A Rolling contct deomtion, etching eect nd ilue

o hightength being teel" Metllu Tn. A, Vol 21A, 1990 . 192119121 Suh, N. P: "A oveview o the delntion theoy o we" WEAR Vol 44 No 1 1977 . 116.

22 AM Meals Handbook 9th Edition, Vol. 10 Fctoghy" ASM Intentionl, Metl Pk, OH 1986.2. Tllin, T E: The Evolution o Rolling Being Lie Model." STLE ecil ubliction, Pk Ridge, IL

39



SourceNo*

002

003

004

007

01

014

08

02

027 074

075

087

093

099

103

07

08

1

7

IST O AGE CONTRIBUTORS

Contributing Institution/ndividua

att & Whitney Aicat Eng. Dv. au Bown Seo ta poject enginee. Eat atod T. 008

att & Whtey Aicat G.EB. . Wiliam E. ooe Seo poject enginee. Wet amBeach FL. 3340-00

Hughe Acat ompany DAA AFWAL-T-83-42 (84) D . N. Gado he

centit. El Segundo A 0245Battele oumbu Dvon D. Wm A Gaee. olumbu OH. 432023

IB opoation D ay G. Baye. Endicott NY. 1370

The Tiken ompany anton O. 4470-278. e. . L. Widne and . A. oye.Some mage om AS epot 7-. ASE pape 5-WAF-2 o NASA S237. D. aod Buie STLE Tib. Tan. 3 2 pp 27285

The Tongton ompany Advanced Technoogy ente . K. eaon g. t.Dev. Tongton T. 070-008

SK USA Inc . W. aph Good E. (et.). Kng o uia A. 140

U. S Navy Wahngton D. 2032-50NTN opoaton SAE pape 87077 D. Tuhma Nakahima & Kahmua. OakaJapan

Koyo Seko o. Ltd. D. S. Ueno Exec. V . Oaka 542 Japan

Beang npecton Inc . Stuat atheon hie Egnee. Santa e Sping A 070

SKF (USA) nc. Kng o uia A. 40

The al opoation wauee W 53201-042

.S. Dape Laboatoy Inc. D. Edwad Kngbuy. ambdge A. 023

FAG Kugeiche Geog Schaee KGaA . Eckehad Scheibe. Schweut D-8720 . . Gemany

Tiboogy Intenatonal Vol 20 No pp. 30 D. N. E oingwoth. Doodecht 3300AA The Netheand

Nucea Electc Bekeey Nuclea Laboatoe S. J. adcie Scentit. BekeeyGL13 B Geat Bitan

Delta ubbe o. . onald acLaen V. . Engineeng. Daeon T. 023

*Achive numbers o PLATEs osst of wo goups o nmeals, separated by a hyphe e.g. 000-00. Te grp preceding the yphen

identiies te image soe

1




22 Vykny Ustav Po Vava Loiska I Cc Z. Rsnak centist Bno 61700 Cech

Repbic23 U A Foce Wight Laboatoies Wight-Patteson AFB OH 45433 I D Neson Foste

124 U A Foce Reseach Laboatoy Wight-Pateson AFB OH 45433 I D Wayne EWad Wght Laboatoy Tecnica Repot WL-TR-954081

The oowng contbtos did not wsh to have the oce nmbes o the mages dentiied n thecedit istng.

Catepia Inc. Peoia IL 6629Phiadepha Gea Cop ing o Pssia PA 9406cott Pape Co Phadepha PA 1913

Wea Anayss Inc I Chevon Reseach Co I aise Amnm Co D Dogas Godey an RaaeCA 94901

Cetan contibtos have eected not to be ncded n the cedt isting

2



Faiue code

1....3

111.113

.41.34.4.1.443

3

.333.334

4414.43431.431.

FAILURE ConE IST

Faiure desinaion

Conc ssembly ilure

Conc pr iure

Mnucring or ssemby deec

Mnucring or ssemby deec, by ocion

Deec by ocion in i surceDeec by ocion in conc surceDeec by ocion in Herz conc surceDeec by ocion in sliding conc surceDeec by ocion in ree surce

NickLoc ckNick wih rised edgesScrch, oolmrk, scumrkCirculr nick on b

Chipped nick in cermic Finshing mrkrinding, hong, pping urrowWheehirinding cherMchiing mrkurning mrker hobbng mrker shving mrk

Pi or uniished re

Surce porosiy or pi Unground re Uhoned reLpping imperecion

Forming deec Forming lp Formg sem Forming incorrec emperure Forging excessive emperureIncipien meling rom orging excessive emperure

3




aiue code

.5.5.1.5.2.5.253.5.45.4.1.5.4.2

.6.6..616..26.1.3.6.2

........2...3..2..3..3.1..3.2..4.5..5...5.2..5.1.5.2..6

..1..2.3.4.5.6..

.99.9..9.2

aiue designation

Caing defecMcro-pooyMacro-pooy ipe or void formed a ngo cenerInecion modng deec (n pac)Srucure defec in ceramicMicropooy in ceramcBinder defec in ceramc

ncluionMco-ncluion ard mcro-incluonSulfde incuion imary cabdeIncuon ringer

Maeria rucure defec pe- or n hea reamenSo rucure (general or locazed)nucien bulk hardneerc conuen Upper baic conuen Of-pecficaon maenie plaee zeDefecve cabide ucureCarbde egregaonamelar carbidebe reaned aueneorgng or hea ea crack Forging crack ea rea crackCack wih oxidized urfacewed (baebal) crackGran ze off-pecfcaonNon-mea rucure o-pecficaon

Maera ucure damage, po-hea reamenGrnding emperReardened grinding bunGrinding cack ydogen embilemen cracking or akngChemica aack durng manuacueCoang damageCod ormng damage

Geomery, aemby or mouning deecGeomery defecScorng from forcible aemby o mounng (no galng)Galng rom forcble aemby or mouning



Faiure code

0009.3

00., 002

00.2 0020 002.0 00.2.0.2 00.2 002 002.2 00.23

00232 00.232.0 00.2320 002320.2 00232.0.3 00232.04 0023205 002320 002320. 002.32. 0.8 00232 00232

00232.2 002.32.. 3 002324 002322 002323 002324 00233 00233 00233.2 00.2333 00.24 0025 0025. 00.252 00253 0025.3 002532 002532 002.5322 00.25323 002.5.324 002 002

Faiure desgnation

Cracng racre) from forcie aemy or monng

Servce aire, conac par

Wear, mdWear, idenied y mechamAdheve mid wearAraive md wear race wear race pohngAdvanced md wear o raceBearing conac wear

Wear in rong rfaceWear rac a load ype ndcaorWear rac when oad roae over nerringWear rac when oad roae over oerrngWear rac or radal preloadWear rac or o-o-rond rngWear rac or cenered axa oadWear rac or comined rada/ axial oadWear rac or miagned oerringWear rac or miaigned nerrngSmooh rolng race wear iih mar removed)Wear rac cenered in conac

Wear rac o-cener n conacWear rac h n conacWear rac a conac edgeScrach mar, nemaic wear mar n rong rfaceSep worn n rolng rface or dmenon worn opecScoring wear macrocopc goging who gang)Sding conac wearWear a edge of ding conacWear, cenered n ldng conacScrach mar in idng conacWear o gdng-componen ppor raceGear ooh wearooh pohngSmooh ooh wearDercive ooh wearArave dercve) ooh wearAdheve dercve, non-galng) ooh wearWavy ooh wearBmpy ooh wearRdgng ooh wear Frrowng ooh wearWear a inended rface conacmpac wear

Failure Cde Lit

445





Faiue code

001602 0016021 0016021.1 0016.02.12 0016.0213 0016022 0016023 00.16024 001602 001603 0016031 0016032

00161 001611 001611 1 0016112 0016113 001612 0016121 0016122 0016123

00.17 0017.01

0017.02 0017.1 0017.1.1 00171.2 001713 00172

00.18 00.1801 0018011 00180111 00180112 00.18.012 00.18013 00.18.02 00.18021 0018022 00181 0018 11 001812 001813 0018 1.4 00182 00.18.21

Faiue designaton

Spallg, dtiid by pogssio stagMcoplastic domato ndcatioMcoplastc domato bads o 'bttsDatchg micoplastic domato oMcosph spalig dbisCotact atig cacgIcipt spalg, sg spalIcipit spalg, mltipl spalsAdvacd spalligSpallg, dtiid by popagato modSpal popagatig by cacig at spall bottomSpall popagatig by -itiatio at sac

Spallg, dtiid by oigi locatioSbsac og spal (high Ht sha stss)Stp ty spal (sbsac ogi)Spall om sbsac dctSbcas-atig spalSac oigi spalShalow ty spall om sac poitdctShalow ty spal om sac i-dctShaow ty spall om ts cacig (camic)

Sac distss (sac atig)Sac distss, o slidig

Sac distss, with sdigGad sac distssGag (icpit sac dstss)Micospalig (advacd sac dstss)Ga plot (sac distss o camic)ocalid sac dstss (halo at dct)

Dtig (idtato)Idtato, dtiid by ocatoIdtatio o (pmaily) olig cotact sacDtig o oling sac, o sidgDtig o oig sac, mio sldgIdtatio o (pmay) sidig cotact sac

Idtato o gid-pat sppot sacDtig, idtd by svtyLight o cipt dtigSv o advacd dtigLocal dtRodd dt (om sot cotamiat)Shap divida dt(s) om mtal dbs, aspitisMt-agmt dt (bitt cotamiat)Mtp igla dtig om i, oos had dbisRold- i i cotactRolld- i at cotact dg

Failure Cde Lit

447





Faiure code

...3.4

33.3.3..333

..345.6

33333334333.33

.4

4.4

5

.6

7

.

Failure desgnation

Oversress crckBulk figue crckRubbing crckemicl orgn sress corrosion embremen) crck

Permnen deormion bukPsc roldown o conc ponc p rodown in beringGer oo conc roldown sic dsorion o buk speDimensonl cnge due o srucure rnsormon

Gudng-pr fure

Sepror fure

Sepror mnufcurng geomery defec

Sepror buk defecSepror meng polymer)Sepror rcure crckngSepror wed ilureSepror csing or molding deecSepror rve prong ng or bol fureSepror ping defec

Sepror psic deormon

Sepror werSepror pocke wornSepror crossbr worn one pocke sdeSepror crossbr worn bo pocke sdesRoler sepror dgonl crossbr werRoer sepror pocke boom wornnd guded sepror gude surce wornnd guded sepror gude surce worn generlnd guded sepror gude surce worn loclSepror wer from uinended conc

Sepror ging

Sepror pocke gedLnd guded sepror gude surfce ged

Sepror corrosion

Sepror e imblnce iure

Sepror conc splng

Guidering lure

Guderng mer deec

Guderng rcure crckng

Failure Code List

449



Faile Atlas fo Hetz Contact Machine Elements

Fue code

01.23 0.24

02

02.1

02.0

02.1

02.12

0213

02.14 02.5

0219

02.2

1

1

10

11

1.2

11.3

1.3011.3.021.31113.21331.3.4

14

1.5

12

120

12.00

1201

2.02

12.1

22

450

Fue desgnon

Guidig waGuidig galig

Sa (iga, faiu

Ruig a df

Maial o maufauig df i uig a

Ruig a wa

To uig al lip

Ruig a oufa wa

Ruig a lakChmial aak o uig a

Gomy o amly df i uig al

No-uig ou df

Luia faiu

Oil failu

Oi quaiy df

Fiio polym, oil uiaio

Wa i oi

Solid oami i oi

ipi oi oamiaioSv oil oamiaioSl oamia i oilNo-l ma oamia i oiAaiv oama i oiSof oamia oil

Diolod oi

Caoid oi dpoi

Ga failu

Ga quaiy df

Ga, a-maufaud

Ga pak ow

Ga pak xiv

Sofd o liqufid ga

Caod ga



Faiue code

12324

2412421243244

125

1250125021251

125212531254

26

126262

27

3

131

3113121313

2

20012001120012200122001222001320014

2002

2003

21

21

22

213

24

Faiue designation

Ficio olm, g lubicioW i g

G icoloio (whiih), om wW ol i g F w i gG como b chmicl g

Soli comi i g

cii g comiioS g comiioSl comi i g

No ml comi i gAbi comi i gSo comi i g

G i ou, icolo

G i ouG icolo

Elcic cu mg o g

Soli o g ubic iu

Vo h ubic iu

Chmic uc c b o h ubicSoli lubic oi om o h ubicPlig oi om o h lubic

Mouig mg

Mouig mg, gl ciioGiz mouig mgociz mouig mg Foulig o mouig b oh moig Mouig ic o gougAxi w o cum o mouig Cicumil w o cum, mouig

Cooio o mouig

Mou oo (bclh) ociicio

ouig mg

ouig cc o cu

ouig

ouig gl

ouig wo

Failure Code List

451




Failure code

2.5

21.6

27

21.8

2.9

22

22

22.2

22322.4

22.5

22.6

229

23

23.

23.2

24

2 5

2 5.1

25.1.0251.1

25.1.2

25.2

25.2.025.2.1252.225.2.325.2.425.25

26

452

Failure designation

ubricant eak from housing or cover

Housng deormed

Housing msmounted

Housng corroded

Geometry or assemby deect in housng

Shat damage

Shaft cracked or broken

Shat fretted

Shaft gaedShat worn

Shat deormed

Shat mismounted

Geometry or assembly deect in shat

Spacer, shouder damage

Spacer, shoulder retted

Spacer, shouder corroded

Mounting seeve, nut, ockwasher damageSeal (externa) falure

Labyrinth sea aure

Manufacturing or assemby defect, abyrnth sealLabyrinth sea l wearabyrnth sea galng

Externa contact sea aiure

Manuacturng or assemby deect, externa contact seaExterna contact sea wearExternal eastomerc contact sea p tornExterna ace sea carbon chppedExterna contact sea conterface worn or gaedExterna contact seal chemca/heat damage

Support bearng damage (of gear, cam



FAILURE MoDE NDEX

Faiure designation

asting defectBiner eec n ceramcInecon mong eec (n plasc)Macro-porosiyMcro-porosyMcro-porosy n ceramicPipe or vo orme a ngo cener

Srucure eec ceramic

ontact assemy faiureConac assembly ailure

ontact part faiureDeec by locaon: conac suraceDeec by locaon: i suraceDeec by locaon: in ree suraceDeec by locaon: in Her conac suraceDeec by locaon: sng conac suraceManuacurng or assemby eecManuacurng or assemby eec, by locaon

orrosionConac corrosionCorrosion ousie conac onyCorroson pingCorrosion sainCorroson, ienie by ocaonCorrosve ingerprin-markGenerae corrosion

racking or fracture, ukAxial cross secion crack in rngBulk aigue crackCemical origin (sress corroson, embremen) crackCircumerenial crack

Fracure cassiie by locaionGear oo crack or racureMi-oo racure Oversress crackRoing elemen (ba, roer) crackRubbng crackoo corner racureoo roo racureoo ip cpping

Faiure code

00.05.4.2 0005.3 0005.2 0005. 1 00.054.1 00.05.21

00.054

0

00.00. 02 00.00.01 00.00.03 0000.02.1 0000.02.2 000 00.00

00.20.1.3 00.20.1.2 00.20.2 00.20.1 00.20.01 00.20.3 00.20.01. 1

0022.01.1 00.22.2 00.22.4 00.22.01.2 00.22.01 00.22.01.4 00.22.01.43 00.22.1 00.22.01.3 00.22.3 00.22.01.42 00.22.01.41 00.22.01.44

453



aiure Atas for Hertz Contact Macine Eements

Faiue designaion

Dening (indenaion)BieiDeti o oi suac, mio sidiDeti o oi suace, o sidiDeti, idetiied by seveityGea tooth peei (ieua oca pastic ow)Gea tooth idi (pastic ides i sidi diectio)Gea tooth ippi (tasvese wavy pastic ow)Gea toot, oca pastic ow i cotactdetatio o (pimaiy) oi cotact suacedetato o (pimaiy) sidi cotact suacedetato o uidepat suppot suacedetatio, idetiied by ocatioLiht o icipiet detiLoca detMutiamet det (bitte cotamiat)Mutipe ieua deti om ie, oose had debisRoed-i cotiuous ie om opposi edeRoedi ie at cotact edeRoedi ie i cotactRoed-i ie iside cotactRoedi ie, both cotact edesRoedi ie, oe cotact ede oyRouded det (om sot cotamiat)

Sevee o advaced detiShap idividua det(s) om meta debis, aspeitesStipped ie(s) o bad(s) om oed-i debis

Eecic eosionEectic eosio utiEectic eosio pitti

Finishing mak Fishi makGea hobbi makGea shavi makGidi chatte

Gidi, hoi, appi uowMachii makTu makWheehit

Foming defec Foi at excessive tempeatue Fomi at icoect tempeatue Fomi deect Fomi ap Fomi seamcipiet meti om oi at excessive tempeatue

454

Faiue code

008 0013 001. 0112 0010111 001.02 00141 00.143 00142 00.14 001011 00101.2 001.013 00101 001021 0011 0011 3 00114 00122.1 00121 0012 00122 001212 001211 00111

001022 00112 001222

00.2 00212 00211

0002 0002 000242 000243 00023

00021 00024 000241 00022

00.04 000431 00043 0004 00041 00042 0004311



Faiue designation

Fetting weaDispacd adia fi fig fom ig s oadxcssi fig, oos o iacca adia fi Fas biig o coac sfac Fi sidfac fig Fig (fig coosio) Fg ca-makd adia fiGaizd fig, adia fi sfacIga fig disod adia fiLocaizd fg, adia fi sfacNoma fig, acca adia fi, adia oad

Noma fig, acca adia fi, s oad Osidd adia fi fig fom apRadia fi sfac fig as moig diagosicSkwd adia fi fig fom misaig

Gaing (smeaing, sevee mehania wea)Coac gaig fom ig accaoCoac sfac gaigxsi gaig Fi sfac gaigGaig a gidig-pa coac sfacGaig fom ick oigi, fi sfacGaig fom apid moio oigi, fi sfacGaig of sidig coac sfacGaig, idifid by siyIcipi gaigRig gaig a oad zo yRoig sfac gagRoig sfac gaig, d o ick isibRoig sfac gag, o d o ck isibToo coac gaig

Geomety, assemby o mounting defetCackig (fac) fom focib assmby o moigGaig fom focib assmby o mog

Gomy dfcScog fom focib assmby o moig (o gaig)

Gease faiueAbasi coamia i gasCaboizd gascic c damag o gas F wa i gas Ficio poym, gas bicaioGas dcomposd by cmica agGas discooaio (wiis), fom waGas discood

Failure Mode Indx

Faiu ode

00.5 00151204 00151203 00152 001513 00151 0015120 001511 001512 001512 0015120

00151201 0015206 001512 00155

00.3 00132112 00132 001302 00131 001323 001311 001312 001322 0013.0 001301 00.132111 00132.1 0013212 0013211 00133

00.09 00093 00092

00090 00091

21253122127124323124412411262

55



ailur Atlas for Hrtz Contact Machin lmnts

Failue designaon

Grease dred outGrease dred out, dscooredGrease pack excessveGrease pack owGrease quantt deectGrease, as-manuacturedIncpent grease contamnatonNonstee metal contamnant n greaseSevere grease contamnatonSot contamnant n greaseSotened or lqueed greaseSold contamnant n grease

Stee contamnant n greaseWater droplets n greaseWater n grease

Guiding-pa failueGuderng aureGuderng racture, crackngGuderng galngGuderng matera deectGuderng wearLand guded separator, gude surace galedLand guded separator, gude surace worn

Land guded separator, gude surace worn, generalLand guded separator, gude surace worn, locaRoler separator, dagonal crossbar wearRoler separator, pocket bottom wornSeparator buk deectSeparator castng or moldng deectSeparator contact spalngSeparator corrosonSeparator crossbar worn, bot pocket sdesSeparator crossbar worn, one pocket sdeSeparator alureSeparator racture, crackngSeparator galngSeparator eat mbaance aureSeparator manuacturng geometry deectSeparator metng (polmer)Separator plastc deormatonSeparator platng deectSeparator pocket galedSeparator pocket wornSeparator rvet, prong, tang or bot aureSeparator wearSeparator wear rom unntended contactSeparator weld aure

456

Faiue code

2.6.112.612.0212.0112.012.0012.5.012.5225.022.5.412.112.5

12.5.12.4.224

02 01.2 01.22 01.24 0.2 0.23 0.4.2 0.3.2

013.2 0113.2.2 0113. 1.3 0113. 1.4 011 01.14 01.17 0.5 0.3.12 0.3.1. 01 01.2

0114 0116 01.10 0.1 01.12 0.1.6 0.4.1 0.3.1 01.5 013 01.133 01.13



Faiure deignation

Heat imbaance faiurercton poymer on gudng part support suracercton poymer on rong trackrcton poymer on sdng trackGeneraed temper coorsHeat dscooraton by rcton poymerHeat mbaance temper coorsHot pastc owHot pastc ow wt buk wedngHot pastc ow wtout wedng (roout)

Loca structure damage rom rctona eatngScae ormatonTemper coors in contact suracesTemper coors on gudepart support surace

Houing damageGeometry or assemby deect n ousngHousng corrodedHousng cracked or racturedHousing deormedHousng rettedHousng gaedHousng msmountedHousng wornLubrcant eak rom ousng or cover

Incuion

Hard mcro-ncusonncuson strnger cro-ncuson rmary carbdeSude ncuson

Lubricant faiureLubrcant aure

Materia tructure damage, potheat treatment

Cemca attack durng manuactureCoatng damageCod ormng damageGrndng crackGrndig temperHydrogen embrttement crackng or akigReardened grndng burn

Failure Mode Inde

Faiure code

00.19 00.19.4.3 00194.1 00.19.4.2 00.191 00.19.4 00.19 0092 009.22 009.2.

0095 00.9.3 00.92 0019.3

21

21.92.82.12.62.223272425

0006

000611 00.06.2 00.06. 00063 00.06..2

1

0008 00.085 00.08.6 00.08. 7 0008.3 0008.1 0008.4 00082

457



ailue Atlas fo Hetz Contact Machine Elements

Faue desgnaton

Mateia stutue defet pe o n heat teatmentCabide segegatiCack ith xidied sfaceDefectie cabide stcteeitic cstitetgig cackgig heat teat cackGai sie -secificatiHeat teat cacksficiet bk hadessLamella cabidemetal stcte ff-secificati Offsecificati matesite lateet sieSft stcte (geea caliedTisted (baseball cacke baitic cstitetVisible etaied asteite

Mounting pat damageAxial ea scffmak mtig atCicmeetial ea scmak, mtig atCsi f mtig atlig mtig at by the mig atGeealied mtig at damage

Lcaied mtig at damageMted lseess (backlash ff-seciicatiMtg at damageMtig at damage, geeal descitiMtg at icked gged

Mountng seeve, nut, okwashe damageMtig sleee, t, lckashe damage

NkChied ick i ceamicCicla fat ick ballLcal ck

ick ith aised edgesScatch, tlmak, scfmak

Oi faiueAbasie ctamiat i ilCabied il desitDiscled iicti lyme, il lbicaticiiet i ctamiati-steel metal ctamiat i i

Oil ality defectSeee il ctamati

48

Faiue ode

00.07 00073 1 000751 00073 00071 0007501 00075 00076 000750 000711 00073 00077 0007 00071 00075 000713 00074

20 0013 0014 00 0011 0011

001 003 001 001

24 2 4

0001 00014 00013 00011

000111 0001

111133115114111113011131101130



Faiur dsignation

Soft ontamnant n olSold ontamnant n olStl ontamnant n olWatr n ol

Prmannt dformation, buk

Contat pat rolldown n bargDmnsonal ang d to strtr transformatonGar toot ontat rolldownPlast dstorton of bl sapPlast rolldown of ontat pat

Pit or unfinishd ara

Lappng mprftonSrfa porosty or ptngrond araond ara

Sa (xtrna) faiur

Extrnal ontat sal mal at damagExtrnal ontat sal ontrfa worn or galldExtrnal ontat sal falrExtrnal ontat sal war

Extrnal lastomr ontat sal lp tornExtrnal fa sal arbon ppdLabyrnt sal falrLabyrnt sal gallngLabyrnt sal warManfatrng or assmbly dft, xtrnal ontat salManfatrng or assmbly dft, labyrnt sal

Sa (intgra), faiur

Cmal atta on rbbng salGomtry or assmbly dft n rbbng sal

Matral or manfatrng dft n rbbng salNonrbbg losr dftRbbng sal ontrfa warRbbg sal dftRbbng sal laRbbng sal warSal (ntgral), falrTorn rbbg sal lp

Sric faiur, contact part

Sr falr, ontat part

Failure Mode Index

Faur cod

1134131312

00.23

00231 00233 002312 00232 00231

0003 00034 0003 00032 00033

25

252525242522521

2522252325125225112520250

02

025 029

020 022 0213 021 0214 021 02 0212

00.1, 002

001, 002

459




Faiure designation

Shat damageGomty o assmly dft in saftSaft ad o onSaft dfomdSaft fttdSaft galdSaft msmontdSaft won

Skid marking microscopic severe wear)Sid maing (mosopi sv wa

Soid or gas ubricant aiureCmia sfa atta y vapo pas iantPing dposit fom vapo pas liantSod ant dposit fom vapo pas iantVapo pas ant fal

Spacer, shouder damage

Spa, sod ooddSpa, sod fttd

Spaing Hertzian contact atigue)Advand spalingCntd spaling, nomal ta widtCntd spalng, wd taContat fatig angDa-ting miopast dfomaton onInipnt spaing, mltp spasInipnt spaing, sing spaMio-sp spaling disMiopast dfomaton ands o 'ttfisMiopast dfomaton indiationSaow nty spal fom sfa ln-dftSaow nty spal fom sfa pont-dftSaow nty spall fom tnsil aing (amiSpal fom ssfa dftSpal popagatng y ang at spal ottomSpal popagatng y -ntation at sfaSpallng at ontat dgSpalling at ontat dg fom tst loadSpaling at ontat dg, fom gomty oSpallng at ontat dg, fom msalgnmntSpaling ntd n ontatSpang, y loatonSpaing, idntfd y ogn oatonSpaling, idntifd y pogssion stagSpaing, dntfd y popagation modStp nty spall (ssfa oigin

60

Faiure code

2222.922.122.522.222322622.4

0014 0014

13

131113.1313.1213.1

2323.223.1

00.16 00.16025 00.16011.1 00.16.011.2 00.16.02.2 00.16.02.1.2 00.16.02.4 00.16.02.3 00.1602.1.3 00.16.02.1.1 00.16.02.1 0016.1.2.2 0016.1.2.1 0016.1.2.3 0016. 1.1.2 0016.03.1 0016.03.2 00.16.012 00.16.012.3 00.16.012.2 00.16.012.1 00.16.011 00.16.01 00.16.1 00.16.02 00.16.03 00.1611.1



Faiure designation

ubcase-aigue spalubsurace origi spal (high er shear sress)urace origi spalTooh pichie or dededum spaigTooh spalig

Support bearing damage (of gear, camuppor bearg damage (o gear cam)

Surface distress (surface fatigueGeeraied surace disressGaig (icipie surace disress)Grai puou (surace disress o ceramic)ocalied surace disress (hao a deec)Microspaig (advaced surace disress)urace disress o sidigurace disress wih sidig

Wear, midbrasive (desrucive) ooh wearbrasive mid weardhesive (desrucive ogallig) ooh weardhesive mid weardvaced mid wear o i suraceBearg coac wear

Bumpy ooh wearDesrucive ooh wear Fi surace poisg Fi surace wear Furrowig ooh wearGear ooh wearImpac wearRdgig ooh wearcorig wear (macroscopic gougig wihou galig)crach marks i slidig coaccrach marks, kiemaic wear marks i rollg suracelidig coac wear

mooh rolig surace wear (ish marks removed)mooh ooh wearep wor i roig surace or dimesio wor ospecTooh poishigWavy ooh wearWear a edge o sidig coacWear a ueded surace coacWear i rolig suraceWear o guidig-compoe suppor suraceWear rack as load ype idicaorWear rack a coac edgeWear rack ceered i coac

Failure Mode Index

Failure code

.161.13.161.1.1612.1613.1.16.13

2626

.17.1.17.1.117.1.3

.17.2.17.1.217.1.17.2

12.5.3.112..2.125.32.12.1.12.1.2.123

.12.53.2.2.12.5.3.12.1.1.12.1.12.53.2.4.12.5.12.7.12.5.3.2.312.3.2412.3.33123.2.212.3.3

12.3.21125.2.12.3.23.12.51125.32.1.12.33.1.126.1232.12.4.12.3.2..12.3.2.1.4.12.3.2.1.1

461



ailue Atlas fo Hetz Contact Machine Elements

Faure desgnation

Wea tack ceteed axa ladWea tack cmbed ada/ axal adWea tack msalged egWea tack salged utegWea tack ut--ud gWea tack adal eladWea tack cete ctactWea tack shts ctactWea tack whe lad tates ve egWea tack whe lad tates ve utegWea ceteed sldg ctactWea deted by mechasm

462

Faiure ode

0012.3.2.0.5 0012.3.2.0.6 00.123.2.08 00.23207 00.23204 00.2.320.3 002.3.2 .2 0012.3.2..3 00.123.20. 00.123.202 00.12332 00.20



TEX INDEX

Appearance 2categories 2cassifcaion 2

Appearance: geomey faiure geomety (assemby) eror permanen bulk defomation

Appearance: point/ine faiure 2crack, acture

den foreign matea

forming casing defect galing inclusion maea defec maea ocaly deformed 29maeria ocaly removed 2materia separation mateial ransfered

nick 29pi 2plowing mark 2 spal 2welding 2

Appearance: wide area failure 22genera surface dispacement 22genera texure change 22maera failure 2

Aas features

Buk crackng racture afer spaing

brittle crack by mechanical sress causes ceramics 3 3chemicay promoted crack

crack face change crack initiation crack progression denition distincive appearance 2

ducie crack

eects faiure process fatigue crack rom beang impact oveoad

from bending stress

om gear impact oveoad

om hoop stress rom herma stress om tooh bending fatigue gear web hub crackng gears iniiaing sress condiion inergranular nomenclature roling beangs rubbing cracks

spine crackng transgranuar

Buk defomation, permanent Pma dfma

Casing defect causes 2deniion 2distinctive appearance 2effects 2faiure process nomenclature

Cassicaionappearance

Appaac casscafaiure

a cassfcaClosure

Iga csComponent�

cosures conact guiding ubricant mouning pa

Contacconcentrated contact

Hz caccontac fatigue

pag ac dsssHetz conact

Contact componentfaiure manufacturing defect service failure

Corrosion 29causes 29chemica attack on non-meas 29contac coosion 29

46




defnition

distinctive appearance

eects failure mode

galvanic couple

general corrosion

intergranular , ,

nomencaue

of metals ,

pitting ,

saing

CackSee Bulk cracking

Crack causes

appied stress

chemical attack forming, casting defect

heat treat defect

residual stress

secondary failure

Cracnghydrogen embrittlement

stress-corrosionSee also Bulk cracking

Cross-indexSee Failure

Damage denition

See Failure defnitionDefect denition

See Failure, defnitionDenition (of failure mode)

Denting

brinel mark

causes

contaminant denting ,

debis dent

definition


eects

failure process

multi-agmen dent nomenclature

rolledin line

rounded dent

stippled line

Elecric eosion

causes

definition


eects

failure pocess

uing

464

nomencature

piting

Engineeringfor failure control

for fnction

Failure

class index

class is

classication

codeSee Failure code

code list ,

cross-index FC 00.01:

cross-index FC 0002-04:

cross-index FC 0005-09 cross-index FC 002

crossindex FC 0013-4

cross-index FC 005

crossindex FC 0016:

crossindex FC 00.7

cross-index F C 008

crossindex FC 0019

cross-index FC 0020-2

crossindex FC 0022-23

cross-index FC 0:

cross-index FC 02:

cross-index FC -3

cross-index FC 20-26 defnition

index list

mechanism

mode index

morpological

nomeclature

otheSee Failu mohological

process

Failure class

lower-order

main class

Failue classifcation , , decimal

See Failure code

Failure code

class index

code groups

code list

failure mode index

Failue mode

database

grouping

False brinelling



auses denon dsnve appearane ees falure proess nomenaure

Fatgueonta fague

ee pallin urace distessear

ee urace distessFnsng damage sruural

oang damage old formng damage 9grndng damage

Fnsng mark auses defnon dsnve appearane effes falure proess nomenlaure

Formng defe auses defnon dsntve appearane

effes falure proess nomenlaure

Freng auses denton dsnve appearane

effets

falure proess gears ams nomenlaure rolng bearngs

Fretng ear defnon

false brnelng

etng etng orroson

ee FettinFron poymer 9

Gallng 9ams auses

defnon 9dsnve appearane

effes faure proess 9

gears nomenlaure 9 ·

rollng bearngs sezure

Geome assembly mountng falure assembly sorng galng raking geomery defe

Grease faure 9arbonzed grease 99annelng 9yl grease falure 9defnon 9dsolored grease dredou grease effes 9eer urren damage o grease exessve grease

ee ease quantity defectfalure proess 9grease pak 9grease quany defe 9eatng 9neffeve lubraon 9nsuffen grease

ee ease quantity defectrreversbe grease falure 9nomenlaure 9

slumped pakee ease quantity defect

sofened queed grease 9

sold onamnan n grease searng 9

aer n grease

Grndng daageee Finishin damae, stuctual

Guderng falure auses 9

defnon dsnve appearane 9effes

falure proess

nomenlaure

Gudngomponent falure 9

Hea mbalane falure arres of falure 9auses emal ange learane loss denton

dsnve appearane 9effets faure proess

Text Idex

65




ho plaic ow 2 9

impaied ubcaion2

load peed excuion 2ubcaion aiue 2machine empeaue excuion 2maeal engh lo 2nomenclaue 2 educed conducive cooling 2econda ailue 2econday gaing, acue 2econday lubicaion ailue 2uace change 2

Image page

appeaance claicaion

Pae Incuion 2

caue

deniion 2

diincive appeaance eec

aiue poce

nomencaue Indenaion

S Nick, DnIndexing

Pae coindexing 2Inegal coue

nega cloue ailue

caue deniion

diincive appeaance

eec ailue poce 2

image limiaion nomencaue

non-conac hied bbing eal 2

Inega ea

S Inga cou

Lubican aiue 9

S ao Oi ga, ubican (o) faiuLubcan ohe ailue 8, 406

ubican vapo phae ailue 407Machine elemen

cam claicaion componen geaing ohe

466

olling beaing

uppoing componen Manuacuing deec uace caing deec nihing ma oming deec pi ineing deec 1 5uninihed aea

Maeial aemby deec ceamic binde deec 1deniion nihing damage geomey aemby ailue

incuion2

Maeia cue deec pehea eamenS Sucu dfc

Mid wea 9cam 2deiniion 9caue 2

diincive appeaance eec ailue poce 9gea 2

kinemaic ma nomencaue 9

piing wea

olling beaing 2mooh wea

ep won in Moding caing ineng deec

pooiy in ceamic 1Mophoogy Mouning componen

Mouning componen ailue 2caue 2coeponding aiue mode 2deiniion 2diincive appeaance 2

eec 2·aiue poce 2

ing componen 2lubcaion componen 2nomencaue 2

noncoeponding aiue mode 2uppo beang 2

Mouning pa

S Mouning componn

Nic caue 2

caue in beang 2



causes in cams 3

causes in gears 3

chipped 4 1

common causes 2

defintion

dsncive appearance

efecs 3

aure process

nomencaure

Oi aure 389

conact ubrcaon ailure 389

cooing ailure 3 90

defnition 389

dscolored o 3 9

aiure process 389rcon polymer 390

nomencaure 389

soid contamnant 392

water n oil 39

Permanent buk deormaton 39

causes 320

deinion 39

deormaion b y phase change 39

dsncive appearance 320

dsortion by residua stress 320

efecs 32

alure process 39

nomencaure 39

plastic ow 39

Pt 53

causes 5

deinion 53

dstncve appearance 53

eecs 5

aiure process 53

nomenclature 53

Pate 6

chaper 8, 2

data 9

descripton

ailure descrpion

ormat 9

mage 9

image descripon

sortng order

suspeced causes

Pubcaons 5

ScufngSee Galling

SeaSee Integral closure, Mounting component

Text Index

Separaor buk dsconnuiy 39

casting molding deec 39

causes 350

causes manuacuring 350

causes, serce 35

crackng acture 39

defnition 39

disinctive appearance 350

eects 35

ailure process 350

asener aiure 39

meting 39

nomenclature 39

weld ailure 39

Separator bulk permanen deormaon 35

causes 352

denition 35

dsnctive appearance 352

effects 352

alure process 352

nomencaure 35

Separaor corrosion 356

causes 357

denition 356

dsincive appearance 357

effects 357

aiure process 356

nomencaure 356

Separaor aiure 39

See also individual separator failure modesSeparator galing 355

causes 356

denition 355


efects · 356

aiure process 355

nomencaure 355

Separaor heat mbalance aiure 357

Separaor spaling 358

Separator wear 352

causes 35

denion 352


efecs 35

ailure process 353

nomencaure 353

ShiedSee Integral closure

Skd markng 3

causes 5

defnion 3

dsinctive appearance

efecs 5

467



Failre Atlas for Hert Contact Machine Elements

failure process 144nomencature 144

SmearingSee Galling

Spaling 179causes 182

causes: number of stress cycles 183

causes load 182causes material 182

causes subsurface defect 183causes: surface defect 183causes surface distress 183

causes temperature 182

causes traction 183deformation bands, butteries

See Spalling, micro-plastic fowdistinctive appearance 180

effects 184

failure process 179fatigue damage accumulation 179

hydraulic propagation 184

macro-cracks 180

micro-pastic ow 179

microcracs 180

nomencature 179

spall crater 180

468

subcase 182subsurface origin 181

surface origin 181three-phase process 179

Structure defect pre- or in heat treatment 74denition 74high hardness steel 74medium hard stee 75

Surface distress 233causes 235denition 233distinctive appearance 234eects 236failure process 233glazing 233

microspalling 233nomenclature 233

Unnished area 54causes 55definition 54distinctive appearace 54effects 55faiure process 54nomenclature 54

WearSee Mild wear



CoLoR IMAGES

469



Plate 636

4



Plate .5

Plate .40

Plate 93

42



:plate 9.4

Plate 95

Plate 96

43



Plate 9

Pate 98

D-

Plate 99

44



Plate 0.2

Plate 3

Plates 3.3 a &

475



Plate 3.2 Pate 35

Plate 36

46



Pate 4.

Plate 14

Plate 4.2

4



Plates 522 a & b

Plate 5.38Plate 168

478



Pate 6.

Plate 6.22

Plate 6.25

49



Plate 16.31

Plate 6.32

Plate 16.33

480



Plates 85 a & b

Plates 18.2 a & b

481



Plate 187

Plates 88 a & b

482



Plate 810

Pate 8.9

Plates 1811 a, b, & c

483



Plates 8.2 a & b

Plates 83 a & b

484



Plate 83 c

Documents

Failure Atlas