8/19/2019 Metrology 2 -Slip Guages

1/14

Slip gauges areextremely accurate and

precise steel blocks. Slip

gauges are stored in a

box set, and the slips can

be built, using two or

more, to form a widerange of sizes to check

dimensional accuracy or

accuracy of measuring

instruments.

LIP GUAGES (Guage blocks, Johansson gauges, or Jo blocks)

8/19/2019 Metrology 2 -Slip Guages

2/14

2

Gauge blocks

8/19/2019 Metrology 2 -Slip Guages

3/14

•Slip gauges are often called Johannsen gauges also, as Johannsen

originated them

•

 These are rectangular blocks of steel having a cross-section ofabout 30 b !0 mm

• These are "rst hardened to resist #ear and carefull stabilised so

that the are independent of an subse$uent variation in si%e or

shape&

Rectangular slip gauge

' combining gauges select

ed from a suitabl arrangedcombination, almost an dimension ma be built-up&

8/19/2019 Metrology 2 -Slip Guages

4/14

The slip gauges are mae !rom high graesteel" cemente carbies (such as tungsten

carbie or tantalum carbie)

$oe%cient o! thermal e&pansion ('' * ') &'+,- per egree $elsius bet.een '+/$ an 0+/$

These are harene throughout an suitabl1heat,treate in orer to stabilise theirimensions or are pro2ie .ith har measuring!aces like carbie !aces

The harness o! the slip gauges are al.a1smore than 3++ 45 (5icker6s P1rami 7umber)

8/19/2019 Metrology 2 -Slip Guages

5/14

' These ma1 be use as re!erence stanars

!or trans!erring the imensions o! the unit o!length !rom the primar1 stanar to gaugeblocks o! lo.er accurac1

8 9or the 2eri:cation an grauation o!

measuring apparatus

0 Length measures !or the regulation ana;ustment o! inicating measuringapparatus

uipment such as

micrometers" gap gauges" sine bars" ialinicators .hen use in an ins ection role

USES ?9 SLIP GUAGES

8/19/2019 Metrology 2 -Slip Guages

6/14

Slip gauges are classi:e accoring totheir guarantee accurac1

aster slip gauges, accurate to plus or minus t.o micetre

erence purpose,accurate up to plus or minus !our mi

etre

@ !or .orking slip gauges, accurate toplus or minus eight microns per

metre

8/19/2019 Metrology 2 -Slip Guages

7/14

Accoring to graes or classes "slip gauges areesigne in :2e graes as uner

Grae 8 This is the #orkshop grade& Tpical usesinclude setting up machine tools, positioning millingcutters and checking mechanical #idths&

Grae ' (sed for more precise #ork, such as thatcarried out in a good-class tool room& Tpical usesinclude setting up sine bars and sine tables, checkinggap gauges and setting dial test indicators to %ero&

Grae + This is more commonl kno#n as the)nspection grade, and its use is con"ned to tool roomor machine shop inspection&

Grae ++ This grade #ould be kept in the Standard*oom and #ould be ke t for #ork of the hi hest

8/19/2019 Metrology 2 -Slip Guages

8/14

Bringing

Wringing is the process o! sliing t.o blockstogether so that their !aces lightl1 bon

@ecause o! their ultraCat sur!aces" .hen .rung" gaugeblocks ahere to each other tightl1

0- Johansson gauge blocks .rungtogether easil1 support their o.n.eight

8/19/2019 Metrology 2 -Slip Guages

9/14

This is accomplishe b1 pressing the !aces into contact

(keeping them perpenicular) an then imparting a smallt.isting motion .hilst maintaining the contact pressureThe contact pressure is ;ust su%cient in orer to hol thet.o slip gauges in contact an no aitional intentionalpressure

4?B BRI7GI7G IS =?7ED

Phenomenon o! .ringing occurs ue to molecular ahesion

bet.een a li>ui :lm (.hose thickness ma1 be bet.een - to & '+,- mm) an the mating sur!aces

 silicone or :ltere kerosene is use aslubricant Appl1 a thin coat o! same an .ipe it asthin as possible

8/19/2019 Metrology 2 -Slip Guages

10/14

In metric units" sets o! '+0" -"

8/19/2019 Metrology 2 -Slip Guages

11/14

!!

Measurement Ranges

(mm)

Jump

(mm)

 No of gauge

 blocks

1.0005 1

From 2.001 to 2.009 0.001 9

From 2.01 to 2.49 0.01 49

From 0.5 to 9.5 0.5 19

From 10 to 100 10 10um! "" block 

8/19/2019 Metrology 2 -Slip Guages

12/14

@asic 9orms o! Slip Gauges

Slip gauges .ith three basic !orms are

commonl1 !oun

!& *ectangular- less epensive to manufacture,applications #here space is restricted , avoidecess #eight

2& S$uare #ithout centre hole 1 epensive, #earlonger and adhere better to each other #hen#rung to high stacks&

3& S$uare #ith centre hole- to permit the use of tierods as an added assurance against the #rungstocks falling apart #hile handling , #ear longerand adhere better to each other #hen #rung tohigh stacks&

8/19/2019 Metrology 2 -Slip Guages

13/14

8/19/2019 Metrology 2 -Slip Guages

14/14

@asic 9orms o! Slip Gauges

Slip gauges #ith three basic forms are commonlfound& These are rectangular, s$uare #ith centre hole, and s$uare #ithout cen*ectangular form is the more #idel used because rectangular blocks are lessmanufacture, and adapt themselves better to applications #here space is restrecess #eightis to be avoided&or certain applications, s$uare slip gauges, though epensive, are preferred&large surface area, the #ear longer and adhere better to each other #hen #rstacks&S$uare blocks #ith centre holes are used to permit the use of tie rods as an adassuranceagainst the #rung stocks falling apart #hile handling& The greatest emphasis in the slip gauges is laid on the t#o gauging surfaces osides of the blocks& The length bet#een measuring surfaces, 4atness and surfaconditions of measuring surfaces are the most important features of slip gauges #hich havecontrolled

Slip gauges are blocks of steel that have been hardened and stabili%edb heat treatment& The are ground and lapped to si%e to ver highstandards of accurac and surface "nish& The are the most accuratestandards of length available for use in #orkshops&