Springer Series in Materials Science

Volume 171

Series Editors

Robert Hull, Charlottesville, VA, USAChennupati Jagadish, Canberra, ACT, AustraliaRichard M. Osgood, New York, NY, USAJürgen Parisi, Oldenburg, GermanyZhiming M. Wang, Chengdu, China

For further volumes:www.springer.com/series/856

The Springer Series in Materials Science covers the complete spectrum of materials physics,including fundamental principles, physical properties, materials theory and design. Recog-nizing the increasing importance of materials science in future device technologies, the booktitles in this series reflect the state-of-the-art in understanding and controlling the structureand properties of all important classes of materials.

K.L. Sundarkrishnaa

Friction MaterialComposites

Materials Perspective

K.L. SundarkrishnaaEllen Centre for Advanced Friction Products

Limited (ECFAFPL)TamilnaduChennai, India

ISSN 0933-033X Springer Series in Materials ScienceISBN 978-3-642-33450-4 ISBN 978-3-642-33451-1 (eBook)DOI 10.1007/978-3-642-33451-1Springer Heidelberg New York Dordrecht London

Library of Congress Control Number: 2012955048

© Springer-Verlag Berlin Heidelberg 2012This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part ofthe material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting, reproduction on microfilms or in any other physical way, and transmission or informationstorage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodologynow known or hereafter developed. Exempted from this legal reservation are brief excerpts in connectionwith reviews or scholarly analysis or material supplied specifically for the purpose of being enteredand executed on a computer system, for exclusive use by the purchaser of the work. Duplication ofthis publication or parts thereof is permitted only under the provisions of the Copyright Law of thePublisher’s location, in its current version, and permission for use must always be obtained from Springer.Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violationsare liable to prosecution under the respective Copyright Law.The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoes not imply, even in the absence of a specific statement, that such names are exempt from the relevantprotective laws and regulations and therefore free for general use.While the advice and information in this book are believed to be true and accurate at the date of pub-lication, neither the authors nor the editors nor the publisher can accept any legal responsibility for anyerrors or omissions that may be made. The publisher makes no warranty, express or implied, with respectto the material contained herein.

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Dedicated to my parentsLakshminarayana Moorthy andSeethalakshmi

Preface

The publication of this book is a culmination of high level interest evinced by theindustrial scientific and academic community worldwide in the subject field brakefriction material composite. It provided the stimuli to publish this first edition ofthe monograph and the other four editions to come. This monograph is intendedto support beginners with the basic insight into the essentials of friction materialcomposite, with a broader sense of evolution of a brake friction material formula-tion, from the materials point of view. This introductory volume of the five volumes,has been written and brought out from the author’s experience and expertise withwide ranging friction material manufacturers, brake manufacturers, vehicle manu-facturers, researchers and testing labs with whom the author has been associatedworldwide for the last 28 years.

This monograph does not cater to any specific process/product formulations aseach industry operates with its own manufacturing setup with process variables andother operating variables and none of the information provided are proprietary. Inthis monograph automotive brake pads have been selected under the class of frictionmaterials group in this entire volume. Although friction materials find wide rangingapplications in domestic appliances, industrial appliances, automotive, rail brakefriction pads, composition brake blocks, liners, and clutch part members, brake padsfor automotive applications have been selected by the author keeping in mind thebasics and essentials of friction, better explained for an easy understanding. Frictionmaterial group, by virtue of its high volume content, author has proposed core issuesof design, development, test procedures in detail, sequentially in the subsequentvolumes to come.

The author would like to express his sincere gratitude to all colleagues engagedin the brake friction material composite discipline who assisted with valuable adviceand suggestions.

K.L. SundarkrishnaaChennai, India

vii

Contents

1 Frictional Force—Introduction . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 BFMC—Brake Friction Material Composite—Definition . . . . . 2

1.2.1 Characteristics Defining the System . . . . . . . . . . . . . 21.2.2 Nature of Brake Friction Material Composite (BFMC) . . . 41.2.3 Definition of Composite Materials . . . . . . . . . . . . . 101.2.4 Friction Material Composites (FMC) . . . . . . . . . . . . 111.2.5 Brake Friction Material Composites (BFMC) . . . . . . . . 111.2.6 Brake Friction Material Composites (BFMC) with Metal

Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.2.7 Brake Friction Material Composite (BFMC) with Polymer

Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.2.8 Brake Friction Material Composites—Multi-matrix . . . . 12

1.3 Basic Issues of Friction Material Particle Interphases . . . . . . . . 121.4 Discpad Rotor and Caliper Assembly . . . . . . . . . . . . . . . . 131.5 An Account of Frictional Force . . . . . . . . . . . . . . . . . . . 141.6 Characteristics of Molecular Forces . . . . . . . . . . . . . . . . . 151.7 What is a Frictional Force? . . . . . . . . . . . . . . . . . . . . . 161.8 What Happens in a Frictional Contact Surface? . . . . . . . . . . . 171.9 Transfer Film Layer in a Frictional Contact Area . . . . . . . . . . 181.10 Nanostructure Metallic Materials for Enhanced Wear and Control

on Friction. Ban on Copper Under the Legislation Bills SB6557and S 346 Passed in USA and California . . . . . . . . . . . . . . 19

1.11 Composite Coatings for Friction and Wear Properties . . . . . . . 191.12 Geometrical Surfaces and the Forces of Friction . . . . . . . . . . 201.13 New Class of Quasicrystalline Materials . . . . . . . . . . . . . . 201.14 Essential Virtues of Brake Friction Material Composite . . . . . . 25

1.14.1 Different Types of Coefficient of Friction . . . . . . . . . . 261.15 Test Conditions of μ–V Testing—BMI (Bismaleimide) Polymeric

Matrix Based Composite System in a Non-asbestos to AsbestosFormulations Compared . . . . . . . . . . . . . . . . . . . . . . . 30

ix

x Contents

1.15.1 Coefficient of Friction—Brake Liner Fitted with “S” CamBrake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

1.15.2 Wear Rate . . . . . . . . . . . . . . . . . . . . . . . . . . 321.15.3 Thermal Damage . . . . . . . . . . . . . . . . . . . . . . 33

1.16 Virtues of a Good Friction Material . . . . . . . . . . . . . . . . . 331.17 Key Characteristics of Friction Material Composite in Meeting

the Above Said Virtues . . . . . . . . . . . . . . . . . . . . . . . 341.18 Fading Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381.19 Noise Elimination Sequence . . . . . . . . . . . . . . . . . . . . . 39

1.19.1 Sequence to Control Good Braking, Low Wear withMinimal or No Noise [49] . . . . . . . . . . . . . . . . . . 40

1.19.2 Vibration in the Vertical Direction to the Rotor FrictionSurface Has the Following Components . . . . . . . . . . . 44

1.19.3 Noise Search Graph . . . . . . . . . . . . . . . . . . . . . 461.19.4 Noise Occurrence with Pressure and Temperature . . . . . 471.19.5 Frequency vs Peak Level Decibels in Relation to

Temperature Scale . . . . . . . . . . . . . . . . . . . . . . 481.19.6 Typical Noise Search for Varying Amplitude . . . . . . . . 48

1.20 Hot and Cold Compressibility vs the Judder Vibration in a DiscBrake Pad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481.20.1 High and Low Speed Judder . . . . . . . . . . . . . . . . . 50

1.21 Kinetic Coefficient of Friction: Theoretical Considerations . . . . . 54

2 Design Essentials—Friction Material Composite System . . . . . . . 632.1 Brake and Vehicle Data . . . . . . . . . . . . . . . . . . . . . . . 64

2.1.1 Data Collection Before Attempting Any Design . . . . . . 652.1.2 Basic Engineering Calculations to Design Based on the

Theoretical Torque . . . . . . . . . . . . . . . . . . . . . . 662.1.3 Limiting Brake Torque . . . . . . . . . . . . . . . . . . . . 67

2.2 Design Drawing as an Input from the Original EquipmentManufacturer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 672.2.1 Brake and Vehicle Data . . . . . . . . . . . . . . . . . . . 68

2.3 Braking Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682.4 Inertia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692.5 Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 702.6 Terrain/Landform Topography as a Design Input . . . . . . . . . . 702.7 Contacting Surface—Rotor Disc and Drum Details as a Design

Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 712.7.1 Friction Induced Changes at the Rotor Surface . . . . . . . 71

2.8 Brake Roughness . . . . . . . . . . . . . . . . . . . . . . . . . . 722.8.1 Roughness—Vibrational Noise . . . . . . . . . . . . . . . 722.8.2 Rotor Wear . . . . . . . . . . . . . . . . . . . . . . . . . . 742.8.3 Rotor Thickness Variation due to Excessive Heat . . . . . . 742.8.4 Disc Brake Roughness (DBR) Measurement . . . . . . . . 742.8.5 AFM—Brake Pad Roughness . . . . . . . . . . . . . . . . 75

Contents xi

2.8.6 Roughness Measurements in a Dynamometer . . . . . . . . 782.8.7 Brake Design Factors—Sliding Calipers . . . . . . . . . . 802.8.8 Thickness Variation due to Manufacturing Reasons . . . . 802.8.9 Abrasive Brake Pads . . . . . . . . . . . . . . . . . . . . . 822.8.10 Metallographic Studies on Grey Cast Iron Samples of the

Drum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

3 Rolling Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 873.1 Pure Rolling Motion . . . . . . . . . . . . . . . . . . . . . . . . . 873.2 Sliding Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

3.2.1 Wear in a Rail Braking Wheel . . . . . . . . . . . . . . . . 893.2.2 Deformation and Static Friction . . . . . . . . . . . . . . . 913.2.3 Torque vs. Angular Velocity . . . . . . . . . . . . . . . . . 923.2.4 Translational Kinetic Energy vs. Rotational Kinetic

Energy of the Gyrating Mass . . . . . . . . . . . . . . . . 923.3 Circular Motion—Theoretical Considerations . . . . . . . . . . . 94

3.3.1 Angular Displacement and Angular Velocity . . . . . . . . 943.3.2 Relation Between Linear and Angular Velocity . . . . . . . 963.3.3 Angular Acceleration . . . . . . . . . . . . . . . . . . . . 973.3.4 Centripetal Acceleration (Uniform Circular Motion) . . . . 983.3.5 Tangential Acceleration and Centripetal Acceleration . . . 1003.3.6 Dynamics of Uniform Circular Motion . . . . . . . . . . . 1043.3.7 Dynamics of Non-uniform Circular Motion . . . . . . . . . 110

4 Formulation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 1154.1 Role of Fibers and Fillers To Be Cited . . . . . . . . . . . . . . . 115

4.1.1 Materials Bear Effect on Formulation and Process . . . . . 1154.1.2 Zero, One, Two and Three Dimensional Fillers and Fibers . 1164.1.3 Axial Planar Reinforcement . . . . . . . . . . . . . . . . . 1174.1.4 Dispersion Strengthened (Particulate) Composites,

Structure and Properties . . . . . . . . . . . . . . . . . . . 1184.2 Formulation Design . . . . . . . . . . . . . . . . . . . . . . . . . 119

4.2.1 What Does a Friction Material Composite Constitute? . . . 1194.2.2 Selection of Design of Experiment DOE as an Option . . . 1204.2.3 Fractional Factorial Design—BFMC . . . . . . . . . . . . 121

4.3 Specific Functional Role of Materials in BFMC—SystemDependent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

4.4 Factors That Can Affect Friction . . . . . . . . . . . . . . . . . . 1244.5 Design Control for Design of “Friction Materials Composite” . . . 124

4.5.1 Design Control for Undertaking Design of ProcessControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

4.6 Documents To Be Generated All Have To Be Numbered andIndexed for Cross Referencing—BFMC . . . . . . . . . . . . . . 125

4.7 Activity Chart for Design Control of “Friction Materials” . . . . . 1264.8 Technical Documents Required for Manufacture of Friction

Material Design Product . . . . . . . . . . . . . . . . . . . . . . . 130

xii Contents

4.9 Design Route Selection for the Brake System in Operation . . . . . 1314.10 BFMC Manufacturer, Sequence of Design Approval Process . . . . 1314.11 Critical Raw Materials Used in BFMC Design and Their

Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1334.12 Typical Specification and Level of Dosage Used in a Friction

Material Formulation . . . . . . . . . . . . . . . . . . . . . . . . 1354.13 General Specification Used in Friction Material Composite MOS2 . 1374.14 Simple Material Selection Sequence . . . . . . . . . . . . . . . . 1604.15 Interrelationship Between Material, Design and Process . . . . . . 1614.16 Design Process for BFMC Selection . . . . . . . . . . . . . . . . 1634.17 Disc Pad Material . . . . . . . . . . . . . . . . . . . . . . . . . . 163

4.17.1 Organic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1634.17.2 Semimetallic . . . . . . . . . . . . . . . . . . . . . . . . . 1634.17.3 Metallic . . . . . . . . . . . . . . . . . . . . . . . . . . . 1634.17.4 Ceramic Brake Pads and Linings . . . . . . . . . . . . . . 1644.17.5 Sintered Friction Material . . . . . . . . . . . . . . . . . . 1654.17.6 Ceramic Potassium Titanate Fiber Filled System

in Non-asbestos Design—Functional MaterialCharacteristics . . . . . . . . . . . . . . . . . . . . . . . . 166

4.18 Design of Formulation, Process for the Above Said Groups ofBrake Pads and Liners . . . . . . . . . . . . . . . . . . . . . . . . 166

4.19 Brake System as an Essential Integration for a Good PerformingPad, Liner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

4.20 Materials Point of View of the Formulation Design . . . . . . . . . 1684.21 Criteria for Selection of Materials for Designing a Friction

Material Formulation . . . . . . . . . . . . . . . . . . . . . . . . 1694.22 Material Specifications as Control in a Formulation . . . . . . . . 1694.23 Materials Used in a Friction Material Composite Formulations for

Automotive and Rail Braking Applications . . . . . . . . . . . . . 1704.24 Basic Physical, Thermal and Mechanical Tests Done

on a Friction Material Formulation—Prototype Samples . . . . . . 171

5 Design of Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . 1735.1 Fractional Factoral Design . . . . . . . . . . . . . . . . . . . . . . 173

5.1.1 General Guiding Principles for a Factoral FactorialExperiment . . . . . . . . . . . . . . . . . . . . . . . . . . 174

5.1.2 Experimental Objective . . . . . . . . . . . . . . . . . . . 1745.1.3 Important Characteristics . . . . . . . . . . . . . . . . . . 1755.1.4 Design of Experiments: Factorial Experiment Design

Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1755.1.5 Determination the Acceptance Criteria . . . . . . . . . . . 1755.1.6 Picking up the Acceptance Criteria . . . . . . . . . . . . . 1805.1.7 Calculating Samples per Run . . . . . . . . . . . . . . . . 180

5.2 Brake Shoe Bonding Factors and Levels . . . . . . . . . . . . . . 181

Contents xiii

6 BFMC—Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1856.1 Process Design Control—Parameters . . . . . . . . . . . . . . . . 185

6.1.1 Mixing, Blending, Tumbling . . . . . . . . . . . . . . . . 1856.1.2 Mixer Designs/Configuration . . . . . . . . . . . . . . . . 1876.1.3 Mixing Sequence with Time of Addition . . . . . . . . . . 1886.1.4 Effective Homogenization—Measure . . . . . . . . . . . . 1896.1.5 Selection of the Press . . . . . . . . . . . . . . . . . . . . 1906.1.6 Press Parameters—Sample Specification (Data Provided

Purely as an Indication of Specification) . . . . . . . . . . 1926.1.7 To Give a Basic Account of the Sequence of Operation of

a Press in One Cycle—Disc Pad . . . . . . . . . . . . . . . 1946.1.8 Possible Hydraulic Press Issues Related to Maintenance

Which Can Normally Hamper the Efficiency of the Press . 1956.1.9 Design Control Plan—Disc Pad Manufacturing.

PFMEA—Product Failure Mode Effect Analysis . . . . . . 1966.1.10 Pre Design Plan . . . . . . . . . . . . . . . . . . . . . . . 1966.1.11 Significant Characteristics . . . . . . . . . . . . . . . . . . 197

6.2 Design Control Plan . . . . . . . . . . . . . . . . . . . . . . . . . 1976.2.1 Disc Brake Pad Control Plan . . . . . . . . . . . . . . . . 1976.2.2 Disc Brake Pad (Press Line) In-process Inspection,

Multilayers Hot Press . . . . . . . . . . . . . . . . . . . . 2356.2.3 Disc Brake Pad (Press Line) In-process Inspection, Single

Layer Hot Press . . . . . . . . . . . . . . . . . . . . . . . 2366.2.4 Number: Disc Brake Pad Final Inspection . . . . . . . . . 2376.2.5 DBP Attachments Incoming Inspection . . . . . . . . . . . 2386.2.6 Store Shipment Pack . . . . . . . . . . . . . . . . . . . . . 2396.2.7 Quality Objectives—Zero Defects . . . . . . . . . . . . . . 2406.2.8 Production Reject Modes (pcs) . . . . . . . . . . . . . . . 2416.2.9 Process Travel Control Card—Disc Brake Pad . . . . . . . 2426.2.10 Incoming Raw Material Inspection . . . . . . . . . . . . . 2436.2.11 DBP Attachments Incoming Inspection . . . . . . . . . . . 2446.2.12 Raw Material—Mixing, Coating and Sieving—In-process

Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . 2456.2.13 DBP (Finishing Line) In-process Inspection . . . . . . . . 2466.2.14 Glue Spray & Oven Drying In-process Inspection . . . . . 2476.2.15 Rivet Incoming Inspection . . . . . . . . . . . . . . . . . . 248

6.3 A Good Manufacturing Layout . . . . . . . . . . . . . . . . . . . 2496.4 Typical Tests Done in a Brake Lining, Brake Pad (Exclude Some

Tests for Brake Pads) Non-asbestos Brake Lining . . . . . . . . . . 252

7 BFMC—Formulations and Processes . . . . . . . . . . . . . . . . . . 2537.1 Backup Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

7.1.1 Hot Shear Test on a Backup Layer—Sample Data . . . . . 2547.1.2 Formulations . . . . . . . . . . . . . . . . . . . . . . . . . 255

7.2 Moulding Process—Brake Linings and Brake Pads . . . . . . . . . 255

xiv Contents

7.2.1 Dry Mix Process . . . . . . . . . . . . . . . . . . . . . . . 2567.3 History of Evolution of Semimetallic Disc Brake Pads . . . . . . . 2587.4 Evolution of NAO Nomenclature After Semimetallic and Metallic

Disc Pads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2597.5 Mixing Cycles—Time and Sequence of Addition as an Important

Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2597.6 Controlling the Mixing Action . . . . . . . . . . . . . . . . . . . 2607.7 Controlling Mixing Efficiency . . . . . . . . . . . . . . . . . . . . 2607.8 Ceramic and Non-asbestos Organic Formulas . . . . . . . . . . . . 2617.9 Horse Power Requirements . . . . . . . . . . . . . . . . . . . . . 2627.10 Wet Mix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2627.11 Mixing Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264

8 Laws and Rules Governing Friction Materials . . . . . . . . . . . . . 267

9 Total Quality Management . . . . . . . . . . . . . . . . . . . . . . . 271

10 Test Requirements in an Automotive BFMC Design . . . . . . . . . . 29110.1 World Class Test Specifications for Disc Brake Pads. Methods of

Testing, Procedures with Standards . . . . . . . . . . . . . . . . . 29110.2 Electrical Resistivity Measurements in Brake Friction Material

Composite (BFMC) . . . . . . . . . . . . . . . . . . . . . . . . . 29210.2.1 Volume Resistance and Surface Resistance Measurements . 292

10.3 Essential Physical Properties Enumerated. Not All Tests AreCovered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

10.3.1 Density . . . . . . . . . . . . . . . . . . . . . . . . . . 29310.3.2 Solvent Extraction—Test for Uncured Resin in the

Material. A Value < 2 % Is Healthy > 2 % Swell IsPossible . . . . . . . . . . . . . . . . . . . . . . . . . . 295

10.3.3 Particle Size for 50 gm Sample . . . . . . . . . . . . . . 29610.3.4 Porosity Measurement . . . . . . . . . . . . . . . . . . 29610.3.5 pH-Index—Hydrogen Ion Concentration . . . . . . . . . 29810.3.6 Pad Shear Test with Shear Force . . . . . . . . . . . . . 29810.3.7 Test for Cold Compressibility of the Pad . . . . . . . . . 30110.3.8 Test for Hot Compressibility of the Pad . . . . . . . . . . 30410.3.9 Test for Pad Swell . . . . . . . . . . . . . . . . . . . . . 30510.3.10 Test for Swell and Growth . . . . . . . . . . . . . . . . 306

10.4 Backing Plate Surface Treatment—Corrosion Resistance . . . . . . 30710.5 System Overview of the Passenger Car Dynamometer . . . . . . . 30710.6 Worst Case Criteria (WCC) . . . . . . . . . . . . . . . . . . . . . 31410.7 Technical Specifications of Passenger Car Dynamometer—One

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31910.8 Scaled down Test for Rail Brake Friction Composite . . . . . . . . 320

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Acronyms

AFM Atomic force microscopyAMS Auto Motor SportsBFMC Brake Friction Material CompositeCNSL Cashew nut shell liquidDTV Disc thickness variationEDAX Energy dispersion X ray analysisFIM Field Ion MicroscopeFT.NMR Fourier transformed Nuclear magnetic resonanceFMC Friction Material CompositeGPC Gel permeation chromatographyJASO Japanese association of standards and organizationLCV Light commercial vehiclePFMEA Product, process failure mode effect analysisRPM Revolutions per minuteMD Molecular dynamicsSABS South African bureau of standardsSOP Standard Operating ProceduresTS Test standardsSAE Society of Automotive EngineersSANS 601 South African StandardsSEM Scanning electron microscopySSTM Small sample test machineSTM Scanning tunneling microscopeXRD X ray diffraction

xv

xvi

Units with Conversion Factors

Thermal conductivity—1 W/K m = 0.86 kcl/m h °C1 W/K m = 0.579 BTU/ft h °F

AccelerationMultiply by To get Multiply by To get

Feet/sec2 0.305 Meters/sec2 3.281 Feet/sec2

Inches/sec2 0.025 Meters/sec2 39.370 Inches/sec2

AreaMultiply by To get Multiply by To get

Inches2 645.16 Millimeter2 0.016 Inches2

Inches2 6.425 Centimeter2 0.155 Inches2

Feet2 0.093 Meter2 10.750 Feet2

Yard2 0.836 Meter2 1.196 Yard2

Acres 0.405 Hectares 2.471 AcresMiles2 2.590 Kilometer2 0.386 Miles2

ForceMultiply by To get Multiply by To get

Ounces-f 0.278 Newtons 3.597 Ounces-fPounds-f 4.448 Newtons 0.232 Pounds-fKilograms 9.807 Newtons 0.102 Kilograms

Fuel ConsumptionMultiply by To get Multiply by To get

Miles / US Gallon 0.425 Kilometers/Liter 2.352 Miles/Gallon

IlluminationMultiply by To get Multiply by To get

Footcandles 10.760 Lumens/Meter2 0.093 Footcandles

LinearMultiply by To get Multiply by To get

Inches 25.400 Millimeters 0.039 InchesFeet 0.305 Meters 3.279 FeetYards 0.914 Meters 1.094 YardsMiles 1.609 Kilometers 0.621 MilesMicroinches 0.025 Micrometers 39.370 Microinches

xvii

MassMultiply by To get Multiply by To get

Ounces 28.350 Grams 0.035 Ounces (av)Pounds 0.454 Kilograms 2.205 PoundsTons (2000 lb) 907.180 Kilograms 0.001 Tons (2000 lb)Tons (2000 lb) 0.907 Metric tons 1.102 Tons (2000 lb)

PowerMultiply by To get Multiply by To get

Horse power 0.746 Kilowatts 1.340 Horse powerFt-lbsf/min 0.023 Watts 44.250 Ft-lbf/min

Speed (or Velocity)Multiply by To get Multiply by To get

Miles/hour 1.609 Kilometers/hour 0.621 Miles/hourFeet/second 0.305 Meters/sec 3.281 Feet/secKilometers/hour 0.278 Meters/sec 3.600 Kilometers/hourMiles/hour 0.447 Meters/sec 2.237 Miles/hour

TorqueMultiply by To get Multiply by To get

Pounds-inches 0.119 Newton-meters 8.851 Pound inchesPound-feet 1.356 Newton-meters 0.738 Pound-feetKgf-cm 0.098 Newton-meters 10.197 Kgf-cmKgf-m 9.807 Newton-meters 0.102 Kgf-m

PressureMultiply by To get Multiply by To get

Pounds/inches2 6.895 Kilopascals 0.145 Pounds/inches2

Inches H2O 60 degreeFahrenheit

0.249 Kilopascals 0.419 Inches H2O 60 degreeFahrenheit

Bars 100 Kilopascals 0.01 BarsPounds/Ft2 47.800 Pascals 0.021 Pounds/ft2

Kgf/cm2 98.070 Kilopascals 0.010 Kgf/cm2

Inches (Hg 960 degreeFahrenheit)?

3.377 Kilopascals 0.296 Inches Hg

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VolumeInches3 16387 Millimeters3 (mm3) 0.000061 Inches3

Inches3 16.387 Centimeter3 (cm3) 0.061 Inches3

Inches3 0.0164 Liters (L) 61.024 Inches3

Quarts (US) 0.946 Liters (L) 1.057 Quarts (US)Gallons (US) 3.785 Liters (L) 0.264 Gallons (US)Feet3 28.317 Liters (L) 0.035 Feet3

Feet3 0.028 Meters3 (m3) 35.315 Feet3

Fluid ounce 29.57 Milliliters (mL) 0.034 Fluid ounceYards3 0.765 Meters3 (m3) 1.303 Yards3

Teaspoons 4.929 Milliliters (mL) 0.203 TeaspoonsCups 0.237 Liters (L) 4.227 Cups

Work (or Energy)Foot-pounds 1.355 Joules (J) 0.737 Foot-poundsCalories 4.184 Joules (J) 0.239 CaloriesBtu 1055 Joules (J) 0.001 BtuWatt-hours 3600 Joules (J) 0.001 Watt-hoursKilowatt-hours 3600 Megajoules (MJ) 0.278 Kilowatt-hour

Temperature° Fahrenheit (°F) (°F − 32)/1.8 °Centigrade (°C) 1.8 + 32 °Fahrenheit (°F)

Common Metric PrefixesMega (M) 1,000,000 or 106 Centi (c) 0.01 or 10−2

Kilo (k) 1,000 or 103 Milli (m) 0.001 or 10−3

Hecto (h) 100 or 102 Micro (µ) 0.000,001 or 10−6

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Physical Constants

Quantity Magnitude

N Avogadro’s number 6.023 × 1023 mol−1

k Boltzmann’s constant 1.380 × 10−23 J K−1

8.614 × 10−5 eV K−1

e Electron charge 1.602 × 10−19 Cm0 Electron rest mass 9.109 × 10−31 kgF Faraday’s constant 96. 49 K C mo1−1 (of electrons)R Gas constant 8.314 J mol−1 K−1

G Gravitational constant 6.673 × 10−11 N m2 kg−2

MH Hydrogen atom mass 1.007825 u938.285 MeV/c2

mn Neutron mass 1.008 u939.57 MeV/c2

μ0 Permeability of free space 4π × 10−7 H m−1

1.257 × 10−6 H m−1

ε0 Permittivity of free space 8.854 × 10−12 m−3 kg−1 s4 A2

h Planck’s constant 6.6255 × 10−34 J secmd Proton mass 1.007 276 u

938.2 MeV/c2

E/m0 Specific charge of electron at rest 1.759 × 1011 C kgσ Stefan’s constant 5.67 × 10−8 W m3 T−4 c

Velocity of light in vacuum 3 × 108 in 2.99776 × 108 in s−1

Wein’s constant 2.898 × 10−3 m Kg Acceleration due to gravity 9.81 m s−2

Notes on Safety

Safety Precautions

With increasing demand for vehicle performance requirements and the growing de-mands, the important aspect of safety is to be borne in mind while designing afriction material composite system.

For example, one of the standards included recently for FMVSS105 rule is thenew FMVSS135 standard that 2001 model year car and 2003 model year trucks haveto meet. FMVSS135 is a minimum braking performance standard of the nationalhighway Traffic and Safety Administration. It is tougher than the former FMVSS105rule, but with 25 % less pedal effort. To meet this specification, manufacturers haveto switch to more aggressive material design on the product. This is one of theapplication specific standard towards better safety.

Be it primary fitments such as original equipment manufacturers, secondary fit-ments or the service segments, it becomes mandatory to follow the stringent rulesof safety while selecting the friction material brake product design, whether it is abrake pad/liner / or a clutch facing.

Care should be taken for selecting materials that are not hazardous because haz-ardous materials can generate dust which will lead to severe physiological disorderson prolonged continuous exposure.

Hence it is necessary that regulations of the government and the authoritiesconcerned be strictly adhered to. The rules prescribed by the respective agencieshave to be strictly adhered to in order to avoid health and other environmental haz-ards.

Brake pad safety procedure for secondary market as a sample is explained herebelow, which is an assessment for safety, as per a legislation adopted in a region.Similar procedures have to be adopted taking into account the local and global leg-islations in force from time to time for brake liners/pads and for other brake frictionmaterial products. Strict compliance of the same is important for an effective, safefriction material usage in any application.

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Safety of Brake Pads Based on ECE90 Safety Index (ECE 90si)

The purpose of ECE 90si is to apply safety index procedure to compare relativesafety of disc brake pads. The compulsory specifications determine the minimumrequirements for brake pad safety applied to Original Equipment and aftermarket ap-plications as a secondary or service fitment. Consumer expectations are ever chang-ing and more demanding. Drivers expect the brake system to stop the vehicle underany possible condition. Compulsory specifications are given, with fade indices un-der varying conditions, along with key safety and environmental considerations todetermine overall safety of a brake pad.

The scope of the index given here is based on International quality standard forcomponent manufacturing (ISO/TS 16949), International health and safety stan-dards (ISO14001/168001), dynamic friction, initial cold and hot performance, andfade characteristics (based on AMS test schedule adopted for dynamometer testing).

It broadly includes six key factors that are used to determine the index.

1. Consistency of supply—Quality accreditation TS 16949.The internationally recognized quality accreditation for automotive compo-

nent manufacturers is the ISO/TS 16949. This important certification ensuresthat the manufacturing facility has all the necessary procedures in place to con-sistently produce a safe critical component.

Conformance to minimum physical compulsory specifications, based on TheUnited Nation Regulation for replacement brake pad assemblies. The regulationrequires that all brake pads comply with minimum standards for shear strength,cold compressibility, and hot compressibility. Shear is the force required to de-tach the friction material from the backing plate. The specification is minimum2.5 N/mm2. Compressibility is that amount the pad will compress by when sub-jected to maximum pedal pressure. The specification for cold compressibility ismaximum 2 % and for hot compressibility (at 400 °C) is maximum 5 %. Productsnot conforming to above standards are deemed to be unsafe.

2. Conformance to compulsory dynamic testing—compulsory specification as perstandards.

This specification what is given here is based on the United Nations Regula-tion 90. There are 3 elements to this test.a. The first element of the test is to determine the pressure sensitivity of the

brake pads. This is done by first determining the reference pressure requiredfor a deceleration of 5 m/sec2 from the speed of 80 km/hr, and, drawing theo-retical pressure-deceleration graph. The deceleration at incremental pressuresfrom 1.5 mpa to 10 mpa is then measured. The specification is a maximumdeviation of ±15 % when compared to the theoretical pressure–deceleration[69] graph. The lower the variation, the more consistent the pad performanceat different pressures will be. The result from three to five batches must beused to determine the rating.

b. The second element of the test is to determine the speed sensitivity of thebrake pads. This is a measure of how consistently the brake pad performs

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when braking from speeds of 75 km/hr, 120 km/hr and 160 km/hr. The specifi-cation is that deceleration at higher speeds must not vary by more than ±15 %to that recorded at the lowest speed. The higher the variation, the greater theadjustments with respect to pedal pressure that the driver will need to maketo obtain the same rate of deceleration. Results from all five batches must beused to determine the rating.

c. The third element of the test is to determine the hot fade characteristics of thebrake pads. The specification is that when the pads reaches high temperatures(up to 450 °C) then the deceleration must not be less than 3.5 m/sec2. Also thegreater the variation of the deceleration, the more inconsistent the brake padwill be when braking at high temperatures. Results from three to five batchesmust be used to determine the rating.

3. Conformance to health and environmental requirements.Asbestos has been banned internationally. Bills SB 6557 and S346 passed in

USA and California respectively, requires that the copper content in excess of0.5 % be banned by year 2025. Copper brake dust washes into the ground watersystem and contaminates it. Companies that have ISO 14001 and ISO 18001 haveprocedures and practices in place that safeguard people and the environment.Manufacturers showing better compliance to all of the above will clearly have asafer product in terms of environmental health and safety.

4. Initial cold and hot performance characteristics of brake pads.Whilst it is recommended good practice to bed-in brake pads before expecting

desired braking performance, many users often do not follow correct bedding-inprocedures. Therefore, if the pads take long to bed-in to have low friction dur-ing initial cold and hot applications, performance will be less than optimum.Newer generation friction materials and innovative processing technologies havegenerally overcome this problem, making for a safer product. The average co-efficient of friction of the first three applications of the bedding-in cycle is usedto determine the initial cold performance. The average coefficient of friction ofall ten stops during “the hot bedding-in cycle” is used to determine initial hotperformance. The bedding-in procedure taken here for reference is specified inSANS601 as is specified in United Nations Regulation 90. A friction value co-efficient of 0.30μ is deemed to be an acceptable level for initial cold and hotperformance (80 % of lower limit of compulsory specification). Results fromfive batches must be used to determine the rating.

5. Fade characteristics of brake pads (AMS Test).The AMS test (European Auto Motor Sport) is a widely accepted test used to

determine the fade characteristics of a brake pad. It requires ten consecutive stopsfrom 100 km/hr with acceleration after each stop based on vehicle manufacturer’sdata. The ECE 90 test using an inertia dynamometer is done at speeds of 60, 80,100 and 120 km/hr which are the legal speed limits in most of the countries. Fivestops are performed at 120 km/hr so that unrealistically high temperatures arenot attained.

6. Safety Index rating with “data recording and assessment form” are to be assessedand complied with.

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Similarly different countries have their own legislations with index and pro-cedures for pad/liner and related materials with local and global legislations in-tegrated which needs to be complied for brake liners/brake pads.

Qualifying Simulated Tests on Dynamometer and on Vehicle, Followed World-wide on Brake Systems Integrated with Brake Pads, Liners and Clutch FrictionMembers

AMS high speed fadeBEEP using SAE J2430Brake torque variation—BTVCTA-FMVSS 121 static torque capacityDrum-in-hat performanceDry friction clutch durabilityDry friction clutch performanceDTV generation and correctionD 465—test prescription for brake padsECE R13 type approval for categories N and OECE R90 type approval categories M, N and OFMVSS 105 and 135 simulationsFMVSS 121D-RP628 qualificationISO 11157-ECE R13 performanceJASO C406 passenger car brake performanceJASO C419 caliper durabilityJIS D 4411—Brake lining for automobilesLaurel Mountain durabilityLACT noise and wear simulationParking brake performanceParking brake drive awayRotor low speed shockRotor crackRotor thermal deflectionRotor thermal fatigueRotor thermal shockSAE J 2115 commercial vehicles performance and wearSAE J 2521 noise squeal matrixSAE J 2522 AK-masterSAE J 2681 friction behavior assessmentStructural integrity testSAE J 2707 – JASO C427 wearTata-TMS 75054 Automotive disc brake pad (mould type)GM, Ford motor co, DCX, TRW, Bosch, FMO, Toyota, Honda protocols

Vehicle Testing

ABS operationAMS fade

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Atlanta corrosion cycleBrake balanceBrake pedal feelBrake roller testing for passenger cars and commercial vehiclesCold judder evaluationCity traffic circuit mapping for inertia dynamometer simulation cold weathernoise and brake performanceDetroit city, Los Angeles traffic on brake DTV, dust, noise and wearDetroit suburban traffic off-brake DTVECE R13 vehicles M, N and O types approval (passenger cars to trailers and semitrailers)ECE R58 drive-by noiseECE R78 vehicles L type approval motorcyclesECE R90 M and N approval (passenger and cargo)FMVSS 105 hydraulic and electric brake systems above 3500 kgFMVSS 121 air brake systemsFMVSS 135 passenger car brake systems less than 3500 kgISO 6597 brake performance for M and N vehicles with hydraulic brakeLaurel mountain descentLoss Angeles City traffic wear and noiseMountain descent for brake fluid boil (Death Valley, Pikes peak, Utah)PBBTSpecial vehicle test protocols for refuse, dolly, city bus, mining, articulated andmilitary vehicles.

The above given test schedules act as a valid preliminary screening process for qual-ifying BFMC materials, with the appropriate brake assembly, knuckles, in respectivevehicles.

Qualifying areas for servicing the original equipment fitments (OE) for passengercar are classified under AMECA, DTV and wear classifications.

For original equipment service segments it is classified under Light duty truck—SUV with BEEP and friction behavior testing.

For secondary fitments or aftermarket, medium duty truck, commercial vehiclecomponents are tested for ECE and NVH. FMVSS and performance for servicingthe overseas segments in the secondary market in-vehicle testing.

For the sample and component level testing the following are tested for

Dry Friction Materials

AK compressibilityAK thermal conductivityAMECA edge code certificationChase speed sensitivityChase pressure sensitivityChase temperature sensitivityChase wear and FAST,

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ISO 6310 compressibilityISO 6312 shear strengthISO 6314 corrosion and contamination resistanceLow pressure wear–rotor kindnessSAE J160 swell and growthSAE J2468 compressibilitySAE J840 adhesive strengthSAE J 661 friction quality control

Component Testing

ASTM B 117 corrosionBelgian-bumps durabilityCaliper drag measurementContaminated environment durabilityCyclic corrosion with or without dynamic brake applicationsECE R13 air actuatorsECE R13 spring brakesECE R 90 draft type approval for rotors and drumsJASO C 448 comprehensive caliper performanceNatural frequency and dampingShaker table based durabilitySAE J 1469 air brake actuatorSAE J 1462 automatic slack adjusterSAE J 2530 sheet certification for cornering fatigueRotor mapping for UTVTorque flex durability

Wet Friction Materials and Clutches

SAE J 2487, 3600 rpm stepped power testSAE J 2488, 6000 rpm stepped power testSAE J 2489 Durability testSAE J 2490, μ-PVT performance test