The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering.
Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings.
The first part of the book covers grease composition, properties and rheology, including thermal and dynamics properties. Later chapters cover the dynamics of greased bearings, including grease life, bearing life, reliability and testing. The final chapter covers lubrications systems – the systems that deliver grease to the components requiring lubrication.
Grease Lubrication in Rolling Bearings:
- Describes the underlying physical and chemical properties of grease.
- Discusses the effect of load, speed, temperature, bearing geometry, bearing materials and grease type on bearing wear.
- Covers both bearing and grease performance, including thermo-mechanical ageing and testing methodologies.
It is intended for researchers and engineers in the petro-chemical and bearing industry, industries related to this (e.g. wind turbine industry, automotive industry) and for application engineers. It will also be of interest for teaching in post-graduate courses.
Table of Contents
Preface xvii
List of Abbreviations xix
1 Introduction 1
1.1 Why Lubricate Rolling Bearings? 1
1.2 History of Grease Lubrication 2
1.3 Grease Versus Oil Lubrication 3
2 Lubrication Mechanisms 5
2.1 Introduction 5
2.2 Definition of Grease 6
2.3 Operating Conditions 6
2.4 The Phases in Grease Lubrication 7
2.5 Film Thickness During the Bleeding Phase 8
2.6 Feed and Loss Mechanisms During the Bleeding Phase 10
2.7 Film Thickness and Starvation (Side Flow) 11
2.8 Track Replenishment 12
2.9 Grease Flow 13
2.10 Wall-Slip 15
2.11 Oxidation 16
2.12 EP Additives 16
2.13 Dynamic Behaviour 17
2.14 Grease Life 17
3 Grease Composition and Properties 23
3.1 Base Oil 24
3.2 Base Oil Viscosity and Density 41
3.3 Thickener 49
3.4 Additives 61
3.5 Solid Fillers/Dry Lubricants 66
3.6 Compatibility 67
3.7 Polymer Grease 67
4 Grease Life in Rolling Bearings 71
4.1 Introduction 71
4.2 Relubrication Intervals and Grease Life 71
4.3 The Traffic Light Concept 72
4.4 Grease Life as a Function of Temperature in the Green Zone 75
4.5 SKF Relubrication and Grease Life 76
4.6 Comparison Grease Life/Relubrication Models 78
4.7 Very Low and High Speeds 82
4.8 Large Rolling Bearings 85
4.9 Effect of Load 86
4.10 Effect of Outer-Ring Rotation 90
4.11 Cage Material 90
4.12 Bearing Type 91
4.13 Temperature and Bearing Material 92
4.14 Grease Fill 94
4.15 Vertical Shaft 95
4.16 Vibrations and Shock Loads 96
4.17 Grease Shelf Life/Storage Life 97
5 Lubricating Grease Rheology 99
5.1 Visco-Elastic Behaviour 99
5.2 Viscometers 102
5.3 Oscillatory Shear 108
5.4 Shear Thinning and Yield 112
5.5 Yield Stress 118
5.6 Wall-Slip Effects 122
5.7 Translation Between Oscillatory Shear and Linear Shear Measurements 125
5.8 Normal stresses 126
5.9 Time Dependent Viscosity and Thixotropy 128
5.10 Tackiness 133
6 Grease and Base Oil Flow 137
6.1 Grease Flow in Pipes 137
6.2 Grease Flow in Rolling Bearings 149
7 Grease Bleeding 157
7.1 Introduction 157
7.2 Ball Versus Roller Bearings 158
7.3 Grease Bleeding Measurement Techniques 158
7.4 Bleeding from the Covers and Under the Cage 159
7.5 A Grease Bleeding Model for Pressurized Grease by Centrifugal Forces 161
8 Grease Aging 171
8.1 Mechanical Aging 172
8.2 Grease Oxidation 179
8.3 The Chemistry of Base Oil Film Oxidation 181
8.4 Oxidation of the Thickener 183
8.5 A Simple Model for Base Oil Degradation 184
8.6 Polymerization 186
8.7 Evaporation 186
8.8 Simple Models for the Life of Base Oil 186
9 Film Thickness Theory for Single Contacts 191
9.1 Elasto-Hydrodynamic Lubrication 192
9.2 Contact Geometry and Deformation 198
9.3 EHL Film Thickness, Oil 202
9.4 EHD Film Thickness, Grease 205
9.5 Starvation 212
9.6 Spin 225
10 Film Thickness in Grease Lubricated Rolling Bearings 227
10.1 Thin Layer Flow on Bearing Surfaces 228
10.2 Starved EHL for Rolling Bearings 234
10.3 Cage Clearance and Film Thickness 239
10.4 Full Bearing Film Thickness 241
11 Grease dynamics 245
11.1 Introduction 245
11.2 Grease Reservoir Formation 245
11.3 Temperature Behaviour 246
11.4 Temperature and Film Breakdown 249
11.5 Chaotic Behaviour 249
11.6 Quantitative Analysis of Grease Tests 253
11.7 Discussion 254
12 Reliability 257
12.1 Failure Distribution 258
12.2 Mean Life and Time Between Failures 261
12.3 Percentile Life 264
12.4 Point and Interval Estimates 265
12.5 Sudden Death Testing 275
12.6 System Life Prediction 281
13 Grease Lubrication and Bearing Life 283
13.1 Bearing Failure Modes 283
13.2 Rated Fatigue Life of Grease Lubricated Rolling Bearings 285
13.3 Background of the Fatigue Life Ratings of Grease Lubricated Bearings 289
13.4 Lubricant Chemistry and Bearing Life 296
13.5 Water in Grease 304
13.6 Surface Finish Aspects Related to Grease Lubrication 306
14 Grease Lubrication Mechanisms in Bearing Seals 309
14.1 Introduction 309
14.2 Lubrication Mechanisms for Radial Lip Seals 309
14.3 Sealing Action of Grease 312
14.4 Softening and Leakage 319
14.5 Compatibility 320
14.6 A Film Thickness Model for Bearing Seals 320
14.7 Importance of Sealing Grease Inside the Bearing 324
15 Condition Monitoring and Maintenance 327
15.1 Condition Monitoring 327
15.2 Acoustic Emission 328
15.3 Lubcheck 330
15.4 Consistency Measurement 331
15.5 Oil Bleeding Properties 332
15.6 Oil Content 332
15.7 Particle Contamination 332
15.8 Spectroscopy 333
15.9 Linear Voltammetry 334
15.10 Total Acid Number 335
15.11 DCS – Differential Scanning Calorimetry 335
15.12 Oxidation Bomb 336
15.13 Water 336
16 Grease Qualification Testing 339
16.1 Introduction 339
16.2 Standard Test Methods 339
16.3 Some Qualification Criteria for Grease Selection 374
16.4 Pumpability 375
17 Lubrication Systems 377
17.1 Single Point Lubrication Methods 379
17.2 Centralized Grease Lubrication Systems 380
17.3 Pumps 382
17.4 Valves 384
17.5 Distributors 386
17.6 Single-Line Centralized Lubrication Systems 386
17.7 Dual-Line Lubrication Systems 393
17.8 Progressive Lubrication Systems 394
17.9 Multi-Line Lubrication System 397
17.10 Cyclic Grease Flow 397
17.11 Requirements of the Grease 398
17.12 Grease Pumpability Tests 402
A Characteristics of Paraffinic Hydrocarbons 413
References 415
Index
