engineering tribology 2e 2011 potx

E NGINEERING TRIBOLOGY ENGINEERING TRIBOLOGY Gwidon W. Stachowiak Department of Mechanical and Materials Engineering, University of Western Australia, Australia Andrew W. Batchelor Department of Mechanical and Materials Engineering, University of Western Australia, Australia To the most important persons in our lives Grazyna Stachowiak Gwidon (Jr.) Stachowiak and Valli M. Batchelor Vicky & Diana Batchelor CONTENTS 1 INTRODUCTION 1 1.1 Background 1 1.2 Meaning of tribology 2 Lubrication 3 Wear 5 1.3 Cost of friction and wear 5 1.4 Summary 7 References 8 2 PHYSICAL PROPERTIES OF LUBRICANTS 11 2.1 Introduction 11 2.2 Oil viscosity 11 Dynamic viscosity 12 Kinematic viscosity 13 2.3 Viscosity temperature relationship 13 Viscosity-temperature equations 14 Viscosity-temperature chart 14 2.4 Viscosity index 15 2.5 Viscosity pressure relationship 16 2.6 Viscosity-shear rate relationship 22 Pseudoplastic behaviour 22 Thixotropic behaviour 24 2.7 Viscosity measurements 24 Capillary viscometers 24 Rotational viscometers 26 · Rotating cylinder viscometer 27 · Cone on plate viscometer 28 Other viscometers 29 2.8 Viscosity of mixtures 30 2.9 Oil viscosity classification 31 VIII ENGINEERING TRIBOLOGY SAE viscosity classification 31 ISO viscosity classification 33 2.10 Lubricant density and specific gravity 33 2.11 Thermal properties of lubricants 34 Specific heat 34 Thermal conductivity 35 Thermal diffusivity 35 2.12 Temperature characteristics of lubricants 35 Pour point and cloud point 36 Flash point and fire point 37 Volatility and evaporation 37 Oxidation stability 38 Thermal stability 39 Surface tension 40 Neutralization number 42 Carbon residue 43 2.13 Optical properties of lubricants 43 Refractive index 43 2.14 Additive compatibility and solubility 44 Additive compatibility 44 Additive solubility 44 2.15 Lubricant impurities and contaminants 44 Water content 44 Sulphur content 45 Ash content 45 Chlorine content 45 2.16 Solubility of gases in oils 45 2.17 Summary 48 References 48 3 LUBRICANTS AND THEIR COMPOSITION 51 3.1 Introduction 51 3.2 Mineral oils 52 Sources of mineral oils 52 Manufacture of mineral oils 54 Types of mineral oils 56 · Chemical forms 56 · Sulphur content 57 · Viscosity 57 CONTENTS IX 3.3 Synthetic oils 57 Manufacturing of synthetic oils 58 Hydrocarbon synthetic lubricants 60 · Polyalphaolefins 60 · Polyphenyl ethers 60 · Esters 60 · Cycloaliphatics 61 · Polyglycols 61 Silicon analogues of hydrocarbons 62 · Silicones 62 · Silahydrocarbons 62 Organohalogens 62 · Perfluoropolyethers 63 · Chlorofluorocarbons 63 · Chlorotrifluoroethylenes 63 · Perfluoropolyalkylethers 63 3.4 Emulsions and aqueous lubricants 65 Manufacturing of emulsions 65 Characteristics 65 Applications 66 3.5 Greases 66 Manufacturing of greases 66 Composition 67 · Base oils 67 · Thickener 67 · Additives 68 · Fillers 69 Lubrication mechanism of greases 69 Grease characteristics 72 · Consistency of greases 72 · Mechanical stability 73 · Drop point 74 · Oxidation stability 75 · Thermal stability 75 · Evaporation loss 76 · Grease viscosity characteristics 76 Classification of greases 78 Grease compatibility 80 Degradation of greases 80 X ENGINEERING TRIBOLOGY 3.6 Lubricant additives 81 Wear and friction improvers 82 · Adsorption or boundary additives 82 · Anti-wear additives 83 · Extreme pressure additives 85 Anti-oxidants 86 · Oil oxidation 86 · Oxidation inhibitors 88 Corrosion control additives 91 Contamination control additives 92 Viscosity improvers 93 Pour point depressants 95 Foam inhibitors 95 Interference between additives 95 3.7 Summary 96 References 97 4 HYDRODYNAMIC LUBRICATION 101 4.1 Introduction 101 4.2 Reynolds equation 101 Simplifying assumptions 103 Equilibrium of an element 103 Continuity of flow in a column 107 Simplifications to the Reynolds equation 109 · Unidirectional velocity approximation 109 · Steady film thickness approximation 109 · Isoviscous approximation 110 · Infinitely long bearing approximation 110 · Narrow bearing approximation 111 Bearing parameters predicted from Reynolds equation 113 · Pressure distribution 113 · Load capacity 113 · Friction force 114 · Coefficient of friction 115 · Lubricant flow 115 Summary 115 4.3 Pad bearings 116 Infinite linear pad bearing 116 · Bearing geometry 116 [...]... of writing Engineering Tribology remains the same, i.e to provide a reader-friendly and comprehensive introduction to the subject of tribology and its implications for engineering This edition, like the first edition, is intended for final year under-graduate and post-graduate students and professional engineers The subject matter of the book is also relevant to mechanical and materials engineering, ... nature can be found Tribology is therefore a very new field of science, most of the knowledge being gained after the Second World War In comparison many basic engineering subjects, e.g thermodynamics, mechanics and plasticity, are relatively old and well established Tribology is still in an imperfect state and subject to some controversy which has impeded the diffusion 2 ENGINEERING TRIBOLOGY of information... engineer Therefore this book is devoted to these fundamental engineering tribology principles 1.2 MEANING OF TRIBOLOGY Tribology, which focuses on friction, wear and lubrication of interacting surfaces in relative motion, is a new field of science defined in 1967 by a committee of the Organization for Economic Cooperation and Development Tribology is derived from the Greek word ‘tribos’ meaning rubbing... form of tribology equation’ can be used to obtain a simple estimate of either costs or benefits from existing or improved tribological practice Such equation can be summarized as: Total Tribological Cost/Saving = Sum of Individual Machine Cost/Saving × Number of Machines 6 ENGINEERING TRIBOLOGY This equation can be applied to any other problem in order to roughly estimate the relevance of tribology. .. Technology), West Germany, 1976 8 Strategy for Energy Conservation Through Tribology, ASME, New York, November, 1977 INTRODUCTION 9 9 L.S Dake, J.A Russell and D.C Debrodt, A Review of DOE ECT Tribology Surveys, Transactions ASME, Journal of Tribology, Vol 108, 1986, pp 497-501 10 H.P Jost and J Schofield, Energy Savings Through Tribology: A Techno-Economic Study, Proc Inst Mech Engrs., London, Vol 195,... Assessment, United States Congress, Naval Air Development Centre, Warminster, 1977 15 C.M Perrott, Ten Years of Tribology in Australia, Tribology International, Vol 11, 1978, pp 35-36 16 P.F Booth, Metals in Mining-Wear in the Mining Industry, Metals Austr., Vol 9, 1977, pp 7-9 10 ENGINEERING TRIBOLOGY 2 2.1 P H Y S I C A L P R O P E R T I E S O F L U B R I C A N T S INTRODUCTION Before discussing lubrication... illustrations In this second edition of Engineering Tribology we aim to update the contents of the first edition while maintaining its style In this edition a number of extra topics have been included to make the book more comprehensive as suggested by the reviewers of the first edition The listings of literature citations have been extended to include recent findings from tribology research Extra diagrams... knowledge of tribology have been completed in the past few decades, and some time in the future our understanding of the mechanisms of friction and wear may be radically changed and improved The bewildering range of experimental data and theories compiled so far has helped to create an impression that tribology, although undoubtedly important, is somehow mysterious and not readily applicable to engineering. .. impression that tribology, although undoubtedly important, is somehow mysterious and not readily applicable to engineering problems Tribology cannot, however, be ignored as many governments and private studies have consistently concluded that the cost of friction 8 ENGINEERING TRIBOLOGY and wear impose a severe burden on industrialized countries Part of the difficulty in controlling friction and wear is... concepts of tribology in terms useful to engineering students and engineers was, however, lacking The situation was rather like attempting to describe the function of a machine to a non-specialist using manufacturers drawings In many cases the basic models of friction and wear were not explained adequately As a result more sophisticated concepts could not be understood The interdisciplinary nature of tribology . E NGINEERING TRIBOLOGY ENGINEERING TRIBOLOGY Gwidon W. Stachowiak Department of Mechanical and Materials Engineering, University of Western Australia, Australia Andrew. 28 Other viscometers 29 2.8 Viscosity of mixtures 30 2.9 Oil viscosity classification 31 VIII ENGINEERING TRIBOLOGY SAE viscosity classification 31 ISO viscosity classification 33 2.10 Lubricant density. characteristics 76 Classification of greases 78 Grease compatibility 80 Degradation of greases 80 X ENGINEERING TRIBOLOGY 3.6 Lubricant additives 81 Wear and friction improvers 82 · Adsorption or boundary