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Bearing Damage and Failure Analysis Contents Bearing damage and failure analysis Contents SKF – the knowledge engineering company ................................ 5 Introduction ......................................................... 7 1 Bearing life and bearing failures ....................................... 8 Factors influencing bearing service life .................................... 8 When to replace a bearing? ............................................ 9 2 Inspection and troubleshooting ........................................ 10 Inspection during operation .............................................. 10 Monitoring noise and vibration .......................................... 11 Monitoring temperature ............................................... 11 Monitoring lubrication conditions ........................................ 11 Inspection during a machine shutdown ..................................... 11 Inspecting bearings .................................................. 11 Inspecting seal counterfaces ............................................ 12 Troubleshooting ....................................................... 12 Common symptoms of bearing trouble .................................... 12 Trouble conditions and their solutions. 15 3 Path patterns ....................................................... 32 Normal raceway path patterns ............................................ 34 Radial bearings – radial load unidirectional and constant ...................... 34 Radial bearings – radial load rotating in phase and constant .................... 35 Radial bearings – axial load unidirectional and constant ....................... 36 Radial bearings – combination of radial and axial loads unidirectional and constant .. 37 Thrust bearings – axial load unidirectional and constant ...................... 37 Raceway path patterns from abnormal operating conditions ..................... 38 Radial bearings – radial load unidirectional and constant ...................... 38 Thrust bearings – axial load unidirectional and constant ...................... 40 4 ISO failure modes classification ........................................ 42 Failure modes classification – ISO workgroup ................................. 42 Failure modes ......................................................... 44 Fatigue ............................................................ 44 Wear ............................................................. 48 Corrosion .......................................................... 52 Electrical erosion .................................................... 55 Plastic deformation .................................................. 58 Fracture and cracking ................................................. 61 5 Damage and actions ................................................. 64 Subsurface initiated fatigue .............................................. 65 Surface initiated fatigue ................................................. 66 Abrasive wear. 68 Adhesive wear ........................................................ 70 Moisture corrosion ..................................................... 71 Fretting corrosion ...................................................... 73 False brinelling ........................................................ 75 Excessive current ...................................................... 76 Current leakage ....................................................... 77 Overload. 79 Indentations .......................................................... 81 Forced fracture ........................................................ 83 Fatigue fracture ....................................................... 84 Thermal cracking ...................................................... 85 6 Other investigations ................................................. 86 7 Case studies ........................................................ 88 Train derailment ....................................................... 88 Variable speed electric motor problem ...................................... 90 Clay mill problem ...................................................... 92 Jaw crusher problem ................................................... 94 8 Appendices ......................................................... 96 Appendix A: SKF classification adapted from ISO 15243:2004 .................... 96 Appendix B: Factors influencing bearing selection ............................. 97 Appendix C: Bearing damage and failures – modes and causes ................... 99 Appendix D: Collecting information ......................................... 100 Appendix E: Glossary ................................................... 101 SKF – the knowledge engineering company From one simple but inspired solution to a misalignment problem in a textile mill in Sweden, and fifteen employees in 1907, SKF has grown to become a global industrial knowledge leader. Over the years, we have built on our exper- Meeting the toughest challenges Working for a sustainable future tise in bearings, extending it to seals, mecha- Our network of knowledge and experience, Since 2005, SKF has worked to reduce the tronics, services and lubrication systems. along with our understanding of how our negative environmental impact from our Our knowledge network includes 46 000 core technologies can be combined, helps operations and those of our suppliers. Our employees, 15 000 distributor partners, us create innovative solutions that meet the continuing technology development resulted offices in more than 130 countries, and a toughest of challenges. We work closely with in the introduction of the SKF BeyondZero growing number of SKF Solution Factory our customers throughout the asset life portfolio of products and services which im- sites around the world. cycle, helping them to profitably and prove efficiency and reduce energy losses, re spon sibly grow their businesses. as well as enable new technol ogies har- Research and development nessing wind, solar and ocean power. This We have hands-on experience in over forty combined approach helps reduce the en vir- industries based on our employees’ know- on mental impact both in our oper ations and ledge of real life conditions. In addition, our our customers’ oper ations. world-leading experts and university part- ners pioneer advanced theoretical research and development in areas including tribol- ogy, condition monitoring, asset manage- ment and bearing life theory. Our ongoing commitment to research and devel opment helps us keep our customers at the forefront of their industries. Working with SKF IT and logistics systems and application experts, SKF SKF Solution Factory makes SKF knowledge and manu facturing expertise Authorized Distributors deliver a valuable mix of product and application available locally to provide unique solutions and services to our customers. knowledge to customers worldwide. Design and develop n Ma tio nu a fac ic tu if re c a e n p d S te s Our knowledge SKF Life Cycle t Management n M o a i – your success i s n s ta i in m SKF Life Cycle Management is how we combine our technology a n m d o platforms and advanced ser vices, and apply them at each stage r c ep d a n of the asset life cycle, to help our customers to be more ir a all nst success ful, sustainable and profitable. Oper I ate and monitor Working closely with you Bearings SKF is the world leader in the design, development Our objective is to help our customers and manufacture of high performance rolling improve productivity, minimize main ten- bearings, plain bearings, bearing units and housings. ance, achieve higher energy and resource efficiency, and optimize designs for long service life and reliability. Machinery maintenance Condition monitoring technologies and main- Innovative solutions tenance services from SKF can help minimize Whether the application is linear or rotary unplanned downtime, improve operational efficiency and reduce maintenance costs. or a combination, SKF engineers can work with you at each stage of the asset life cycle to improve machine performance by looking at the entire application. This approach Sealing solutions doesn’t just focus on individual components SKF offers standard seals and custom engineered like bearings or seals. It looks at the whole sealing solutions to increase uptime, improve application to see how each com po nent in- machine reliability, reduce friction and power losses, and extend lubricant life. teracts with each other. Design optimization and verification SKF can work with you to optimize current Mechatronics or new designs with proprietary 3-D mod- SKF fly-by-wire systems for aircraft and drive-by- ell ing software that can also be used as a wire systems for off-road, agricultural and forklift virtual test rig to confirm the integrity of the applications replace heavy, grease or oil consuming mechanical and hydraulic systems. design. Lubrication solutions From specialized lubricants to state-of-the-art lubrication systems and lubrication management ser vices, lubrication solutions from SKF can help to reduce lubrication related downtime and lubricant consumption. Actuation and motion control With a wide assortment of products – from actu- ators and ball screws to profile rail guides – SKF can work with you to solve your most pressing linear system challenges. 6 Introduction Rolling bearings are among the most Consequently, by examining a failed or 3 Path patterns important components in the vast majority damaged bearing, it is possible in the major- Once damage has occurred, the bearing of
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