SKF vibration institute brg failure presentation 7 8 2010

Vibration Institute © SKF Group Slide Vibration Institute Piedmont Chapter Symposium 2011 Presented by Tom McDermott SKF Sr Application Engineer Friday May 13, 2011 ® SKF is a registered trademark of SKF USA Inc © 2010 SKF USA Inc The contents of this publication are the copyright of the publisher and may not be reproduced (even extracts) unless prior written permission is granted Every care has been taken to ensure the accuracy of the information contained in this publication but no liability can be accepted for any loss or damage whether direct, indirect or consequential arising out of use of the information contained herein Discussion topics • • • • • • • • • • Bearing basics Bearing life expectancy Bearing failure statistics Pre-operational damage mode causes Operational damage mode causes Identifying loading patterns ISO Standard 15243 Bearing damage analysis Securing evidence Conducting analysis Vibration Institute © SKF Group Slide SKF bearing basics • Purpose and functions of a bearing • Bearing components and materials • Types of bearing loads • Rolling elements – ball vs roller • Contact angle • Precision class • Radial and axial clearance Vibration Institute © SKF Group Slide Purpose of a bearing and friction • To provide low friction rotation of machine parts • To support and locate rotating equipment Resistance to motion which occurs when one object slides or rubs against another object If not controlled, friction will result in: • Heat generation • Increased noise Vibration Institute © SKF Group Slide • Increased wear • Loss of power Roles of a bearing • Reduce friction • Transmit loads • Support the shaft • Locate the shaft Vibration Institute © SKF Group Slide Bearing components Outer ring Outer ring raceway Cage / retainer Bore surface Inner ring Inner ring raceway Rolling elements (balls) Vibration Institute © SKF Group Slide OD surface Functions of the cage • Minimize friction and heat generation • Prevent contact between adjacent rolling elements • Guide the rolling elements • Provide a surface for the lubricant to adhere to • Retain the rolling elements when bearings of a separable design are mounted or dismounted Vibration Institute © SKF Group Slide Types of bearing loads Radial load Axial load Combined load Vibration Institute © SKF Group Slide Point and line contact Vibration Institute © SKF Group Slide Plastic deformation: indentation from debris Vibration Institute © SKF Group Slide 70 Plastic deformation: indentation from handling 5.1 Overload Plastic deformation 5.2 Indentation from debris 5.3 Indentation by handling Vibration Institute © SKF Group Slide 71 Indentation from handling: localized overloading Vibration Institute © SKF Group Slide 72 Fracture: forced fracture 6.1 Forced fracture Fracture 6.2 Fatigue fracture 6.3 Thermal cracking • Stress concentration > tensile strength • Impact / overstressing Vibration Institute © SKF Group Slide 73 Fracture: forced fracture 6.1 Forced fracture Fracture 6.2 Fatigue fracture 6.3 Thermal cracking Vibration Institute © SKF Group Slide 74 Fracture: forced fracture Vibration Institute © SKF Group Slide 75 Fracture: fatigue fracture 6.1 Forced fracture Fracture 6.2 Fatigue fracture 6.3 Thermal cracking • Rings and cages - Crack initiation / propagation • Exceeding fatigue strength under bending • Finally forced fracture Vibration Institute © SKF Group Slide 76 Fracture: fatigue fracture Vibration Institute © SKF Group Slide 77 Fracture: thermal cracking 6.1 Forced fracture Fracture 6.2 Fatigue fracture 6.3 Thermal cracking • High sliding and / or insufficient lubrication • High friction heat • Cracks at right angle to sliding direction Vibration Institute © SKF Group Slide 78 Fracture: thermal cracking 6.1 Forced fracture Fracture 6.2 Fatigue fracture 6.3 Thermal cracking Vibration Institute © SKF Group Slide 79 Classifications: securing evidence • Collect operating data, monitoring data • Collect lubricant samples • Check bearing environment • Assess bearing in mounted condition • Mark mounting position • Remove, mark and bag bearing and parts • Check bearing seats • Lubricant condition (color, presence of water, viscosity, consistency, distribution in the bearing, etc.) Vibration Institute © SKF Group Slide 80 Classifications: conducting the analysis • Examine bearing and parts • Record visual observations • Record pictures of bearing and pertinent parts • Use the failure modes to eliminate improbable causes and determine the original cause of the failure • Use external resources such as SKF Bearing Inspector at @ptitudeXchange.com or SKF Bearing Installation and Maintenance Guide #140-710 • Contact external resources for assistance, if needed • Initiate corrective action, if desired • Consider SKF analysis services ($) Vibration Institute © SKF Group Slide 81 Available training courses • WE201: Bearing Maintenance and Technology • WE202: Bearing in Rotating Machinery Applications • WE203: Lubrication in Rolling Element Bearings • WE204: Root Cause Bearing Damage Analysis Vibration Institute © SKF Group Slide 82 Thank you! Vibration Institute © SKF Group Slide 83 Vibration Institute © SKF Group Slide 84 ... flaking Vibration Institute © SKF Group Slide 46 Wear: adhesive wear 2.1 Abrasive wear Wear 2.2 Adhesive wear Vibration Institute © SKF Group Slide 47 Wear: adhesive wear Vibration Institute © SKF. .. Zone Vibration Institute © SKF Group Slide 25 Load zone when thrust loads are excessive Vibration Institute © SKF Group Slide 26 Thrust load + radial load = combined loads Vibration Institute © SKF. .. a bearing Vibration Institute © SKF Group Slide 30 Misalignment in a ball and roller bearing Vibration Institute © SKF Group Slide 31 Bearing damage analysis Vibration Institute © SKF Group Slide