Comparing Bearing and Gear Options: How to Buy Bearings Based on Life, Not Just Price
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Sentient Science’s Computational Tribologist, ElonTerrell, PhD, for a discussion on comparing bearing performance and failure rates within the new DigitalClone computational testing solution. We compared the performance of 3 unidentified bearing OEMs and display the weibull comparisons. DigitalClone can be used to compare bearings, gears, gearboxes, and drive trains within a software environment to accelerate testing and get new products to market faster. We will examine the different failure modes and look at potential changes to improve component life.
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Comparing Bearing and Gear Options: How to Buy Bearings Based on Life, Not Just Price
- 2. • What is the #1 failure component in rotating equipment? • Do you trust your bearings? • Do you trust you bearing provider? • Did the life your bearing provider told you actually happen? • Do they tell you that they make perfect bearings and the reason their bearings did not last is that you destroy them in your assets? • Are you able to test bearings in your asset, product or design with the real loading conditions unique to every fielded asset? • What is the effect of different oil and additives on your bearings? • Have you considered Chinese or Indian bearings but were afraid of quality or counterfeit? • Does bearing performance anxiety keep you up at night? Look at the clock - do you know how your fielded bearings are degrading right now and what that will that cost tomorrow, next month and for the next 20 years? Why Focus on Bearings? 9/30/2015 How to Buy on Life, Not Just Price
- 3. 1. How many of my bearings need to be replaced but what cost, life and size this year and over the next 10-20? 2. Can I negotiate a win-win long term supply contract and warranty based on my newly gained knowledge on life? 3. How are bearings of the same part number different between vendors and assets? 4. How much more should I pay my vendor to to provide 2X life? 5. Should I use my current supplier of lubricant and additives or should that be customized mix to the specific needs of a particular asset, location and duty cycle? The Demand for Better Bearings is Forcing OEMS & Operators to ask Themselves Many Tough Questions Which Require Bearing Comparisons 9/30/2015 How to Buy on Life, Not Just Price
- 4. DigitalClone Live UI Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Fleet 1 9/30/2015 How to Buy on Life, Not Just Price
- 5. GBX Subcomponent Assessment Note: Clipper GBX Example 9/30/2015 How to Buy on Life, Not Just Price
- 6. Gearbox Bearing Performance Comparison 9/30/2015 How to Buy on Life, Not Just Price “As Is” Quantify Impact of: Lubrication change, auto-lubrication systems, uptower change, etc. Prognostics allows you to quantify “what-if” scenarios to extend RUL. “To Be” Years Until Gearbox FailureYears Until Gearbox Failure
- 7. How to Buy on Life, Not Just Price GE 1.5MW GEARBOX Trade-Off Studies Asset/Customer specific trade-off option to confidently predict impact on life/ROI (e.g. gearbox replacements) ROI Optimization All trade-offs based on ROI at the individual asset level/group, maximizing ROI for the fleet. Gearbox Bearing Configuration Option September 30, 2015 OEM Configuration Gearbox w/ OEM 1 Gearbox w/ OEM 2 Gearbox w/ OEM 3
- 8. 1. The conventional approach to bearing selection is based solely on bearing engineer experience with limited test data, which can lead to unexpected performance in the field 2. The same bearing model from different vendors will behave differently in the field. Sentient provides the ability to understand life and performance of bearings from multiple vendors, with different lubricants and additives in your specific asset or system, without physical testing 3. Sentient's computational modeling approach provides the ability to "virtually test" the effect of operation and maintenance (O&M) changes, and determine an optimum O&M strategy for life extension and asset management 3 Key Points 9/30/2015 How to Buy on Life, Not Just Price
- 9. Challenge of Machinery OEMs in Bearing Selection 9/30/2015 How to Buy on Life, Not Just Price Selecting bearings that meet design specifications while balancing performance and cost Standard selection criteria include • Dimensional constraints: inner bore, outer bore, and width • Tolerance: dimensional accuracy and operating tolerances • Rigidity: Elastic deformation occurs along the contact surfaces of a bearing’s rolling elements and raceway surfaces • Load capacity
- 10. Conventional Approach to Life Rating 9/30/2015 How to Buy on Life, Not Just Price Static load rating, C, is defined as the static load which the bearing can carry for 1,000,000 revolutions with 10% probability of fatigue failure Bearing life, in millions of revolutions with 10% probability of fatigue failure: p P C L 10 P = equivalent bearing load, kN p = 3 for ball bearings 10/3 for roller bearings
- 11. Empirical Adjustments to Life Ratings 9/30/2015 How to Buy on Life, Not Just Price Adjustments are made to life ratings based upon materials and operating conditions aM = Adjustment for material - Factor of 1.0 for vacuum-degassed steels - Factor for premium steels is 0.6-1.0 aL = Adjustment for lubrication conditions - Determined by lubricant film parameter, Λ = h/Rq
- 12. Limitations of Conventional Approach 9/30/2015 How to Buy on Life, Not Just Price Lack of accounting of varying operating conditions • Operating temperature • Misalignment Lack of accounting of internal features • Surface finish (roughness, skewness, kurtosis) • Surface coatings • Roller crowning Lack of accounting of material characteristics • Grain size distribution • Presence of inclusions and defects • Residual stress distribution 100X - Case-Core Transition
- 13. Parameter Conventional Sentient DigitalClone Varying Load Yes Yes Varying Speed No Yes Lubricant No Yes Surface Finish No Yes Microgeometry No Yes Material Quality No Yes Sentient vs. Conventional Approach 9/30/2015 How to Buy on Life, Not Just Price
- 14. Sentient’s Technical Approach 9/30/2015 How to Buy on Life, Not Just Price Tribological Analysis and Failure Prediction Material and Surface Characterization Component-Level Analysis System-Level Analysis
- 15. Sentient’s Technical Approach 9/30/2015 How to Buy on Life, Not Just Price Tribological Analysis and Failure Prediction Material and Surface Characterization System-Level Analysis Component-Level Analysis
- 16. Sentient’s Technical Approach 9/30/2015 How to Buy on Life, Not Just Price Tribological Analysis and Failure Prediction Component-Level Analysis System-Level Analysis -700 -600 -500 -400 -300 -200 -100 0 100 200 0 50 100 150 ResidualStress,MPa Subsurface Depth, µm Residual Stress Material Quality Surface Roughness 100X Non-metallic Inclusion Material and Surface Characterization
- 17. Subsurface Crack Network Interfacial Contact Pressure and Subsurface Stress Sentient’s Technical Approach 9/30/2015 How to Buy on Life, Not Just Price Material and Surface Characterization Component-Level Analysis System-Level Analysis Tribological Analysis and Failure Prediction
- 18. All Bearings are NOT Created Equal… 9/30/2015 How to Buy on Life, Not Just Price Bearing material microstructure, surface finish, and material quality impact life…depending upon location and stresses experienced Here’s how some of these factors can influence life for a wind turbine gearbox bearing Stress / Life Curve Bearing Supplier Hardness (Ra) Range 0 to 4500 um depth Microstructure Inclusions Microstructure Quality Supplier 1 60–58 HRC Supplier 2 60-53 HRC (Design requirement >58 HRC) DigitalClone®Simulation HSS Bearing DigitalClone Comparison BEST BEST BEST Stress / Life Curve Cycles to Damage (L66) MaxContactPressure(MPa) Stress – Life Curve Supplier 2 Better Life BetterStressPerformance BEST Supplier 1
- 19. New Prognostic Solution to Predict Failures • Prognostics vs. Diagnostics • Data Model versus Material Science Model - Compatible • Calculates Remaining Useful Life (RUL) and Recommends Options to Extend Life. • Simulates “what if” scenarios to optimize performance. • Enables efficient Asset Management. • Reduces the Time and Cost of Physical Design Testing How to Buy on Life, Not Just Price 9/30/2015
- 20. Bearing Selection: Model Designators 9/30/2015 How to Buy on Life, Not Just Price Cylindrical roller bearing Lips on outer ring Width series 0 Diameter series 3 70 mm bore (14x5) N U 2 143 Bearing models have standard designators that are universal to all major manufacturers [code for bearing type][code for bearing cross section][code for bore size]
- 21. Case Study: Tapered Roller Bearings in Industrial Application 9/30/2015 How to Buy on Life, Not Just Price FEA Analysis 0 500 1000 1500 2000 2500 3000 3500 IR OR DB_Inboard Equivalent Crown R KOYO NTN TIM Microgeometry Measurements Supplier A Supplier B Supplier C EquivalentCrown Radius(mm) Bearing-Shaft Assembly
- 22. Material Model Development • Industrial bearing was used for microstructure residual stress, chemical and micro- hardness analysis • Optical zoom microscopy, scanning electron microscopy (SEM), Inverted microscopy, optical profilometry, and micro-hardness testing are used for characterization • Goal is to identify key microstructural features, input to DigitalClone fatigue damage simulation, based on ASM standards 9/30/2015 How to Buy on Life, Not Just Price As-Received EDM Sectioned
- 23. Supplier A Supplier B Supplier C Surface Roughness Measurement 9/30/2015 How to Buy on Life, Not Just Price
- 24. Supplier A Metallic Inclusion Supplier B Material Quality Measurement 9/30/2015 How to Buy on Life, Not Just Price Supplier C Non-metallic Inclusions Non-metallic Inclusions
- 25. 9/30/2015 How to Buy on Life, Not Just Price 40 45 50 55 60 65 0 500 1000 1500 2000 RockwellHardness Subsurface Depth (µm) Supplier A Supplier B Supplier C -1000 -800 -600 -400 -200 0 200 0 20 40 60 80 100 120 140 160 180 200 ResidualStress(MPa) Subsurface Depth (µm) Supplier A Supplier B Supplier C Subsurface Hardness and Residual Stress
- 26. Deterministic Mixed-EHL How to Buy on Life, Not Just Price Physics-based modeling of interfacial surface contact, frictional heating, and lubrication Contact Pressure Asperity Contacts Lubricant Pressurization Surface Deflection Piezoviscosity Asperity Contact
- 27. Subsurface Crack Pattern 9/30/2015 How to Buy on Life, Not Just Price Supplier A Supplier B Supplier C Contact Surface Contact Surface Contact Surface
- 28. Subsurface Crack Pattern 9/30/2015 How to Buy on Life, Not Just Price Supplier A Supplier B Supplier C Contact Surface Contact Surface Contact Surface
- 29. Subsurface Crack Pattern 9/30/2015 How to Buy on Life, Not Just Price Supplier A Supplier B Supplier C Contact Surface Contact Surface Contact Surface
- 30. Operating Condition 1: Low Gear, Left Misalignment DigitalClone Prediction of Bearing Life Supplier A Supplier C Supplier B 9/30/2015 How to Buy on Life, Not Just Price
- 31. Supplier A Supplier B Supplier C DigitalClone Prediction of Bearing Life Operating Condition 2: High Gear, Right Misalignment 9/30/2015 How to Buy on Life, Not Just Price
- 32. 1. The conventional approach to bearing selection is based solely on bearing engineer experience with limited test data, which can lead to unexpected performance in the field 2. The same bearing model from different vendors will behave differently in the field. Sentient provides the ability to understand life and performance of bearings from multiple vendors, with different lubricants and additives in your specific asset or system, without physical testing 3. Sentient's computational modeling approach provides the ability to "virtually test" the effect of operation and maintenance (O&M) changes, and determine an optimum O&M strategy for life extension and asset management 3 Key Points 9/30/2015 How to Buy on Life, Not Just Price
Editor's Notes
- Should I simply change the bearing material to a super material and request a specific surface treatments such as carburization, super-finish, coatings or textures? 7. Could this mix of materials and surface treatments be my unique competitive advantage lowering my cost per hour to maintain equipment? 8. Should I add a torque damper to control loads? 9. Can I solve for White Etching and other specific failure modes? 10. Can I easily change these bearings in the field or do I wait for the re-manufacturing step? 11. How far ahead should I plan my bearing buys? Will the suppliers have inventory available for me if other operators needs those bearings at the same time? 12. How much should I pay for a full wrap warranty from my OEM compared to doing it myself? 13. Given this new information is available, should I change the bonus income for my team based on 1 year and multi-year targets. 14. Should I setup a meeting with my team to open discussion and ask them some of these questions.
- Take off NextEra Make Site 1, 2, 3
- Replace with GE
- It’s a PhD in the application. Sophisticated technology that runs the simulations. Technical differentiaton. But you don’t need to be a PhD or engineer to make decisions based on this. Easy to use. Ultimately, marry the life (engineering information) with ROI (financial information)
- Add polling slide after each point 1-What are the typical problems with the classical approach? 2-Are these operating conditions important to you? 3-If we are able to help you determine bearing differences, would you be interested in taking a closer look? Key 1: Based on experiments in nature and assumptions are often made
- Classic -> conventional
- Conventional – on some parameters, the detail is limited
- Remove bearing supplier names
- Possibly include statistical summary…Ra, Rq, Sk, Ku Combine 30 and 32 or 31 and 32 Combine 31 and 33
- Supplier A - Micrograph’s illustrating size and morphology of non-metallic inclusions. Dual phase inclusions were observed close to the contact surface. Inclusion Size=14.15um; Area Fraction=0.36% Supplier C - Micrograph’s illustrating size and morphology of non-metallic inclusions in NTN Inner race. Presence of large amount of inclusions was noticed close to the contact surface
- Supplier A: Micro-hardness meets design specifications Case and core hardness was 60HRC and 44 HRC, respectively Case depth: 800.00 m Supplier B: Micro-hardness meets design specifications Through hardened Koyo bearing, 61-60 HRC Supplier C: Micro-hardness is slightly below the spec Case and core hardness was 57HRC and 45 HRC, respectively Case depth: 912.00 m Compared to Suppliers B and C, Supplier A’s bearing had higher surface and slightly subsurface compressive stresses – improves fatigue performance
- Show crack animations for each of the three bearings
- Show crack animations for each of the three bearings
- Show crack animations for each of the three bearings
- Operational Conditions: Low gear, normal loading, left misalignment For this case, Supplier B bearing fatigue performance is superior compared to Suppliers A and C Supplier C bearing has higher contact stress Supplier A: Pmax = 3293.7 MPa Supplier B: Pmax = 3350.7 MPa Supplier C: Pmax = 3532.6 MPa Supplier B bearing fatigue life scatter is relatively higher due to lower inclusion size density, less probability of having inclusions at subsurface maximum shear stress location
- Operational Conditions: High gear, worst loading, right misalignment Supplier C bearing has higher contact stress Supplier A: Pmax = 3315.1 MPa Supplier B: Pmax = 3364.1 MPa Supplier C: Pmax = 3534.1 MPa
- Add polling slide after each point 1-What are the typical problems with the classical approach? 2-Are these operating conditions important to you? 3-If we are able to help you determine bearing differences, would you be interested in taking a closer look? Key 1: Based on experiments in nature and assumptions are often made