1. Bench Top Screening of Wet Clutch Materials
S.J. Shaffer, Ph.D.
Steve Papanicolaou
TRIBODAYS 2015
October 6-7, 2015
Nynashamn, Sweden
Luleå University of Technology
in association with the Swedish Tribology Group and hosted by Nynas AB

2. Background Smooth wet clutch operation tied to velocity
Full scale tests currently done on SAE No.2 type friction machines/JASOM348
Increasing demand for higher torque capacities at reduced sizes
Harshness, vibration and noise (HVN) strongly tied to V dependence of COF
SAE No.2 Friction machines are the first analysis step in material development program
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3. SAE No.2 Friction test machine and Sample
Typical sample size 133mm/99mm
Clutch disc photo courtesy of Par Marklund, Doctoral Thesis, “Wet Clutch Tribological performance optimization methods” Lulea Univ of Technology 2008
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4. Why do we need a valid bench top test?
ROI Discussion
What does it cost to buy an SAE No.2 Friction machine? $400K to $800K
What does it cost to run the machine?
What does it cost to make the SAE No.2 Samples?
Production down time costs?
Production personnel costs?
How long does it take to set up an SAE No.2 Test?
~2 Hours
SAE No.2 Friction machine downtime/maintenance?
Researchers that run these tests at a third party spend ~$1,200/test
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5. Defining the Tribotest
What are the important parameters ?
Materials
Contact Geometry
Loading
Motion
Environment
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6. Materials and Contact Geometry
Benchtop Tester Sample to be of same material of interest
Contact Geometry Flat Ring on Flat, Scaled Down
133 mm Dia.
29 mm Dia.
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7. Non Homogenous Nature (Material and Geometry Features)
Size Effect Concerns
Minimum Contact Size
Non Homogenous Nature (Material and Geometry Features)
Ra=9.09mm
Ra=12.88mm
Ra=3.11mm
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8. Loading, Motion and Environment
J3.3 Calls for Max Pressure of 2.96MPa
2.96Mpa on Benchtop Sample = 750N Load
Max Speed on J3.3 calls for 235 RPM
Equivalent Linear Velocity on Benchtop Sample = 1237 RPM
Temperature steps of 40C, 90C and 120C can be achieved on benchtop system, per standard
Constantly recirculating ATF
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9. Bench Top System Bruker UMT-TL (TriboLab)
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10. Bench Top System Bruker UMT-TL (TriboLab)
Self Leveling
Upper Sample Holder
Torque Sensor
Load Cell
Lower
Sample Holder
ATF Supply
ATF Return
Peristaltic Pump
ATF Supply Port
Heating Chamber/Rotary Drive
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11. Bench Top System Bruker UMT-TL (TriboLab)
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12. Results
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13. Results
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14. Observations Agreement Very Good In Relative rankings Curve Shape
Magnitude of COF for each material
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15. Bruker Confidential Information
© Copyright Bruker Corporation. All rights reserved
15. November 2018
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May 2, 2011

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