Bench Top Screening of Wet Clutch Materials
S.J. Shaffer, Ph.D.
steven.shaffer@bruker.com
Steve Papanicolaou
Steve.papanicolaou@Bruker.com
TRIBODAYS 2015
October 6-7, 2015
Nynashamn, Sweden
Luleå University of Technology
in association with the Swedish Tribology Group and hosted by Nynas AB
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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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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Why do we need a valid bench top test?
• ROI Discussion
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What does it cost to buy an SAE No.2 Friction machine?
$400K to $800K
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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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Defining the Tribotest
What are the important parameters ?
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Materials
Contact Geometry
Loading
Motion
Environment
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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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Size Effect Concerns
Minimum Contact Size
• Non Homogenous Nature (Material and Geometry Features)
•
Ra=9.09mm
Ra=12.88mm
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Ra=3.11mm
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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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Bench Top System
Bruker UMT-TL (TriboLab)
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Bench Top System
Bruker UMT-TL (TriboLab)
Torque Sensor
Lower
Sample
Holder
Self Leveling
Upper Sample Holder
Load Cell
ATF Supply
ATF Return
Peristaltic Pump
ATF Supply Port
Heating Chamber/Rotary Drive
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Bench Top System
Bruker UMT-TL (TriboLab)
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Results
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Results
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Observations
• Agreement Very Good In
• Relative rankings
• Curve Shape
• Magnitude of COF for each material
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Bruker Confidential Information
©May
1.
Juli2,
Copyright
2016
2011Bruker Corporation. All rights reserved
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