Int. workshop Super-lubricity in the automotive real world, May 5 th 2015, Sao Paolo, Brazil Optimization of the TriboconditioningProcessfor Low Friction Surfaces ZlateDimkovski
Outline A studyon Triboconditioningprocess on a valvetraincomponents Introduction Process/Friction Tests Surface Analysis Conclusions Triboconditionedliner surfaces 2
Introduction: Valve Train Mechanical losses 3
Pin-roller contact 4
Tool sample F Wear width increases Ring sample Triboconditioning as a cost-effective process n WS 2 Tool sample Ring sample asperities flatten 5
Process tests on tribometer Test variables: Load-F (180 & 360N) Speed-n (600 & 1200 rpm) Surface finish (Ground & Honed) Time: ~6 min Test outputs: Coef. of friction El. resistance Block-on-ring module F Tool Ring n 6
Friction (start-stop) tests Test variables: Load: F=3N Speed: n=0-714rpm Surface finish (Ground & Honed) 3 repetitions (3 diff. ring samples) Test outputs: Coef. of friction (COF) El. Resistance (R) Block sample Width=3mm F=3N n Ring sample Width=6mm Block-on-ring module 7
Start-stop tests: Testing sequence (5min total test time) 5 5 5 5 8
Analyzed interval COF & R (resistence) Signals Rotational Speed V2=0-11.9 rev/s (0-714rpm) 9
Functional friction (start-stop) tests 0,12 COF Ground 0,12 COF Honed 0,11 0,1087 0,11 0,1084 0,1034 0,1033 0,10 0,10 0,0950 0,09 0,088 0,0867 0,09 0,08 0,076 0,08 0,07 0,07 0,06 0,06 360/600 180/600 360/1200 180/1200 360/600 180/600 360/1200 180/1200 Load (N)/Speed(rpm) Load (N)/Speed(rpm) 10
3D roughness parameters Honed Ground Load/Speed Sq S10z Shv Sha Spk Sk Sk reduct. N/rpm µm µm µm³ µm² µm µm % 180/360 Before 0,145 0,813 7,5 791,2 0,110 0,367 180/360 After 0,088 0,829 6,6 918,3 0,074 0,206 43,8 180/1200 Before 0,149 0,846 5,9 650,0 0,115 0,388 180/1200 After 0,098 0,914 7,1 771,2 0,082 0,225 360/600 Before 0,141 0,782 8,3 910,1 0,107 0,366 360/600 After 0,109 1,039 8,2 779,7 0,083 0,244 360/1200 Before 0,154 0,856 10,7 1101,4 0,135 0,358 360/1200 After 0,127 1,019 4,6 476,7 0,117 0,298 180/360 Before 0,084 0,785 3,9 306,9 0,061 0,195 180/360 After 0,076 0,877 5,9 619,7 0,056 0,142 180/1200 Before 0,102 0,897 3,8 263,0 0,093 0,231 180/1200 After 0,075 1,064 6,6 769,4 0,059 0,140 360/600 Before 0,081 0,725 4,2 337,3 0,054 0,185 360/600 After 0,079 0,897 4,4 526,9 0,073 0,121? 360/1200 Before 0,083 0,757 4,2 331,9 0,058 0,195 360/1200 After 0,096 Zlate 1,021 Dimkovski, Halmstad 4,5 University 401,9 0,107 0,179 42,0 33,3 16,9 26,9 39,5 34,4 8,3 11
Multi-scale analysis: Morphological decomposition for 180N/600rpm Ground Honed (Before-After)/Before*100 (Before-After)/Before*100 12
Morphological decomposition for 180N/600rpm Ground Honed 4 measurements/ring Roughness Waviness Roughness Waviness Zoom on Roughness Scales Zoom on Roughness Scales 13
Morphological decomposition (Averages of 3 samples) Increase/decrease percentage over all the scales Sqchange [%] (Sq before Sq after)/sq before*100 100 0-100 -200-300 -400-500 100 0-100 -200-300 180N/600rpm 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 Ground Honed 360N/600rpm Scales Scales 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 Ground Honed 100 0-100 -200-300 -400-500 100 0-100 -200-300 180N/1200rpm 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 Ground Honed 360N/1200rpm Scales 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 Ground Honed Scales -400-500 -400-500 14
Conclusions (Valvetrainsurfaces) The lowest friction showed the ground surface treated by low load/low speed process parameters Contrary to the ground rings, the longer wavelengths of the honed surfaces increase during triboconditioning The ground (rougher) surface before treatment better than the honed (smooth) one due to the better reduction of the waviness & core roughness 15
Cylinder liner surfaces 16
Power Lossesin IC Engines (Richardson D. E. 2000) Focus: Cylinder Liner Twin Land Oil Control Ring 17
TriboconditionedLiner Surfaces Coated Uncoated ISO 25178 Height Parameters Sa 0.4087 µm Sz 6.239 µm Ssk -2.27 Sku 9.079 EUR 15178N Functional Parameters Sk 0.6115 µm Spk 0.2293 µm Svk 1.583 µm Sr1 7.962 % Sr2 77.81 % SMOOTHER PLATEAUS ISO 25178 Height Parameters Sa 0.6387 µm Sz 9.222 µm Ssk -1.275 Sku 4.531 EUR 15178N Functional Parameters Sk 1.153 µm Spk 0.2353 µm Svk 1.608 µm Sr1 5.263 % Sr2 71.56 % 18
Truck ring-liner tribotests Testing parameters: 10mm wide liner samples: 2 Load: 8N Speeds: 0.5Hz, 1Hz, 2Hz & 5Hz Stroke: 24mm Nominal contact pressure: 1.42 MPa Liner samples half-coated, half-uncoated New (TLOCR) Twin Land Oil Control Rings: 2 Viscous engine oil: 20W50 Room temperature Time: 10min 19
Setup Force sensor Stiffer suspension in tangential direction 20
0.5Hz Sample 1 COATED Sample 2 21
1Hz Sample 1 COATED Sample 2 22
2Hz Sample 1 COATED Sample 2 23
5Hz Sample 1 COATED Sample 2 24
ObviousFrictionReductionin Boundary& Mixed LubricationRegime Speed: 1Hz COATED 25
Conclusions/Futurework (Liner Surfaces) Conclusions Triboconditioned surfaces reducefriction(morein boundary/mixed regime). Coating/Surface topography contribution? Future work Novel stratified/honed/textured surfaces in production Coated(plasma/DLC) surfaces with low viscosity oils Better models/simulations/tribotests 26
References 1. DimkovskiZ. et al, 2014, Int. Conference on Metrology and Properties of Engineering Surface, Charlotte, USA 2. ZhmudB., 2011, Tribology and Lubrication Technology, 67,42 3. ZhmudB., TomanikE. and Xavier F.-A., 2014, Lubrication Science, 26,277 27
Acknowledgements Vinnova, Swedish Energy Foundation Volvo Groups Truck Technologies Volvo Cars AppliedNano Surfaces GnuttiCarlo Sweden Scania Digitalsurf, France 28
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