Optimization of the TriboconditioningProcessfor Low ...€¢ Coated(plasma/DLC) surfaces withlowviscosityoils • Better models/simulations/tribotests ... • Scania • Digitalsurf,

Optimization of the

Triboconditioning Process for Low

Friction Surfaces

Zlate Dimkovski

Int. workshop “Super-lubricity in the automotive real world”, May 5th 2015, Sao Paolo, Brazil

Outline

• A study on Triboconditioning process

on a valvetrain components

– Introduction

– Process/Friction Tests

– Surface Analysis

– Conclusions

• Triboconditioned liner surfaces

2Zlate Dimkovski, Halmstad University

Introduction: Valve Train

Mechanical losses


Pin-roller contact


Triboconditioningas a cost-effective process

F

n

Ring sample

Tool

sample

Wear

width

increases

Tool sample

asperities

flatten

WS2

Ring sample


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

nRing

Tool


7

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-on-ring module

F=3N

n

Ring sampleWidth=6mm

Block sampleWidth=3mm

Zlate Dimkovski, Halmstad University

8

Testing sequence (5min total test time)

5 5 5 5

Start-stop tests:


9

COF

&

R(resistence)

Signals

Analyzed interval

Rotational Speed V2=0-11.9 rev/s (0-714rpm)Zlate Dimkovski, Halmstad University

Functional friction (start-stop) tests

0,1084

0,1034 0,1033

0,0950

0,06

0,07

0,08

0,09

0,10

0,11

0,12

360/600 180/600 360/1200 180/1200

COF Honed

0,088

0,076

0,1087

0,0867

0,06

0,07

0,08

0,09

0,10

0,11

0,12

360/600 180/600 360/1200 180/1200

COF Ground

Load (N)/Speed(rpm) Load (N)/Speed(rpm)


3D

ro

ug

hn

ess

pa

ram

ete

rsLoad/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

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 1,021 4,5 401,9 0,107 0,179

42,0

33,3

16,9

Ho

ne

dG

rou

nd

26,9

39,5

34,4

8,3

43,8

?11Zlate Dimkovski, Halmstad University

12

Morphological decomposition for 180N/600rpm

Ground Honed

(Before-After)/Before*100(Before-After)/Before*100

Multi-scale analysis:


13

Morphological decomposition for 180N/600rpm

Ground Honed

13

Roughness Waviness

Zoom on

Roughness

Scales

Roughness Waviness

Zoom on

Roughness

Scales

4 measurements/ring


Morphological decomposition (Averages of 3 samples)Increase/decrease percentage over all the scales

-500

-400

-300

-200

-100

0

100

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61

180N/1200rpm

Ground

Honed

-500

-400

-300

-200

-100

0

100

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61

180N/600rpm

Ground

Honed

-500

-400

-300

-200

-100

0

100

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61

360N/600rpm

Ground

Honed

-500

-400

-300

-200

-100

0

100

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61

360N/1200rpm

Ground

Honed

14

Sq

cha

ng

e [

%] (S

qb

efo

re –

Sq

aft

er)

/Sq

befo

re*1

00

Scales Scales

Scales Scales


Conclusions (Valvetrain surfaces)

• 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


Cylinder liner surfaces

Zlate Dimkovski, Halmstad University 16

Power Losses in IC Engines

(Richardson D. E. 2000)

17

Focus: Cylinder Liner – Twin Land Oil Control Ring


Triboconditioned Liner SurfacesCoated Uncoated

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 %

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

PLATEAUSZlate Dimkovski, Halmstad University 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


Setup

Stiffer suspension

in tangential direction

Force sensor


0.5Hz

Sample 1

Sample 2

COATED


1Hz

COATED

Sample 1

Sample 2


2Hz

COATED

Sample 1

Sample 2


5Hz

COATED

Sample 1

Sample 2


Obvious Friction Reduction in Boundary & Mixed

Lubrication Regime

COATED

Speed: 1Hz


Conclusions/Future work

(Liner Surfaces)

Conclusions

• Triboconditioned surfaces

reduce friction (more in

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


References

1. Dimkovski Z. et al, 2014, Int. Conference on

Metrology and Properties of Engineering

Surface, Charlotte, USA

2. Zhmud B., 2011, Tribology and Lubrication

Technology, 67, 42

3. Zhmud B., Tomanik E. and Xavier F.-A., 2014,

Lubrication Science, 26, 277


Acknowledgements

• Vinnova, Swedish Energy Foundation

• Volvo Groups Truck Technologies

• Volvo Cars

• Applied Nano Surfaces

• Gnutti Carlo Sweden

• Scania

• Digitalsurf, France



Documents

Optimization of the TriboconditioningProcessfor Low ...€¢ Coated(plasma/DLC) surfaces withlowviscosityoils • Better models/simulations/tribotests ... • Scania • Digitalsurf,