science of friction -...

4th CTI Symposium and ExhibitionAutomotive Transmissions and Drive Trains North AmericaJune 2010, Ann Arbor, MI, USA

- Volker Plehn, Dipl.Ing., DuPont Automotive -

DuPont Market Driven Innovation:

Science of Friction

Volker Plehn

Director Development & Sales

DuPont™ Kalrez® & Vespel®



Science of Friction

Increased Importance of Friction

Friction from a Polymer Point of View

Examples of Value Chain Co-operation

Summary



Transportation Megatrends

New materialsNew wear and friction demands

Increased need for thermal isolation

Actuators, DC drives, stability systems, electric pumps (fuel, oil, etc.)Increasing use of electronic controls

New transmission designs(6-8 speeds, CVT, electric/hybrid)

New propulsion (hybrids)

Variable valve timing & liftTurbochargers

EGR technologies

Fuel efficiency / emissionsPerformance

ApplicationsInnovation programs

Green House Gas emissions

Petroleumconsumption



Unprecedented # of new technologies!

Transportation Technology Drivers

Improve efficiency of current devices

% of energy in fuel available at wheels? 15%

Controlling Friction

% of energy lost to friction between rotating or

moving parts? 10%

Over 2,000,000 barrels /

DAY

6 out of 7 liters

wasted

+



Polymers, fillers & processes for wear & friction solutions

Friction Control

Increased need for friction control - especially lubricated friction.

Teflon®

ETFETeflon®

FEP

Low

High

High

0.05

0.1

0.4

0.6

Zytel®nylon + Kevlar® fibers

Teflon®

PTFE

Vespel® S polyimide

0.08

0.3

0.2

+ Kevlar® fibers

Vespel® TP polyimide

+ PTFE

Delrin®

acetal

+ PTFE

Dry

Fric

tion

Performance (e.g.: temp & wear)

brake pads

2X-4X improved

wear



MaterialDesign

Temperature

T

HighMetal disc

Lubricant

Polymer ringV

P

Science of Friction: Reducing Energy Loss

Variables to control friction

Experimental Results on Seal Rings & Thrust Washers

Boundary

MixedHydrodynamic

Fric

tion

Low

Oil Viscosity x Speed (V) / Load (P)



Revolution

Thrust load

Mating material

Sample ring

Thrust Washer Test equipment

0

0.1

0.2

0.3

Vespel® SP- 2515

PEEK Vespel® SP- 2515

PEEK

Coefficient of friction

55% Reduction

45% Reduction

-30oC 23oC

Coe

ffici

ent o

f Fric

tion

Vespel®SP-2515

Vespel®SP-2515

PEEK PEEK0

0.1

0.2

0.3

Vespel® SP- 2515

PEEK Vespel® SP- 2515

PEEK

Coefficient of friction

55% Reduction

45% Reduction

-30oC 23oC

Coe

ffici

ent o

f Fric

tion

Vespel®SP-2515

Vespel®SP-2515

PEEK PEEK

ATF D-III

DuPont™ Vespel® SP-2515 to improve component efficiency.

For more data and technical paper visit: tryvespel.dupont.com

Material Optimization:



Housing RPM

Material + Design = Improved Energy Efficiency

Rectangular

0.6mm

Oil Pressure

Higher PV capability allows less contact area & less frictional loss.

“T” Type

Vespel® w/ optimized oil grooves

0.1

0.2

0.3

0.4

0.5

60 80 100 120 140Groove Surface Temperature (°C)

PEEK

50%

Optimized oil groove design expands low friction hydrodynamic zone.

1000 3000 60000.15

0.20

0.25

0.30

Fric

tiona

l Los

s (N

-m/ri

ng)

PEEK Vespel®

34%

T-Type: Vespel®

13%



Temperature & Friction

Vespel® SP-2515Observations:

4 X higher

THERMAL CONDUCTIVITY

than many polymers

> 30%lower surface temperatures

Thrust washer test results

0.043

0.0260.033

0.027 0.0250.015

0.15

175 180170

195*195*195*

116

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Bronze PEEKCF+PTFE+graphite

PEEK30% CF

PAI Low wear

PAI+PTFE+graphite

SP-21 SP-2515

Coe

ffici

ent o

f Fric

tion

0

50

100

150

200

250Coefficient of FrictionSurface Temperature

*safety interlock at 195 ° C

Lowest observed

temperature



Thermal ConductivityNew test protocol developed

Rotation (V) Load (P)

Oil In

Insulating Plate

Thrust Washer (test sample)

Heat flow

-> Lower operating temperature-> Lower Friction

Coe

ffici

ent o

f Fric

tion

Support Plates w/ thermocouple



Thrust Washer – Magna PowertrainVespel® SP-21 thrust washer• Low wear• Broad Temperature range• Stable in transmission oils



Seal Ring – ZF GetriebeVespel® SP-21 Seal Ring• Assembly cost savings• Lighter weight• Maintenance-free operation



FRICTION CONTROL in Hot, Dirty environments?

Higher TEMPERATURES

Increased USE OF ALUMINUM (light weight)

Emission Systems Turbochargers

Potential for CONTAMINATION



Theory: Wear or contamination particles embed into Vespel® parts, remaining below the wear surface and protecting mating parts.

Metal Substrate (A6061-T5):

Contamination remains on surface

Contamination embeds below surface

Vespel® SP

Longer Life

Embedded Contamination

Particle (note lack of wear groove formation)

Contamination Particles on Surface

(note groove formation)

oil

oil



0

0.2

0.4

0.6

0.8

1

1.2

1.4

Wea

r Vol

ume

(mm3 )

Clean Oil With Particles

Vespel®SP-21

Vespel®SP-2515

PEEK

1.15

0.400.50

0.08 0.07 0.080

0.2

0.4

0.6

0.8

1

1.2

1.4

Wea

r Vol

ume

(mm3 )

Clean Oil With Particles

Vespel®SP-21

Vespel®SP-2515

PEEK

1.15

0.400.50

0.08 0.07 0.08

Vespel® SP-2515 exhibits 65% less wear

Intentionally introduced particles (~14 μm)

Wear Resistance



Emission SystemsEGR (exhaust gas recirculation) ValvesBypass ValvesControl Arms & CamsPintel & Shaft Guide BushingsActuation Cams or Slides

BenefitsRepeatable, consistent operationLonger life



Turbo ChargerShaft oil seal ringsShaft spacersLinkage & control arm rod endsSpherical bushings

BenefitsRepeatable, consistent operationClose tolerances: thermal expansion close to aluminum,

stainless & cast iron.Good wear against metal surfaces



Efficiency Improvements & Reduced Total System Cost

1. Direct: lower friction in rotating components

2. Indirect: better control of fluids and leak rates = lower parasitic losses (e.g.: smaller pumps)

3. Mass: ability to run directly against aluminum housings or shafts reduces system mass and start/stop losses.

4. Cost: improved assembly techniques (e.g.: no need for steel inserts) and longer life drives out costs.



SummaryHotter TemperaturesHigher PVHigher TorqueSmaller PackagingComponent Life / Wear

DuPont™ Vespel®DELIVERING BIG SCIENCE, PART BY PART.

FASTER THAN EVER BEFORE...Additional information at www. tryvespel.dupont.com



The information set forth herein is furnished free of charge and is based on technical data that DuPont believes to be reliable and falls within the normal range of properties. It is intended for use by persons having technical skill,

at their own discretion and risk. This data should not be used to establish specification limits nor used alone as the basis of design. Handling precaution information is given with the understanding that those using it will satisfy

themselves that their particular conditions of use present no health or safety hazards. Since conditions of product use and disposal are outside our control, we make no warranties, express or implied, and assume no liability in connection with any use of this information. As with any product, evaluation under end-use conditions prior to

specification is essential. Nothing herein is to be taken as a license to operate or a recommendation to infringe on patents.

Caution: Do not use in medical applications involving permanent implantation in the human body. For other medical applications, discuss with your DuPont customer service representative and read Medical Caution

Statement H-50103-3.

The DuPont™ Oval logo, DuPont™, The miracles of science™, Delrin®, Kevlar®, Kalrez®, Teflon®, Vespel®, Zytel® are registered trademarks of E.I. duPont de Nemours or its affiliates.

Copyright 2010

science of friction -...

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