smart nvh solutions for next generation brake design

SAE INTERNATIONAL

Smart NVH Solutions for

Next-Generation Brake Design

Gary Weber Application Engineering & Technical Service

Molykote® brand Specialty Lubricants from Dow Corning

Discussion Outline

• Evolution of Automotive Brake Systems

• Next-Generation Design Trends and Challenges

• Tribological Lubrication Regimes

• Range of Smart Lubrication™ Solutions

• Examples of Smart NVH Solutions for Brakes

• Proactive Design to Minimize Brake NVH

• Q & A

2

Evolution of Automotive Brake Systems

3

• Reducing residual brake drag

• Regenerative braking

• Stop-start systems braking

• Autonomous emergency braking (AEB)

Next-generation design

trends and challenges

Drum brake

and mechanical

parking brake

Caliper is introduced

and parking brake is

integrated into drum brake

Proliferation

of electronics into

braking system

Smart Science Drives Mobility Innovation™

4

Energy Efficiency

Connectivity & Safety

Comfort & Design

Eliminate/reduce NVH

Material & temperature capability

Vehicle system longevity

Brake performance

Fuel economy/efficiency

Lightweighting

Legislative & consumer pull

Brake by wire

Autonomous emergency braking

Reduce brake drag and rolling

resistance

Meet or exceed regulatory limits on

solvents and additives

Ensure compatibility with different

design materials – elastomers,

plastics and metals

Provide “lifetime” lubrication solutions

for controlling noise, vibration and

harshness

Improve component service life and

reliability with optimized friction-

control

Enhance lubricant resistance to

chemical, mechanical, thermal and

electrical stresses

Improve resistance to extreme heat,

corrosion and oxidation

TRENDS INDUSTRY FOCUS BRAKE NVH LUBRICANTS

• LINKING TRENDS

TO TRIBOLOGY

Using Tribology to Solve Brake NVH

OEM/Supplier Design Needs:

• Brake NVH performance is critical for:

− Improving user experience (UX)

− Reducing vehicle warranty claims

Smart Solutions:

• Tribology (study of friction, wear

and lubrication) identifies different

lubrication regimes for addressing

brake NVH performance – from the

pedal to the pad

• Stribeck Curve – basis of tribology

6

Tribological Lubrication Regimes

7

Asperity Friction

Hydrodynamic

Friction

Greases

Fluids/oils F

ric

tio

n C

oe

ffic

ien

t

Total Friction

Film Friction

Hydrodynamic

Lubrication

(3 ≤ λ)

Brake System

Lubrication 3

Boundary Friction

Solid lubes

Pastes

AFCs

Mixed Friction

Greases w/solids

Dispersions

Boundary

Lubrication

(0 ≤ λ ≤ 1)

Mixed Lubrication

(1 ≤ λ ≤ 3)

STRIBECK CURVE

1 2

Specialty Lubricant Solutions

8

Greases

Pastes

Oils

Compounds

Dispersions

Anti-Friction

Coatings

Lubricating

fluid,

thickening

agent,

additives

Grease-like

with high

percentage

of solid

lubricants

Lubricating

fluids with

specialty

additives

Grease-like

silicone

fluids with

silica filler

Finely

dispersed

solids in

lubricating

fluids

“Lubricating

paints”; cure

to form dry,

solid lubricant

coatings bonded

to the surface

Using Tribology to Reduce Brake NVH

• Breaking down NVH

− Noise acoustics

− Vibration transmitted feel

− Harshness sound quality and occupant perception

• Approach for NVH reduction

− Damping – allow smooth and consistent operation

− Isolation – prevent fretting, stick-slip, seizure

− Absorption – materials of construction, material compatibility

• What is the smart way to tackle surface engineering and

tribology issues related to brake system NVH?

− With specialty lubricants

9

Specialty Lubricants Aid

in Smart Brake Design

• Greases provide damping to allow smooth and consistent

operation and performance at temperature extremes

• Solid lubricants create isolation between contacting surfaces to

prevent stick-slip, seizure and corrosion

• Compounds act as absorption mediums to interrupt the sound

path from source to receiver

− Materials of construction and material compatibility are key

considerations

10

Greases as Smart NVH Solutions for Brakes

Guide Pin Lubrication Requirements

• Eliminate fretting corrosion, sticking and binding

• Reduce excessive pin wear causing noise and

operation issues

• Prevent high-temperature seizure and reduced

braking power

Proven, Effective Solutions

• Silicone or PAG (polyalkylene glycol) greases

‒ Rubber/metal and metal/metal pairings

‒ Elastomer compatibility at elevated temperatures

(150ºC)

‒ Low frictional force

‒ Good compatibility with brake fluids

11

0 5 10

Time, min

0

20

40

60

80

100

Fo

rce

, N

Silicone with MoS2

Molykote® G-3407

Caliper Pin Grease

Silicone

with PTFE

Greases as Smart NVH Solutions for Brakes

Electric Parking Brake

• Lubrication of polymer gear sets

‒ Multiple gear reductions

• Material compatibility is key – brake fluid, polymer,

elastomer

• Dielectric capability


• PAO and PAG (polyalkylene glycol) greases

‒ Polymer/metal and polymer/polymer pairings

‒ Performance over entire lubrication regime

‒ Low frictional force; high-pressure performance

‒ DOT3 and DOT4 brake fluid compatible

12

Molykote® G-1074 Grease: A Noise-Damping EP Grease

13

30% reduction in noise versus

competitive offering

Extreme-pressure capabilities and noise-damping

abilities allow Molykote® G-1074 Grease to excel

in high-speed polymer-based gear trains.

Property tested, unit Competitor A Competitor B Molykote® G-1074 Grease

OK load, N 300; 200; 100 500; 600; 800 1,000; 1,000; 900

Temperature: 50˚C;

stroke: 1 mm;

frequency: 50 Hz; test

ball: SUJ-2; test disk:

SUJ-2, procedure A

*Data variations are acceptable based on ASTM D5706, #11. Precision and Bias. Repeatability is less

than 0.7X at 95% probability, where X = the average of two results, N.

Molykote® G-

1074 Grease has

much greater

extreme-pressure

value than

Competitors A

and B.*

Molykote® G-

1074 Grease Competitor A Competitor B

SRV extreme-pressure test results – ASTM D5706

Noise test results vs. Competitor A

Molykote® G-1074 Grease

Competitor A

Property tested, unit Molykote® G-1074

Grease Competitor A

Average noise, dB 50.2 53.3

Smart NVH Solutions for Shims and Clips

Brake Shims and Abutment Clip Coatings

• Travel path for brake noise

• Reduce and control friction and wear

• Ensure quiet and consistent pad movement


• Solid lubricants of pastes and anti-friction coatings

‒ Performance over wide temperature range

‒ Noise-damping and vibration absorption capacity

‒ Minimizing vibrations due to DTV

‒ Excellent corrosion protection

14

Coefficient of friction

36 N load and 10 Hz

TIME, SECONDS

Molykote® D-709 Anti-Friction Coating:

Next-Generation NVH Coating

15

• Molykote® D-709 Anti-Friction Coating

exhibits 3x wear life versus Molykote® D-708

Anti-Friction Coating

• Greater wear resistance and lower CoF than

competitive offerings

• Silver color to minimize appearance of

coating scratches

TEST CONDITIONS

Load: 9.8 N

Stroke: 4 mm

Speed: 100 osc/min

Ball: 1/2 inch SUJ2 steel

Test temperature:

Room temperature

LOAD

AF

COATING

SUS #304

PLATE

Lubricity (oscillation test)

Molykote® D-708 Anti-Friction Coating

Competitor A

Molykote® D-709 Anti-Friction Coating

Cross-cut test

Molykote® D-708


Molykote® D-709


Scratch mark Scratch mark

Considerations for Proactive Design to Minimize

Brake NVH

• Vehicle cabin continually becoming quieter

• Innovative materials bring new tribological challenges

• Materials of construction are KEY in system design

− Lightweight alloys; fibers and composites

• Root causes of unacceptable brake NVH include inadequate

lubrication, high friction or excessive wear

• Temperature, load, speed – all reaching new extremes

− Lubricant solution needs to be compatible with all materials

Specialty lubricants – smart, effective solutions for

approaching next-generation design

16

Questions?

BOOTH 431 SEPTEMBER 25-28

The Westin Kierland

Resort & Spa

Scottsdale, Arizona

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