Changes in Lubricants and Application Conditions Drive the Selection and Development of Materials us

1

• "Changes in Lubricants and Application Conditions
  Drive the Selection and Development of Materials
  used in Automotive Shaft Seals"

by Doug Coulthard Director of Materials
Engineering Chicago Rawhide Americas
2

• Major Automotive Shaft Seal Applications

These can be conveniently split into six
categories Engine Seals Valve Stem
Seals Transmission Seals Wheel Axle
Seals Steering Seals Bearing Seals
3

• Change Drivers in OE Shaft Seal Applications

• The factors listed below are driving the design
  and
• materials selection criteria for today's shaft
  seals.
• Lubricant Formulation Developments
• Higher Operating Temperatures
• Renewed Focus on Low Temperature Performance
• Cost/Value Considerations
• Development Improvements in Specialty Polymers

4

• Elastomers in O.E. Shaft Seals

VMQ or ACM
Engine
Reg. FKM
?
ACM
Valve Stem
Reg. FKM
?
AEM,BR FKM Or HNBR
?
VMQ or ACM
Transmission
AEM, BRFKM Or HNBR
Wheel Axle
NBR
?
Steering
HNBR
NBR
?
Bearing
NBR
NBR
?
5

• Elastomers for Seal Compounds

6

• Change Drivers in OE Shaft Seal Applications cont.

The current situation is fairly clear but there
is potential (especially if "driver" 1 undergoes
a radical change) for major upheavals to the
cost/ performance equation. The historical usage
of the various types of Specialty Elastomer, in
Automotive Shaft Seals, can be correlated to past
trends in most of these "drivers." By analyzing
today's "drivers," we can try to anticipate the
future needs and trends in Polymer Materials, and
provide all segments of the industry (from
Suppliers through to Automobile Producers) with
valuable insights.
7

• Change Drivers - Current Situation

• Today's trends and the associated problems which
  affect
• material choices and alternatives are concisely
  reviewed
• Lubricants Mineral and/or Synthetic hydrocarbon
  base stocks with "sophisticated" additive
  packages. Problems
• Variable swell due to base stock differences
• Amine additives can be ultra aggressive to
  regular FKM's
• Low temperature viscosity "improvements" can
  cause leaks

8

• Change Drivers - Current Situation cont.

• Higher Operating TemperaturesSome escalation
  seen, but 302F/150C still the zone of
  continuous operating with intermittent "spikes"
  up to 325F/163C
• Problems
• Long term aging of ACM, AEM HNBR materials
• Fluid degradation changes material compatibility

9

• Change Drivers - Current Situation cont.

• Low Temperature Performance True minus 40
  sealing needed in critical situations, e.g.
  start up, with all possible fluid types (Mineral
  or Synthetic base) Problem The "good" low
  temperature sealing properties of most
  elastomers, which are not subject to fracture
  failure modes (FKM is the prime example), depends
  on the high viscosity of the fluid under those
  conditions.

10

• Change Drivers - Current Situation cont.

• Cost/ValueBalance between part cost and warranty
  charges is still heavily weighted towards the
  warranty 's.Problem
• Reluctance to consider lower cost design/material
  options when warranty record is very good.
• Foresighted development of material alternatives
  to meet "crisis" situations.

11

• Change Drivers - Current Situation cont.

• Development Improvements in Specialty
  Polymers Although the introduction of new or
  improved materials can generate changes in
  Shaft Seals' compositions, manufacturing
  technologies, and design, almost all of
  today's examples have been developed in
  response to fabricator and seal user
  demands. Clearly seen by the volume usage
  trends in Shaft Seal materials and by analysis of
  the previously listed "drivers,"
  "state-of-the-art" material preferences can be
  summarized

12
Change Drivers - Current Situation cont.

• Speci alty Polymers Development - Summary

• Increasing use of high temperature capable, base
  resistant, inherently lower swelling, materials
  with acceptable low temperature sealing
  performance. Alone or in combination.
• Specifically growing are Base Resistant
  FKM's Hydrogenated NBR's PTFE
  (Hydrodynamic Lips only)
• Specifically holding share Polyacrylate, ACM's
• Specifically decreasing are Regular
  FKM's Ethylene Acrylic,
  AEM's Regular NBR's
• Other (non-application or material cost driven)
  reasons for polymer usage preferences include
  such considerations as Supply Assurance, HSE,
  and Manufacturability.

13

• Elastomers in O.E. Shaft Seals

Reg. FKM or Bonded PTFE With ACM or HNBR
Engine
Reg. FKM
VMQ or ACM
Valve Stem
Reg. FKM
Reg. Or BRFKM
ACM
AEM,BRFKM or HNBR
BRFKM or HNBR
Transmission
VMQ or ACM
AEM,BRFKM or HNBR
Wheel Axle
BRFKM or HNBR
NBR
NBR
HNBR
HNBR
Steering
NBR
Bearing
NBR
NBR or HNBR
14

• Materials Engineers "Wish" List

• Assuming a "reasonable" cost scenario, some
  breakthroughs would of themselves, significantly
  alter our future material use predictions
• Oil and ultra temperature resistant T.P.E.,
  capable of fabrication in shaft seal composites
• Flouroelastomers with true -40 flexibility
• HNBR with significantly improved resistance to
  high temps (150- 165C) and attack by degraded
  fluids
• AEM, improved swell stability in alternative
  fluids, and durability at high temperatures
• ACM, improved processability/shelf stability and
  low temp. fracture resistance

15

• Conclusion

In the technically challenging area of automotive
shaft seal materials, Chicago Rawhide is well
positioned, through its understanding of the
"drivers" of change, to meet our customers'
current and future needs. We continue to work at
the leading edge of Polymer RD with our supplier
partners and customers to maintain our
"state-of-the-art" knowledge base and develop
competitive advantages.