Plastics vs. Metals in Automobiles

1
Plastics vs. Metals in Automobiles

• Greg Boehm
• Kendall Chapman
• Gordon Clarke II
• Gary Gomlak
• April 10, 2001

2
General Overview

• History / Background
• General Design Characteristics
• Select Parts for Comparision
• Fuel Tanks
• Interior / Exterior
• Cooling and Air Intake Systems

3
History

• History
• Polymers first use in vehicles
• Tires.
• Rubber in bumpers. (1940s)
• Electrical wiring.
• Interior (late 60s 70s)
• Upholstery cushioning.
• Dashboard / Instrument Panels.
• Electronic components and housings.

4
History

• Exterior
• Body panels from composites (fiberglass) on the
  Corvette.
• Bumper fascias on almost all models today.
• Compression molded polyester body panels.
• Highly sophisticated polymers, such as injection
  molded nylons, are now being developed for
  mechanical and operational systems.

5
General Design Characteristics

• Mechanical Strength
• Weight
• Temperature
• Material Cost and Manufacturability
• Coatings Applications
• Recyclability

6
Mechanical Strength

• Temperature
• Plastics making inroads to high temperature
  engine accessory applications.
• Corrosion
• Weight
• Permeability
• Issue in fuel and high pressure systems.

7
Materials Cost

• Biggest barrier to plastic in automobiles.
• Raw material cost.
• Basic polyethylene to specialty plastics.
• Strength and weight to cost ratio.
• Cost in manufacturing.
• Challenge in high end parts.
• Recyclability.

8
Coatings Applications

• Materials and manufacture.
• Economical raw material costs.
• Lower tooling costs.
• Coating Process.
• Greatest expense lies with paint materials and
  their adhesion difficulties with plastics.

9
Introduction to Fuel Tanks

• Terne-coated steel mainstay for automotive for
  automotive gas tanks.
• Drivers for change include
• Legislation
• Permeability
• Weight
• Safety
• Cost

10
Plastic Fuel Tanks

• Since mid 1980s plastic replacing steel fuel
  tanks.
• HDPE is the resin of choice for plastic gas
  tanks.
• Barrier technology enables plastic fuel tank
  manufacturers more stringent emission standards.
• Some see multi-layer tank technology as the
  answer to stricter emission standards

11
Steel Fuel Tanks

• Currently a steel substrate coated with
  zinc-nickel or terne.
• Stainless steel tested but are difficult to form
  without severe breakage. Also very expensive.
• Testing painted galvanneal found it effective for
  resisting corrosion on both sides of the tank.

12
Performance AttributesManufacturability

• Terne plate holds a cost advantage over HDPE.
• Cost not the only driver reliability within the
  total fuel system.
• Plastic tanks need to be chlorinated or
  fluorinated to retard permeation. Can be toxic
  if mishandled.

13
Performance AttributesFeatures and Weight

• Plastics have the ability to meet packaging
  constraints.
• Design engineers have flexibility in the car
  design without worry of fitting the gas tank
• Plastic tanks can boast of weight savings of up
  to 30. New permeability requirements diminish
  weight savings.

14
Performance AttributesSafety and Corrosion

• Ability to meet crash requirements is the key.
• Plastic considered safer because they are
  seamless.
• Plastic are also not a source of sparks. Retard
  heat transfer to the fuel.
• When deformed they have the ability to rebound.
• Thermal properties are an issue in determining
  material.

15
Interior

• Polyurethane foam has long been used due to
  design and economic benefits.
• ABS plastic instrument panels reduce production
  costs and weight of autos.
• Seamless, single units are easier to assemble and
  install.
• Steering wheels made from molded vinyl resins or
  pigmented urethanes.

16
Interior

• HVAC vents and control consoles produced from ABS
  and polypropylene resins.
• Key parameters to all plastics in this area are
• Reduced weight.
• Reduced noise and vibration.
• Reduced manufacturing costs.

17
Exterior

• Materials and manufacture.
• Cost effective.
• Highly filled and cross-linked polyesters.
• Premium mechanical Properties.
• Compression molding process.
• Coating process.
• Unique problems to solve.
• Adhesion problems with paints.
• High cost of coatings and off-line preparation.

18
Cooling and Intake Systems

• Cooling Systems
• Radiator end caps
• Radiator fan
• Water pump
• Air / Fuel Intake Manifolds
• Fuel injectors
• Temperature resistance and cost drivers.

19
Cooling

• Radiator end caps injection molded Nylon
• 30 weight savings.
• Molded into complex shapes to save space.
• High resistance to corrosion and temperatures.
• Water pumps also made of Nylon.
• Withstand high pressures.
• Radiator fans from Nylon.
• Mechanical strength to avoid warping.
• Short molding cycle for Nylon.

20
Air / Fuel Intake Systems

• Air intake manifold
• Nylons again used for its flexibility in design.
• Smooth interior surfaces to allow for better flow
  of air into engine.
• Fuel intakes now emerging with integrated
  injectors, filters and sensors.
• Cost is still a barrier to widespread use.