Plastics Used on the Exterior of Vehicle

Polymers are used in many areas on the exterior of the vehicle. These include a variety of components such as moldings, trim, appliques, body panels, doors and exterior mirror housings, front and rear fascia, and lighting systems and pickup beds. Door seals can be made from thermoplastic elastomers. These materials must meet performance, durability, weatherability, and styling criteria.

Moldings and Trim Exterior plastic moldings are a fairly recent addition to the automobile. The move toward reduced mass has driven the trend for the original all-steel body panels to be made increasingly lighter. Plastics offer flexibility of shape, relatively lower energy to form, and are significantly lighter in weight. Plastic trim started replacing metal trim in the early 1980s because it eliminated the corrosion problem and reduced weight [3]. The addition of plastic moldings also helps to maintain dent resistance on the body panels, which increased customer appeal while allowing the panels to be lighter weight. Typical materials for this application are PVC, ionomer, and TPO.

Plastics allow innovative styling while minimizing mass and also allow covered joints and attachments. Styling trends have led to shapes in modern vehicles that are difficult or even impossible to create in metal.

Body Panels Plastics can help considerably reduce the mass of body panels while providing better durability, damage resistance, and corrosion resistance. Their first application in body panels was in 1953 [1]. General Motors introduced the Corvette with a fiber-reinforced thermoset plastic body (see Fig. 17.4). At almost the same time, Kaiser introduced a reinforced-plastic body on a sports car. Since then polymers have been used for fenders, hoods, trunk lids, roofs, doors, quarter panels, and lift gates.

Fenders Fenders are particularly good candidates for polymer use. A PPO/nylon blend (presently used in Saturn models) is one material that has been shown to

Figure 17.4. 1953 Corvette.

Mass of typical fenders (kg)*

Mass of typical fenders (kg)*

Saturn SL2 Honda Accord Dodge Neon Ford Focus PPO/Nylon Steel Steel Steel

VW Passat Honda Insight Steel Plastic

Figure 17.5. Mass of typical fenders (based on General Motors benchmarking disassembly data).

Saturn SL2 Honda Accord Dodge Neon Ford Focus PPO/Nylon Steel Steel Steel

VW Passat Honda Insight Steel Plastic

Figure 17.5. Mass of typical fenders (based on General Motors benchmarking disassembly data).

work well in this application. RIM urethane also works for fenders and was used on the 2000 Corvette and the 1996 GM APV minivan. The Honda Insight also used a polymeric fender. Figure 17.5 shows the comparative masses of some steel and polymeric fenders.

Doors Doors are an area where efforts to reduce the mass is limited by structural load criteria. Several vehicles have been designed with doors made of structural polymers to reduce the overall mass. The doors in a Saturn are a PC/ABS blend while the GM APV minivans used SMC doors. The GM EV1 design was optimized for mass and performance. The doors in the EV1 are a

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