Plastic Components

GENERAL INFORMATION

With the increasing use of plastic parts in automotive construction (for example, bumpers, fender liners and, in some cases, major body panels), repair of more serious damage to these components is becoming a task for specialists or a matter of replacing the entire component.

Repairing this body panel at a repair shop is not very cost-effective due to the high cost of the equipment and materials required for such a repair.

The technique is based on cutting a groove along the crack line in the plastic using a rotary file fitted in an electric drill. The damaged parts are then welded together using a hot air gun to heat and fuse a plastic filler rod into the groove. Excess plastic is then removed and the entire area is finished to obtain a flat and smooth surface.

It is very important to use a filler rod of the correct plastic type, since body panels may be made from different types of plastic (such as polycarbonate, ABS, polypropylene).

Minor damage (scuffs, small cracks, etc.) can be repaired at a repair shop using a two-component epoxy repair compound. When mixed in equal proportions, this compound is used for body repair in the same way as body filler on metal surfaces. The compound usually hardens in 20–30 minutes and is ready for sanding and painting.

If the owner replaces an entire body panel or repairs it using epoxy compound, they will have a problem finding paint that is compatible with the type of plastic used.

Universal paints cannot be used due to the large number of different types of plastic from which body panels are made. Conventional paints generally will not adhere well enough to plastic or rubber.

However, it is now possible to purchase a plastic finishing kit, which includes a surface pre-treatment agent, a primer, and colored topcoat compounds.

A complete list of instructions for use is usually supplied with the kit, but in general, the method consists of applying the pre-treatment agent to the surface to be treated and then waiting 30 minutes for it to dry.

The primer is then applied and allowed to dry for approximately one hour before the colored topcoat is applied. The result is a body panel painted in the required color, on which the paint adheres firmly to the rubber or plastic surface. Ordinary paint does not offer these advantages.