Leading global automobile producer General
Motors has recently introduced two parts (Bumper
fascia and rocker panels) in five of their
new car models. Unlike past usage of paint
replacement film on parts, GM has chosen a
thick thermoformed sheet. With the bumpers,
not only did the companies eliminate the need
to paint a plastic part, they also replaced
an injection-molded part with thermoforming.
The thick-sheet thermoforming reduces the
number of manufacturing steps, which shortens
development time and cuts costs, as the tooling
for thermoforming is less expensive than standard
injection-molding tooling.
GM first used a thermoformed sheet that combined
a thermoplastic polyolefin base with a body-color
film on a stone shield for its Chevrolet SSR
pickup. Soon the roads will see the Chevrolet
HHR wagon's stone shields and the Buick Lucerne
and Cadillac STS-V's thermoformed rocker panels
as well as the GMC Envoy's thermoformed bumper
fascia. GM is targeting specific applications
on each vehicle it has selected for its paint-replacement
project. In the case of the HHR, the company
needed to protect a fender area of the car
where stones from road debris would chip away
the paint on a standard part. GM and its suppliers
had to design a shield that would stand up
to the damage but also precisely mimic the
shape of the vehicle, sitting flush with the
body.
Prior to this technology, the automotive sector
had started switching over to In-mold decoration
(IMD). IMD with formable films is a quick,
efficient and relatively low-cost way to impart
colors and Class-A finishes on injection-molded
plastic automotive parts on standard thermoforming
and injection molding equipment, making it
less capital-intensive than painting stations.
By molding in all requisite features, automobile
OEMs can reduce the number of steps required
to produce finished parts.
Only the future will decide whether this new
development in thick-sheet thermoforming succeeds
and leads to a complete changeover in the
automotive sector.