Thin-wall bumper fascias save cost, weight

Detroit--For its 1998 LH platform cars, Chrysler wanted a redesign that would differentiate the Dodge Intrepid from the Chrysler Concorde. One component that set the Intrepid apart from its "kissing cousin" is its bumper fascias.

Integral to the new look is a new material developed by Solvay Engineered Polymers (formerly D&S Plastics International), Auburn Hills, MI. The material, SEQUEL(reg) 1440 engineered polyolefin, was specifically designed to reduce wall thicknesses in applications intended for thermoplastic olefins (TPOs).

The 1998 Intrepid program includes three fascia tools: two front fascias--one for the base model and one for the ES upgrade--and a rear fascia common to both models. The rear fascia and the base-level front fascia are fully painted, as are dark-color versions of the ES front. Four light colors of the ES front, however, are partially painted, with a blackout panel of bare substrate between the fog lamps.

Choosing the SEQUEL 1440 polyolefin over a conventional TPO, or a competing RIM process, enabled Chrysler to cut costs in several areas. Although all-new in design, the 1998 front fascias are about the same size as their 1997 counterparts molded in a TPO. However, the new fascia assemblies weigh six lbs less than the previous iteration, with most of the weight loss attributed to the thin-wall fascia skin. Victor Liu, engineering manager at the molder--the Plydex division of Magna's Decomma Exterior Systems--estimates the savings to Chrysler over a run of 200,000 parts at more the $1 million.

The rear fascia is "the largest fascia anybody in our company makes," notes Bob Stewart, supervisor of exterior systems for Chrysler's large-platforms. Still, it is much lighter. It also uses less material than had it been molded with a 3.5 mm wall section typical for traditional TPOs. In fact, wall thickness on the rear fascia has shrunk to 2.9 mm, while the nominal thickness for the front fascias now measures a slim 2.7 mm.

"With the higher flex modulus of the material, we can meet the stiffness requirements at the thinner wall stock," notes Chrysler Senior Engineer Dave Gasko. "Even with the thinner part, we get the same feel as the previous fascias."

"We picked this material, because it exhibited better surface durability," Stewart adds.