Ingenuity in automotive plastics for 1998


This year's SPE Automotive Division awards for design and processing innovation gave the Big Three a chance to say, "Take a look at us now." Criticized in the past for moving too slowly toward incorporating new technology into vehicle design, these OEMs have truly taken giant steps toward the fast lane. Speaking at the 28th annual awards dinner in November, Division chairperson Bonnie Bennyhoff explained, "Plastics allow design possibilities to increase exponentially, and many engineers today are developing an almost artistic sense in creating plastic parts that can improve vehicle design."

From a group of 27 finalists, judges chose award winners in seven categories. Five of the awards went to injection molded applications ranging from fans to fully integrated air induction modules. In every case, these breakthrough projects stemmed from a concerted and concurrent effort between OEM designers, material suppliers, molders, and moldmakers.

Environment Award

Visteon Automotive Systems was the first to implement a recycling program for TPO bumper fascia scrap. Currently, the program involves taking post-industrial, painted bumpers from both Milan and Utica plants and recycling them for use in new TPO bumpers. According to Tony Brooks, materials engineer for Visteon, the plants mold bumpers with Solvay's D-161B virgin resin. "Once they are painted, if the parts are blemished, we send them to American Commodities Inc. (ACI), which invented a process for removing paint and coatings from TPO," Brooks says. The process restores physical and mechanical properties, making the recyclate identical in characteristic to the virgin resin. The Milan and Utica plants then blend 20 percent of ACI's recycled TPO with virgin resin at the press using proportion feeder blenders. "In effect, Visteon is now its own materials supplier," he adds.

Recycled TPO costs somewhat less than virgin, on average, and projected savings on over 1 million lb recovered this year are significant, according to Brooks. Eliminating landfill disposal costs for post-industrial scrap also adds to the savings.

Now that Visteon has proven the process works, it is partnering with ACI to begin a post-consumer program this month. "ACI will collect and clean old bumpers, which they will purchase for a set price, then remove paint, grind up the TPO, and add whatever is necessary to bring the material up to spec," says Brooks.

Chassis Awards

Two finalists in this category shared the honors this year, as judges could not break a tie-a steering column support bracket for the '99 Chrysler NS van and a new GM truck clutch pedal assembly.

Designing structural ribs into a plastic steering column support bracket paid off handsomely on Chrysler's 1998-1/2 Caravan/Voyager minivan platform, which is projected at volumes of 750,000 units annually. InMold Corp., a Detroit-area molder, and DuPont Automotive partnered with the OEM to produce the first bracket ever to replace magnesium. Eight bolts are insert-molded into the part to eliminate secondary fastener attachments with weight reduction reaching 10 percent and projected cost savings of $3 million. In addition, the OEM saved $150,000 in tooling costs up front.

Dupont supplied a 33 percent glass-filled nylon 6/6 (Zytel 70G33 HS1L) and technical support on this project. "What makes it unusual in terms of plastics replacing metal," says DuPont's Greg Corda, "is that the nylon part actually improved crash testing ratings for the steering column." Chrysler's Dennis Stedman, supervisor of minivan body-in-white engineering, envisions further part integration in the future, including a thermoplastic brake and accelerator pedal box.

Also a winner in this category, the GM T800 pickup truck's clutch pedal and bracket assembly replaced stamped steel parts to save 65 percent of the weight at an equivalent per-assembly cost. Assembly cost, however, is greatly reduced, thanks to collapsible hinge pins that permit snap assembly of pedal and bracket. A first in North America, the nylon 6 (Ultramid from BASF) part is molded by Florida Production Engineering on tools made by Cumsa (Spain).

To save time during installation, the assembly contains a snap-fit receptacle for quick connection between the slave cylinder push rod and pedal. The snaps eliminate the need for an assembly worker to climb into the driver's cockpit and make the necessary connection with traditional pins. Workers merely depress the pedal when it is installed on the line, according to GM design engineer James Walden.

The clutch pedal features hexagonal hinge pins, which eliminate the need for the lash bushings and fasteners that formerly had to be applied on the assembly line. In addition, the use of molded plastic makes it possible to have a larger pedal offset for better packaging flexibility, Walden notes.

Powertrain Award

Visteon strikes again with this cost-and-weight-saving integrated air-induction module for the '99 Ford F350 light trucks. Designed for the 7.4-liter turbo diesel engine, the module was developed and commercialized by Visteon and is projected to save Ford more than $2 million annually in manufacturing and assembly costs. By the way, it also boosts engine performance for the mammoth turbo diesel described above. Less cost, less weight, and better performance-where are the tradeoffs? There are none, says Visteon's David Setsuda.

Visteon molds the 9-lb module in four parts-a battery tray and cover and air cleaner tray and cover-at its Sandusky, OH plant. All parts except the air cleaner cover use a polypropylene (Gapex from Ferro Corp.). Material for the air cleaner cover is post-consumer nylon from Wellman. Toolmaker Michael Tool also collaborated to help reduce the development cycle to an amazing 12 months.

While saving 2.9 lb per vehicle, the module incorporates several functions: an air cleaner tray and cover, battery tray and cover, a resonator, and a clean air tube. It also passes clean air by the battery to keep it cool, extending battery life without separate ductwork.

Hall of Fame Award

This is a special category created to honor cutting-edge designs that have withstood the test of time, according to SPE. This year, judges presented the award to French automaker PSA for the first engine fan molded from nylon (DuPont Zytel) and introduced on the Citroen DS19 sedan at the 1955 Paris Auto Show. The integral fan design saved money by replacing 10 stamped metal parts and also debuted thread-forming screws as a method for attaching thermoplastics. Believe it or not, variations of this fan design are used on nearly every car in the world today. Why? It is more aerodynamic than metal, which improves engine efficiency, reduces noise, and lowers part fatigue failures.

More Winners

On the theory that a rising tide lifts all boats, we'd like to acknowledge award winners using plastics processes other than IM. Taking the Grand Prize and Exterior category awards was a compression-molded bumper beam that replaced RF steel in the '99 Mitsubishi Galant. The I-beam used Azdel material from GE Plastics. For the Body Interior, kudos to a double-walled, blow-molded PP load floor and spare tire cover for the '99 Jeep Cherokee. In the process category, the award went to compression molded door rails for the Jeep TJ, made possible by a continuous extrusion process from Composite Products Inc. that disperses long glass fibers without breaking them. And for Materials, the winners were Textron Automotive and Bayer Corp., who jointly developed an aliphatic TPU for cast-molding onto instrument panels in the Chrysler Concorde LHS and 300M models.

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