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The first wave of a potential deluge of thermoplastic bumper beams has hit North American shores, according to GE Plastics officials. New blow molded front beams currently are in production for two General Motors Corp. midsize cars.

The parts, used on the 1997 Chevrolet Malibu and Oldsmobile Cutlass, are among the first blow molded beams on North American passenger cars.

Another new application is a one-piece rear bumper beam that is injection molded in a single step to include energy absorbers and 19 other bumper components. The solitary beam is being rolled out on GM's 1997 Saturn coupe.

In addition, GE Plastics is developing one of the first thermoplastic bumper systems designed for minivans, light trucks and sport-utility vehicles.

GE Plastics and the Plydex division of Magna International Inc. of Markham, Ontario, are shipping its Step Pad rear bumpers to automakers, said bumper systems industry manager Maria Grosser of GE Plastics, based in Pittsfield, Mass.

``These are growing signs of success for thermoplastic bumper systems,'' Grosser said from GE's Southfield, Mich., automotive offices. ``A lot more cars will soon be available with some fairly new thermoplastic designs. It's a huge win for the [plastics] molding community.''

In fact, GE Plastics officials predict that by 2000, as many as 8 million bumper systems — or about 4 million vehicles — will have thermoplastic bumper beams using GE resins. Using current figures, that would represent about one-third of passenger vehicles built in North America.

Today, less than 10 percent of the market worldwide uses plastic bumper beams, said plastics consultant Robert Eller of Robert Eller Associates Inc. in Akron, Ohio. Most of those parts are being made by Japanese automakers in Asia, he said. In North America, the figure is estimated at less than half a million vehicles produced annually.

In contrast, plastic resins — most notably thermoplastic olefins — are used frequently for bumper fascias. The fascias are the cover plates for the structural beam and energy-absorbing materials that comprise the rest of the bumper system.

Blow molded beams recently caught the industry's eye. The relatively new process involves the use of either a polycarbonate/polyester blend, such as GE's Xenoy material, or high density polyethylene. Grosser said the blow molded beams used by GM are 13 pounds lighter than standard beams and eliminate the need to assemble 16 additional parts.

The two GM models, which are expected to generate sales of about 200,000 vehicles this year, already have adopted the lighter-weight, blow molded beams made with Xenoy. In addition, Mazda Motor Corp.'s 1998 Mazda 626 sedan and Subaru-Isuzu Automotive Inc.'s 1999 Outback station wagon and sedan will use blow molded beams made from HDPE, according to industry experts.

Hyundai Motor Co. in Japan also uses blow molded beams on some of its models, according to Grosser.

Carlisle Engineered Products Inc. of Livonia, Mich., is making the blow molded beams for the GM, Mazda and Subaru platforms at its Lapeer, Mich., plant, sources said. Carlisle officials declined comment for this article.

The blow molded beams also present a tooling opportunity for Mach Molds Inc. in Benton Harbor, Mich.

The aluminum tool went through several design iterations since the mold for the GM cars was requested by Carlisle in late 1995, said Mach Molds sales engineer David White.

Meanwhile, GE Plastics is involved in the development of a solitary injection molded beam that offers significant parts reduction, Grosser said.

The molded beam for the Saturn coupe embraces such auxiliary pieces as fascia supports, bolts and brackets and also features energy-absorption materials.

The polycarbonate/polyester beams, which are molded by Nascote Industries Inc. in Nashville, Ill., are being used this year on about 70,000 Saturn vehicles, Grosser said. Officials at Nascote, a division of Conix Corp. in Dearborn, Mich., were unavailable for comment.

In addition, GE is helping develop a Step Pad bumper system for minivans, trucks and sport-utility vehicles.

The rear bumpers, which can double as a loading platform and towing hitch, integrate an energy-absorbing bumper beam with a painted fascia into one piece.

As an added benefit, the injection molded Step Pad can be designed with rounded lines to match current vehicle designs, Grosser said.

Currently, about 6 million minivans, light trucks and sport-utility vehicles are produced in North America, Grosser said. None as yet uses a plastic bumper system except for fascias.

The bumper system should be on the road by the year 2000, Grosser said.