The soon-to-be-introduced Plymouth Prowler, touted as the super-sleek roadster with the all-aluminum body, has a dirty little secret.
As much as 30 percent of the Prowler's body actually is made from sheet molding compound, according to Chrysler Corp. officials.
The change to SMC was made during the design process to help the vehicle maintain its lightweight design and save production costs.
``In some cases, aluminum parts were more expensive to produce,'' said materials engineer Nipponi Rao of Chrysler's Conner Avenue assembly plant in Detroit, where the Prowler will be assembled. ``Parts that required a lot of metal stampings were molded in one or two steps with SMC,'' he said.
While Prowler production will be low-volume, the use of SMC gives a high-visibility push to an industry undergoing a bit of a shakeout. The first 1950s-style show cars are expected to come rumbling off the assembly line around June 1, accompanied by a bevy of media and public attention.
The car will contain a number of innovative structural uses for the thermoset SMC composite, all of which were developed during the design process and some of which could make their way to other vehicles.
In addition, the use of SMC by Chrysler continues that company's recent growth spiral in SMC use.
In 1997, the company will use 289.1 million pounds of SMC on passenger cars, according to figures from the Troy, Mich.-based SMC Automotive Alliance. Of that number, 59.2 million pounds, or more than a fifth of Chrysler's total SMC use, will be on the Prowler.
The news puts a shiny gloss on an industry undergoing change. Two major companies that make SMC components — Cincinnati-based Eagle-Picher Industries Inc. and Goodyear Tire & Rubber Co. of Akron, Ohio— said earlier this year that they were leaving the business and selling their plants. Both companies have not yet completed the sale of those plants.
In addition, the SMC industry suffered a blow last year when General Motors Corp. converted its minivan program from SMC body panels to stamped sheet metal.
The use of SMC in the Prowler paves a path for more optimism. The convertible will use compression molded SMC parts for its front fender, front and rear quarter panels, rear valance, fuel filler door and windshield surround.
All the SMC components will be manufactured by Budd Co. of Troy.
Chrysler's Detroit plant, which expects to assemble 20 Prowlers a day, will produce about 2,000 of them this year and about 4,800 roadsters each year after that.
Budd is banking on the use of SMC in the Prowler to show off the material's possibilities.
``The Prowler is a great demonstration of these applications for exterior body panels,'' said Michael Dorney, manager of North American sales and marketing for Budd. ``It's a big market for us, especially in vehicles of under 100,000 units. We think we have a real competitive advantage with the material.''
One of the most unusual parts on the Prowler is the window surround, a structural part that holds the window in place. The part was a last-minute addition to the Prowler program in April 1996, after other aluminum and metal materials failed to provide the styling, low cost and light weight needed, Rao said.
The SMC surround consists of two pieces molded together with a tongue-and-groove joint to contain the window and wiring harness. Traditional surround systems contain 14 metal stampings spot-welded together; the SMC part contains only two pieces, according to Budd's Prowler program manager, Michael Shinedling.
The small part count helped Chrysler achieve another design goal: to give the body a seamless flow without the intrusion of cut lines dividing body panels, Shinedling said.
The hot rod's SMC-molded quarter panels give the car the same seamless look.
The panels meet near the front of the car to create only one line, as opposed to several seam lines produced by aluminum stampings. At least four metal pieces would be needed to create the same parts, according to Shinedling.
The panels — the 5-foot-long front panel and 8-foot-long rear panel — are made with Budd's Hi-Flex compound for increased flexibility to avoid denting. The parts, the first body panels using the Hi-Flex material, do not shrink or expand dramatically from heat during the painting process.
The front fender and rear valance are similar in design. They also allow molded-in embossing of the Prowler name on the car's rear flank.
Budd's 250,000-square-foot Kendallville, Ind., plant began production of the SMC parts this month. From there, the parts are shipped in different directions. The rear quarter panel and rear valance are sent by Budd for assembly at a Norwalk, Ohio, plant owned by Mayflower Vehicle Systems plc, which provides the Prowler's aluminum body shell.
Meanwhile, the front fender, front quarter panel and fuel door are shipped to a Detroit plant owned by MSX International Inc. of Auburn Hills, Mich. The parts, plus the Mayflower body shell, are painted at the Detroit plant in the Prowler's signature purple color.
The window surround, which is painted in black by an outside supplier, is shipped directly from Budd's Kendallville plant to the Chrysler facility.
The Budd plant uses 12 compression molding presses that have clamping forces of 330-4,800 tons.
The plant also produces a variety of SMC parts for other applications.
Chrysler uses SMC on several other models, including a deck lid on the new Sebring convertible; the hood and radiator support for the Dodge Viper GTS coupe; a structural window cowl for several models; and a new pigmented SMC for the roof assembly on the Jeep Wrangler.