IMM Focus: Automotive: Automotive awards target technical leaps

The 2003 winners in automotive plastics design and application prove that innovation and creativity are alive and very well in the car and truck world.

When the Society of Plastics Engineers (SPE) Automotive Div. held its Automotive Innovation Awards program in November, it became clear that plastics technology aimed at the automotive market is continuing to evolve. Did you think there was nothing new about injection molded air intake manifolds? The power train winner will make you think again. Wondering when horizontal plastic body panels will start showing up on production vehicles? Check out the grand award winner. SPE’s bevy of plastic “beauties” emphasizes the increasing role plastics play in the automotive market. The envelope please . . .

Grand Award WinnerIt’s hard to believe the two-part roof module on the 2004 Smart Roadster isn’t painted. The Class A surface, high gloss, and depth of color are courtesy of three-layer, coextruded Lexan SLX film (GE Plastics) applied to a glass-filled polyurethane. SPE recognized the new roof module from Smart GmbH, a business unit of DaimlerChrysler, with the Grand Award as well as the award in the Body Exterior category. Molder Arvin Meritor Light Vehicle Systems, headquartered in Detroit, produces the targa top halves at its facilities in Gifhorn, Germany.

According to V. Umamaheswaran, global industry manager for GE Plastics Automotive, the substrate for the roof module is formed via polyurethane long-fiber injection, a technology prevalent in Europe. The thermoset material is reaction injection molded. “First, the film is thermoformed, and this application represents the first time a Class A thermoforming tool was created,” he says. “The film is then inserted into the open tool, where a robot sprays a mixture of PU and glass fibers. After the mold closes, the part cures for about 2 minutes in the horizontal clamp press.”

By combining the PC film and PU substrate, designers were able to meet the structural requirements for horizontal body panels, which are more stringent than those for vertical versions. The film also achieves a Class A surface, a feat that is difficult for glass-filled resin alone. At 5 kg each, the roof halves are more than 50% lighter than the previous painted steel versions.

Unlike other SLX film applications based on two-layer films, the roof module makes use of a tri-layer version. “The third layer has a modified formula, and acts as a tie layer to increase adhesion to the polyurethane,” Umamaheswaran says. “Tie layers enable SLX film to adhere to different surfaces, both thermoplastic and thermoset.”

Avoiding the cost of additional paint processes is a major driver toward using this technology, according to John Carrington, GE Plastics Automotive global marketing director. “More OEMs are focusing on color contrast with a different color roof or hood, and these are ideal applications for SLX because it doesn’t require any added painting process. Capital expenses saved include $40 million in annual maintenance, plus $400 million to $500 million to install a full paint line.” He also notes that VOC emissions are not an issue with the paintless method.

While Smart GmbH is considering this process for future vehicles (it plans to enter the U.S. market in 2006), it still produces vertical body panels via injection molding and painting. Vertical body panels on the Roadster are molded from PC/PBT (Xenoy, GE Plastics) and then painted to color match with the hood and trunk, which are SMC parts. The vehicle also contains molded-in-color Xenoy trim parts that wrap around the body and define the headlights, featuring a sparkle effect from GE’s Visualfx technology.

The Roadster is a limited-build vehicle, with an estimated 10,000 units annually. Vertical body panels for this vehicle are being produced by Peguform in the Hambach, France facility run by Smart, while Dynamit Nobel, also located at this campus, continues to mold the panels for the coupe version.

Body Interior WinnerPolypropylene has become ubiquitous in car interiors. At the November awards, PP struck again, this time as a replacement for filled styrene maleic anhydride (SMA) in an instrument panel lower carrier for 2004 GMT 800 full-size trucks. Delphi, as both system supplier and injection molder, was able to make the switch to homopolymer PP without any changes to tooling and only minor changes to automated assembly equipment.

Key objectives for this project were to obtain the same modulus, creep resistance, and tool shrinkage of SMA with a lower-cost resin. Using the homopolymer PP from supplier Spartech-Polycom, material cost was reduced by 43% while physical properties necessary to meet part performance requirements were achieved. Linear shrink was also maintained so that the 10 former SMA tools could be used with no rework. Another plus for commodity-resin PP: Lower-frequency response reduces the risk of buzz, squeak, and rattle.

Materials Cowinners

A two-way tie brought two winners in this category. The first, an underbody shield for 2004 BMW 5 Series vehicles, relies on thermoformed composite sheet to reduce weight by 30% (or 4 kg per vehicle) over similar glass-reinforced PP versions, whether compression or injection molded. Produced by Seeber with material from Quadrant Plastic Composites, the panels feature variable stiffness and density values without added mass or material volume. The sheet itself is composed of mixed fiber fleece laminated with PP film.

Also awarded in this category was a load floor for the 2003 midyear Renault Megane series of vehicles. It was compression molded by InoPlastic Omnium from SMC thermoplastic. Material development at supplier MCR Composite focused on high-volume (1200 parts/day) production, with a part-to-part cycle of 60 seconds.

Power Train Winner

Plastic air intake manifolds have come a long way in the 30-plus years they’ve been used on production vehicles. This category winner, the world’s first continuously variable intake manifold, appears on BMW 5, 6, X5, and 7 Series cars. An injection molded thermoset material (Duroplast glass-fiber phenolic from Vyncolit NV) was able to handle the complex geometries, stringent tolerances, and dimensional stability under temperature and load conditions. The manifold is supplied by German supplier Pierburg GmbH, and molded by Baumgarten GmbH.According to the SPE, this manifold uses the principle of continuously variable runners for the first time. Previous manifolds used flaps made out of thermoplastic to achieve variable operation, but did not meet engine performance goals. This application’s fully variable intake system allowed BMW to realize its goals for torque and power output by adapting port lengths to desired characteristics. Weight savings over aluminum are about 25%.

Process/Enabling Technologies Winner

A multiple-process application garnered this award using High Performance Integration (HPI) technology for the first time in North America. HPI produces a single-piece instrument panel with a soft foam-in-place upper and a hard molded-in-color lower half and integrated components. Reduced tooling, manufacturing, and assembly costs trimmed $15/vehicle from the 2003 Mazda 6 (North American version).

To make the IP, supplier and processor Intertec Systems used standard equipment. HPI combines PVC slush molding for the skin, injection molding for the IP retainer, and foam-in-place processing. A patented mechanism in the skin/foaming tool enables accurate registration of the IP skin (PVC from PolyOne) directly onto the rigid TPO substrate (Hostacom from Basell). The TPO material was optimized for molded-in color and scratch resistance, eliminating the need for paint. Integrated components included the defroster grille, center trim panel, and end panel for reduced buzz, squeak, and rattle issues.