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The SMART for four roof

The SMART for four roof shown here may be the thin end of the wedge when it comes to replacing painted exterior body panels with film. It uses GE Advanced Materials' Lexan SLX film over a substrate of polyurethane long fiber injection (PULFI) to obtain a high-gloss appearance good enough to meet the standard of "glass optic." GE's Venkatakrishnan Umamaheswaran says his company is concentrating on PULFI for all horizontal applications and on Xenoy polybutylene terephthalate / polycarbonate (PBT/PC) for vertical panels, since the adhesion layer needed to bond the film to those substrates is fully developed.

Who Needs Paint?

Automakers have long dreamed of building assembly plants that don't need expensive, emissions-intensive paint shops. With plastic film technologies maturing quickly that dream may soon be within reach.

The auto industry may be on the verge of a paintless future. "There is great interest in paint-free technology at the highest possible levels in the car companies," says Venkatakrishnan Umamaheswaran, global industry manager, automotive exteriors, GE Advanced Materials (Pittsfield, MA), "The momentum behind going paintless has never been greater." Why? Paint shops are really nothing but trouble. They cost $600 million and up to build, take up a tremendous amount of floorspace, and are the source of most of the heavily regulated emissions produced by an assembly plant. Add to that the fact that painting is by far the most time-consuming single plant activity, and that the process is so sensitive to contamination that even paint line workers' deodorant choices are a source of concern, and you can see why executives must dream of unloading these nettlesome departments. But good paint jobs sell vehicles, and up until now painting has been the only way to get an acceptable exterior finish. That's changing. In-mold decoration using plastic film is slowly migrating from automotive interiors, where it is used to mimic woodgrains and metallic surfaces, to vehicle exteriors, where it is beginning to offer an alternative to paint.

Film Buffs. Exterior body panels made of plastic and covered with film offer a lot of advantages over traditional stamped steel and paint. First, there are the plusses of the plastic substrate itself, which can be half the weight of steel and can be molded into shapes that defy a stamping press. (Both key drivers as automakers look to create more radical designs while saving weight to achieve better fuel economy.) Then there is appearance. Using film eliminates deformities like orange peel that have always bedeviled paint shops, and therefore provides what proponents say is a superior finish. Umamaheswaran is blunt: "Film makes paint look bad."

But by far the biggest argument for going with film is the investment saving associated with not building a paint shop in the first place. "The cost of the film right now is above what it would take to justify going to film versus paint," says Jim Drouillard, executive vice president, Global R&D, Decoma International Inc. He adds, "But that's if you look at it part-to-part based on current vehicles. If you look at the big picture in which you don't need a paint plant, then the cost might be significantly less, even if you have to pay a premium for the film." He continues: "You could almost be at the point where you have a shopping mall building that only does final assembly, and you receive filmed parts from someone else's facility." Drouillard explains that this scenario is particularly appealing for car companies that want to set up shop in developing countries, but don't want to invest $1-billion plus in what could turn out to be a volatile market. Also, according to Drouillard, going paintless can save costs on plastic substrate materials that would help to balance out the higher cost of film. "Today's paint systems require such high-heat that there are very few plastic materials you can use to put into the paint line and those are expensive," he says. "If you eliminate the paint line, you can use much less-expensive materials."

Faster Cycle Times. Using film also helps to dilute a traditional drawback of molded panels: lengthy cycle times. Though molding equipment still cannot equal the speed of a stamping press, when you combine the total cycle time for stamping and painting a steel panel versus molding a panel with film, Umamaheswaran claims the plastic solution is already competitive in terms of both cycle time and cost. To help prove that assertion and convince OEMs and tier one suppliers that filmed plastic exterior panels are viable options, GE Advanced Materials constructed a $2-million in-mold decoration production cell in Pittsfield, Massachusetts. "The cell demonstrates what we can do in technical areas like scrap rate and cycle time," explains Umamaheswaran, "and proves we can create a world-class manufacturing facility in a clean room environment for the film itself that gets it to the quality level that car companies expect." The cell uses a traditional in-mold decoration process where the film, which comes in rolls or sheets, is thermoformed into the geometry of a part and then backmolded via injection or compression molding. Umamaheswaran says that over time the process has been refined to compress total cycle times and automate and sequence steps to avoid bottlenecks. Droulliard echoes that, saying that Decoma has made steady progress in reducing cycle times by combining both compression and injection molding techniques. Still, he acknowledges, "We've been working on this for years, but we have to have a quantum leap, a significant event."

Paintless Future? Mutsuo Aoki, global programs director, body panels and glazing, GE Advanced Materials, thinks that significant event has already occurred in the form of the filmed plastic roofs used on the smart roadster and forfour models: "The smart roof has created momentum in the marketplace because it proved that it could be done with larger body panels." He adds, "In the next two to three years we will be in a phase where we will be introducing more and more examples into the market, and then once everyone sees it in production things will go rather quickly. After that we hope to see more explosive growth." Umamaheswaran is more specific: "We're working with eight car companies globally, and each of them is in various stages of validation. Three programs are identified to launch within the next three years. Film is moving to the next step." Which begs the question: when can we expect to see the first paintless vehicles? Sooner than you might think. "We hope to see an all-plastic vehicle using film before 2010," says Aoki.