While most of the attention in the Chevy Volt was focused on the electric battery and power train, several close-to-commercialization materials’ technologies shown in the concept car provide significant other environmental and design benefits.
The headliner is the new thermoplastic composite hoods and doors, which will go on to a production model next year, but not of a GM car. GE Plastics, the chief technology developer on all of the concepts shown on the Volt, has several partners in the process, most of whom are confidential. GE Plastics is considering three different processes, including one using electromagnetic induction heating of tools developed by a French company called RocTool. The advantage: speed. The process heats a tool section that is just 0.2 mm deep. One of the licensees is Azdel, which is a joint venture of GE Plastics and PPG Industries, which has been testing the forming of SuperLite glass mats made with polypropylene and Xenoy polycarbonate/PBT composites.
The key issue is the ability of the process to achieve a high-gloss Class A finish for automotive surfaces. GE Plastics has tested the process on a Krauss-Maffei injection and compression machine at its Plastics Polymer Processing Development Center in Pittsfield, MA, with good results, according to Robert Butterfield, global market director for design innovation for the GE Plastics automotive business. Butterfield says the process produces parts with comparable stiffness to hoods made from steel or thermoset sheet molding compound, bus they weigh less than half as much.
Azdel hopes to commercialize conductive (for electrostatic painting) and nonconductive grades later this year. Butterfield says the best option, long-term, may be a composite covered with a high-gloss film.
Regenerated Bottle Scrap
The materials used in the composite can be made from regenerated plastic bottle scrap. In a proprietary GE Plastics process, bottles are reduced to their chemical constituents, which are then recovered for the manufacture of Xenoy iQ resins, which were first announced last July. As a result, there is no sacrifice in physical properties of the material, as can be the case with recycle resins. Denso, a Tier One automotive supplier, based in Kariya, Japan, has been validating applications.
Another materials innovation in the Volt creates an interior that makes significant use of ambient light.
The Volt’s roof, side glass and beltline are made of transparent, glazed polycarbonatethat is said to provide the scratch resistance and gloss surface of glass. The windshield is the only glass in the Volt. “The transparent upper roof provides the Volt with more natural light than most other vehicles,” comments Wade Bryant, GM design director. “It’s very distinctive and appealing.”
There is also a big change on the wire coating used in the Volt. Flexible Noryl replaces polyvinyl chloride for environmental and weight-saving reasons. “The average car has over a mile of wiring, which is typically made with PVC coating,” says Butterfield. “PVC is not great for the environment because it has halogen and gives off dioxins when it burns.” The Noryl coating is also smaller in diameter than the PVC, making it easier for engineers to manipulate wires in the car. The main developmental partner for the Flexible Noryl wiring is Delphi Automotive.
Explore our exclusive Chevy Volt coverage for more behind-the-scenes engineering information.
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