High-Performance Composites

MAR 2013

High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.

Issue link: https://hpc.epubxp.com/i/110847

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Page 44 of 67

you move from a few thousand to tens of thousands of cars annually, autoclave cure becomes too slow and expensive — hence the scramble to find faster-curing resins and to develop new out-of-autoclave process derivatives. "Corvette has pioneered the use of innovative, lightweight materials since its introduction in 1953 as the industry's first production car with a fiberglass body," notes Corvette chief engineer Tadge Juechter. "The new Stingray ... will continue that tradition by becoming the industry leader in high-volume use of carbon fiber. For the standard Stingray coupé, we'll use 18 lb [8.2 kg] of carbon fiber just on the roof and hood. Based on last year's sales of 14,132 units, Corvette will account for at least 238,000 lb [107,955 kg] of carbon fiber annually — and we expect to sell significantly more Corvette Stingrays than that." Notably, the reborn Stingray and the pressure-press for its roof and hood were developed during the darkest days of the post-2008 recession. GM was in bankruptcy. Although Plasan had supplied autoclave-cured CFRP body panels for Corvettes since 2006, its new owners, who had purchased the automotive side of Vermont Composites Inc., were wondering why on earth they'd decided to diversify from their core defense business into the capricious world of cars. GM persevered, even renovating the Corvette Bowling Green, Ohio, assembly plant. Likewise, Plasan's owners invested "tens of millions of dollars" to develop the new molding process, build a new technical center in Wixom, Mich., and then build a new production facility in Walker, Mich. Hood and roof production will occupy only half of the facility's available 170,000 ft2/15,794m2 manufacturing space, leaving room for growth. Gary Lownsdale, Plasan's chief technology officer and coinventor of the process, sees the Walker facility's mission as nothing less than an opportunity "to bring CFRP into mass production for cars." Minimizing the makeover variables Although the new Stingray panels are similar in size to those used on the previous ZR1, they have different contours. Plasan's president, James Staargaard says the company simplified approvals and minimized the number of variables during the changeover process by using the same resin, structural adhesive, clearcoat chemistry and laminate technology. Plasan did, however, make one significant change: the company is now hot bonding the hood's inner and outer panels. The adhesive is heated while it is robotically applied, and parts are fixtured for cure at ambient temperature. This is 72 percent faster than the oven-cure method used on the ZR1. The pressure presses are fitted with 6-ft by 6-ft (1.8m by 1.8m) platens. Lownsdale says the large hood inner and outer panels and smaller roof can be molded on the same size press. Plasan uses single-sided, thin-shell nickel vapor deposition (NVD) tools from Weber Manufacturing Technologies Inc. (Midland, Ontario, Canada). A reusable bladder/canopy closes off the part's B-side. Plasan produces the bladder in-house using silicone heat-cured rubber (HCR) from an undisclosed source. The bladder's smooth surface eliminates wrinkles, read-through and other blemishes typical of vacuum bag. Each tool features built-in oil-type heating/cooling elements and, according to Plasan, provides precise thermodynamic control without inductive mold heating. When failure is not an option Temperature Measurement for Composites AccuClave® Cost Effective • Zero Failure • Leak Proof Online Traceability • Save Time During Autoclave Layup Load and Unload • Global Distribution TE Wire & Cable LLC Since 1941 888-4TE-WIRE (888-483-9473) International (001) 201-845-9400 www.tewire.com • sales@tewire.com A Berkshire Hathaway Company march 2013 | 43

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