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MacLean Vehicle Systems Produces First Class A Carbon Fiber Body Panel for Mass Production Vehicle

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The following information comes from a press release published by MacLean Quality Composites, the company that manufactured the 2004 Commemorative Edition Z06 Corvette's carbon fiber hood. This press release is copyright - MacLean Quality Composites, photographs are copyright - General Motors Corporation

MUNDELEIN, IL and TACOMA, WA, May 2, 2003–Working with General Motors and Toray Composites (America) Inc. (TCA), MacLean Vehicle Systems (MVS) has succeeded in developing, qualifying and entering production of a lightweight, structurally stiff carbon fiber hood for GM’s 2004 Chevrolet Corvette Z06 Commemorative Edition. The hoods are supplied to GM’s Bowling Green, Kentucky assembly plant where they will beprocessed identically to current production fiberglass body panels. Between 2,000 and 3,000 Corvettes will be fitted with the carbon fiber hood for the 2004 model year. MVS is the first supplier demonstrating delivery of aerospace quality advanced composites into a traditional automotive assembly environment. The hoods are produced in West Jordan, UT at MacLean Quality Composites, an operating unit of MVS. 

"This application of carbon fiber is a major innovation, marking a significant milestone in performance and value for the industry," says Dave Hill, Vehicle Line Executive and Chief Engineer for the Chevrolet
Corvette. "It helps further celebrate Corvette's racing success, and is a very appropriate addition to the Z06, the Corvette for the extreme performance enthusiast."The carbon fiber hood represents the first time the material has been used as original equipment for a painted exterior panel on a North American-produced vehicle.

 Weighing only 20.5 lbs, the carbon fiber hood is 10.6 lbs. lighter than thestandard fiberglass SMC hood. The painted, class-A outer skin is only 1.2 mm (0.048 inch) thick, similar to stamped sheet metal, and is the thinnest polymer composite skin on a street legal production vehicle. SMC typically runs 2.0 to 2.5 mm thick. The hood is of a unique construction–the exterior skin panel is fabricated from 100 percent carbon fiber/epoxy prepreg, while the inner structure is a hybrid of carbon fiber SMC and low density fiberglass SMC. The finished assembly has passed all GM requirements for strength, stiffness and durability.

For many years, the aerospace industry has relied on advanced carbon fiber composites to achieve maximum structural performance at minimum weight. Such components are typically produced using laborious processes with slow-reacting epoxy resins, and cured under heat and pressure in an autoclave,where cycle times often reach 20 hours or more. At the time of contract award in late 2001, the challenge facing GM, MVS and TCA was to develop a manufacturing system capable of producing thousands of parts per year, suitable for moderate volumes, while keeping the overall investment costs low.

The MVS process relies on cellular manufacturing and a combination of automated and manual techniques. As in aerospace components, an autoclave is used, however, the unidirectional carbon/epoxy prepreg, supplied by TCA, is formulated to fully cure in only 10 minutes at 300ºF. This unidirectional epoxy prepreg is a proprietary formulation of G83C quick cure resin and Torayca®T600SC standard modulus carbon fiber. The P3831C prepreg was specially developed for GM and meets the stringent structural design and class-A surface finish requirements of the Corvette hood. It also withstands the high temperatures of the prime and paint ovens.

The prepreg is automatically cut into patterns and oriented in multiple directions to achieve balanced strength and stiffness properties. A significant challenge for MVS was the development of a mold release compatible with existing GM power wash and approved paint systems without the need to scuff sand or solvent wipe the molded components. To achieve the 2004 model year volumes and provide tooling durable enough for years of aftermarket production, Invar, a nickel/iron alloy was selected for the molds. Following cure, the hood outer skins are removed from the mold, automatically routed, and urethane adhesive robotically applied. The outer skins are bonded to the compression molded inner panels and a primer applied prior to delivery to Bowling Green.

The hood is believed to be the highest production volume of a single carbon fiber component using aerospace autoclave technology and the first use of Invar tooling for serial automobile components.“We expect this project is the first of many automotive applications for our carbon fiber technology, from body panels to structural components,”emphasizes Jeff Keller, VP and General Manager, Plastics and Composites for MVS.

MacLean Vehicle Systems is a wholly owned subsidiary of MacLean-Fogg Company. MacLean-Fogg is a privately heldmanufacturing company, based in suburban Chicago, employing about 2000 people in 24 facilities in eight states and six countries. MacLean-Fogg produces engineered products and component parts for the automotive, transportation equipment, general industrial, electrical equipment and telecommunications markets worldwide.

Toray Composites (America), Inc. is a wholly owned subsidiary of Toray Industries, Inc., a $9 Billion publicly traded company founded in 1926 and headquartered in Tokyo, Japan. The P3831C prepreg material used in the GM Hood program is produced in TCA’s modern plant located in Tacoma, WA. This facility was originally built to supply primary structure materials to Boeing for the 777 aircraft empennage. However, since its establishment in 1994, TCA has expanded its business into the recreation, industrial and the growing automotive markets for high performance composite materials and is registered with BSI as being certified to ISO 9001 and AS9100 quality systems. TCA is one of a number of companies that comprise Toray’s Advanced Composite Materials Division, a core business unit that encompasses carbon fiber, prepreg, and composite structures. As the world’s largest manufacturer of carbon fiber, with production facilities in the United States, France, and Japan, Toray has over 33 years of experience in manufacturing carbon fiber and offers a broad product line of standard modulus, intermediate modulus, and high modulus carbon fiber.

MacLean Quality Composites 3392 West 8600 South West Jordan, UT 84088


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