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While most NASCAR teams form those sheet metal panels for their cars that are invariably dented, ripped, or otherwise destroyed on a weekly basis by hand (imagine your hand-formed work getting mangled by Tony Stewart!), Hendrick Motorsports (Charlotte, NC) is using a different approach in its Metal Shaping Dept. Says Ralph Brawley, manager of that department, "In our business, we must remain flexible. Body panel designs change continually and we have to be ready to change with them." So they're using a castable polyurethane to produce diesets for some 300 replacement parts for the cars.
It takes about a week to produce a dieset with the RenCast 6470 polyurethane from the RenShape Solutions Group of Huntsman Advanced Materials. According to Brawley, "Our RenCast polyurethane dies are strong enough to withstand the 400 tons of pressure used to form large panels like C-posts." C-posts are used for body side support. Brawley adds about the polyurethane dies, "They're also suitable for deep, three-inch draws." The cured material has a Shore hardness of 91D, ultimate compressive strength of 13,900 psi, and ultimate tensile strength of 4,700 psi.
What about kirksite? "If kirksite dies were used, we'd have to melt down the tooling and start over with every alternation. Polyurethane allow us to simply mill out the die section being modified, recast the surfaces and we're back in production." Being fast is important for racing teams off the track as well as on.