Hitting the Jackpot

Rubber and epoxy molds rev-up production

Manufacturer of casino gaming equipment, Tripp Plastics. Sparks. NV, uses rapid part pro-duction techniques to produce components for its Addams Family slot machines. Al Grinsell, project manager at Tripp Plastics explains, "We don't have the time or the budget to use metal tooling. We just replace our silicone rubber molds when necessary and keep shooting roof and porch components from the Parts-In-Minutes polyurethane."

To mold several thousand roofs and porches for these slot machines, Tripp Plastics casts large tin-catalyzed silicone rubber molds from hand-carved wooden masters. A silicone release agent is applied to all surfaces of the mold, and an automated meter/mix machine dispenses RP 6456 R/H polyurethane, supplied by Vantico, E Lansing, MI, into the tool cavity to produce the ¼-in. thick parts. The material gels in about a minute and is demolded after 10 minutes. To ensure dimensional stability, the large parts are postcured in an oven at 180°F for eight hours before being painted and installed on slot machines. After postcuring, the polyurethane exhibits a flexural modulus of 148,000 psi, notched Izod impact strength of 0.7 ft-lb/in. and heat deflection temperature of 210°F. "The problem-solving and fast production capability we have with Parts-In-Minutes polyurethanes has allowed us to take on projects we had difficulty handling before. As a result, we are now better equipped to serve our customers," says Grinsell.

Parts-in-Minutes Polyurethanes

To help promote gaming equipment, Tripp Plastics developed a proprietary technique for production of 3D graphics using epoxy thermoform molds. Toolmakers start with a machined Ren Shape 460 master. Then, depending on the size of the polycarbonate panel to be formed, molds are cast or laminated over the pattern. To produce graphics panels, tools are mounted in an aluminum jacket and installed in the thermoforming machine. Then, clear sheets of polycarbonate, pre-imprinted with features of characters on the surface, are draped and formed over the mold in the precise orientation required to yield a high-quality, three-dimensional image. "The epoxy thermoform molds are quick to build and tough enough to produce thousands of parts with virtually no surface wear," says Grinsell.

—SG

Epoxy thermoform mold with finished part