A machinable composite helps Vantage Tool and Engineering (VTE), Fort Wayne, Ind., crank out thermoform prototypes in only two days. The composite molds machine in about half the time it takes to produce metal tools. The easy-to-machine composite boards called Ren Shape 450 are laminated into a machinable block using Ren Weld 103 adhesive. Once cured, the bondlines are tough — the board shears before the bondline breaks, reports Sam Geiger, general manager of VTE.
VTE thermoforms molding for food trays, bowls, and other highly contoured containers. Materials formed in the Ren Shape molds include polypropylene, polystyrene, polyvinyl chloride, and polyethylene. The Ren Shape 450 material from Vantico Inc., Ren Shape Tooling Systems, East Lansing, Mich., lets VTE cut prototype tooling for up to 500 parts.
VTE cuts mold cavities with a high-speed threeaxis mill. The mill first makes about a 1⁄2-in.-deep cut. Followed by a 1 and 1.5in. deep cut for deep cavities. A two-flute, hardened steel ball-end mill is said to work well at 3,500 rpm and 120 ipm for rough cuts, while a 1⁄4-in. tapered, fluted-end mill running at 4,500 to 5,000 rpm and 150 to 160 ipm with 0.007-in. stepover, produces finished surfaces (no secondary finishing).
Finished molds have a glass-transition temperature of 205F, a Shore D hardness of 65, a 2,300-psi tensile strength, and stand up to numerous thermoforming cycles.
Laminated blocks of Ren shape 450 composite are cut on a three-axis mill to produce thermoform molds in about half the time required for machining metal tools. |
To mold a container, the machined Ren Shape tool is mounted in a standard base and installed in the thermoforming machine. Plastic sheet is inserted in a frame over the mold, heated until soft, and then formed into the mold cavity. |
Vantico Inc. Ren Shape Tooling Systems, 4917 Dawn Ave., East Lansing, MI 48823, (517) 351-5900, www.vantico-aandt.com