Two-part epoxy casting compounds and polyurethane boardstock are gaining acceptance as tooling materials for thermoforming high-end industrial and packaging parts. The trend is exemplified by a cast epoxy tool for automotive trim and a machined PUR tool for electronic and medical trays.
In both cases, the mold materials were supplied by the RenShape Solutions Tooling Group of Vantico’s Adhesives & Tooling Div. Kurt Frischmann, v.p. of tooling, says these methods can cut tool delivery times from months to a week or less. Moreover, today’s thermoset materials are more durable than ever, making the tools viable for volume production as well as prototyping. Thermosets also are more easily polishable than before, making them practical for forming clear, high-gloss parts.
Frisch mann notes that the trend toward “mass customization” results in lower-volume runs of a wider variety of parts. He says this typically swings economics in favor of lower-cost thermoset tools versus more expensive metal or hand lay-up composite versions.
Two case histories
Molded Plastic Industries in Holt, Mich., replaced aluminum with Vantico’s Cast-IT 2000 epoxy when tooling a 200-part-per-month program for ABS automotive trim parts. The tools range from 60 x 6 x 6 in. to 48 x 60 x 18 in. and are mounted on vacuum-chamber bases of 0.125-in. aluminum sheet.
The epoxy tool has 90D Shore hardness, 36,400 psi compressive strength, and a glass-transition temperature of 403 F. After making 10,000 parts, it shows no visible wear. Epoxy tools can be modified by simple machining.
CMT Materials in Attleboro, Mass., a Vantico distributor, says one of its customer is using a low-porosity, easy-to-machine PUR board to make a tool for forming clear, thin-wall medical and electronic trays made of PC and PETG. RenShape 5169 board reportedly offers excellent edge definition and abrasion-resistance. The tools have 85D Shore hardness and Tg of 206 F. They have produced nearly 1000 parts apiece.
The smooth surface and non-porous finish of PUR board makes for efficient tool polishing. And PUR tooling can be repaired or modified using Ren Patch 5169, a color-matched paste.