High quality tooling for production of thermoset composite parts can be viewed as a cross between the structural needs of die-cast metal tooling and the complex geometries often associated with intricate features of thermoplastic and machined metal parts. Molds for thermoset plastic parts are unique in their requirements when compared with other molding materials and processes.
Good mold design, coupled with good part design, is key to production of high quality thermoset parts.
Thermoset composites are generally prone to cause erosion of tooling due to the material makeup with fiber-glass and fillers, and therefore much care must be taken in the design of tooling. Hardened tool steels, coupled with hard chrome plating and special coatings, accomplish this requirement for longevity of the tooling.
Relatively low viscosity of the molding material during cavity fill requires tight fits in the tooling to prevent flashing that can result from less than satisfactory mold construction.
Thermoset tooling must be heated to process temperatures as high as 325°-350°F to allow cross-linking and curing (hardening) to peak exotherm of the material during molding. Heat requirements and methods are established early in design of thermoset molds.
Design and construction of high quality tooling for thermosets requires a combination of experience, engineering, and empirical knowledge. It often takes several years to develop relationships with mold builders to provide the designs and construction of specialized molds required for molding of thermoset parts.
