A weighed charge of SMC or BMC, or a preform of glass reinforcement shaped to the mold is placed on a press ranging in size from 300 to 4,000 tons. Resin is added with the preform while SMC and BMC contain all components including fiber, resin, fillers, catalyst etc. Heat and pressure is applied, with temperature ranges of 225 to 325 oF. and 150 to 1,000 psi pressure required to cure parts.
Cycles can range from less than one to five minutes.
Typical thermoset resins used in compression molded parts are polyesters, vinyl esters, epoxies, and phenolics. Compression molded products vary from dinnerware, trays, buttons, appliance housings, large containers, electrical, to recreational vehicle body panels such as snow mobiles, and jetskis.