BMC Thermoset Molding

BMC, or Bulk Molding Compound, is a common type of moldable thermoset material or composite. BMCs are unsaturated polyesters or vinyl esters, and may be injection or compression molded with thermoset molding machines. The properties of BMC molded parts exhibit exceptional dielectric strength, electrical insulation, heat resistance, and chemical resistance. These beneficial material properties lend BMC materials to be molded in a variety of safety-critical applications and component assemblies within the Electrical, Automotive, and Industrial markets. In its raw state, BMC resembles a play-dough like form usually filled with glass fibers and or minerals dispersed within the resin system. Molding wise, BMCs are more commonly injection molded, but can also be compression or transfer molded. Injection molding BMCs require the use of a molding machine stuffer or ram to help inject material into the screw and barrel to preheat and plasticize prior to injecting into the molds.

Electrical components such as terminal blocks, connectors and circuit breakers are molded from thermoset BMCs due to these desirable electrical properties, keeping the product assembly and components safe even during a power failure or electrical trip. Automotive transmission and powertrain components utilize heat resistance and chemical resistance properties of BMC for parts exposed to automotive fluids, oils, and grease. Likewise, the high temperature resistance allows BMC parts to remain strong and durable even within applications experiencing high operating temperatures.