Sheet Molding Compound (SMC) is a compression molding compound often used for larger parts where higher mechanical strength is needed. SMC is a fiber reinforced thermoset material. Glass reinforcement is between 10% and 60%, and glass length is slightly longer than Bulk Molding Compound (BMC) - between 1/2-inch and 1-inch (25mm).
SMC is a mixture of polymer resin, inert fillers, fiber reinforcement, catalysts, pigments and stabilizers, release agents, and thickeners and possesses strong dielectric properties. Manufacture of sheet molding compounds is a continuous in-line process. The material is sheathed both top and bottom with a polyethylene or nylon plastic film to prevent auto-adhesion. The paste is spread uniformly onto the bottom film. Chopped glass fibers are randomly deposited onto the paste. The top film is introduced and the sandwich is rolled into a pre-determined thickness..
Sheet molding compounds can be molded into complex shapes. Superior mechanical properties and surface appearance, plus excellent electrical insulation make this thermoset material ideal for automotive Class A body panels, high-strength electrical parts, business equipment cabinets, personal watercraft, and various structural components.