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Thermoset Sheet Molding Compound (SMC)

Sheet molding compound is a combination of TS polymer resin, fillers and other additives, and chopped glass fibers (randomly oriented) all rolled into a sheet of typical thickness = 6.5 mm (0.250 in). The most common resin is unsaturated polyester; fillers are usually mineral powders such as talc, silica, limestone; and the glass fibers are typically 12-75 mm long and account for about %30 of the SMC by volume. SMC’s are very convenient for handling and cutting to proper size as molding charges. Sheet molding compounds are generally produced between thin layers of polyethylene to limit evaporation of volatiles from the thermosetting resin. The protective coating also improves surface finish on subsequent molded parts. (Mikell P. Groover; Fundamentals of Modern Manufacturing Materials, Processes, and Systems 3rd Edition; pg.323)

Thermoset Bulk Molding Compound (BMC)

BMC consists of similar ingredients as those in SMC, but the compounded polymer is in billet form rather than sheet. The fibers in BMC are shorter, typically 2-12 mm, because greater fluidity is required in the molding operations for which these materials are designed. Billet diameter is usually 25-50 mm. The process of BMC is similar to that SMC, except extrusion is used to obtain the final billet form. (Mikell P. Groover; Fundamentals of Modern Manufacturing Materials, Processes, and Systems 3rd Edition; pg.323)

Thermoset Dough Molding Compound (DMC)

Dough molding compound is same with bulk molding compound (BMC). BMC name is commonly used is US and DMC is used in Europe. DMCs are completely formulated preim-pregnant fiberglass reinforced plastics molding materials that are either prepared by the molder or are purchased from a compounder. They can be chemically thickened, in which case generally it is important to control the storage environment to minimize the maturation period of reaction time. When thermoplastic additives are included to control surface finish or surface appearance, the material generally is referred to as low shrink or low profile DMC. (Raymond W. Meyer; Handbook of Polyester Molding Compounds and Molding Technology; pg. 2)

Electrocoat

Electrocoat is a kind of dip coat, in which the part is electrically charged and then dipped into a paint bath that has been given an opposite charge. This improves adhesion and permits use of water-based paints(which reduce fire and pollution hazards). (Mikell P. Groover; Fundamentals of Modern Manufacturing Materials, Processes, and Systems 3rd Edition; pg.682)