Published By: SME
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This chapter examines the following concepts: process overview, equipment, bulk molding compound (BMC)/sheet molding compound (SMC) molding, preform compression molding, prepreg compression molding, part complexity, properties, and other performance considerations. This chapter discusses the most important manufacturing method for composites that employs closed molds. The process is called compression molding, or alternately, matched-die molding. During this process a specific amount of material—the charge of uncured resin and fibers — is placed into the cavity of a matched mold in the open position. The mold is closed by bringing the male and female halves together, and pressure is exerted to squeeze the composite material so it uniformly fills the mold cavity. While under pressure, the material is heated so that it cures. Compression-molded parts are generally not able to achieve the high complexity that is possible with the open-molding systems. Matched-die or compression molding has an important place among the processes used to make composite parts. The principal advantages of using compression molding are low labor and high volumes, especially where high accuracy and well-defined surfaces are required.