Extrusion compounding is a pre-process for thermoplastic injection molding. Resin and chopped strand fiber glass are mixed together by counter rotating screws in an extrusion machine. The thermoplastic composite material is extruded into a noodle like shape, cooled and chopped into pellets ready for injection molding
Injection molding is a closed mold process used predominantly for the production of filled and unfilled thermoplastic resins into finished forms. The materials, usually in pellet form, are melted then injected into the mold, the molded part hardens as it is cooled, and then is ejected from the mold. Injection molding is an automated, high volume process with the capability of making complex parts. Common uses are in automotive under the hood parts, electrical components, power tools, electronic equipment, housings and parts.
Filament Winding is an open molding process. Fiber glass rovings are pulled through a bath of catalyzed resin and impregnated. The resin impregnated rovings are wound under tension onto a cylindrical mandrill. The composite material cures and the mandrill is removed. Filament Winding is used to make high strength, hollow, and typically columnar composites, such as pipe and storage tanks.
Spray-up is an open mold process. Mold release and gel coat are applied to the mold. Catalyzed resin along with fiber glass roving is fed through a gun at the same time. The roving is chopped into 12 to 24mm lengths and deposited on the mold along with the resin. A roller is used to remove air and insure complete wet out and wet through.
Pultrusion is a continuous process for manufacturing composites with a uniform cross-sectional shape. A fiber reinforcement is pulled through a resin-impregnation bath and into a shaping die where the resin is subsequently cured, or set. Heating to both gel and cure the resin is accomplished within the die length. Pultrusion yields continuous lengths of material with high unidirectional strengths.
Resin Transform Molding (RTM) is a closed mold process. Liquid resin is injected into a closed mold which contains fiber glass reinforcement materials such as mats, woven fabrics and veils. Then wet through the reinforcement and the composite material is cured under low pressure.
Vacuum Bag Molding Process utilizes plastic film to cover pre-impregnated reinforcements such as mats and woven fabrics placed in a mold. Air is extracted by drawing a vacuum, also removing excess resin. This process is low cost process for making large and complex parts, such as windmill blades and aerospace parts
Sheet Molding Compounds (SMC) and Bulk Molding Compounds (BMC) are used in compression molding. SMC or BMC compounds are place between matched metal dies representing the part shape. The mold closed and under temperature and pressure, the compound is cured. Compression molding is widely used in making car body panels, truck cabs and other high volume large parts