Injection molding is a manufacturing process for producing parts by injecting molten material into a mold. Injection molding can be performed with a host of materials mainly including metals, glasses, elastomers, confections, and most commonly thermos plastic and thermo setting polymers. Material for the part is fed into a heated barrel, mixed and injected into a mold cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, molds are made by a mold-maker from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection molding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection molding of some lower temperature thermoplastics, can be used for some simple injection molds.
Parts to be injection molded must be very carefully designed to facilitate the molding process, the material used for the part, the desired shape and features of the part, the material of the mold, and the properties of the molding machine must all be taken into account. The versatility of injection molding is facilitated by this breadth of design considerations and possibilities.