Molding material inspection in a mold Injection molding can be made with a variety of materials including mainly metals, glasses, elastomers, confectionery, and more commonly thermoplastic and thermosetting polymers. Material of the piece is inserted into a heated cylinder, mixed and injected into a mold cavity, where it is cooled and hardened for the configuration of the cavity. After a product is designed, usually by an industrial designer or a Engineer, molds are made by a manufacturer of metal molds, usually made of steel or aluminum, and machined with precision to form the characteristics of the desired part. China injection molding is widely used for manufacturing. Advances in 3D printing technology, using photopolymers, which do not melt during thermoplastic injection molding at some lower temperatures, can be used for some simple injection molds. The parts that must be molded must facilitate the molding process; The material used for the part, the desired shape and chara