Usually hinges are made of metal, which has been flattened into a sheet or roll, usually steel, aluminum, stainless steel or brass. Due to the efficiency of progressive die metal stamping, stamping hinges have higher quality and accuracy than extrusion hinges, and cost less. Metal stamping hinges are usually produced in stamping machines using metal forming processes (such as stamping, forming, bending, perforating, etc.), depending on the design of the part and the design of the mold.