Investment casting, usually refers to the pattern made of fusible materials, in the pattern surface coated with a number of layers of Refractory to form shell, and then the pattern will be melted out of the shell, so as to obtain a non-parting surface of the mold, after high temperature roasting, the casting scheme can be filled with sand. Because the pattern widely uses the waxy material to manufacture, therefore often calls the investment casting “loss-of-wax casting” , including wax pressure, wax repair, tree formation, paste, wax melting, casting liquid metal and post-treatment processes. Lost wax casting is to use wax to make the cast parts of the wax mold, and then wax mold coated with mud, which is mud mold. After the clay mold is dried, the internal wax mold is melted in hot water. The clay mould of the melted wax mould is taken out and baked into a ceramic mould. Once baked. In general, when making the mud mold, the sprue is left, and then the molten metal is poured into the sprue from the sprue. After cooling, the required parts are made.