1 - Casting processes

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This chapter discusses casting processes. In sand casting, moist bonding sand is packed around a pattern. The pattern is removed to create the mold, and molten metal poured into the cavity. In shell molding, a heated metal pattern is placed over a box of thermosetting resin-coated sand. The box is inverted for a fixed time to cure the sand. Molds produced from other casting processes may be joined with shell molds. In gravity die casting, molten metal is poured under gravity into a preheated die, where it solidifies. The die is then opened and the casting ejected. In pressure die casting, molten metal is inserted into a metallic mold under very high pressures, where it solidifies. The die is then opened and the casting ejected. In centrifugal casting, molten metal is poured into a high-speed rotating mold until solidification takes place. In investment casting, a mold is used to generate a wax pattern of the shape required. In ceramic mold casting, a precision pattern generates the mold which is coated with ceramic slurry. The mold is dried and baked, molten metal is then poured into the mold and allowed to solidify. In plaster mold casting, a precision metal pattern generates the two part mold which is made of a gypsum slurry material. In squeeze casting, molten metal fills a preheated mold from the bottom and during solidification the top half of the mold applies a high pressure to compress the material into the final desired shape.