Permanent mold casting is a non-expandable casting technique where the mold is not reformed after each casting is made. In this method, instead of using sand as the mold material, a metal is used as a mold. Typically, cast iron or Meehanite (a dense cast iron) is used as the mold material and the cores are made from metal or sand. Cavity surfaces are coated with a thin layer of heat resistant material such as clay or sodium silicate.
