Permanent mold casting

 Permanent mold casting is metal casting process that employs reusable molds "permanent molds" , usually made from metal. The most common process uses gravity to fill the mold , however gas pressure or a vacuum are also used. A variation on the typical gravity casting process, called slush casting, produces hollow castings . Common casting metals are aluminium , magnesium, and copper alloys. Other materials include tin, zinc , and lead alloys and iron and steel are also cast in graphite molds. 
Typical parts include gears, splines, wheels , gear housings, pipe fittings , fuel injection housings, and automotive engine pistons.