The permanent mould process employs gravity pouring of metals using steel, cast iron or graphite moulds. The castings produced have excellent grain structure and extremely low porosity which result in superior ductility and outstanding strength. The castings can be designed with thinner walls and less weight with good dimensional accuracy. Used primarily for low melting temperature metals such as aluminum & zinc, permanent mould castings produce excellent finishes & pressure tightness when compared to sand castings. Savings in reduced machining operations can also be realized due to the dimensional uniformity of the castings and details that can be cast in, as well as reducing some secondary operations such as polishing due to the excellent surface finish. Permanent moulds have a production life of 10,000-50,000 parts, casting sizes range from a few ounces to 50lbs.