Vacuum casting is a means of casting small metal parts or jewelry that have fine detail or for casting various plastic materials. A porous or vented mold is used and is placed on a table or container where vacuum is applied. The liquid to be cast will be driven into the mold by atmospheric pressure, while the vacuum will also remove trapped air that would otherwise impede the free flow of the liquid casting material. Vacuum casting is applied as an alternative to centrifugal casting of metals which is used in similar situations.
Vacuum pressure casting or VPC is a recent development in metal casting, whereby vacuum is used in combination with various gases under pressure to improve the quality of the casting and minimize porosity in the metal. Typically VPC casting machines consist of an upper and a lower chamber. The upper chamber or melting chamber housing the crucible, and the lower casting chamber housing the investment mould. Both chambers are connected via a small hole containing a stopper. A computer program governs the various cycles involved in the casting process. A typical casting cycle, would progress as follows;