A vacuum casting machine uses a vacuum to suck the molten metal into the mold. A force is needed to overcome the surface tension of the molten metal. The centrifugal machine must be securely bolted to a level surface with a protective fence around it. A metal washtub or a drum from a clothes dryer can be used.

The advantages offered by plaster casting include: A very smooth surface finish. The ability to cast complex shapes with thin walls. The capacity for forming large parts with less expense than other processes, such as investment casting.

Vacuum casting or vacuum duplication involves injecting a resin into a silicone mould. Because of its cost and deadline, this method is most suited to pre-series, with a faithful reproduction of the original model and a result close to the end result in the “right material”. Vacuum casting technology is recommended for the production of around ten to one hundred parts for mechanical or visual tests.

You can get at least 20 shots out of a silicon mold. After 20 shot, the vacuum casted mold starts to decrease in quality.

It can be molded into finished product by application of heat and pressure.

Vacuum casting results in significant economies of scale. It is recommend to use this prototyping technology for quantities exceeding ten pieces. From this number, the cost of creating the silicone tooling is paid off and the technology of vacuum casting generally becomes more attractive than CNC machining. The tooling consists of a master part and a mould. The economies of scale generally reach their maximum from 100 to 200 prototypes. Beyond this quantity, it is recommended to design an injection mould from aluminium or steel.