What is vacuum casting in rapid prototyping ?

In rapid prototyping, vacuum casting is an important technology to complement processes, like CNC machining and 3D printing. It allows to produce small series of identical prototypes.

Process of vacuum casting:

First of all, a master part is made by CNC machining, to have better accuracy and better graining surfaces.

The master part is then placed in a tank and covered with liquid silicone. The liquid silicone is then cured, after it is hard enough, it is opened cut and the master part is removed out of the cured silicone mould.

After that, a polymer resin is injected inside the cavity of the cured silicone mould with the shape of the master part inside and then the polymer resin is cured.

The process occurs under a vacuum environment, which ensures that air bubbles are removed from the polymer resin, resulting in dense and identical high-accuracy parts as the master part.

When the polymer resin is hard, the cured silicone mold can be opened and the part removed out. Then the mould is reused to make more identical copies, most of the time up to 10 times.

Uses of vacuum casting:

Today, vacuum casting is a common technology used in rapid prototyping process for pre-series prototyping, pre-series testing and small series batches.