Vacuum casting is one of the most widely used techniques in the manufacturing sector especially when it comes to the making of plastic prototypes. Not only is this manufacturing technique economical it's also suitable for low and medium production of plastic prototypes.

In much simpler terms, vacuum casting allows its users to create identical copies of a wide array of functional parts. Compared to other manufacturing techniques, vacuum casting is fairly fast, the parts produced are of higher quality as well as having excellent surface finishing.

Vacuum casting came into being when the scientist and engineers were actually looking towards solving the air entrapment problem. What scientists deduced from the experiment is that during normal casting is that the air in the molds tends to get trapped inside the final structure resulting in the formation of air pockets. This weakened and compromised the overall structure of the final part or product.

Brief low-down of the casting process

The overall vacuum casting process involves multiple stages and processes, the whole production process is quite intense and tasking but the upside is the fact that it's quite fast and has a quick turn-around time.

1. Master model creation

The master can be created from scratch or taken off the shelf if you are working with a casting firm. The master can be made using rapid manufacturing techniques such as CNC machining or 3D printing. It can also be made from an industrial part.

Most of the parts created using 3D printing are normally created using stereolithography/SLS techniques. The master must have correct dimensions which ensure that the final casted parts are exactly as the master.

2. Production of the mold

Liquid silicone is mostly used to make the silicone mold, once the master has been placed into the casting box. Liquid silicone is poured all over it; it's then inserted into an oven and left for curing to commence.

The liquid silicone mold is cut open, the master is removed leaving behind an empty and hollow cavity. The hollow cavity is the exact dimensions and shape of the master model. The silicone mold can be used over 15 to 20 times before they wear out.

3. Production of the casting copies

The newly formed resins are usually mixed to ensure that the new mixture has similar properties to the industrial parts. Most manufacturers usually have a comprehensive material data sheet that has all the info about the properties and composition of the material to be used in casting.

This information is key and it's used to create resins that will have a close resemblance to the master model. This mixture is, in turn, poured onto an empty cavity creating your desired product or mold. The resin must be cured in a vacuum ensuring that there are no air bubbles trapped inside.