Vacuum casting

Rapid prototyping with vacuum casting

Vacuum casting enables us to quickly and inexpensively manufacture plastic components for sample copies of customer-specific input systems. Our 3D construction drawing forms the basis for the later casting of a sample. This model is first produced in a 3D printer and serves as a molded part for the silicone mold created by vacuum casting. For this process, we work with a supplier that specializes in rapid prototyping. In the following we describe the basic process of vacuum casting and its advantages and disadvantages.


Manufacturing process of an injection molded part in vacuum casting

First, a molded part is produced from the 3D model file of the desired product using a 3D printer. Since the surface of the component from the printer has a coarse surface structure and this is usually not desired, the surface of the plastic part is reworked according to the requirements for the product that will later be mass-produced. From this initial sample, a silicone rubber mold can now be produced, which then serves as an injection molding tool. This is where the actual process of vacuum casting begins.

The silicone mold is poured off in a vacuum casting system to avoid air pockets in the casting part. This is the only way to produce cheap silicone molds of sufficient quality for sample production. The molded part is cast around with the rubber and then hardens. This hardening process can be accelerated by additives in the rubber or by heat. However, it has to be taken into account that silicone hardens differently during curing, depending on the process, which can lead to dimensional deviations in the part to be cast.

After the silicone mold has hardened, the original model enclosed in it is removed using sharp cutting tools, the rubber mold heated and thereby closed again. Now the mold can be used to cast the parts. It is filled with liquid plastic, which then hardens in the mold, removed and deburred if necessary. In this way, the silicone mold can be used up to 30 times to produce a sample part.


Advantages and disadvantages of vacuum casting

  • Shapes with smooth surfaces can be produced
  • Quality of the samples comparable to mass-produced injection molded parts
  • Inexpensive and short-term mold production
  • High reproduction accuracy
  • Various casting resins available that simulate series plastics
  • Integration of molded and standard parts such as threaded bolts into the plastic parts possible during casting
  • Rapid wear of the mold (max. 30 castings)
  • The processing temperature of the casting material must be realizable through the silicone mold


Prototyping in our house

In order to make prototyping as efficient as possible, we rely on different procedures for sample production depending on the requirements. However, 3D printing always plays a significant role in the sample production of plastic parts. We have individual parts produced on the basis of our 3D design data by one of our selected suppliers in a 3D printer and reworked for the quality of an injection molded part. Then we assemble the first sample in our house from these plastic parts and the other mechanical, electronic and connecting components.

In many cases, it makes sense to make several sample copies before you can decide on series production. For small sample series and for easier production of particularly smooth or finely structured surfaces, the 3D printed product offers the basis for a silicone casting mold. With the vacuum casting process, we can inexpensively manufacture several identical parts for sample production, in which time-consuming reworking of the surfaces is not necessary.


Related Links

Silicone (Wikipedia explanation)

Rapid prototyping (Wikipedia explanation)

Vacuum casting (Wikipedia explanation)



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