What are the technical characteristics of silicone moulds in rapid prototyping?

Example of a Silicon mold

Silicone molds are part of the tooling required for the production of vacuum-molded plastic parts. Their re-use results in significant economies of scale. It is therefore essential to ensure that they are produced in an appropriate manner to permit optimal use. They are characterized by several parameters, the most important of which are listed below:

– The size and weight of the molds depend on the geometry of the parts.

– The ventilation method and number of openings are linked to the choice of the production technique. The latter differs from one prototypist to another.

– The possible presence of tapers or undercuts may influence the decisions made during the design of the mold, to ensure the removal of the parts without damaging the tooling.

– Each mold has a cavity to allow the liquid material to be inserted during production. This is created by the negative of a master model of the part to be manufactured. This master part is designed either with CNC machining or 3D printing technology.

– The silicone molds are also characterized by the type of silicone used.

– The quality of the mold depends on the silicone and also the care taken during manufacturing.

– The method of incorporating finishes into plastic parts may differ from one mold to another. In fact, it is possible to apply finishes to the mold directly instead of performing manual manipulations after the removal of the parts.

– It is also possible to overmould inserts on the parts by positioning them directly in the mold.

– In general, a rapid prototyping workshop is capable of performing 20 runs with one mold. In addition, a mold can be used for a period of about 45 days. However, this data differs depending on the geometry of the parts and the type of silicone used to design the mold. The lifetime and the number of possible uses of the molds can therefore vary and some molds allow only 5 runs, for example.