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About Metal Casting

Investment casting

By covering a wax model with ceramic material a shell is created. After melting down the wax, the shell can be used for casting metal. 

Materialise offers a full prototype and pre-series support for the product development of investment cast parts.

  1. In the early stage of the product development process it is possible to use selective laser sintering of polystyrene or wax models (ThermoJet) to produce a single part or a very small series of models. The models can be turned around very quickly as the production process consists of laser sintering and wax impregnation. The quick turnaround enables design optimization.
  2. Small series of up to 100 parts can be produced by vacuum casting of wax in silicone tools. These tools are based on a stereolithographic master. The first parts can be delivered within 2 weeks; a weekly production of 10 wax parts is achievable.
  3. High speed milling of aluminium allows tool production in a lead time of a few weeks; these can be used for series production. 

The lead time depends on the complexity of the tools.

Rubber-plaster moulding

This is a technique to make metal copies from stereolithography masters by casting metal in a plaster mould. The plaster mould is cast around a rubber copy of the stereolithography model.

The RPM process first of all involves the manufacturing of tools to produce rubber parts. For each metal part, plaster blocks are cast around these rubber models. The different plaster parts are assembled to form a cavity in which a metal is then cast. Once the metal has solidified, the plaster is broken, leaving a moulded part.

 

The production of rubber tools consists of the following steps:

  1. Stereolithography (positive)
  2. Silicone mould with definition of the required parting planes (negative)
  3. Rubber copy (to be used several times) (positive)
  4. Plaster mould (for once-only use) (negative)
  5. Metal copy (positive)

This sequence of conversions results in a small loss of accuracy, which may necessitate post-finishing. The surface structure remains fairly unaffected throughout the sequence and unlike investment casting, rubber plaster moulding must have models free of undercuts.
The use of rapid tooling techniques simplifies this process and raises the quality level.

 

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