Precision milling of a compression mould

To develop and evaluate the design and structures of new products, a Sirris member company is using compression moulds. They are doing this to give their products the desired structures. It evaluated both an additive and a subtractive process.

The compression moulds, whose functional upper surface is constructed from various detail geometries (see figure), can be made in various ways, both subtractive and additive. As part of the evaluation procedure, the company has explored both routes.


For the subtractive compression mould process, which is made of a high alloy steel, the company successfully called in the precision cell expertise of Sirris in Diepenbeek. This was because Sirris has a highly accurate Fehlmann Versa P825 five-axis milling machine at its Diepenbeek site. This allows milling geometries accurate to 5 microns. The design of the compression mould involves details with such small radii that milling tools with diameters up to 0.4 mm are required. To minimise tool wear - a thorny issue with miniature milling tools - a very precise and very temperature stable milling machine is vital. This requirement has been met by installing the milling machine in a climate-controlled room and ensuring that critical machine components have the required temperature compensations.

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