Process planning considerations for micromilling of mould cavities used in ultrasonic moulding technology

• Analyze machine strategies to select appropriate tool path based on precision requirements.
• Compare machine strategies for machining versus micro-machining features.
• Methodology to establish eligible machining strategy for micro-features based on precision results.

The current trend in miniaturization of products and components requires appropriate technologies for the manufacture of miniature dies and moulds. The work presented here deals with the process planning of micromilling for the production of miniature mould cavities, required in ultrasonic moulding in order to reach high precision. Several aspects of process planning are addressed, including cutting tool geometry selection, segmentation of cavity geometry, minimum chip thickness, chordal tolerance, and type of interpolation. The case study involves the successful micromilling of a complex aluminium mould cavity for ultrasonic moulding. The proposed process plan is demonstrated through the micromilling of the mould cavity and silicone replicas of the miniature geometrical model. In general terms, good precision is obtained following the proposed methodology. In a randomly located set of geometric features, the dimensional error was below 5% for most features (32 out of a total of 40).