Exact Tool Sizing for Feature Accessibility

This paper presents an algorithm for calculating the volume of a 2D-profile, accessible by a given diameter of milling cutter. The method is independent of the generation of cutter tool paths, and exploits facilities commonly found in kernel modellers. Exact results are obtained despite the simplicity of the procedure. As a proof of the concept, the algorithms have been implemented in the Heriot-Watt University feature recogniser as a pre-processor for a part programming system. The aim of these algorithms is to assist and optimise the selection of multiple tools for the machining of complex components. The methodology has applications in process planning research where it is currently common to assume that a single tool will machine each feature. Although cutter selection is a critical step in planning the manufacture of components, computer-aided process planning (CAPP) systems rarely make any attempt to analyse the tradeoffs involved. Perhaps this is because, traditionally, exact tool accessibility calculations have been viewed as a side effect of generating a cutter tool path. Consequently, accessibility calculations are not carried out explicitly but they appear implicitly in the results of a complex geometric algorithm (i.e. cutter path generation). Because this implicit checking of tool accessibility is carried out, downstream from the higher-level reasoning about set-up and sequencing, the results are generally available only after a detailed process plan has been generated.