Optimising Automatic Tool Selection for 2/2d Components

An important step in planning the manufacture of a component by CNC machining is the selection of cutting tools. Although it has long been known that the choice of cutter sizes can have a dramatic effect on the overall machining time, few algorithms for optimisation have been available to the production engineer. This paper describes a method for determining a theoretical optimal combination of cutting tools for machining a given set of 3D volumes or 2D profiles. The algorithm considers residual material left behind by oversized cutters and the relative clearance rates of cutters that can access the selected machining features. The current implementation of the procedure described does not give exact results because several machining parameters are not included in the selection process such as tool path length, plunge rates, etc. However, the experimental results suggest that while these factors may make changes to the absolute values calculated, they typically make only a small difference to the relative ranking of the tools. The results presented here suggest that the correct combination of tools could reduce machining times by significant amounts. Consequently the paper concludes with a discussion of how the tool path generation routines used in commercial CAM systems could be modified to achieve this.