Tool selection in three-axis rough machining

An approach to tool selection and sequencing is presented for three-axis ro ugh machining. The trade-off in the selection of tools is as follows: large r tools have reduced access while smaller tools are capable of reduced cutt ing speed. Furthermore, every tool change incurs a time penalty. The object ive of this paper is to select a tool sequence that minimizes the total rou gh-machining time. In our approach, the removal volume is stratified into 2 .5D machining slabs and, for each tool, the area accessible in each slab is computed incrementally, keeping in mind the cutting portion of the tool an d the shape of the tool holder and spindle assembly. This reduces the three -axis problem to a series of two-axis problems with complex precedence cons traints. Two models are presented to understand this new form of the proble m. First, an integer linear programming formulation is discussed to show th e complexity of the task. Second, a network flow formulation is presented, by which we show that it is possible to obtain efficiently an approximate s olution of the problem. Examples are discussed to illustrate the algorithms discussed.