Micro-EDM milling of free form surfaces exploiting a 2 DOF high-precision rotary table: preliminary tests

Traditional 3-degree of freedom micro-EDM milling adopts the layer-by-layer approach to easily compensate for the tool wear and reduce the corresponding machining error. However, the layer-by-layer approach discretizes the nominal geometry and influences machining accuracy. The problem becomes more evident when free-form surfaces are fabricated. Similar to conventional milling, the adoption of interpolating rotational axes can potentially improve the process performance in terms of geometrical accuracy. In the present study, high-precision rotating axes are adopted to investigate the machining strategy when the tool is engaged using a 4th rotating axis in freeform surface finishing. The study is developed by performing micro-milling tests of cylindrical slots, analyzing the tool wear behavior and the process performance, and comparing them to the planar layer-by-layer micro-milling approach. Results show the feasibility of the proposed approach.