Experimental study on micro electrical discharge machining with helical electrode

With the development of micro electro mechanical system (MEMS), the application of micro components is becoming increasingly wide. Micro electrical discharge machining (micro EDM) is one of the most effective manufacturing processes for micro components. During past few decades, some innovative methods for improving micro EDM performance have been proposed. Using special-shaped electrode is just one of them. Although micro EDM with helical electrode has been proposed and the availability has been proved for several years, relatively little is known about the precise effect of helical electrode rotation on micro EDM performance. In this study, micro through-holes were machined on Ti6Al4V sample with a cylindrical electrode and helical electrode. The helical electrode achieves better machining performance overall compared to the cylindrical electrode due to its favorable debris removal ability. The higher the rotational speed of helical electrode, the higher the material removal rate (MRR). When using the cylindrical electrode, the MRR first increases and then decreases after reaching a peak at 3000 rpm. Higher MRR is obtainable with the helical electrode with reverse rotation; with forward rotation, it yields higher machining precision (lower overcut and taper rate).