Planetary EDM of Micro Holes

Abstract

Moving an electrode in planetary motion is useful particularly for drilling micro holes because flushing is difficult for a thin electrode. However, there have been few reports on such research. In the present study, therefore, the planetary electrical discharge machining (EDM) of micro holes of less than 50μm in diameter has been attempted. The results of drilling copper using tungsten electrodes show that the planetary motion of the electrode improves the material removal rate and the volumetric wear ratio, reduces the overcut and enables the drilling of deep holes. Under the experimental conditions used, the material removal rate is highest with a planetary-motion diameter of approximately 25% the electrode diameter. The volumetric wear ratio can be reduced to less than 1%, which is very small for EDM using an RC circuit. A small overcut of less than 1μm is also possible, enabling high-accuracy machining.