Study on debris behavior in inter-electrode area and its influence on electrode feed in micro-hole drilling

Abstract

The debris and bubbles accumulation in the inter-electrode area cause the increases in abnormal discharges, which limits the feed depth during micro-hole drilling with electrical discharge machining (EDM). From the direct observation, it is found that debris always adheres to the negative electrode, and the powder-shaped debris gathers to form block-shaped one. On the one hand block-shaped debris makes the inter-electrode gap narrower and hinders the exchange of dielectric, but on the other hand the weak adhesion of block-shaped debris to the electrode leads to the possibility of falling off at any time. In this study, the influence of block-shaped debris and bubbles on the drilling depth was analyzed based on experiments, in which metal debris was artificially put into inter-electrode area.