Observation of Bubble Expansion and Flying Debris in Parallel Flat Gap Space in Electrical Discharge Machining

摘要

This paper reports the observed results of bubble expansion and contraction and flying debris in parallel flat gap space in order to discuss the mechanism of material removal in electrical discharge machining (EDM). Metal rod and plastic flat plate with metal wire inserts are used for electrodes, and bubble expansion and contraction caused by a single pulse discharge, as well as flying debris, is observed using a high-speed video camera. It is found that bubbles generated under conditions where other bubbles exist in the gap space expand but often do not contract, whereas bubbles generated under conditions where no bubbles exist in the gap space expand and often contract. It is also found that debris are scattered from the discharge point during discharge duration and while bubble is expanding.