New micro EDM technique for fine complicated hole with triangular section electrode

In EDM process, material removal is performed by repetitious generation of a micro crater produced by a single discharge, and the machining force acting on tool electrode and workpiece can be reduced by controlling electrical discharge energy. Therefore, EDM is particularly effective method in micro machining. However, in die-sinking EDM process, it becomes more difficult to make a fine complicated shape electrode when its size becomes smaller, and it takes a lot of time to form the electrode, which makes the process inefficient. On the other hand, in the case of wire EDM, the corner of machined hole becomes round, since the wire electrode has round section. Furthermore, in the case of thinner wire electrode, it is not easy to handle the wire. From the above points of view, a new micro EDM technique for machining various fine complicated shape holes with a simple shape electrode is proposed. In this method, a slender electrode with triangular section, which was made by extrusion with fine precision die, is efficiently used. Experimental analysis made it clear that fine hole could be machined efficiently with the electrode. Various fine complicated shape holes could be obtained easily by combining machined holes with a triangular section electrode. It was also made clear that smaller corner radius shape could be machined with the electrode, which was reformed on the machine using the reverse discharge method.