Abstract
An erosion mechanism of the electric discharge machining process has been studied on a view-point of a cathode phenomena. The T-F theory was applied to the electron emission from a cathode in this method and the electron current density at a cathode spot was calculated from that theory and the Mckeown's relation. Then the energy distribution between the gap electrodes was found to be mainly decided by the positive ion current density at a cathode.
The electrode erosion of various materials was measured. It became clear from the results that the electrode erosion per one discharge is dependent on three elements of energy, discharging duration and its thermal property. The kind of the tool electrode materials has a relatively small effect upon machining speed while the erosion of the tool electrode is widely changed by its thermal property.
The negative half cycle of the oscillatory discharging current in a condenser discharge was rectified by using a silicon power rectifier, but the erosion ratio of electrodes was not improved so much and in some cases it became worse than that by the oscillatory current.
