Abstract
In the electro-discharge machining, the discharge current is usually oscillatory. But the majority of energy which is discharged from charged condenser is dissipated in the first half cycle of the discharge current, so even if the second half cycle (which is reverse polarity) of the discharge current were stopped by germanium rectifiers, the ratio of electrode-wear (=wear of cathode/that of anode) does not decrease so much.
According to the results of the experiments made on various metals of anode and cathode respectively, an alloyed cathode metal having higher value of thermal conductivity, vaporizing point and latent heat of vaporization, has smaller ratio of the electrode-wear. Furthermore, a cathode metal which contains lower value of work-function has smaller ratio of electrode-wear. In the case of ferromagnetic cathode metal, the ratio of electrode-wear is getting higher value by longitudinal magnetic field.
