Dynamic Evolution of Events Accompanying the Low-Voltage Discharges Employed in EDM

Experimental studies of the evolution of events accompanying a transient, low-voltage sparkover-initiated discharge between closely-spaced electrodes in a liquid dielectric are described. The discharge parameters and the electrode configuration are similar to those found in electrical discharge machining (EDM) applications. High-speed photomicrographic records of the dynamic evolution of the discharge column and the gas bubble created by the discharge are presented. Additional photographic evidence of the details of electrode metal erosion dynamics is given. The photo-micrographs suggest that metal erosion takes place at the beginning of the discharge current pulse and after the termination of the discharge current pulse.