Electrochemical spark trepanning of alumina and quartz

Alumina and quartz (brittle, electrically non-conducting, and inert in nature) are popular materials in advanced engineering industries, but their shaping by the conventional machining processes is not possible; even ECM and EDM can't be employed to shape them because of their electrically nonconducting nature. However, an attempt has been made to find out the capabilities of a new process called electro-chemical spark machining (ECSM), in machining these electrically non-conducting, hard, brittle, and high temperature resistant materials. In this work, eccentrically rotating tools have been used. This tool configuration has made it possible to relax the limited depth constraint, and it has been possible to drill 2.35 mm deep through holes in quartz samples and 1.35 mm deep holes in alumina. Through an experimental parametric study, it was found that beyond a certain value of electrolyte temperature, the ECSM process performance starts deteriorating. SEM photographs reveal that the combined action of melting and chemical etching seems to be the probable mechanism of material removal.