On the mechanism of material removal in electrochemical spark machining of quartz under different polarity conditions

Electrochemical spark machining (ECSM) process has been successfully applied for cutting of quartz using a controlled feed and a wedge edged tool. Contrary to the common belief that only cathode works as a tool, both cathode and anode have been used as a tool, i.e. ECSM with reverse polarity (ECSMWRP) as well as ECSM with direct polarity (ECSWDP) have been used to machine quartz plates. In ECSMWRP, deep crater on the anode (as a tool) and work-piece interface is formed because of chemical reaction. Chemical analysis of electrolyte solution after the ECSM experiments, also agrees with the feasibility of dissolution of quartz into solution due to chemical reaction. Reverse polarity cuts quartz plate at a faster rate as compared to the direct polarity. But in reverse polarity overcut, tool wear and surface roughness are higher as compared to the direct polarity machining. Magnified view of the machined surface also shows a difference in the mode of material removal in ECSMWDP and ECSMWRP. The cutting is possible even if we make auxiliary electrode of small size. In conclusion, experiments have revealed that cutting can be performed simultaneously at both the electrodes (anode and cathode) during ECSM. (C) 2007 Elsevier B.V. All rights reserved.