On pressurized feeding approach for effective control on working gap in ECDM

Electrochemical discharge machining (ECDM) process is promising for machining of micro features on glass and ceramic materials. ECDM requires an effective control on process parameters for high productivity and accuracy with an increase in the depth of penetration. Among all parameter settings, the most important requirement is the effective control on working gap. The present article reports the development of pressurized feeding system for effective control on working gap during ECDM. In pressurized feeding system, the exerted pressure maintains constant working gap (almost zero) during machining, and that was provided by the development of a workpiece holding fixture. The existence of micro cavities between abrasive coated tool and work material generates thin and stable gas films underneath the tool electrode. The breakdown of these films results in high-frequency and low-intensity discharges with reduced critical voltage (Vc), and these discharges seem to be responsible for the machining of deep holes even with the use of high applied voltage. The developed pressurized feeding system exhibits 207.4% improvement in machining depth while compared to the other feeding systems. The effect of exerted pressure along with applied voltage, pulse on time, and electrolyte concentration on material removal rate, hole over cut, and taper was also investigated.