PARAMETRIC INVESTIGATIONS ON ELECTROCHEMICAL DISCHARGE FORM MACHINING

Abstract

Elcctrochemical discharge machining (ECDM) is a hybrid non-traditional machining process which combines the features of electrochemical machining (ECM) and Electrical discharge - machining (EDM) and overcomes the drawbacks of these individual processes. In ECDM, machining is performed by combined effect of chemical etching and melting. This process is generally used for micrornachining. The notable advantage of this process is that it can be used for machining both conductive and non-conductive materials with the higher material removal rate (MRR) and high surface finish. The need of glass micromachining is increasing tremendously as it is becoming an important material in micro electro mechanical systems (MEMS) field because of its unique properties. Micromachining on glass can be effectively performed using ECDM process. Parametric optimization and their effects on process performance measures was to be studied for ECDM process. To perform the experiments an ECDM process setup was fabricated. Pilot experiments were carried out to check the feasibility of process parameters using soda-lime glass as the workpiece. An investigation was done on the effects of process parameters like voltage, electrolyte concentration, pulse on time, pulse off time and feed rate on process performance measures like material removal rate (MRR). channel width and depth using One-factor-at-time (OFAT) approach. The range of parametric values for best results, was obtained from results of OFAT approach. This range of these parametric values was used for predictive modelling using response surface methodology (RSM) using design expert soliware. The experiments were performed according to the RSM plan and the results were analyzed. The analysis revealed that the voltage and electrolyte concentration had the most significant effect on the process performance while pulse on time, pulse off time and feed rate are less significant but they also play an important role in process output. The empirical models for MRR, channel width and depth were also calculated. The results reveal that MRR, channel width and depth are directly proportional to voltage, concentration and pulse on time while inversely proportional to pulse off time. While, with the increase in feed rate the MRR increases. but channel width and depth decreases.