Author : Shashikant, Apurba Kumar Roy and Kaushik Kumar

EDM (Electro-discharge Machining) is a nonconventional machining process utilizing an electric spark discharge from the electrode (-) towards the work piece (+) through the dielectric fluid. The Dimensional accuracy in this is very important consideration for the accuracy of the finished product. The objective of this experimental study is to determine parameters that offer the best dimensional accuracy in electrical discharge machining (EDM). Discharge current, pulse on time, pulse off time and gap voltage are taken as machining parameters for blind hole operation on EN 19 steel. The experimental investigations are carried out using copper electrode. CCD design of experiment of Response Surface Methodology (RSM) is used to identify the effect of machining parameters on overcut. Machining parameters are optimized for minimum overcut. ANOVA analysis is carried out to identify the significant parameters that affect the dimensional accuracy. Confirmation tests are performed on at predicted optimum process parameters and results are verified. It is observed that the discharge current has greatest impact over the overcut followed by gap voltage, however the impact of the other two input parameters namely pulse on time, pulse off time, was very less.

Keywords: Anova, EDM, EN19, Optimization, Overcut, RSM.