Assessment of Radial Overcut During EDM of AISI 4147 Using RSM Technique

The present assessment is carried out to analyze the influence of EDM variables on radial overcut during the machining of AISI 4147. The additional sparks that strike the workpiece's wall cause the machined hole to be larger than the required dimension. This oversizing result is radial overcut which reduces the precision of EDM. To minimize the overcut and enhance the machine performance, trials were performed based on the Response surface methodology to assess the set of parameters suitable to achieve minimum enlargement. Based on initial test trials, the current was set between 1A and 7A, on-duration between 10µsec and 30µsec, and depth of machining between 0.5 mm and1.1 mm. The size of the machined hole was measured with the help of scanning electron microscopy. The analysis revealed that current and depth of machining are the major influencing parameters for radial overcut and the minimum overcut is obtained at 1A current and 0.5 mm depth of machining. The point prediction method was employed to perform validation of the data obtained. The residual errors were found to be 2.10% and 2.83% which specifies the adequacy of the model to predict the radial overcut under 95% CI.