Optimization of Surface Roughness and MRR in EDM Using WPCA

The objective of the present study is to find out the optimum combination of process parameters in EDM process so that surface roughness reaches a minimum value and the metal removal rate (MRR) reaches a maximum value. In this study, five roughness parameters (viz. center line average roughness, root mean square roughness, mean line peak spacing, skewness and kurtosis) along with MRR have been considered. To optimize the multi-response problems, Taguchi method alone is unable to solve the problem. Thus, the multi-response characteristics must be converted to a single performance index. In this study weighted principal components analysis (WPCA) method is used for this conversion. For the experimentation, Taguchi L27 orthogonal design with four process parameters, viz., pulse on time, pulse off time, discharge current and voltage at three different levels is used. The optimum combination of process parameters has been found out and verified through the confirmation test. The result of the confirmation test shows a good agreement with the predicted value. This indicates the utility of the WPCA technique as multi-objective optimizer in the field of EDM. In addition, the surface morphology is studied with the help of scanning electron microscopy (SEM) analysis.