Optimisation of the correlated responses of EDM process using modified principal component analysis-based utility theory

One of the most extensively used non-traditional machining processes is electrical discharge machining (EDM). Achieving the best quality performance from the EDM process requires simultaneous optimisation of multiple performance characteristics (responses). Researchers have applied different techniques of multi-response optimisation for optimising the EDM processes. But those approaches do not take care of the possible correlation between the responses, whereas some of the responses of EDM process are usually correlated. In recent times, different principal component analysis (PCA)-based approaches for multi-response optimisation have been proposed, which take into account the correlations among the responses. One of such approaches is the PCA-based utility theory (UT) approach. This paper highlights one weakness of the PCA-based UT approach and proposes the necessary modifications. Two sets of past experimental data on EDM processes are analysed using the modified procedure. The results show that the modified PCA-based UT approach leads to better optimisation performance than that obtained by the earlier researchers. This implies that the modified PCA-based UT approach can be very useful technique for optimising the EDM processes.