Determination of optimal performance in wire electrical discharge machining of Al/Al2O3/22p composites using response surface methods and grey relational analysis

In this study, wire electrical discharge machining of aluminium matrix composites has been experimentally investigated. A metal matrix composite Al/Al2O3/22 (p) has been machined at various combinations of machining parameters such as pulse on-time, off-time, wire speed and wire tension. Empirical models have been developed to predict the cutting rate, surface roughness and kerf width of the machined composite material. The models were developed by using the technique of response surface methodology. The experiments were conducted in standard roughing mode by using carefully planned response surface design matrix (central composite design). The model predictions are in good agreement with the experimental results. The R-2 values of the proposed cutting rate and kerf width models are above 0.99, where as it is 0.98 for the surface roughness model. The pulse on-time was found to influence cutting rate and surface finish significantly. Kerf width was found to be affected by pulse on-time, off-time, wire speed and wire tension. In addition, a model was developed to correlate the multiple performance characteristic called as grey relational grade and the process parameters. The grey relational grade was significantly affected by pulse on-time and off-time time. The R-2 value for the grey relational grade model was 0.94. Optimal parameter setting was determined for the multiple performance characteristic. The improvement in cutting rate was significant with reasonably smooth surfaces and narrow kerf width. However, the surface finish was found to be dominated by the presence of protruding ceramic particles on the machined surfaces.