Modelling and parametric optimization of EDM of Al 8081/SiCp composite through DEAR approach

Aluminum metal matrix composites are gaining ample interest because of the growing need for lightweight structural materials in aerospace and automotive areas. Conventional machining of such composites does not provide higher accuracy, due to their hardness deteriorates the reliability of the tool. Among various non-conventional machining processes, electrical discharge machining (EDM) is regarded as one of the efficient and cost-effective processes in machining of composites. This article discusses the EDM of Aluminum 8081 reinforced with 10Wt% silicon carbide has developed by stir casting technique. Experiments were carried out with central composite design with controllable EDM factors such as current, and pulse-on-time and pulse-off-time were used to investigate machining performance such as material transfer rate (MTR) and average surface roughness (TWR).The second order quadratic models are developed between EDM parameters and responses by regression analysis. Analysis of Variance was employed to validate the accuracy of the established statistical models and the impact of the process variables. Data Envelopment Analysis based Ranking Methodology (DEAR) was used to evaluate optimum parameters to achieve maximum MRR of 0.27542 mm³/min and minimum TWR of 0.05926mm³/min with optimal–parameters of P_on (3 µs), P_off (10 µs) and I Current (20amps). Validation result indicates that the predicted values of the optimization are in accordance with the experimental values. Surface morphology of the machined surface was performed by using scanning electron microscopy in order to study the mechanisms of material removal under the different settings of EDM.

Craters of large size formed during higher current and pulse on time.