Study on Machinabilty of Al2O3 Ceramic Composite in EDM Using Response Surface Methodology

Abstract

Electric discharge machining (EDM) has been proven as an alternate process for machining complex and intricate shapes from the conductive ceramic composites. Al2O3 based electrodischarge machinable Al2O3–SiCw–TiC ceramic composite is a potential substitute for traditional materials due to their high hardness, excellent chemical, and mechanical stability under a broad range of temperature, and high specific stiffness. The right selection of the machining condition is the most important aspect to take into consideration in the EDM. The present work correlates the inter-relationships of various EDM machining parameters, namely, discharge current, pulse-on time, duty cycle, and gap voltage on the metal removal rate (MRR), electrode wear ratio (EWR), and surface roughness using the response surface methodology (RSM) while EDM of Al2O3–SiCw–TiC ceramic composite. Analysis of variance is used to study the significance of process variables on MRR, EWR, and surface roughness. The experimental results reveal that discharge current, pulse-on time, and duty cycle significantly affected MRR and EWR, while discharge current and pulse-on time affected the surface roughness. The validation of developed models shows that the MRR EWR and surface roughness of EDM of Al2O3–SiCw–TiC ceramic can be estimated with reasonable accuracy using the second-order models. Finally, trust-region method for nonlinear minimization is used to find the optimum levels of the parameters. The surface and subsurface damage have also been assessed and characterized using scanning electron microscopy. This study reveals that EDMed material unevenness increases with discharge current and pulse-on time.