Multiresponse optimization of performance indicators through Taguchi-grey relational analysis in EDM of cemented carbide

Abstract

Cemented carbide is mostly used in the mold and tool industry due to their high hardness, temperature and wear resistance, and it is very difficult to shape with conventional machining methods. Because, during the machining of certain geometry from these materials, microcracks on surface and flaking at the machined edges due to their brittleness as well as rapid tool wear mostly due to their high hardness occur. In this case, EDM is considered one of the most suitable machining technologies for brittle material such as carbides, as it provides a non-contact shaping with electrical sparks between the tool and the workpiece. This study focused on the simultaneous optimization of the most important performance indicators namely material removal rate, tool wear rate and surface roughness in creating a keyway on WC-15Co material with the die-sinking EDM. As a result of experiments using copper electrode, the impacts on performance indicators of discharge current, pulse time and pulse interval were investigated with 3D surface topography images. It was determined that the peaks and craters formed on the machined surface expanded with the increase of pulse time, and the decreased with the increase in the pulse interval. As a result of the Taguchi-grey relational analysis (TGRA) application, discharge current of 6 A, pulse time of 25 µs and pulse interval of 100 µs were found as optimum parameters. ANOVA results showed that Ip, Ton and Toff affected GRG values by 44.23%, 28.77% and 5.87%, respectively. A 23.95% improvement in performance indicators was achieved thanks to the TGRA multiresponse optimization.