Study of Correlation of machining performance and geometrical tolerances of Si3N4 -TiN composites using EDM process

Abstract

Abstract The aim of this research work is to enhance the machining characteristics and geometrical tolerances of Si3N4–TiN ceramic composite using a copper electrode as the EDM tool. The investigation encompassed a comprehensive exploration of various machining parameters, including polarity, current (amp), pulse on time (µs), pulse off time (µs), dielectric pressure (Kg/cm2), gap voltage (v), spark gap (mm), and servo speed (m/s), utilizing a Taguchi L18 orthogonal array. Throughout the EDM process, meticulous scrutiny was applied to output characteristics such as material removal rate (MRR), tool wear rate (TWR), wear ratio (WR), surface roughness (Ra), top radial overcut (ROC-Top), bottom radial overcut (ROC-Bottom), top diameter of the drilled hole, bottom diameter of the drilled hole, taper angle (Ѳ), circularity (CIR), cylindricity (CYL), perpendicularity (PER), and runout (RO). The higher pulse current promotes the formation of a stable plasma channel which results in increasing the material removal rate. The improved flushing action helps to minimize the recast layer, leading to a smoother surface finish and reduced surface roughness. The experimental results demonstrate that as the spark gap increases from 0.18mm to 0.25mm, the Runout, Electrode Wear Rate, ROC Bottom, ROC Top, and Taper Angle drastically reduce.