Machining of curved profiles on tungsten carbide-cobalt composite using wire electric discharge process

Tungsten carbide-cobalt composite (WC-Co) is commonly considered a difficult to machine material due to its very high hardness. High strength and wear resistance make WC-Co a preferred material for manufacturing of tools, dies, and molds, etc. All such applications require complex shapes to be machined including curved features. The present study is carried out to evaluate the potential of wire electric discharge machining (WEDM) to fabricate concave and convex curved profiles of different radii in WC-Co. Taguchi design of experiments technique has been employed to investigate the influence of six control variables including open circuit voltage, pulse-on time, pulse-off time, servo voltage, wire tension, and dielectric pressure, on two response characteristics namely radius of concave profile and radius of convex profile. The analysis of variance (ANOVA) has been performed to identify the significant parameters affecting the performance measures. Regression models have also been developed for both profiles to predict the radii of curved profiles against any combination of machining parameters. It has been observed that machining performance in terms of overcut and undercut depends on the geometry to be machined. However, proposed combinations of machining parameters could effectively reduce undercut/overcut of the profiles to 10 mu m. Moreover, scanning electron microscopy has been performed in order to visualize recast layer, micro-cracks, and micro-chipping caused by WEDM process.