Experimental Investigation on Tool Electrode Wear Rate and Radial Overcut in Electric Discharge Drilling of NiTiCu Shape Memory Alloy

Tool wear, accuracy and precision are the key parameters in the hole fabrication process. Machining cost is directly affected by tool wear, particularly during machining of difficult-tomachine materials such as NiTiCu shape memory alloy (SMA). Electric discharge drilling (EDD) provides an effective alternative for producing holes in advanced materials. In this study, copper (Cu) and copper-tungsten (CuW) tool electrodes were used for EDD of NiTiCu shape memory alloy (SMA). The experiments were performed using a Taguchi L18 orthogonal array. Analysis of variance was employed to investigate the effects of the process parameters on the tool electrode wear rate (TEWR) and radial overcut (ROC). The most significant process parameters for TEWR and ROC were pulse current (Ip) and tool electrode material (TEM), with contributions of 35.69 % and 25.74%, respectively. Furthermore, scanning electron microscopy and X-ray diffraction were conducted to investigate the surface morphology and phase characteristics of machined samples. It was noticed that machined surfaces contain surface microcracks, debris, and the formation of some compounds. The microhardness of machined surfaces was improved from 385 to 530 and 570 Hv for Cu and CuW tool electrodes, respectively.