Among the family of carbides, tungsten carbide (WC) and its variants have extensive use in numerous applications including cutting tools, dies, and many wear resistant parts. Such applications need machining of WC, which is famously considered as challenging due to high tool wear mainly in traditional machining. Sinking electric discharge machining (EDM) can be considered as a suitable alternate but the low machining rate of EDM, with conventional tool design, poses limitations. In this research, the conventional tool design is modified by providing relief angles to the tool electrodes. The relief-angled tool electrodes are first time introduced in this research to machine through holes. The role of the relief angle during EDM has been investigated in terms of six response characteristics, i.e., machining time, hole taper angle, radial overcut at the hole entrance, radial undercut at the hole exit, longitudinal tool wear, and roughness of inside hole surfaces. The performance of the relief-angled electrodes is found to be significantly better than the performance of conventional cylindrical tool. In addition to improvements in other responses, a 49% reduction in the machining time has been realized by the use of relief-angled electrode indicating a worthwhile contribution in the field of electric discharge machining.

Electric discharge machining (EDM) of tool steel (D2 grade) has been performed using different tool designs to produce through-holes. Machining performance has been gauged with reference to machining time, hole taper angle, overcut, and surface roughness. Inaccuracies and slow machining rate are considered as the most common limitations of the electric discharge machining (die-sinking). Traditionally, a cylindrical tool is used to form circular holes through EDM. In this study, the hole formation is carried out by changing the tool design which is the novelty of the research. Two-stage experimentation was performed. The newly designed tools substantially outperformed a traditional cylindrical tool, especially in terms of machining time. The main reason for the better machining results of modified tools is the sparking area that differs from the traditional sparking. Comparing against the performance of a traditional cylindrical tool, the newly designed tools offer a considerable reduction in the machining time, radial overcut, and roughness of the inside surfaces of machined holes, amounting to be approximately 50%, 30.6%, and 38.7%, respectively. The drop in the machining time along with a condensed level of radial overcut and surface roughness can shrink the EDM limitations and make the process relatively faster with low machining inaccuracies.

A low material removal rate and a high tool wear rate are two major concerns among the research and development community of electric-discharge machining. From the literature, it is evident that several researchers have attempted to improve the material removal rate and minimize the tool wear rate by different means, such as parametric optimizations, powder mixing in the dielectric, induced vibrations in the electrode and/or workpiece, etc. Herein, an attempt is made to make use of a non-conventional electrode with a relief angle along with the taper angle of the machined feature and perform electric-discharge machining on D2-steel using copper as an electrode material. Preliminary level mathematical models were developed and validated for sparking the area of each non-conventional electrode’s design type. Three-stage experimentation was performed to identify the most appropriate electrode design. An approximately 70% improvement in the material removal rate, an around 45–50% reduction in the tool wear rate, and a nearly 10% reduction in the taper angle were realized with the newly designed non-conventional electrode. Similarly, to validate the machining performance, the most appropriate identified electrode design was used for each workpiece of different thicknesses. The confirmatory experimental results revealed that the identified electrode design is not only limited to a specific workpiece thickness but is well-suited for varying workpiece thicknesses as well.

Manufacturing of dies, molds, and their allied components requires the machining of holes with different profiles. Electric discharge machining (EDM) die-sinking is a crucial process used in the dies and molds manufacturing industry. By nature, EDM die-sinking is a relatively slow process in terms of material removal rate (MRR) and there are high amounts of tool material loss in terms of tool wear rate (TWR) which directly influence dimensional accuracies and surface roughness (SR). Therefore, the process is continuously evolving to address these limitations. The present research is aligned in this direction such as to bring improvements in MRR, TWR, and SR through modifications to the conventional electrode design and its geometrical parameters. Traditional designs of EDM electrodes have a uniform cross-section through the tool’s entire length and have only one geometrical parameter, i.e., the tool’s cross-section. To improve the EDM performance, traditional designs are completely modified by introducing several geometrical parameters such as relief angles, land thickness, cross-sectional area, shank height, circular relief, and non-circular relief, etc. Electrode designs are employed to mill non-circular profiles including triangular, square, and hexagonal shaped holes. The EDM performance measures strongly depend on the tool’s geometrical parameters (design type, relief angle, land thickness), machining profile (circular, square, triangle, hexagon), as well as the height/depth of the machining feature. By selecting proper tool designs and corresponding geometrical parameters, the EDM performance measures can be improved significantly.

During laser milling, the objective is not always to maximize the material removal rate (MRR). Milling of new material with targeted MRR is challenging without prior knowledge and established sets of laser parameters. The laser milling performance has been evaluated for three important aerospace alloys, i.e., titanium alloy, nickel alloy and aluminum alloy using the response surface method experimental plan (54 experiments for each alloy). Parametric effects of five important laser parameters, statistical analysis (main effects, interaction effects, strength and direction of effects), mathematical modeling and optimality search is conducted for the said alloys. Under the non-optimized laser parameters, the actual MRR significantly varies from the targeted MRR. Variation in the aluminum alloy is at the top as compared to the other two alloys. Among other significant terms, three terms have the largest effect on MRR in the case of TiA, two terms in the case of NiA, and five terms in the case of AlA. Under the optimized sets of laser parameters, the actual material removal highly close to the desired level (100%) can be achieved with minimum variation in all the three alloys. Mathematical models proposed here have the capability to well predict material removal prior to the actual machining of Ti6Al4V, Inconel 718 and AA 2024.