Electrical discharge turning is a unique form of electrical discharge machining process, which is being especially developed to generate cylindrical forms and helical profiles on the difficult-to-machine materials at both macro and micro levels. A precise submerged rotating spindle as a work holding system was designed and added to a conventional electrical discharge machine to rotate the workpiece. A conductive preshaped strip of copper as a forming tool is fed (reciprocate) continuously against the rotating workpiece; thus, mirror image of the tool is formed on the circumference of the workpiece. The machining performance of electrical discharge turning process is defined and influenced by its machining parameters, which directly affects the quality of the machined component. This study presents an investigation on the effects of the machining parameters, namely, pulse-on time, peak current, gap voltage, spindle speed and flushing pressure, on the material removal rate (MRR) and surface roughness (Ra) in electrical discharge turning of titanium alloy Ti-6Al-4V. This has been done by means of Taguchi's design of experiment technique. Analysis of variance as well as regression analysis is performed on the experimental data. The signal-to-noise ratio analysis is employed to find the optimal condition. The experimental results indicate that peak current, gap voltage and pulse-on time are the most significant influencing parameters that contribute more than 90% to material removal rate. In the context of Ra, peak current and pulse-on time come up with more than 82% of contribution. Finally, the obtained predicted optimal results were verified experimentally. It was shown that the error values are all less than 6%, confirming the feasibility and effectiveness of the adopted approach.
Turning by electrical discharge machining is an emerging area of research. Generally, wire-cut electrical discharge machining is used for turning because it is not concerned with electrode tooling cost. The process variant die-sinking electrical discharge machining can also be effectively used to generate free-form cylindrical geometries on difficult-to-cut materials with complex shapes at both macro and micro levels. The machining performance of electric discharge machine is defined and influenced by its process parameters, which significantly affects production rate and the quality of machined component. Thus, it is very important to select machining parameters and their levels cautiously in order to improve the outcome of the process. In this article, the authors have reviewed the research work carried out in the area of electrical discharge turning in the last decade for the improvement of material removal rate, surface integrity and roundness. In this review, various techniques reported by electrical discharge machining researchers on turning have been categorised in different electrical discharge machining variants. The article also discussed the future direction of research work in the same area.
SummaryThis study presents a novel EDM turning process specially designed and developed to generate precise cylindrical forms on hard and difficult-to-machine materials. For this purpose, a specially designed turning spindle is used. The spindle was mounted on a conventional die-sinking EDM machine to rotate the workpiece. Axially symmetric parts can be manufactured by feeding the shaped tool into the rotating workpiece. In this way an axisymmetric workpiece can be made with small tools at both macro and micro levels. Effects of machining parameters, such as the current, pulse-on time, rotational speed, flushing pressure, and duty factor, on the surface roughness of Ti-6Al-4V alloy in electrical discharge turning were investigated. Taguchi's design of experiment technique was used. Analysis of variance and regression analysis were performed on experimental data. The signal-to-noise ratio analysis was employed to find the optimal condition.
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