Analysis of over cut in electrical discharge machining of nickel-based alloy using Taguchi approach

Electrical discharge machining (EDM) has recently become popular in manufacturing industries but numerous issues are associated with it like recast layer, surface roughness, and overcut (OC) that result in poor quality and rejection by customers. To overcome these issues, manufacturers are looking for precise methods of machining. In this line, current study aims to investigate the effect of machining input characteristics upon OC during machining of nickel-based alloy, i.e., Inconel 718 by means of EDM. This will help in reduction of OC and improvement in precision. Test experiments were designed as per Taguchi's DOE approach and conducted by varying different machining input characteristics namely tool diameter discharge current, pulse-on time, pulse-off time tool rotation and depth of hole. Rotary copper tool electrode is used as the drilling tool. Microstructure of drilled hole over the work piece is observed and distinguished through scanning electron microscopy (SEM) images and same was used for OC measurement. Further analysis of variance has been applied for discovering optimum factors for minimum OC. It can be concluded from the test results that discharge current and pulse on time are most influencing factors affecting OC. This study will help the industry to improve precision in manufacturing which can enhance the quality of products.