Effect of deep cryogenic treatment on copper electrode for non-traditional electric discharge machining (EDM)

Abstract

Abstract. In the last few decades, non-traditional machining made the machining process easier than the traditional machining method. Electric discharge machining (EDM) is one of the most prominent methods of non-traditional machining processes. By the use of EDM, a complex profile and high hardness materials can be easily machined, which cannot easily be machined by the traditional machining method. EDM is widely used by the industries. This paper investigates an experiment with the cryogenically treated copper electrode and an ordinary copper electrode with various input parameters like the electrode rotation, gap voltage and discharge current for an EN24 (a high-strength and wear-resistant steel) material. An experiment was performed with electric discharge machining. Designs of an experiment are carried out using the Taguchi approach. An orthogonal L16 array prepared and used the different combination of the three input parameters (current, electrode rotation and gap voltage) to find an optimum value of the factors. The output factors are the overcut (OC), the tool wear rate (TWR) and surface roughness (Ra). The optimal level and importance levels of each of these parameters are obtained statically using an analysis-of-variance (ANOVA) table through the analysis of the S∕N ratio. The study also compares the theoretical and experimental values of the overcut, tool wear rate and surface roughness for traditional and non-traditional EDM. The following research finds optimal or dominating factors (current and rotational speed) for the TWR and Ra in both traditional and non-traditional electric discharge machining; moreover there was a reduction of approximately 9 % in overcut, 13.25 % in the tool wear rate and 15.75 % in surface roughness for the deep cryogenic and non-traditional machining process.