Reducing the geometrical machining errors incurred during die repair and maintenance through electric discharge machining (EDM)

Abstract

The importance of geometrical accuracy can never be overruled in dies and molds which governs the dimensional precision of the parts being manufactured. The continuous use of such tooling requires repair and maintenance. Among the different processes used to upkeep the dimensional consistency of the tooling, machining is essentially required in most cases. The intricacy of the dies and molds’ cavities requires the use of electric discharge machining (EDM). However, in EDM it is challenging to develop control over the machined dimensions owing to the inherent issues of overcut/undercut. This aspect was not comprehensively investigated so far which is the core focus of this research. Three electrode materials, namely, copper, graphite, and tungsten carbide, which belong to the category of metals, nonmetals, and ceramics, respectively, have been compared for the said perspective on the comprehensive list of parametric variables. The results revealed that the average value of the axial errors is 2.5 times lesser in comparison to lateral dimensional errors. In the case of lateral dimensional errors, the electrode of graphite has proved to be a promising choice in comparison to the other two types of electrode materials, namely, copper and tungsten carbide. The copper electrode is noticed to be the most appealing option for reducing axial error (A.E). The mean A.E obtained with Cu electrode is 80.9% and 47.6% lower than that achieved in case graphite and tungsten carbide, respectively. Furthermore, the optimal parametric combination based on 7 variables has also been proposed using desirability analyses whose validity is proved during confirmation trials.

Electric Discharge Machining of Ti6Al4V ELI in Biomedical Industry: Parametric Analysis of Surface Functionalization and Tribological Characterization

“…Various parametric-analysis-based approaches have been used to improve the process conditions. For instance, Ehsan et al [ 12 ] used grey relational analysis, Rafaqat et al [ 13 ] used objective compromise, Sharma et al [ 14 ] used ANFIS, and Ishfaq et al [ 15 ] used the desirability function. Recently, much focus has been shifted towards black box models, which accurately model complex processes with multiphysics problems.…”

“…The process settings and operating conditions determine the thickness of the reformed layer. For instance, the dielectric effect resulted in substantial carbon diffusion into the reformed layer during its production and solidification in the case of hydrocarbon as compared with deionized water [ 15 ]. Moreover, Ti6Al4V can generate thick oxide layers which merge with the recast layer formed during machining, providing an extra benefit for developing new surface layers.…”

A Novel Electrode Front-End Face Design to Improve Geometric Accuracy in Electrical Discharge Machining Process

“…They employed analysis of variance (ANOVA) to assess the significance of each process parameter on the MRR, TWR, and surface quality when different type of electrodes were employed. Ishfaq et al [23] investigated three types of electrode material, namely, copper, graphite, and tungsten carbide, which are metals, nonmetals, and ceramics, respectively, and they were compared for their performance in relation to different parameters. The results indicate that the axial errors are 2.5 times less than lateral dimensional errors.…”

A Novel Flushing Mechanism to Minimize Roughness and Dimensional Errors during Wire Electric Discharge Machining of Complex Profiles on Inconel 718

“…In this regard, different electrode materials and process optimization methodologies are opted to enhance surface integrity, reduce spark gap, and minimize dimensional errors, which are current limitations of the process. Ishfaq et al [ 17 ] machined AISI D2 material to reduce geometrical machining errors incurred during die repair and maintenance. Maher et al [ 18 ] highlighted challenges such as longer unattended operation periods, thicker workpieces, high taper angles, and complex profiles.…”