Functional Surface Generation by EDM—A Review

Abstract

Electro-discharge machining (EDM) removes electrically conductive materials by high frequency spark discharges between the tool electrode and the workpiece in the presence of a dielectric liquid. Being an electrothermal process and with melting and evaporation being the mechanisms of material removal, EDM suffers from migration of materials between the tool and the workpiece. Although unwanted surface modification was considered a challenge in the past for many applications, this inherent nature of the EDM process has recently become of interest to the scientific community. As a result, researchers have been focusing on using the EDM process for surface modification and coating by targeted surface engineering. In order to engineer a surface or generate functional coatings using the electro-discharge process, proper knowledge of the EDM process and science of electro-discharge surface modification must be understood. This paper aims to provide an overview of the electro-discharge surface modification and coating processes, thus assisting the readers on exploring potential applications of EDM-based techniques of surface engineering and coating generation. This review starts with a brief introduction to the EDM process, the physics behind the EDM process, and the science of the surface modification process in EDM. The paper then discusses the reasons and purposes of surface modification and coating practices. The common EDM-based techniques reported in the literature for producing coatings on the surface are discussed with their process mechanisms, important parameters, and design considerations. The characterization techniques used for the analysis of modified surfaces and coating layers, as well as the tribological and surface properties of modified surfaces or coatings are discussed. Some of the important applications of EDM-based surface modification and coating processes are generating surfaces for protective coating, for aesthetic purposes, for enhancing the biocompatibility of implants, for improving corrosion resistance, for improving wear resistance, and for improving tribological performance. The current state of the research in these application areas is discussed with examples. Finally, suggestions are provided on future research directions and innovative potential new applications of the electro-discharge-based surface engineering and coating processes.

Comparative performance investigation and sustainability assessment in electrical discharge machining of SS316 using different dielectrics

“…Hard carbide phases such as Cr 3 C 2 , Ni 3 C, Mn 3 C, Mo 2 C, Fe 3 C may be exist in the recast layer, contributing to enhanced hardness of the machined surfaces. 43 In addition, melting the work and tool materials and then rapidly cooling by dielectric generates metastable structures following a non-equilibrium phase transformation might lead to an increase in hardness. 44 The higher machined surface hardness under palm oil because of its increased thermal conductivity, which led to a quenched surface, and its higher viscosity, which allowed for efficient flushing for debris evacuation and ensured a minimum solidification time for debris re-solidification.…”

Recent Trends and Developments in the Electrical Discharge Machining Industry: A Review

“…Figure 1 summarizes the technology development identified in our comprehensive review. However, the widespread adoption and advancement of EDM is primarily driven by its diverse applications, ranging from micromachines to biomedicine and spanning various industries such as aviation and shipbuilding [17,23,32,63].…”

Inducing hydrophobicity in Stainless Steel 304 by mechanical texturing and chemical functionalization

“…Shirsath et al [16] studied the effect of laser and wire EDM texturing and conclude that wire EDM is capable for pillar formation, which enhance the hydrophobicity. Electrical Discharge Machining (EDM) is a versatile manufacturing method that uses electric discharges between a wire electrode and a conductive workpiece to precisely remove material and create intricate shapes [23,24]. It's suitable for both mass production and precision machining, making it valuable in modern manufacturing where high-volume output and precision are needed.…”