Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2022 Dec 31;14(1):115.
doi: 10.3390/mi14010115.

Functional Surface Generation by EDM-A Review

Muhammad Abdun Nafi  1 , Muhammad Pervej Jahan  1
Affiliations
Review

Functional Surface Generation by EDM-A Review

Muhammad Abdun Nafi et al. Micromachines (Basel). .

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.

Keywords: EDM; biocompatibility; corrosion performance; electro-discharge coating; surface modification; tribological properties.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Number of papers considered in this study with publication years.
Figure 2
Figure 2
The layers formed over (a) Ti-6Al-4V [14] and (b) 55NiCrMoV7 [15] after EDM processing. (With kind permission from the respective publications).
Figure 3
Figure 3
Amount of S. aureus bacteria on a Ti-6Al-4V surface, machined using (a) 0%, (b) 3.78%, (c) 5.15%, and (d) 9.61% silver on the dielectric fluid [39]. (With kind permission from Elsevier).
Figure 4
Figure 4
Scars produced due to corrosion in the (a) Ti-6Al-4V alloy, (b) ESA in air, (c) ESA in N2, and (d) ESA in silicone oil [44]. (With kind permission from Elsevier).
Figure 5
Figure 5
Types of EDM processes reviewed in this study.
Figure 6
Figure 6
Types of electrodes used in different EDM processes.
Figure 7
Figure 7
Types of powders used in different EDM processes covered in this study.
Figure 8
Figure 8
Surfaces of machined SiCp/Al composite obtained by (a) conventional EDM and (b) powder-mixed EDM [53]. (With kind permission from Elsevier).
Figure 9
Figure 9
Variation of machined H13 surfaces achieved by (a) conventional EDM process and (b) powder-mixed EDM by using electrodes with an area of 32 cm2 [54]. (With kind permission from Elsevier).
Figure 10
Figure 10
The change in the recast layer thickness with the change in aluminum powder particle size and powder concentration [55]. (With kind permission from Elsevier).
Figure 11
Figure 11
Change in the CoF with sliding distance. (a) AISI H13 steel; (b) H13 + SM-SEDM]; (c) H13 + SM-SEDM + TiAlN; (d) H13 + SM-SEDM + SR + TiAlN [90]. (With kind permission from Elsevier).
Figure 12
Figure 12
Change in the coefficient of friction (CoF) with the sliding distance for different samples of (a) cemented carbides and (b) ZrO2 based composites [91]. (With kind permission from Elsevier).
Figure 13
Figure 13
SEM images that represent the surfaces of tungsten carbide produced by (a) EDM and (b) EDC [87]. (With kind permission from Elsevier).
Figure 14
Figure 14
EDS analysis of machined Ti-6Al-4V alloy when Cu-SiC electrode was used at current = 1.5 A, pulse on-time = 15 µs, and pulse off-time = 15 µs [68]. (With kind permission from Elsevier).
Figure 15
Figure 15
XRD patterns when EDM was conducted on Ti-6Al-4V alloy: (a) using Cu electrode at current = 1.5 A, pulse on-time= 15 µs, and pulse off-time = 15 µs; (b) using Cu-SiC electrode at current = 1.5 A, pulse on-time = 15 µs, and pulse off-time = 15 µs [68]. (With kind permission from Elsevier).
Figure 16
Figure 16
Schematic diagram representing the mechanism of the EDC process [112]. (With kind permission from Elsevier).
Figure 17
Figure 17
Cell counting performed on the treated and EDMed Fe-Al-Mn alloy [122]. (With kind permission from Elsevier).
Figure 18
Figure 18
SEM images of the untreated and EDMed Fe-Al-Mn alloys at different culture times: (a,b) 8 h, (c,d) 24 h, and (e,f) 48 h [122]. (With kind permission from Elsevier).
Figure 19
Figure 19
MG-63 cells attachment and proliferation after 7 days of cell culturing on the (A) untreated Ti64 specimen, (B) EDMed Ti64 specimen at 10 s pulse on-time, and (C) EDMed Ti64 specimen at 60 s pulse on-time [123]. (With kind permission from Elsevier).
Figure 20
Figure 20
SEM micrographs showing the attachment of MG-63 cells on (a) conventionally machined surface and (b–e) samples prepared by WEDM by different parameters [43]. (With kind permission from Elsevier).
Figure 21
Figure 21
A comparison of the time-dependent coefficient of friction of the as-polished substrate and the coated and EDMed samples at various loads: (a,b) HSS substrate and (c,d) 304 SS substrate [130]. (With kind permission from Elsevier).
Figure 22
Figure 22
Change in wear rate with respect to the peak current and duty factor when the TiC-TiB2-coated Ti alloy experienced the ball-on-disc sliding wear test [85]. (With kind permission from Elsevier).
Figure 23
Figure 23
Coated alloy after wear at (a) room temperature, (b) 100 °C, (c) 200 °C, (d) 300 °C, and (e) 400 °C [131]. (With kind permission from Elsevier).
Figure 24
Figure 24
SEM images showing the wear tracks of 304 stainless steel coated by Si, TiC, TiC + Si, and Cu [132]. (With kind permission from Elsevier).
Figure 25
Figure 25
SEM micrograph of the BB-EDC treated β-phase Ti alloy surface [133]. (With kind permission from Elsevier).
Figure 26
Figure 26
(a–c) Alternating energy electrical discharge machining (AE-EDM) process [136]. (With kind permission from Elsevier).
Figure 27
Figure 27
SEM images showing micro-holes produced in AlN by the micro-EDM process [137]. (With kind permission from Springer).
Figure 28
Figure 28
Contribution of EDM in different applications (found in different publications reviewed in this study).
Figure 29
Figure 29
Types of dielectric fluids used in EDM processes (found in different publications reviewed in this study).
See this image and copyright information in PMC

References

    1. Ho K.H., Newmann S.T. State of the art electrical discharge machining (EDM) Int. J. Mach. Tools Manuf. 2003;43:1287–1300. doi: 10.1016/S0890-6955(03)00162-7. - DOI
    1. Ramasawmy H., Blunt L. Effect of EDM process parameters on 3D surface topography. J. Mater. Process. Technol. 2004;148:155–164. doi: 10.1016/S0924-0136(03)00652-6. - DOI
    1. Gentili E., Tabaglio L., Aggogeri F. Review on micromachining techniques. Courses Lect. Int. Cent. Mech. Sci. 2005;486:387–396.
    1. McGeough J.A., Rasmussen H. A macroscopic model of electro-discharge machining. Int. J. Mach. Tool Des. Res. 1982;22:333–339. doi: 10.1016/0020-7357(82)90010-5. - DOI
    1. Schumacher B.M. After 60 years of EDM the discharge process remains still disputed. J. Mater. Process. Technol. 2004;149:376–381. doi: 10.1016/j.jmatprotec.2003.11.060. - DOI