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Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition

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A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D：Materials and Processing".

Deadline for manuscript submissions: 31 July 2024 | Viewed by 8609

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Dr. Irene Fassi

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Guest Editor

Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, National Research Council (STIIMA-CNR), 13900 Bari, Italy
Interests: micro manufacturing; micro robotics; micro assembly; micro EDM; micro injection molding
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Dr. Francesco Modica

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Guest Editor

Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, National Research Council, 70124 Bari, Italy
Interests: micro EDM; micro manufacturing; additive manufacturing; virtual prototyping
Special Issues, Collections and Topics in MDPI journals

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Dear Colleagues,

Micro Electrical Discharge Machining (micro-EDM) is a thermo-electric and contactless process most suited for micro-manufacturing and high-precision machining, especially when difficult-to-cut materials, such as super alloys, composites, and electro conductive ceramics, are processed. Among the various micro-machining processes, micro-EDM is known to have many industrial applications, such as high-aspect-ratio micro holes for fuel injectors, high-precision moulds, and biomedical components. The main issues restricting the application of micro-EDM involve handling and fixturing, electrode and workpiece preparation, process parameter optimization, the identification and minimization of source of errors as tool wear, and measurement issues.

In the recent past, numerous EDM systems have been developed for performing micro- and nano-scale EDM. These systems use newer control strategies and optimization methodologies to perform the EDM processes.

This Special Issue pursues contributions (research papers, communications, and review articles) that focus on recent developments in micro-EDM machining. Topics of interest include but are not limited to the following:

Process mechanism modeling and simulation;
Process monitoring and control;
Parameters optimization;
Tool wear management;
Novel machine concept;
New material processing;
Dielectrics;
High-aspect-ratio features and surface texturing;
Hybrid machining;
New application of micro-EDM process.

We look forward to receiving your submissions.

Dr. Irene Fassi
Dr. Francesco Modica
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

micro EDM
parameters optimization
process simulation
tool wear
difficult-to-cut material

Related Special Issues

Micro-Electro Discharge Machining: Principles, Recent Advancements and Applications in Micromachines (14 articles)
Micro-Electro Discharge Machining: Principles, Recent Advancements and Applications, Volume II in Micromachines (11 articles)

Published Papers (9 papers)

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Research

13 pages, 9140 KiB

Open AccessArticle

Comparative Study of Ultrasonic Vibration-Assisted Die-Sinking Micro-Electrical Discharge Machining on Polycrystalline Diamond and Titanium

by Cheng Guo, Longhui Luo, Zhiqiang Liang, Hao Li, Xiawen Wang and Bin Xu

Micromachines 2024, 15(4), 434; https://doi.org/10.3390/mi15040434 - 25 Mar 2024

Viewed by 593

Abstract

Die-sinking micro-electrical discharge machining (micro-EDM) is a potential method used to fabricate intricate structures without complex electrode motion planning and compensation. However, machining efficiency and poor discharge states are still bottlenecks. This study conducted a comparative investigation into the impact of ultrasonic vibration on die-sinking micro-EDM of polycrystalline diamond (PCD) and pure titanium (TA2). By adjusting discharge parameters, this study systematically evaluated the influence of ultrasonic vibration on these two materials based on discharge waveforms, motion trajectories, effective discharge counts and groove profiles. At an open-circuit voltage of 100 V, ultrasonic vibration promotes die-sinking micro-EDM of PCD. However, when the open-circuit voltage increases to 200 V, ultrasonic vibration exhibits inhibitory effects in general. Conversely, for TA2, ultrasonic vibration shows a promoting effect at both voltages, indicating the differences of ultrasonic vibration-assisted die-sinking micro-EDM on PCD and TA2. For PCD, ultrasonic cavitation improves the discharge gap environment, accelerating the removal of discharge debris. For TA2, due to its poor thermal conductivity, ultrasonic cavitation acts to break the arc, accelerating heat transfer. These research findings provide guidance for ultrasonic vibration-assisted die-sinking micro-EDM in industrial applications. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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21 pages, 3585 KiB

Open AccessArticle

Simulation and Optimization of Surface Roughness and Process Performance during Machining of HSS by Micro-WEDM Technology

by Ľuboslav Straka and Ivan Čorný

Micromachines 2024, 15(3), 372; https://doi.org/10.3390/mi15030372 - 09 Mar 2024

Viewed by 667

Abstract

When machining high-speed steels (HSS) with micro-wire electrical discharge machining (micro-WEDM), high surface quality is achieved as standard. The value of the roughness parameter Ra is less than 0.2 μm. However, the problem is the performance of the electroerosion process (MRR), which is low. This problem is related to the mechanical and physical properties of the HSS in combination with the setting of the main technological parameters (MTP). The proposed solution to eliminate this problem relies on the selection of proper procedures for the determination of optimization criteria in relation to Ra and MTP, with the inclusion of properties of the machined material. The solution consisted in the identification of four significant physical (ρ, κ) and mechanical (Rm, HRC) indicators of HSS properties, on the basis of which a suitable combination of the process output parameters Ra and MRR can be determined through established mathematical regression models using simulation and optimization. In the next step, the proper values of the MTP output process parameter settings, which correspond to the optimized output parameters Ra and MRR during machining of HSS by micro-WEDM technology, were then obtained by the same approach. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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15 pages, 6217 KiB

Open AccessArticle

How the Electrical Conductivity of Water Fluids Affects Micro-EDM in the Short-Pulse Regime

by Valeria Marrocco, Francesco Modica, Vincenzo Bellantone, Marcello Valori and Irene Fassi

Micromachines 2024, 15(2), 266; https://doi.org/10.3390/mi15020266 - 13 Feb 2024

Viewed by 864

Abstract

This work investigates micro-electro discharge machining (EDM) performance involving deionized and tap water. The chosen machining regime was semi-finishing, where open voltage (from 100 to 130 V) and current values (5–10 A) were applied using a 0.5 µs pulse-on time and a frequency of 150 kHz, i.e., a duty cycle of 25%. First, numerical analyses were performed via COMSOL Multiphysics and used to estimate the plasma channel distribution and melted material, varying the current, sparking gap, electrical conductivity, and permittivity of the two fluids. Then, experimentally, the micro-EDM of holes and channels in hardened thin steel plates were replicated three times for each considered fluid. The material removal rate (MRR), tool wear ratio (TWR), radius overcut, and surface roughness were plotted as a function of open voltage and electrical conductivity. The study proves that as voltage and current increase, the MRR and TWR decrease with electrical conductivity. Nonetheless, for higher electrical conductivity (tap water), the process did not proceed for lower open voltages and currents, and the radius overcut was reduced, contrary to what is commonly acknowledged. Finally, the crater morphology and size were evaluated using a confocal microscope and compared to simulated outcomes. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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21 pages, 17190 KiB

Open AccessArticle

Research on Geometric Constraint Strategies for Controlling the Diameter of Micro-Shafts Manufactured via Wire Electric Discharge Grinding

by Jianyu Jia, Zan Li, Bo Hu, Yanqing Wang, Jing Wang, Congbo Li and Wenfeng Xiang

Micromachines 2023, 14(12), 2178; https://doi.org/10.3390/mi14122178 - 29 Nov 2023

Viewed by 605

Abstract

Micro-tools comprising difficult-to-machine materials have seen widespread application in micro-manufacturing to satisfy the demands of micro-part processing and micro-device development. Taking micro-shafts as an example, the related developmental technology, based on wire electric discharge grinding (WEDG) as the core method, is one of the key technologies used to prepare high-precision micro-shafts. To enable efficient and high-precision machining of micro-shafts with target diameters, instead of performing multiple repeated on-machine measurements and reprocessing, a geometric constraint strategy is proposed based on the previously introduced twin-mirroring-wire tangential feed electrical discharge grinding (TMTF-WEDG). This strategy encompasses the tool setting method, tangential feed distance compensation, and an equation that establishes the relationship between tangential distance and diameter variation. These components are derived from a key points analysis of the geometric constraints. The micro-shafts with diameters of 50 µm and consistencies of ±1.5 µm are repeatedly processed. A series of micro-shafts with diameters ranging from 30 µm to 120 µm achieve geometric constraints with a diameter accuracy of ±2 µm, accompanied by the complete continuous automation of the entire process. Accordingly, it can be concluded that the geometric constraint strategy is flexible and stable and can be controlled with high precision in the TMTF-WEDG process. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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12 pages, 5683 KiB

Open AccessArticle

Investigation of Machining Characteristics in Electrical Discharge Machining Using a Slotted Electrode with Internal Flushing

by Minghao Gao, Ming Liu, Jianqing Han and Qinhe Zhang

Micromachines 2023, 14(11), 1989; https://doi.org/10.3390/mi14111989 - 27 Oct 2023

Viewed by 791

Abstract

In die-sinking electrical discharge machining (EDM), it is challenging to implement internal flushing, mainly because it is easy to produce residual material columns on the workpiece cavity’s bottom surface, affecting the processing quality and efficiency. In order to solve this problem, the internal flushing slotted electrode EDM technology was proposed. The slotted electrode was designed, and its preparation method was described. The influence of pulse width, pulse interval, and flushing pressure on the performance of the internal flushing slotted electrode EDM was studied using single-factor experiments. The experimental results indicate that, with the increase in pulse width, the material removal rate (MRR) increases first and then decreases, while the electrode wear rate (EWR) and the relative electrode wear rate (REWR) decrease gradually; with the increase in pulse interval, the MRR decreases, while the EWR and the REWR increase gradually; with the increase in flushing pressure, the MRR increases first and then decreases, while the EWR and the REWR increase gradually. When the slotted electrode is used for continuous internal flushing EDM, the appropriate pulse width, flushing pressure, and smaller pulse interval can improve the MRR and reduce the EWR and the REWR. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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16 pages, 5369 KiB

Open AccessArticle

Mechanism Analysis of Discharge Energy in the Electrostatic-Field-Induced Electrolyte Jet Micro-EDM

by Yaou Zhang, Xiangjun Yang, Qiang Gao, Jian Wang and Wansheng Zhao

Micromachines 2023, 14(10), 1919; https://doi.org/10.3390/mi14101919 - 10 Oct 2023

Cited by 1 | Viewed by 940

Abstract

The discharge energy determines the machining resolution, minimum processable feature size, and surface roughness, which makes it a hot research topic in the microelectrical discharge machining (EDM) field. In this paper, a kind of novel discharge-energy-generation method in micro-EDM is investigated. In this method, the opposite induced charges on the electrolyte jet and workpiece serve as the source of the discharge energy. The operating mechanism of this discharge energy is revealed by analyzing the equivalent discharge circuit. The unique discharge current and voltage between the electrolyte jet and the workpiece are sampled and investigated. In contrast with the pulsating energy in conventional EDM, this study shows that the direct current (DC) voltage source can automatically generate a continuously periodical pulsating discharge in the electrostatic-field-induced electrolyte jet (E-Jet) EDM process. After further analyzing the electric signals in a single discharge process, it can be found that the interelectrode voltage experienced a continuous sharp electric breakdown, a nearly unchanging process, and a fast exponential recharging process. The discharge frequency increases as the electrolyte concentration and interelectrode voltage increase but decreases as the interelectrode distance increases. The discharge energy per pulse increases with the increasing interelectrode distance and electrolyte concentration but with the decreasing interelectrode voltage. Finally, the electrostatic-field-induced discharge-energy generation and change mechanisms are revealed, which provides a feasible method for micro-EDM with continuous tiny pulsed energy only using the DC power supply. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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21 pages, 12255 KiB

Open AccessArticle

Study of the High-Efficiency Ejecting-Explosion EDM of SiCp/Al Composite

by Yu Liu, Jiawei Qu, Keguang Zhao, Xuanyuan Zhang and Shengfang Zhang

Micromachines 2023, 14(7), 1315; https://doi.org/10.3390/mi14071315 - 27 Jun 2023

Cited by 1 | Viewed by 926

Abstract

SiCp/Al composites have excellent physical properties and are widely used in aerospace and other fields. Because of their poor machinability, they are often machined by non-traditional machining methods such as electrical discharge machining (EDM). In the process of EDM, due to the “shielding” effect of the reinforced particles of SiC, the local ejection force is low during the processing process, and it is difficult to throw the reinforced particles smoothly, which ultimately leads to a low material removal rate and poor surface quality. In this paper, a high–low-voltage composite ejecting-explosion EDM power supply is developed to explore the explosive effect of reinforced particles in the ejecting-explosion EDM process and the unique process law of the explosion process. The experiment platform uses self-developed CNC machining machine tools based on an ejecting-explosive EDM power supply, and the influence of a detonation-increasing wave on the processing of SiCp/Al composites with different volume fractions was studied by changing four factors: the open-circuit voltage difference, pulse current difference, pulse phase difference, and pulse width difference of the back wave behind the step front. The material removal rate and surface roughness were measured. The research results showed that the material removal rate could be increased to 164.63%, and the material surface roughness could be increased to 30.03% by adjusting the high and low pulse current difference from 1 A to 8 A. When the voltage difference between high and low wave (HLW) pulses increases from 40 V to 120 V, the material removal rate can be increased to 150.39%, and the material surface roughness can be increased to 20.49%. The material removal rate increases with the increase in pulse phase difference and open-circuit voltage difference. With the increase in peak current difference and pulse width difference, the material removal rate becomes faster at first and then slower. The surface roughness of materials increases with the growth of open-circuit voltage difference, peak current difference, pulse width difference, and pulse phase difference. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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13 pages, 9042 KiB

Open AccessArticle

Study of Gas Film Characteristics in Electrochemical Discharge Machining and Their Effects on Discharge Energy Distribution

by Hao Liu and Adayi Xieeryazidan

Micromachines 2023, 14(5), 1079; https://doi.org/10.3390/mi14051079 - 20 May 2023

Cited by 3 | Viewed by 1087

Abstract

Glass is a hard and brittle insulating material that is widely used in optics, biomedicine, and microelectromechanical systems. The electrochemical discharge process, which involves an effective microfabrication technology for insulating hard and brittle materials, can be used to perform effective microstructural processing on glass. The gas film is the most important medium in this process, and its quality is an important factor in the formation of good surface microstructures. This study focuses on the gas film properties and their influence on the discharge energy distribution. In this study, a complete factorial design of experiments (DOE) was used, with three factors and three levels of voltage, duty cycle, and frequency as the influencing factors and gas film thickness as the response for the experimental study, to obtain the best combination of process parameters that would result in the best gas film quality. In addition, experiments and simulations of microhole processing on two types of glass, quartz glass and K9 optical glass, were conducted for the first time to characterize the discharge energy distribution of the gas film based on the radial overcut, depth-to-diameter ratio, and roundness error, and to analyze the gas film characteristics and their effects on the discharge energy distribution. The experimental results demonstrated the optimal combination of process parameters, at a voltage of 50 V, a frequency of 20 kHz and a duty cycle of 80%, that achieved a better gas film quality and a more uniform discharge energy distribution. A thin and stable gas film with a thickness of 189

μ

m was obtained with the optimal combination of parameters, which was 149

μ

m less than the extreme combination of parameters (60 V, 25 kHz, 60%). These studies resulted in an 81

μ

m reduction in radial overcut, a roundness error reduced by 14, and a 49% increase in the depth–shallow ratio for a microhole machined on quartz glass. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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10 pages, 7710 KiB

Open AccessArticle

Enhancing Wire-EDM Performance with Zinc-Coated Brass Wire Electrode and Ultrasonic Vibration

by Apiwat Muttamara and Patittar Nakwong

Micromachines 2023, 14(4), 862; https://doi.org/10.3390/mi14040862 - 16 Apr 2023

Cited by 3 | Viewed by 1497

Abstract

This study aimed to investigate the performance of zinc-coated brass wire in wire-cut electrical discharge machining (EDM) using an ultrasonic-assisted wire on tungsten carbide. The research focused on the effect of the wire electrode material on the material removal rate, surface roughness, and discharge waveform. Experimental results demonstrated that using ultrasonic vibration improved the material removal rate and reduced surface roughness compared to conventional wire-EDM. Cross-sectional SEM of the white layer and discharge waveform were investigated to explain the phenomena of ultrasonic vibration in the wire-cut EDM process. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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