Improving Electrical Discharge Machining Process for Bodies of Rotation

In modern mechanical engineering, electrical discharge machining (EDM) methods are widely used for machining bodies of rotation from difficult-to-machine materials. Those methods ensure sparing cutting and make it possible to machine any electrically conductive material irrespective of its physical and chemical properties, in particular hardness. There is a known method for dimensional machining of bodies of rotation with electric arc using a wire electrode tool that is pulled along in the machining area thus "compensating" for that tool's EDM wear and tear. The machining accuracy is therefore significantly heightened. However, when implementing this method, an effect of splashing the working fluid outside the working area of the machine and a pronounced luminous effect from the burning of the electric arc in the machining area are observed. That worsens the working conditions. In addition, when pulling the wire electrode tool along the convex surface of the electrode holder, the sliding friction arises, which eventually leads to mechanical destruction of the contact point. As a result, a deep kerf is formed on the electrode holder. When the depth of the kerf reaches the diameter of the wire electrode tool, the destruction of the electrode holder by the electric arc begins. Consequently, the durability of the electrode holder in the known method is unsatisfactory. A method of dimensional machining of bodies of rotation with electric arc using a wire electrode tool with the immersion of the machining area in the working fluid has been proposed, which makes it possible to improve the working conditions of the operator by eliminating the effect of fluid splashing and removing the luminous effect of arc burning in the machining area. In addition, it has been proposed to make the electrode holder in the form of a roller that rotates with a guide groove for the wire electrode tool, while the nozzle for creating the transverse hydrodynamic fluid flow has been proposed to be mounted in a separate fixed housing that is adjacent to the electrode holder. This technical solution replaces the sliding friction with the rolling one thus enhancing the durability of the electrode holder. Mathematical models of the process characteristics of the DMA-process (dimensional machining with electric arc) for bodies of rotation using a wire electrode tool with the immersion of the machining area in the working fluid have been obtained that make it possible to control the machining productivity, the specific machining productivity, the specific electric power consumption, and the roughness of the surface machined.

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Wire Electrical Discharge Machining—A Review

Machines ◽

10.3390/machines8040069 ◽

2020 ◽

Vol 8 (4) ◽

pp. 69

Author(s):

Laurenţiu Slătineanu ◽

Oana Dodun ◽

Margareta Coteaţă ◽

Gheorghe Nagîţ ◽

Irina Beşliu Băncescu ◽

...

Keyword(s):

Electrical Discharge ◽

Electrical Discharge Machining ◽

Machining Process ◽

Wire Electrical Discharge Machining ◽

Wire Electrode ◽

Machining Processes ◽

Scientific Papers ◽

The Wire ◽

Machining Productivity ◽

Machined Surfaces

Wire electrical discharge machining has appeared mainly in response to the need for detachment with sufficiently high accuracy of parts of plate-type workpieces. The improvements introduced later allowed the extension of this machining technology to obtain more complex ruled surfaces with increasingly high requirements regarding the quality of the machined surfaces and the productivity of the wire electrical discharge machining process. Therefore, it was normal for researchers to be interested in developing more and more in-depth investigations into the various aspects of wire electrical discharge machining. These studies focused first on improving the machining equipment, wire electrodes, and the devices used to position the clamping of a wire electrode and workpiece. A second objective pursued was determining the most suitable conditions for developing the machining process for certain proper situations. As output parameters, the machining productivity, the accuracy, and roughness of the machined surfaces, the wear of the wire electrode, and the changes generated in the surface layer obtained by machining were taken into account. There is a large number of scientific papers that have addressed issues related to wire electrical discharge machining. The authors aimed to reveal the aspects that characterize the process, phenomena, performances, and evolution trends specific to the wire electrical discharge machining processes, as they result from scientific works published mainly in the last two decades.

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Study on Surface Evenness of Super-high-thickness Cutting in High-speed Wire Electrical Discharge Machining

10.21203/rs.3.rs-312872/v1 ◽

2021 ◽

Author(s):

Cong Deng ◽

Zhidong Liu ◽

Ming Zhang ◽

Hongwei Pan ◽

Mingbo Qiu

Keyword(s):

Electrical Discharge ◽

High Speed ◽

Electrical Discharge Machining ◽

Point Of View ◽

Working Fluid ◽

Wire Electrical Discharge Machining ◽

Wire Electrode ◽

Positional Accuracy ◽

Vibration Absorption ◽

The Wire

Abstract Surface machined by high-speed wire electrical discharge machining (HS-WEDM) at super-high thickness (more than 1000 mm) cutting suffers from uneven surface, a major problem that has been investigated in this paper. According to the analysis, as wire frame span increases, the rigidity of the wire electrode decreases, and under the action of discharge explosive force, wire electrode vibration intensifies. As a result, the machining stability inevitably decreases. However, the core problem is whether there is enough working fluid in the slit to dampen and absorb the vibration of the wire electrode so as to ensure the positional stability of the wire electrode. To verify the above point of view: first, the wire guide and gravity take-up with bidirectional tension in the wire feeding system were installed to improve the positional accuracy of the wire electrode; second, to improve the flow of the working fluid into the slit, the slit width was increased by improving the working fluid and a medium carrier with a higher melting point and vaporization point can reduce the vaporization of the working fluid in the slit as much as possible. The experiment showed that the outlet flow of the improved working fluid is 56.72% higher than that of the original working fluid when cutting a 750 mm thick workpiece, which increases the damping and vibration absorption effect of the working fluid on the wire electrode in the long and narrow gap. After the above measures were implemented, super-high thickness cutting can be carried out continuously and steadily, the surface evenness was significantly improved, and the workpiece with a thickness of 2000 mm was cut successfully.

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Influence of Energy Parameters of Micro WEDM on Kerf

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.576.527 ◽

2012 ◽

Vol 576 ◽

pp. 527-530

Author(s):

Mohammad Yeakub Ali ◽

W.Y.H. Liew ◽

S.A. Gure ◽

B. Asfana

Keyword(s):

Experimental Data ◽

Electrical Discharge ◽

Electrical Discharge Machining ◽

Kerf Width ◽

Wire Electrical Discharge Machining ◽

Machining Parameters ◽

Wire Electrode ◽

Wire Vibration ◽

The Wire ◽

Micro Wedm

This paper presents the estimation of kerf width in micro wire electrical discharge machining (micro WEDM) in terms of machining parameters of capacitance and gap voltage. An empirical model is developed by the analysis of variance (ANOVA) of experimental data. Using a wire electrode of 70 µm diameter, a minimum kerf width is found to be 92 µm for the micro WEDM parameters of 0.01 µF capacitance and 90.25 V gap voltage. Around 30% increament of the kerf is found to be high. The analysis also revealed that the capacitance is more influential parameter than gap voltage on kerf width produced by micro WEDM. As the gap voltage determines the breakdown distance and affects the wire vibration, the wire vibration factor is to be considered in the analysis and in formulation of model in future study.

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Modeling and Simulation of Wire Electrode Deflection in WEDM

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.541-542.708 ◽

2014 ◽

Vol 541-542 ◽

pp. 708-712

Author(s):

Zhi Chen ◽

He Li ◽

Yu Huang ◽

Zhen Zhang

Keyword(s):

Modeling And Simulation ◽

Electrical Discharge Machining ◽

Negative Impact ◽

Electrostatic Force ◽

Simulation Method ◽

Impact Factors ◽

Machining Accuracy ◽

Wire Electrode ◽

The Wire ◽

Wire Deflection

In the process of wire electrical discharge machining, the wire electrode inevitably suffers bending deformation due to wire tension, electrostatic force, electrodynamics force, etc., and the deflection would make an clearly negative impact upon the machining accuracy, productivity and stability. In this paper, first of all, a novel modeling and simulation method is proposed for quantitatively calculating the wire deflection. Secondly, the mainly impact factors and trend of wire deflection have been concluded. Moreover, the feasibility of the model is proved by comparing with other researchers models. Eventually, the practical approaches of reducing wire deflection and improving the machining accuracy have been proposed.

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Dynamic Response of the Wire Electrode in Electrical Discharge Machining Under Continuous Discharge Forces

Journal for Manufacturing Science and Production ◽

10.1515/ijmsp.1998.1.3.209 ◽

1998 ◽

Vol 1 (3) ◽

pp. 209-218

Author(s):

T.M. Yue, ◽

Z.N. Guo, ◽

T.C. Lee, ◽

W.S. Lau,

Keyword(s):

Dynamic Response ◽

Electrical Discharge ◽

Electrical Discharge Machining ◽

Wire Electrode ◽

The Wire ◽

Continuous Discharge

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Combination of capacitance and conductive working fluid to speed up the fabrication of a narrow, deep hole in electrical discharge machining using a dielectric-encased wire electrode

International Journal of Machine Tools and Manufacture ◽

10.1016/j.ijmachtools.2005.09.001 ◽

2006 ◽

Vol 46 (12-13) ◽

pp. 1536-1546 ◽

Cited By ~ 4

Author(s):

Seiji Kumagai ◽

Naoki Sato ◽

Koichi Takeda

Keyword(s):

Electrical Discharge ◽

Electrical Discharge Machining ◽

Working Fluid ◽

Wire Electrode ◽

Deep Hole ◽

Speed Up

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Automatic Stripping of Dielectric-Encased Wire Tool Electrode Used in Electrical Discharge Machining

Journal of Manufacturing Science and Engineering ◽

10.1115/1.2738541 ◽

2007 ◽

Vol 129 (5) ◽

pp. 973-978

Author(s):

Seiji Kumagai ◽

Naoki Sato ◽

Koichi Takeda

Keyword(s):

Control System ◽

Electrical Discharge ◽

Electrical Discharge Machining ◽

Threshold Value ◽

Electrode System ◽

Tool Electrode ◽

Feed Speed ◽

Wire Electrode ◽

Aspect Ratios ◽

The Wire

A new electrical discharge machining (EDM) system using a wire encased in a dielectric jacket is proposed as an alternative to conventional hole-fabrication EDM systems. The jacket suppresses secondary discharges occurring between the sidewalls of the wire and the fabricated hole, which allows fabrication of holes with higher aspect ratios compared to those formed by a conventional EDM system using naked pipe electrodes. In this new system, the tip of the wire electrode is stripped by displacing the jacket, which produces continuous sparks for workpiece erosion and keeps the bore and shape of the fabricated holes constant. In the present study, we developed a control system to maintain the exposed length of the tip without the need for visual observation and without the assumption that wear is constant over time. The exposed length of the tip of the wire electrode is related to the feed speed (toward the workpiece) of the electrode system. The jacket was displaced when the feed speed of the electrode system exceeded a threshold value, which resulted in slowing of the electrode system feed. The feed speed was kept within the specified range by determining a threshold value, which led to maintenance of a constant exposed length of the tip. This control system was validated in actual drilling tests. Optimizing the threshold feed speed contributed to a higher machining speed.

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Optimization of Nozzle Flushing Method for Smooth Debris Exclusion in Wire EDM

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.516.73 ◽

2012 ◽

Vol 516 ◽

pp. 73-78 ◽

Cited By ~ 7

Author(s):

Takuya Fujimoto ◽

Akira Okada ◽

Yasuhiro Okamoto ◽

Yoshiyuki Uno

Keyword(s):

Flow Field ◽

Removal Rate ◽

Working Fluid ◽

Wire Electrode ◽

Wire Edm ◽

Machining Performance ◽

Shape Accuracy ◽

Spark Generation ◽

The Wire ◽

Machining Rate

In a wire EDM using a thin wire electrode, better exclusion of debris from the machined kerf is important in order to maintain stable machining performance, since the area of spark generation is along a line and very small. When large amounts of debris stagnate in the gap, secondary discharges possibly occur and these discharges easily concentrate on the same location, which leads to unstable machining performance, wire breakage, low machining rate and a low shape accuracy. Conventionally, the exclusion of debris is carried out by jet flushing with an upper and lower nozzle. However, the flow field of machining fluid in the kerf due to the jet flushing and the effect of jet flushing conditions from the nozzles on debris exclusion have not yet been sufficiently examined. This study aims to clarify the flow field in the machined kerf by computational fluid dynamics (CFD) and to propose new jet flushing methods for smooth debris exclusion in the wire EDM. The effects of workpiece thickness and machined kerf length on the flow field of working fluid in the kerf under conventional jet flushing conditions are discussed. Then, jet flushing with a tilting nozzle is proposed in order to decrease the debris stagnation area near the wire electrode. As a result, by using the tilting nozzle, removal rate can be improved because of the smooth debris exclusion.

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