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Electrical Discharge Machining (EDM): A Review

September 2016
International Journal of Engineering Materials and Manufacture 1(1):3-10

DOI:10.26776/ijemm.01.01.2016.02

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Authors:

Mohammad Yeakub Ali

Universiti Teknologi Brunei

Asfana Banu

Electro discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used in industry for high precision products. EDM is known for machining hard and brittle conductive materials since it can melt any electrically conductive material regardless of its hardness. The workpiece machined by EDM depends on thermal conductivity, electrical resistivity, and melting points of the materials. The tool and the workpiece are adequately both immersed in a dielectric medium, such as, kerosene, deionised water or any other suitable fluid. This paper provides an important review on different types of EDM operations. A brief discussion is also done on the machining responses and mathematical modelling.

Schematic diagram of dry EDM.

…

SEM micrograph of kerf produced by micro-WEDM with 70 µm diameter tungsten wire electrode.

…

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Content uploaded by Mohammad Yeakub Ali

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International Journal of Engineering Materials and Manufacture (2016) 1(1) 3-10

Electrical Discharge Machining (EDM): A Review

Asfana Banu and Mohammad Yeakub Ali

Received: 16 July 2016

Accepted: 31 July 2016

Published: 05 September 2016

Publisher: Deer Hill Publications

Creative Commons: CC BY 4.0

ABSTRACT

Electro discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used

in industry for high precision products. EDM is known for machining hard and brittle conductive materials since it

can melt any electrically conductive material regardless of its hardness. The workpiece machined by EDM depends

on thermal conductivity, electrical resistivity, and melting points of the materials. The tool and the workpiece are

adequately both immersed in a dielectric medium, such as, kerosene, deionised water or any other suitable fluid. This

paper provides an important review on different types of EDM operations. A brief discussion is also done on the

machining responses and mathematical modelling.

Keywords

WEDM, Micro-EDM, Non-conductive ceramics, dry EDM, dry WEDM, MRR, Kerf

1 INTRODUCTION

Electro discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used

in industry for high precision products especially in manufacturing industries, aerospace and automotive industries,

communication and biotechnology industries [1-7]. EDM as shown in Figure 1, is known for machining hard and

brittle conductive materials since it can melt any electrically conductive material regardless of its hardness [4-5]. EDM

is a type of thermal machining where the material from the workpiece is removed by the thermal energy created by

the electrical spark [5, 8, 9]. The workpiece machined by EDM depends on thermal conductivity, electrical resistivity,

and melting points of the materials [10-12]. A series of electrical sparks or discharges occur rapidly in a short span of

time within a constant spark gap between micro sized tool electrode and workpiece material. The nature of sparks

is repetitive and discrete. The tool and the workpiece are adequately both immersed in a dielectric medium, such as,

kerosene, deionised water or any other suitable fluid [5, 13, 14]. The non-contact nature of the process with nearly

force free machining allows a soft and easy to machine electrode materials to machine a very hard, fragile or thin

workpieces [15-17]. Thus, due to its non-contact nature; mechanical stresses, chatter, and vibration problems during

machining can be eliminated [18]. This paper is reviewed comprehensively on types of EDM operation. A brief

discussion is also done on the machining responses and mathematical modelling.

Figure 1: Schematic diagram of EDM.

A. Banu and M. Y. Ali

Department of Manufacturing and Materials Engineering

International Islamic University Malaysia

PO Box 10, 50728 Kuala Lumpur, Malaysia

E-mail: mmyali@iium.edu.my

Reference: Banu, A. and Ali, M. Y. (2016). Electrical Discharge Machining: A Review.

International Journal of Engineering Materials

and Manufacture

, 1(1), 3-10.

Electrical Discharge Machining: A Review

2 TYPES OF ELECTRO DISCHARGE MACHINING (EDM)

Some of the variations of EDM process that can be altered for micro fabrication applications are micro-EDM, wire

EDM (WEDM), dry EDM [4, 19-21].

2.1 Wire EDM (WEDM)

Wire electrical discharge machining (WEDM) was introduced because it has the ability to cut intricate shapes and

extremely tapered geometries with high performance especially in precision, efficiency, and stability [5, 22, 23].

WEDM operation has a very similar material removal mechanism as EDM process except WEDM uses winding wire

as an electrode [5, 6, 24]. Micro-WEDM operation uses a very small diameter wire (Ø 20-50 µm) as the electrode

to cut a narrow width of cut in the workpiece. The wire is pulled through the workpiece from a supply spool onto

a take-up mechanism. Discharge occurs between the wire electrode and the workpiece in the presence of a flood of

dielectric fluid. The most important control parameters for this process are discharge current, discharge capacitance,

pulse duration, pulse frequency, wire speed, wire tension, voltage, and dielectric flushing condition [6, 20, 25].

2.2 Micro-EDM

EDM operation has already been developed in micro scale industries, as delicate micro tools can machine workpiece

surface without any deviation or breakage. Micro-EDM follows the similar principle of conventional EDM

technology. However, there are some differences between these two machining in terms of circuitry. EDM uses

resistance capacitance relaxation (RC-relaxation) circuit while micro-EDM uses RC-pulse circuit. In RC-relaxation

circuit, current and voltage are usually assumed as constant in modelling process. However, in reality, for RC-

relaxation circuit, current and voltage are controlled at a predefined level throughout the pulse on-time. In contrast,

based on the modelling process and parametric analysis, RC-pulse generator for a single discharge shows that the

current and voltage are not maintained to any predefined level. Still, the RC-pulse generator depends on capacitor

charge state at any instant. The RC-pulse circuit type is known to have low material removal rate (MRR) since it can

produce very small amount of discharge energy. Micro-EDM is particularly developed to manufacture component of

sized between 1 and 999 µm. Hence, in order to produce high precision and high accuracy micro geometries products,

micro-EDM is a suitable type of machining [26-29].

2.3 EDM of Non-Conductive Materials

Materials that are able to provide a minimum electrical conductivity of 0.1 Scm-1 can be processed using EDM. Thus,

materials like metals and conductive ceramics are capable to undergo this process [30-32]. Researchers are applying

EDM and micro-EDM to machine ceramics since they are difficult to machine using conventional cutting techniques

[33, 34]. But, in order to make the machining process to be continuous, the ceramics need to be conductive. So, one

of the solutions is to create a composite with dopants such as titanium nitride (TiN) or tungsten carbide (WC) onto

the ceramic. Other alternative is to create a conductive compound by embedding the ceramic particles in a metal

matrix. Another approach is by using the ultrasonic assisted spark erosion. The ultrasonic energy can assist in creating

spark erosion and lead to crack formation that causes spalling [10, 31, 32]. Non-conductive ceramics also have been

successfully machined by EDM using the assisting electrode method (AEM) (Figure 2) with some modifications done

in the process which is one of the commonly method used [31, 32, 35-37]. In AEM, a conductive layer is applied on

top of the non-conductive ceramic in order to generate spark between the workpiece and the tool electrode. High

temperature around the dielectric fluid will degenerate the polymer chains and creates carbon elements from cracked

polymer chains. The carbon elements, together with the conductive debris cover the ceramic surface to sustain the

conductivity [10, 31, 32, 36, 38-40].

Figure 2: Schematic diagram of micro-EDM of non-conductive zirconia using adhesive copper assisting electrode [38].

Banu and Ali (2016):

International Journal of Engineering Materials and Manufacture

, 1(1), 3-10

2.4 Dry EDM

In EDM process, dielectric fluid plays an important role in order to flush away the debris from the machining gap. In

addition, the dielectric fluid also helps to improve the efficiency of the machining operation as well as improving the

quality and economy of the machined parts. The commonly used dielectric fluids are mineral oil-based liquid or

hydrocarbon oils which cause fire hazard and environmental problems. This is because dielectric wastes generated

during the machining operation are very toxic and non-recyclable. Besides that, during the machining operation,

toxic fumes (CO and CH4) are produced because of the high temperature chemical breakdown of mineral oils. The

toxic fumes also pose a health hazard to the machining operators [24, 41-45]. In order to avoid these problems,

researchers introduce dry EDM which includes dry WEDM, dry micro-EDM, and dry micro-WEDM [4, 5, 24, 46, 47].

Dry EDM (Figure 3) is a green machining method where the electrode used is in a pipe form and gas or air flows

through the pipe instead of the liquid as a dielectric fluid which removes the debris from the gap and cools the

machining surface [48-52]. As for dry WEDM, also known as the WEDM using dry dielectric fluid is a modification

of the oil WEDM operation where gas is used as dielectric fluid instead of liquid. The flow of gas with high pressure

helps to remove the debris and also avoids unnecessary heating of the wire and workpiece at the discharge gap.

Lower tool wear, better surface quality, lower residual stresses, thinner white layer, and higher precision in machining

are the prime outcome of this dry technique [1, 24, 53-56]. This dry technique can be applicable for almost all micro

level machining operation [52, 57].

Figure 3: Schematic diagram of dry EDM.

There are researchers who do not agreed with the idea of using the gas instead of the liquid as the dielectric fluid.

It is because when the sparks happened in the air, the erosion effect would be very small since the electrical discharge

loses its energy. Moreover, the bubble of vapour expands which resulted from the spark into the dielectric fluid and

causes the dynamic plasma pressure to rise. It is due to the surrounding dielectric fluid restricts the plasma growth.

The bubble collapses and removes the molten metal out of the crater when the temperature decreases during the off

time. Even though there are some disagreements among the researchers, the dry EDM was first introduced and

reported by NASA in 1985 [58]. The commonly used gases as the dielectric fluid are atmospheric air, compressed air,

liquid nitrogen, oxygen, argon and helium gas [51, 56, 59]. Some research shows that material removal rate (MRR)

improves when oxygen is used as the dielectric fluid [60, 61]. It is because the oxidation reaction occurs with the

supply of the oxygen gas which increases the work removal volume during one discharge cycle. In addition, there is

no corrosion on the machining surface but it may suffer from rusting due to the oxidation [61].

Compared to conventional WEDM, the vibration of the wire electrode, narrower gap distance, and very

negligible process reaction force in dry micro-WEDM assists this process to enable high accuracy in finishing of cut.

Higher machining speed and lower electrode wear ratio are achieved in dry EDM milling. Three dimensional (3D)

machining of cemented carbide can be done by using dry EDM milling [53, 62]. Higher material removal rate (MRR)

can also be achieved in dry EDM when the workpiece is added with the ultrasonic vibration. This is because the

ultrasonic vibration helps to flush of the molten metal from the craters [19]. Polarity is a one of the important factor

in machining dry EDM. When the polarity of the tool electrode is negative, the tool wear ratio is smaller and the

material removal rate is higher compared to the positive polarity [1, 56]. The machining operation stability is

maintained when the tool is in rotation or planetary motion [63]. Low electrode wear ratio in dry EDM is due to

the small physical damage of the tool electrode caused by the reactive force. It is because the dry EDM is free from

the vaporization of liquid dielectric fluid when the discharge occurs. Besides that, adhesion of machining debris on

the electrode helps to reduce electrode wear [61].

Electrical Discharge Machining: A Review

3 MACHINING RESPONSES

3.1 Kerf

Kerf (Figure 4) is a width of the machined slots which is one of the most vital characteristics of WEDM [64, 65]. The

corner errors and kerf variation are usually caused by the wire tool deflection and vibration in the discharge gap.

These are the main factors that affect the WEDM machining accuracy. However, the kerf variations have higher

influences on dimensional accuracy in micro-WEDM compared to the conventional WEDM. This is because, the

relative error found in miniature parts produce by the micro-WEDM are bigger than the corresponding values in

conventional WEDM [20]. Besides that, a stable machining performance in micro-WEDM is related to the debris free

machined kerf. It is evident from the debris tracking analysis that the most debris are left out from the kerf section

under any constant fluid flow rate. More effectively debris can be excluded and high micro-WEDM performance is

obtainable with the improvement of jet flushing conditions of the working fluid from the nozzles [66].

In another study, the spark locations using the recorded images, and the effects of servo voltage, pulse interval

time, and wire running speed on the distribution of spark location were investigated. The spark distribution is found

uniform when servo voltage is high, pulse interval time is long, and wire running speed is low when experimental

results are clarified [67]. Based on the research, the kerf on germanium wafers in micro-WEDM process was analysed

using different thin wires with various voltage and capacitor settings. Up to 57% more wafers can be sliced in micro-

WEDM which depends on wafer thickness and the thin wires. The wafer slicing with WEDM is suggested for mainly

expensive semiconductor materials [68]. A model on lateral vibration of wire is established where co-related micro-

WEDM parameters and vibration amplitude of the wire are analysed. The wire vibration is affected by the open

voltage which also measures the breakdown distance. Kerf width can be controlled and subsequently machining

precision can be improved by controlling the parameter [20].

Figure 4: SEM micrograph of kerf produced by micro-WEDM with 70 µm diameter tungsten wire electrode.

3.2 Material Removal Rate (MRR)

Dimensional accuracy becomes vital when it comes to EDM since close tolerance components are required for

products like tools, dies, and mold for press works, plastic molding, and die casting. Thus, MRR has been one of the

main concerns. The MRR is expressed as the weight of material removed from workpiece over a period of machining

time. Many researchers have attempted to develop empirical models to estimate MRR. The MRR depends on the

amount of pulsed current in each discharge, frequency of the discharge, electrode material, work material, polarity,

and dielectric flushing condition. [12, 69, 70]. MRR is low when electrode is connected to negative polarity or

cathode. This is due to the dissociated carbon element in dielectric fluid tends to remain to anode and formed the

recast layer [41].

Material removal mechanism in micro-EDM is debatable according to some of the researcher. This is because they

are certain deviations in fundamental process mechanism. Even though they are many uncertainties regarding the

mechanism of the material removal in micro-EDM, this machining process is still widely being used in industry for

high-precision machining for conductive materials. Micro-EDM has the capability in removing the material in sub-

grain size range (0.1-10 µm) regardless of their hardness [51].

4 MATHEMATICAL MODELLING

There are quite a numbers of studies are found on parametric study and development of empirical model on micro-

WEDM parameters. Gap voltage, capacitance, and feed rate were considered as the control parameters and material

removal rate (MRR), over cut, kerf, and surface roughness as the performance measures. The optimal parametric

settings were derived using simulation. Some of the modelling are done through central composite design (CCD),

response surface method (RSM), neural network method, regression analysis, neural network with back-propagation,

kerf

Banu and Ali (2016):

International Journal of Engineering Materials and Manufacture

, 1(1), 3-10

neuro-fuzzy inference system (ANFIS), grey relational analysis, and Taguchi L18 orthogonal array method [20, 24,

64, 71, 72]. Modelling is a strong tool for the integration of relationships between output performance and

controllable input parameters. There are a few examples of mathematical modelling shown in this review. Eqn (1) is

an example of mathematical model for vibration in micro end milling using Taguchi as the design while the analysis

is done by the ANOVA [73]. As for Eqn (2) and (3), shows the mathematical model of hardness and MRR of non-

conductive zirconia using micro-EDM [38].

V = 65.94 + 2.13 × 10n0.99f + 1.73 × 10d6.84 × 10nf 1.93 × 10nd + 1.01fd

(1)

Where; V is average vibration, n is spindle speed (rpm), f is feed rate (mm/min), d is depth of cut (µm).

H = 9201.15 62n +16v + 0.15n0.05nv 1x10n (2)

Where, H = hardness (Hv), n = rotational speed (rpm), v = gap voltage (V).

MRR = 101.7 + 1.9n 2.93v 4.36 ×10 n+ 0.012v + 1.1 × 10nv + 3.1 × 10 n (3)

Where; MRR = material removal rate (µg/min), n = rotational speed (rpm), v = gap voltage (V).

5 SUMMARY

EDM process is a flexible machining operation which has the capability in producing complex three dimensional (3D)

shapes especially in manufacturing industries, aerospace and automotive industries, communication and

biotechnology industries. It is known for machining hard and brittle conductive materials. The tool and the workpiece

are adequately both immersed in a dielectric medium. This paper provides an important review on different types

of EDM operations. A brief discussion is also done on the machining responses and mathematical modelling. This

reviewed paper summarizes that:

1. WEDM has the ability to cut intricate shapes and extremely tapered geometries with high performance.

2. Micro-EDM is developed to manufacture micro geometries component with high precision and high

accuracy.

3. Non-conductive ceramics machined by EDM using assisting electrode method (AEM) which leads to new

structuring of advanced ceramic without geometry diversity.

4. Dry EDM is a process where gas is used as the dielectric fluid instead of the liquid. It is a process where

certain modification during the machining operation is needed in order to achieve a stable machining

process.

5. Machining responses such as kerf and MRR are important in order to achieve maximum material removal

with high accuracy and precision components.

ACKNOWLEDGEMENT

This research was funded by Ministry of Science, Technology and Innovation, Malaysia under Research Grant SF15-

016-0066. The authors are grateful to those who contributed directly and indirectly in producing this paper.

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51. Paul, G., Roy, S., Sarkar, S., Hanumaiah, N., & Mitra, S. (2013). Investigations on influence of process variables

on crater dimensions in micro-EDM of titanium aluminide alloy in dry and oil dielectric media. International

Journal of Advanced Manufacturing Technology, 65, 1009-1017.

52. Skrabalak, G. & Kozak, J. (2010). Study on dry electrical discharge machining. Wear, 5, 7.

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CIRP, 6, 344-350.

56. Singh, P., Chaudhary, A. K., Singh, T., & Rana, A. K. (2015). Comparison of outputs for dry EDM and EDM with

oil: a review. International Journal for Research in Emerging Science and Technology, 2(6), 45-49.

57. Yu, Z. B., Takahashi, J., Nakajima, N., Sano, S., & Kunieda, M. (2005). Feasibility of 3-D surface machining by

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58. Leao, F. N. & Pashby, I. R. (2004). A review on the use of environmentally-friendly dielectric fluids in electrical

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60. Teimouri, R. & Baseri, H. (2013). Experimental study of rotary magnetic field-assisted dry EDM with ultrasonic

vibration of workpiece. International Journal of Advanced Manufacturing Technology, 67(5-8), 1371-1384.

61. Jahan, M. P., Rahman, M., & Wong, Y. S. (2011). A review on the conventional and micro-electrodischarge

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66. Okada, A., Uno, Y., Onoda, S., & Habib, S. (2009). Computational fluid dynamics analysis of working fluid flow

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Effect of Electrical Discharge Machining Parameters and Cryogenic Treatment on Surface Roughness of Aluminum Metal Matrix Composite (Al6061/SiC/Graphite)

Article

Jul 2024

This study examines how process parameters -Current (Amp), Pulse on time (Ton), Duty cycle, and voltage ( v) affects the surface finish of the hybrid aluminum composite (Al6061/SiC/Graphite), comparing the effectiveness of cryogenic treatment on the EDM tool with a non-treated tool. One factor at a time (OFAT) approach shows that increasing current from 4 A to 12 A raises surface roughness from 0.2 µm to 2.5 µm. However, using silicon carbide, cryogenically treated electrodes, and longer pulse-on times can reduce roughness, though debris removal may be needed. Higher voltages above 120 V also increase roughness, which can be lessened by better flushing and cryogenic treatment. Lower duty cycles (0.36 to 0.48) yield smoother surfaces, while medium duty cycles (0.6 to 0.72) increase roughness, which can also be mitigated by cryogenic treatment.

Optimizing the Die-Sink EDM Machinability of AISI 316L Using Ti-6Al-4V-SiCp Electrodes: A Computational Approach

Article

Full-text available

Sep 2024

Die-sink electric discharge machining (EDM) is essential for shaping complex geometries in hard-to-machine materials. This study aimed to optimize key input parameters, such as the discharge current, gap voltage, pulse-on time, and pulse-off time, to enhance the EDM performance by maximizing the material removal rate while minimizing the surface roughness, residual stress, microhardness, and recast layer thickness. AISI 316L stainless steel was chosen due to its industrial relevance and machining challenges, while a Ti-6Al-4V-SiCp composite electrode was selected for its thermal resistance and low wear. Using Taguchi’s L27 orthogonal array, this study minimized the trial numbers, with analysis of the variance-quantifying parameter contributions. The results showed a maximum material removal rate of 0.405 g/min and minimal values for the surface roughness (1.95 µm), residual stress (1063.74 MPa), microhardness (244.8 Hv), and recast layer thickness (0.47 µm). A second-order model, developed through a response surface methodology, and a feed-forward artificial neural network enhanced the prediction accuracy. Multi-response optimization using desirability function analysis yielded an optimal set of conditions: discharge current of 5.78 amperes, gap voltage of 90 volts, pulse-on time of 100 microseconds, and pulse-off time of 15 microseconds. This setup achieved a material removal rate of 0.13 g/min, with reduced surface roughness (2.46 µm), residual stress (1518.46 MPa), microhardness (259.01 Hv), and recast layer thickness (0.87 µm). Scanning electron microscopy further analyzed the surface morphology and recast layer characteristics, providing insights into the material behavior under EDM. These findings enhance the understanding and optimization of the EDM processes for challenging materials, offering valuable guidance for future research and industrial use.

Multi-objective optimization in EDM of functionally graded Fe-Al using grey relational analysis

Article

Full-text available

Nov 2024

Functionally Graded Materials (FGMs) are multipurpose materials with a specific goal of managing changes in structural, thermal, or functional qualities. They feature a spatial variation in microstructure and/or composition. The current work prepared three layers of sample with different chemical compositions of Fe-Al FGM (50 Al-50 Fe, 45 Al-55 Fe, and 40 Al-60 Fe) at. % produced by powder metallurgy, then studied the machining behavior of these samples. The literature on the machining behavior of FGM was reviewed, and the influence of electrical discharge machine (EDM) process parameters such as voltage (V), current (I), pulse-on time, and pulse-off time on performance characteristics (material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra)) was investigated. The optimal machining settings for Fe-Al FGM samples will be ascertained by use of Grey Relational Analysis (GRA), which is based on the Taguchi approach, after an experimental investigation of the L18 orthogonal array design of trials. The GRA findings verify that V 140 volts, Ip10 A, Ton 100 μs, and Toff 75 μs is the optimal combination of process parameters. It has been found that the voltage is more significantly affected than the rest of the input parameters to obtain greater material removal rate (MRR) and lower tool wear rate (EWR) and surface roughness (Ra) through the response table. According to the study, choosing the right process parameters can improve the multi-performance feature.

Optimization Design for Die-sinking EDM Process Parameters and Stock Allowance in Machining of SKD61 Steel for Various Output Responses Using Statistical Methods

Conference Paper

Full-text available

Oct 2024

Electric discharge machining (EDM) is well known as a prominent technique applied in the creation of extremely precise mechanical parts. The purpose of this study is to optimize process parameters in die-sinking EDM by employing copper electrodes and SKD61 steel workpieces to enhance various output responses. The research encompasses an examination of four input parameters, namely current (I), pulse on time (Ton), pulse off time (Toff), and stock allowance (SA). Utilizing statistical methodologies such as Taguchi and analysis of variance (ANOVA), the study aims to identify the most effective set of parameters for the output responses, specifically material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR), as well as to ascertain the primary influential factor among the input variables. Through the implementation of the L27 orthogonal array (OA), the analytical findings reveal that the optimal parameter configuration for MRR consists of I = 8 A, Ton = 120 μs, Toff = 15 μs, and SA = 3 mm. Conversely, the ideal values for EWR and SR are indicated as I = 4 A, Ton = 120 μs, Toff = 15 μs, and SA = 3 mm, and I = 4 A, Ton = 60 μs, Toff = 15 μs, and SA = 1 mm, respectively. Furthermore, the study highlights the significant impact of input factor I on the output responses, with Ton and Toff following closely in influence.

Optimization of Electroless Plating Solution Parameter for Coating PETG Electrode with Copper using Design of Experiment (DOE)

Article

Oct 2024

In the study, an attempt was made to electrolessly plate copper onto PETG plastics that aren't conductors. Three manipulating factors, i.e. volume of copper sulphate and sulphuric acid (A), volume of sulphuric acid (B), and mass of copper sulphate (C), were selected and carried out using Taguchi method with three levels to examine their interactions and effects on the responses, including plating thickness, and electrical resistance. The Design Expert 13 software creates a total of nine runs with a single centre point. Three days were spent submerging every electroplated sample part in a different bath solution concentration. The resistance of the metalized PETG component was measured in the meantime using a digital multi-meter. The Cu-deposited PETG was analysed and measured using scanning electron microscopy (SEM). The ideal situation was identified as having 10 possibilities for achieving the goal, based on interaction effects. According to the results of the experiment, run number 3 provides the ideal solution parameter for copper deposition metallization. For the lowest electrical resistance of 0.64 ohm and the highest plating thickness value of 211.49 m, these runs yield the best ideal results. Because each factor reacts to a response individually, the Analysis of Variance (ANOVA) demonstrates that there are little interactions between the factors and responses. The lowest electrical resistance and highest plating thickness values are obtained with the best chemical composition parameter choices.

Influence of machining conditions on dry EDM with workpiece cooling of Inconel 625 alloy in the milling kinematics

Article

Full-text available

Aug 2024
INT J ADV MANUF TECH

Agnieszka Żyra

One potential eco-friendly variant of electro-discharge machining is dry electro-discharge machining (EDM), in which the liquid hydrocarbon–based dielectric is substituted with a gaseous medium. The primary challenge associated with dry EDM is the excessive dissipation of heat within the machining gap, which restricts its utilisation only to a microscale machining. Consequently, further modifications to the underlying mechanism of the process are being undertaken with the aim of efficient industrialising it on a larger scale. In the present study, a novel approach is proposed to enhance the efficiency of dry-EDM process while using carbon dioxide as a gaseous medium together with introducing additional external workpiece cooling with deionised water. A series of experiments were conducted to determinate the impact of external workpiece cooling with deionised water and the main machining parameters, namely pulse-on time and current intensity gas pressure, on the material removal rate, working electrode wear, and surface integrity of Inconel 625 during EDM in milling kinematics. The results demonstrated that, under the same machining parameters, the wear of the working electrode, the surface roughness, and the thickness of the recast layer were significantly reduced in the EDM with external workpiece cooling in comparison to the dry-EDM process without water cooling. Furthermore, the EDM with coolant exhibited superior performance in comparison to the dry-EDM process due to the fact that there were fewer changes in the surface morphology and chemical composition of the machined material.

A comparative experimental study on abrasive flow machining vs flow peening GOV processes on Inconel 718

Article

Oct 2024

A Dual-Parametric G-Type Coaxial Thermocouple With Superior Thermal Measurement Capabilities

Article

Oct 2024

In the context of hyperthermal aerodynamics, where the heat transfer rate changes rapidly, there is an urgent need to obtain thermal data on the surface of structures. To address this, we propose a novel G-type coaxial dual-parametric sensor that utilizes the Seebeck thermoelectric effect to measure the temperature of high-temperature airflows and derive heat fluxes based on the 1-D semi-infinite body assumption method. In a laboratory environment, we performed static calibration of the sensor’s performance indices in the temperature range of

200~^{\circ }

C–

1500~^{\circ }

C. The calibration results of voltage versus temperature indicate that the sensitivity of the sensor is approximately

21~\mu

V/°C, with a fitting coefficient exceeding 0.9999. Compared to the national standard for G-type thermocouples regarding the temperature-voltage relationship, the maximum voltage deviation is only 0.1 mV. Additionally, when we calibrated the heat flux of the sensor using a laser calibration method, the sensor monitored a heat flux upper limit of over 21 MW/m2, with an absolute error of less than 1.5%, corresponding to a heat flux response time of 1.15 ms. Finally, the G-type coaxial sensor, prepared using the natural growth method for the insulating layer, successfully achieved dual-parameter monitoring of structural surface temperature and heat flux exceeding

1250~^{\circ }

C and 5.1 MW/m2 in the high-temperature environment of supersonic flame washout. This provides a feasible solution for the accurate acquisition of structural surface thermal data in various rocket motor components.

Multi-response Optimization of Electro-Discharge Machining Parameters by Using Jaya Algorithm for Thin Wire-Arc Additive Manufactured IN625 Surface

Chapter

Oct 2024

Optimization of Machining Process on Coated Tungsten Carbide Electrode Tool and Titanium Alloy Workpiece Using EDM: A Critical Review

Article

Aug 2024

Commercial applications for Ti 6Al 4V, an alloy composed of titanium, aluminium, and vanadium, are possible. The features of titanium alloy include: Lightweight, non-magnetic, high melting point, outstanding fatigue strength, superior specific strength, great corrosion resistance, and biocompatibility. Reviewing the electro-discharge machining of titanium alloy (Ti 6Al 4V) as a workpiece, silicon carbide particle combined with EDM oil, and coated tungsten carbide electrode, this research examines this process. Dielectric fluid's impact on microhardness, surface finishing, TWR, and MRR. MRR is raised by silicon particles and coated tungsten carbide electrodes with EDM fluid. According to the study, the most important input parameters for determining TWR, MRR, surface finishing, and micro-hardness are voltage, current, pulse on time (Tonne), and pulse off time (Toff).

Non-conventional optimization techniques in optimizing non-traditional machining processes: A review

Article

Full-text available

Jan 2013

With the ever-increasing demands for high surface finish and complex shape geometries, conventional metal removal methods are now being replaced by non-traditional machining (NTM) processes. These NTM processes use energy in its direct form to remove materials in the form of atoms or molecules to obtain the required accuracy and burr-free machined surface. In order to exploit the optimal capabilities of the NTM processes, it is often required to determine the best possible combinations of their controllable parameters. Different non-conventional optimization techniques have been used for dealing with these process optimization problems because of their inherent advantages and capabilities for arriving at the almost global optimal solutions. This paper reviews the applications of different non-conventional optimization techniques for parametric optimization of NTM processes. It is observed that electrical discharge machining processes have been optimized most number of times, followed by wire electrical discharge machining processes. In most of the cases, the past researchers have preferred to maximize material removal rate. Genetic algorithm has been found to be the most popular non-conventional optimization technique

Erratum to: Application of Taguchi, ANFIS and grey relational analysis for studying, modeling and optimization of wire EDM process while using gaseous media

Article

Full-text available

Feb 2017
INT J ADV MANUF TECH

Thermal Model of the Electro-Spark Nanomachining Process

Article

Full-text available

Jan 2014

Review on Current Research Trends in Wire Electrical Discharge Machining (WEDM)

Article

Full-text available

Feb 2013

Wire-electro discharge machining (WEDM) has become an important non-traditional machining process, as it provides an effective solution for producing components made of difficult-to-machine materials like titanium, zirconium, etc., and intricate shapes, which are not possible by conventional machining methods. Due to large number of process parameters and responses lots of researchers have attempted to model this process. This paper reviews the research trends in WEDM on relation between different process parameters, include pulse on time, pulse off time, servo voltage, peak current, dielectric flow rate, wire speed, wire tension on different process responses include material removal rate (MRR), surface roughness (Ra), sparking gap (Kerf width), wire lag (LAG) and wire wear ration (WWR) and surface integrity factors. Furthermore, different types of WEDM methods introduced and discussed. In addition the paper highlights different modelling and optimization methods and discussed their advantage and disadvantage. The final part of the paper includes some recommendations about the trends for future WEDM researches.

A Review on Advances in Wire Electrical Discharge Machining

Chapter

Apr 2014

Wire electrical discharge machining has become an important non-traditional machining process, as it provides an effective solution for producing components made of difficult-to-machine materials such as titanium, zirconium and intricate shapes, which are not possible by conventional machining methods. Due to large number of process parameters and responses, lots of researchers have attempted to optimize the process parameters. This paper reviews the advances in research of WEDM on relation between different process parameters, include pulse-on time, pulse-off time, servo voltage, peak current, dielectric flow rate, wire speed, wire tension on different process responses include material removal rate (MRR), cutting speed (Vc), surface roughness (Ra), and wire wear ratio (WWR) of the wire electrode. Effect of composition of material on the manufacturability of wire EDM has also been reviewed. And at last, wire failure analysis is discussed.

Feasibility of 3-D surface machining by dry EDM

Article

Jan 2005

State of the art electrical discharge machine (EDM)

Article

Jan 2003
INT J MACH TOOL MANU

A review on the use of pollution free dielectric fluids in wire electrical discharge machining process

Article

Jan 2015

Fundamentally Wire Electrical discharge machining (WEDM) is a well-established non-traditional machining process, used for machining geometrically difficult or hard and electrically conductive material parts that are extremely difficult to cut by regular conventional machining processes. Erosion pulse discharge occurs in a small gap between the workpiece and the tool electrode. This removes the unnecessary material from the workpiece metal through melting and vaporizing in presence of dielectric fluid, which affects factors such as productivity and quality. Operator's health, safety and environment are also important factors, particularly when oil-based fluids are used. Performance measures are different for different materials, process parameters as well as for dielectric fluids. Presence of metal partials in dielectric fluid diverts its properties, which reduces the insulating strength of the dielectric fluid and increases the spark gap between the tool and workpiece. As a result, the process becomes more stable and metal removal rate (MRR) and surface finish (Ra) increases. The WEDM process is mainly used for making dies, moulds, parts of aerospace, automotive industry and surgical components etc. This paper presents a literature survey on the use of water based gaseous dielectric medium that provide an alternative to dielectric fluids. It has been reported that water-based dielectrics may replace gas-based fluids in WEDM applications. Gaseous dielectrics such as oxygen, Helium, Argon may also be the alternative. Nonetheless, these need further research in order to be commercially viable.

Application of Uniform Design in Experiments of WEDM in Gas

Article

Jan 2012

Comparing with conventional WEDM in emulsion, dry finishing of high-speed WEDM (HS-WEDM) has advantages such as higher material removal rate, better surface roughness and straightness. Authors have presented a new procedure as gas-liquid combined multiple cut, in which roughing is processed in dielectric liquid, and semi-finishing is in liquid or gas, while finishing is in gas. For better understanding the effect of machining parameters on surface roughness(R a) and cutting speed (V w) in dry finishing, a L 25(5 ⁶) Design test was implemented. The analysis of variance shows that offset and wire length are not significant on R a and V w. In this paper, the other four significant parameters, such as pulse duration, pulse interval ratio, peak current and no load worktable feed, were selected as factors in Uniform Design test. The final regression equations for R a and V w in terms of the actual parameter values were calculated out with MATLAB. Regression statistics of values R ² imply the two regression equtions fit well with test data and Model F-Values imply the two models are significant. Values t and a for regression equation coefficient tests of R a and V w show the major impacting items and interactions between them.

Material Removal Rate of Zirconia in Electro Discharge Micromachining

Article

Jul 2015

This paper investigates the material removal rate (MRR) in electro discharge micromachining (micro-EDM) of zirconia. Experimental investigation is carried out with 800 μm diameter tungsten electrode with two varying parameters rotational speed and gap voltage. The MRR data are analyzed and an empirical model is developed using Design Expert software. The optimum parameters for maximum MRR are found to be 375 rpm rotational speed and 80 V gap voltage.