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Conventional machining of Ti6Al4V parts with complex shapes is often a tough task due to its low thermal conductivity and its high strength-to-density ratio. Thus, electrical discharge machining (EDM) comes as a better alternative that surpasses these manufacturing difficulties. In this work, a coupled thermo-mechanical model was built using the FEM software package Abaqus to estimate the sublayers final microstructure of a Ti6Al4V machined workpiece. The proposed numerical model aims to replicate a single-spark electrical discharge machining process. Phase transformations kinetic laws of the biphasic titanium alloy and heat flux distribution subroutines were implemented. XRD analysis, metallurgical sample preparation and optical microscope imaging were performed to investigate electrical discharge machining effects on Ti6Al4V part and to validate the numerical proposed model. Close agreement was found between experimental investigation results and numerical outcomes. The numerical model considers the remaining amount of 10% of β phase redeposited at the end of the discharge phase additionally to the martensitic phase α'. [ABSTRACT FROM AUTHOR]

Surface formation in electrical discharge machining (EDM) involves melting, evaporation, re-solidification and crater overlapping. However, almost all existing models concerning surface formation in EDM only consider the thermal process and ignore hydrodynamic phenomena during machining. Herein, a novel three-dimensional thermo-hydraulic coupling model incorporating the arbitrary Lagrangian–Eulerian scheme was developed to address the above problem. The model comprehensively considered the surface deformation caused by melt flow, temperature-dependent material properties, phase changes and the effects of practical forces on melt pools to simulate surface formation on an anodic workpiece at a discharge current of 2 A. Simulation results demonstrate that during single-pulse discharge, molten material flowed radially to the crater periphery. The radial melt flow was driven by evaporation recoil pressure and thermocapillary force. The effect of evaporation recoil pressure on melt flow was gradually counteracted by that of surface tension after discharge ignition, and thermocapillary force became the dominant factor that maintained the existence of bulges around craters. During multiple discharges, the bulges generated by different discharges underwent superposition owing to the flow of molten material and subsequently formed surface peaks. The simulation results also provide the measurements of crater diameter, surface roughness and recast layer thickness, which are consistent with experimental results. The proposed modelling method can provide a useful reference for further investigations on surface integrity in EDM with minimal computing resource requirements. • A novel 3D thermo-hydraulic coupling surface formation model for EDM was proposed. • The effects of evaporation recoil pressure and thermocapillary force on melt pool dynamics in EDM were investigated. • Simulation results of multiple discharges show good consistency with experiment results concerning surface properties. [ABSTRACT FROM AUTHOR]

This paper aims to enhance the machining characteristics of sinking electrical discharge machining by superimposing an impulse current on a conventional rectangular pulse. The material removal was found to be more significant when the time point of superposition was set earlier after the dielectric breakdown, as the plasma diameter is smaller. However, superimposition immediately after the discharge ignition leads to a higher tool wear ratio. Through experimentation and simulation, it was determined that the optimal time point to increase material removal while keeping tool wear low is approximately 12.5 μs when the rectangular pulse duration was 50 μs. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is one of the earliest nontraditional machining processes being considered one of the most popular machining methods today. The EDM process basis on thermoelectric energy between the workpiece and an electrode, so that the discharge energy generated during the operation characterizes the productivity of the process. Due to the well-established machining options utilized in the industry of aerospace, automotive industry and surgical components for precision machining and making complex geometrical shapes in hard-to-cut materials, a significant amount of research interests has been created in this field. This paper provides a review of numerous academic research activities carried out in the previous years, as well as numerous developments in the field of EDM related to increased machining rates, improved performance, materials and dielectrics used, electrode design and manufacture. [ABSTRACT FROM AUTHOR]

Inconel 718 finds extensive applications in the aviation and aerospace industries, particularly in the manufacturing of jet engines and high-speed airframe components like fasteners, bolts, buckets, instrumentation parts, wheels, and spacers. It is also utilised in the production of cryogenic tankage and gas turbine blades. The present study focuses on investigating the machining performance of graphene nanosheets on Inconel 718. Various aspects of Inconel 718's machinability through electrical discharge machining (EDM) have been examined, including material removal rate (MRR), surface roughness, surface morphology, tool rear Rate (TWR), residual stresses on the machined surface, Vickers hardness, and recast layer thickness. The investigation reveals a significant impact of process parameters on these machining characteristics. The effects of graphene nanosheets have been observed using several analytical instruments such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), particle size analyzer, and X-ray diffraction (XRD). Furthermore, optimization of the response data with respect to input parameters has been performed in this study. TEM analysis is used to determine the size of individual debris particles in deionised water and mixed graphene nanosheet dielectric mediums. To verify that the debris particles are the same as the parent material, energy dispersive X-ray spectroscopy (EDX) is used. To determine the compounds and crystal structures present in the base metal and machined surfaces, XRD analysis is used. A high-resolution X-ray diffractometer (HRXRD) is used to measure the residual stresses on the machined surface. EDX composition testing is used to analyze surface modification. Due to the rapid heating and quenching that takes place in the dielectric medium, the machined surface becomes harder. Deposited materials, microholes, and surface textures can all be observed through FESEM microstructure observation. Comparing conventional EDM to nanosheets mixed dielectric, the thickness of the recast layer is reduced. To recapitulate, the study explores how various machining parameters and dielectric mediums affect EDM processes. It examines debris particle size, compound formation, residual stresses, surface modification, hardness, microstructure, and recast layer thickness. The addition of graphene nanosheets to the dielectric medium produces promising results, reducing the thickness of the recast layer and improving surface quality. The results offer suggestions for improving Inconel 718 material surface properties and EDM machining effectiveness.

Electrical discharge machining (EDM) method is an innovative method for the fabrication of structured array surfaces on binderless tungsten carbide (WC) which is a typical embossing mold material, compared to traditional machining methods. To improve the convenience of electrode replacement and the fabrication efficiency of the structured array, a novel self‐assembly ball electrode is innovatively developed. The feasibility of machining binderless WC with a self‐assembly ball electrode was studied and its effect on profile deviation analyzed. Furthermore, the discharge condition's effect on surface roughness, material removal rate (MRR), and tool wear ratio (TWR) was investigated. The microstructure, phase structure, and element distribution of binderless WC caused by EDM were characterized by Raman spectroscopy, scanning electron microscopy, and energy dispersive x‐ray spectroscopy. The results indicated that the maximum profile deviation of the different random structured arrays was about 3.7 μm. The surface roughness of all structured arrays was below 1 μm. The maximum TWR was about 0.008 mm3/min. Besides, the binderless WC surface after EDM presented strong D and G carbon peaks, which means the precipitation and transformation of the WC phase during the discharge process. Finally, different kinds of self‐assembly ball electrodes are developed and used to fabricate the lens array structures on binderless WC. The fast fabrication of the micro‐lens array surfaces in different arrangements sheds some light on the design and manufacturing of other functional structured surfaces. [ABSTRACT FROM AUTHOR]

Electrical discharge machining is a versatile machining technology that uses precisely directed sparks within the range of the dielectric fluid and between the electrodes to make electrically conductive products. The influence of different processing parameters on diverse metal matrix composites, including new reinforcing elements (silicon carbides, aluminium oxides and nitrides), and the modifications that occur as a consequence of each of these components are discussed in this article. As a result, new reinforcing materials and ways for optimising performance have emerged. The goal of this study is to provide analysts with research data that will allow them to effectively use EDM principles and, more particularly, to investigate process characteristics in order to enhance the process of advanced PMEDM operation. [ABSTRACT FROM AUTHOR]

The most effective and cutting-edge method for achieving a 0.004 mm precision on a typical material is to employ die-sinking electrical discharge machining (EDM). The material removal rate (MRR), tool wear rate (TWR), residual stresses, and crater depth were analyzed in the current study in an effort to increase the productivity and comprehension of the die-sinking EDM process. A parametric design was employed to construct a two-dimensional model, and the accuracy of the findings was verified by comparing them to prior research. Experiments were conducted utilizing the EDM machine, and the outcomes were assessed in relation to numerical simulations of the MRR and TWR. A significant temperature disparity that arises among different sections of the workpiece may result in the formation of residual strains throughout. As a consequence, a structural model was developed in order to examine the impacts of various stress responses. The primary innovations of this paper are its parametric investigation of residual stresses and its use of Haynes 25, a workpiece material that has received limited attention despite its numerous benefits and variety of applications. In order to accurately forecast the output parameters, a deep neural network model, more precisely, a multilayer perceptron (MLP) regressor, was utilized. In order to improve the precision of the outcomes and guarantee stability during convergence, the L-BFGS solver, an adaptive learning rate, and the Rectified Linear Unit (ReLU) activation function were integrated. Extensive parametric studies allowed us to determine the connection between key inputs, including the discharge current, voltage, and spark-on time, and the output parameters, namely, the MRR, TWR, and crater depth. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) has emerged as a pivotal non-conventional production technique due to its unique capability to machine without the cutting tool's physical contact with the workpiece, making it apt for brittle, delicate, and complex materials. This research delved into the influence of operational parameters—pulse duration (Ton), peak current (Ip), duty cycle (T), and gap voltage (Vg)—on machining attributes, namely material removal rate (MRR), electrode wear rate (EWR), and radial overcut (ROC) for AISI D2 steel. Utilizing the Taguchi L9 orthogonal array for experimental design, nine experiments were conducted, followed by signal-to-noise ratio (S/N ratio) computations. Key findings highlighted a 4.02 dB improvement in the S/N ratio for MRR, leading to a 29.13% improvement; a 10.35 dB enhancement in the S/N ratio for EWR, resulting in a 33.33% reduction; and a 2.20 dB increase in the S/N ratio for ROC, leading to a 28.57% increment. ANOVA analyses further underscored the predominant influence of all four parameters. The significance of these findings lies in optimizing the EDM process for increased efficiency, reduced tool wear, and enhanced precision, potentially leading to cost savings and improved production quality in industrial applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This work aims to optimize the machining parameters and study the effect of powder-mixed dielectric fluid on the electrical discharge machining (EDM) process. The TOPSIS method of optimization is adopted to identify the optimal machining parameters. HCHCr die steel is preferred as a machining material. Due to their hard and ductile nature, Ni, Zr, and Ni+Zr were selected as powder inclusion in dielectric fluid. An L9 array Taguchi DOE is preferred to perform the experiments with parameters like peak off time, pulse off time, and pulse current. TOPSIS study revealed that the third level of powder dielectric fluid (Ni+Zr), 7A peak current, 9 µs pulse on time, and 2 µs pulse off time were specified as the optimal condition. Pulse on time (Ton) significantly impacted metal removal rate and surface roughness while machining operation on HCHCr die steel. SEM analysis was done to find the effect of powder-mixed dielectric fluid, while EDAX analysis was done to ensure the presence of powder inclusion. [ABSTRACT FROM AUTHOR]

Multiwall carbon nanotube buttressed aluminium 7075 metal matrix composite was synthesized through an amended liquid metallurgy method, which consisted semisolid stirring, ultrasonic treatment and squeeze casting. Aim was to investigate its machinability and surface morphology during electrical discharge machining. Variable machining factors were peak current, pulse‐on time and gap voltage, whereas the responses under investigation were electrode wear rate, material removal rate and average surface roughness. Results revealed electrode wear rate, material wear rate and average surface roughness increased on increasing peak current and pulse‐on time, but all these responses behaved inversely with the increase of gap voltage. Average surface roughness reduced by around 44 % on reducing the peak current from 10 A to 4 A and increasing gap voltage from 55 V to 80 V at constant pulse‐on time of 300 μs; however, it increased by around 25 % on reducing the gap voltage from 80 V to 55 V and increasing the pulse‐on time from 100 μs to 300 μs at constant peak current of 10 A. Significance of the process parameters were verified, regression models were developed and morphology of the machined surfaces was studied. Finally, multiple response optimization was conducted following grey relational approach. [ABSTRACT FROM AUTHOR]

Machining hard-to-cut materials, such as cobalt (Co)-based superalloys, is a common problem in manufacturing industries. Background: wire electrical discharge machining (W-EDM) is one of the widely used cutting processes that causes layer (white layer—WL and heat-affected zone—HAZ) formation, and microcracks on the material's surface. Purpose: this study investigates the effects of WL and HAZ on the electrochemical grooving (EC grooving) performance of Co-based superalloys. Two different surface types (W-EDMed and VFed) were used in the experiments. Result: the experiments showed that material removal rate (MRR) values increased up to 212.49% and 122.23% for vibratory finished (VFed) and wire-electrical-discharge-machined (W-EDMed) surfaces, respectively. Conclusion: This result indicates the presence of HAZ and WL that prevent current transition between two electrodes. However, increased voltage causes an increase in surface roughness, with increment rates at 71.13% and 36.08% for VFed and W-EDMed surfaces, respectively. Moreover, for the VFed surfaces, the groove lost its flatness at the bottom after an approximately 100 µm depth due to the different electrochemical machineabilities of HAZ and real surface texture. This result can be attributed to the different microstructures (HAZ and surface texture) showing different electrochemical dissolution rates. Therefore, high-depth distance HAZ and WL must be removed from the workpiece. [ABSTRACT FROM AUTHOR]

The study was performed to determine the optimum flushing condition for electrical discharge machining (EDM) of functional material titanium VT6 obtained by plasma cladding with a thermal cycle. Copper is used as an electrode tool (ET) to machine functional materials. The optimum flushing flows are analyzed theoretically by using ANSYS CFX 20.1 software which is also validated by an experimental study. It was observed that while machining the functional materials to adepth of 10 mm or more, the turbulence fluid flow dominates when nozzle angles are 45° and 75°, consequently drastically affecting the quality of flushing and the performance of the EDM. For the highest machining performance, the nozzles should be at an angle of 15° relative to the tool axis. The optimum flushing at deep hole EDM process minimizes the occurrence of debris deposition on tool electrodes, thus facilitating stable machining of functional materials. The adequacy of the obtained models was confirmed experimentally. It has been established that EDM of a hole with a depth of 15 mm, an intense accumulation of sludge, is observed in the processing zone. There arebuild-ups exceeding 3 mm in cross-section after EDM. This build-up leads to a short circuit and a reduction in surface quality and productivity. It has been proven that not correct flushing leads to intensive wear of the tool and a change in its geometric shape and, accordingly, to a decrease in the quality of EDM. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is one of the important machining processes to produce mold components. When using the EDM process, surface quality, processing time, accuracy, and electrode cost must be considered. The electrode wear is the main factor that causes error on the geometric accuracy, especially the workpiece corner. Therefore, this study proposes a novel electrode design to improve the geometric accuracy for the EDM process. Firstly, the effect of discharge current, electrode diameter, and depth of cut on the electrode wear and workpiece corner were investigated. Multiple regression and analysis of variant were used to analyze the experiment data. The electrode end-face design with compensation rule and algorithm was established based on the data analysis and error value. Furthermore, a compensated electrode end-face design system with human machine interface, which has a procedure guiding function, was developed. The system can design the electrode end-face for minimizing workpiece corner error and improve geometric accuracy. Finally, cutting experiments were conducted to verify the proposed method, and the results show that the proposed method can effectively enhance the geometric accuracy by around 22~37%. [ABSTRACT FROM AUTHOR]

A film cooling hole is an efficient and reliable cooling method, which is widely used in aeroengine turbine blades to effectively improve the thrust–weight ratio of the engine. Electrical discharge machining is the most common manufacturing process for film cooling holes. Due to the rapid quenching after high-temperature melting, a certain thickness of the recast layer will be formed in the vicinity of the hole wall. The microstructure of the recast layer is considered to be an important factor affecting the performance of single-crystal blades. Generally, the recast layer has been thought of as one of the main reasons for the failure of turbine blades. Accordingly, the formation of the recast layer is an important and interesting issue to be revealed. In this work, the recast layer formed using electrical discharge machining on a single-crystal superalloy is studied with TEM. It is found that the recast layer is in the state of supersaturated solution with a single-crystal structure epitaxially grown from the matrix, and many dislocations were observed therein. [ABSTRACT FROM AUTHOR]

Recently, the requirements for machining shape-complex products made of hard-to-machine materials, including carbide, have been increasing significantly. However, their machining is rather problematic. Additionally, a high-quality standard of the machined surface is generally required, not only in terms of roughness but also in terms of the geometric accuracy of the machined surface. All this while maintaining a high level of economy in the machining process. However, meeting these demanding requirements in real technical practice is not always an easy task. Moreover, in combination with modern machining processes, only a limited number of production technologies can meet this requirement. Therefore, due to the high demands placed on today's modern production and the required high standard of the machined surface, progressive EDM technology is increasingly finding its application. And it is through this progressive technology that it is possible to achieve relatively good success in carbide machining. The aim of this paper was therefore to describe in detail the results of an experimental investigation aimed at identifying the quality of the machined surface achieved in terms of the roughness parameters of the machined surface in the electrical discharge machining of selected types of carbides using a wire tool electrode. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is widely applied for machining difficult-to-cut materials in mold and die industries. However, the major limitations associated with the EDM are low productivity and poor surface integrity of the machined surfaces. In recent years, several developments have been applied to overcome such limitations of EDM. Electrical discharge grinding (EDG) is a hybrid machining process that simultaneously involves the spark erosion action of EDM and the mechanical abrasion action of the grinding wheel for the material removal purpose. The rotating motion of the grinding wheel also contributes to the easy removal of debris particles, thereby improving the material removal. It is evident from the literature that the rotating motion of the grinding wheel enhances the flushing mechanism resulting in better performance of the process. This paper aims to present a comprehensive review of the research carried out in EDG, highlighting the result of the experimental, modeling, and optimization techniques applied in this area. Initially, the background of EDM and the need for hybrid EDM processes have been presented. Then, a few hybrid EDM processes have been discussed, addressing their advantages and limitations. Further, the concept of EDG and electrical discharge diamond grinding (EDDG) has been discussed, along with the classification of the EDDG process. Finally, this paper explores the current research status and future research perspective in the area of EDG and EDDG processes. [ABSTRACT FROM AUTHOR]

The paper aims to extend the current knowledge on electrical discharge machining of insulating materials, such as cutting ceramics used to produce cutting inserts to machine nickel-based alloys in the aviation and aerospace industries. Aluminum-based ceramics such as Al2O3, AlN, and SiAlON are in the most demand in the industry but present a scientific and technical problem in obtaining sophisticated shapes. One of the existing solutions is electrical discharge machining using assisting techniques. Using assisting Cu-Ag and Cu mono- and multi-layer coatings of 40–120 µm and ZnO powder-mixed deionized water-based medium was proposed for the first time. The developed coatings were subjected to tempering and testing. It was noticed that Ag-adhesive reduced the performance when tempering had a slight effect. The unveiled relationship between the material removal rate, powder concentration, and pulse frequency showed that performance was significantly improved by adding assisting powder up to 0.0032–0.0053 mm3/s for a concentration of 14 g/L and pulse frequency of 2–7 kHz. Further increase in concentration leads to the opposite trend. The most remarkable results corresponded to the pulse duration of 1 µs. The obtained data enlarged the knowledge of texturing insulating cutting ceramics using various powder-mixed deionized water-based mediums. [ABSTRACT FROM AUTHOR]

Amorphous alloys are a new type of multi-functional advanced material with the properties of general metal materials and glass, which are also called metallic glasses. They have good comprehensive properties, such as a wide application range, low cost, and high reusability. Using reasonable process parameters, non-traditional machining can not only realize the machining of complex amorphous parts, but also avoid the crystallization and oxidation of amorphous alloys, realizing tasks that cannot be accomplished by traditional machining. Therefore, this review systematically summarizes the research status and development potential of amorphous alloys fabricated using non-traditional machining methods. First, we introduce the principles of laser machining, ultrasonic machining, electrical discharge machining, electrochemical machining, and other non-traditional machining methods for amorphous alloys. Subsequently, the influence of the machining parameters and other external conditions on the machining effect is summarized. The machining cost, machining efficiency, and environmental impact of these non-traditional machining methods were compared. Finally, non-traditional machining technology for amorphous alloys is summarized and discussed. • The processing principles of non-traditional machining methods are summarized. • The influences of processing parameters on the machining effect are reviewed. • Costs, effects, and pollution of non-traditional machining are compared. • The limitations or shortages of non-traditional machining methods are summarized. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a nonconventional machining process that involves the formation of a plasma in an interelectrode gap filled with a dielectric that melts and vaporizes the electrodes (tool and workpiece) when a voltage is applied across them. This work models the plasma discharge in the EDM process to describe plasma characteristics such as electron density, heavy species densities, plasma potential, and plasma temperature using chemical kinetics, fluid flow, and heat transfer mechanisms in a 1D domain in the direction of the gap. The 1D domain allows the model to utilize surface reactions on the electrode walls necessary for sustaining the plasma reactions. The domain also provides a perspective of the plasma characteristics near the workpiece. Temperature results are compared with the experimental data obtained from spectrometer measurements. Additionally, an estimate of the plasma diameter is made and compared with actual high-speed camera images. The effect of EDM parameters such as supply voltage and interelectrode gap size on plasma characteristics is studied. The model predicts the incumbent heat flux on the workpiece electrode for small gaps which could have applications in the development of melt-pool models of EDM. Finally, the model provides a physics-based understanding of the mechanisms of plasma generation in the EDM process. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a well-known manufacturing process that is reported for several times as an effective technique for cutting of nickel-based superalloy of Inconel 718 (IN718). A majority of existing researches in EDM of Inconel 718 are focused on machinability of material considering production rate, tool wear, surface roughness and dimensional tolerances. To the best of author's knowledge, corrosion resistance EDMed Inconel 718 has hardly been taken into consideration. In the present work, an experimental study was made to understand how the electrical discharge machining parameters, viz. pulse current, pulse on time and rotational motion of the tool electrode, influence the corrosion properties of IN718. Technique of potentiodynamic polarization curve was utilized to measure IC and EC of the samples. A number of seven samples were machined using single-factor experiments design, and the effect of EDM parameters on foresaid corrosion indices was studied. Surface roughness, surface morphology, hardness and residual stress distributions were taken into account for justification of the variations. It was obtained from the results that as a result of increase in current from 5 to 15A, the corrosion rate increases, where the current density increases from 0.15 to 0.28 μA/cm2, and corrosion potential decreases from 0.51 to − 2.49 VSCE. In addition, it was found that less value of pulse on time, i.e., 600 μs, results in best corrosion properties where increase up to 800 μs results in increase in corrosion density from 0.11 to 0.19 μA/cm2 and also reduction of corrosion potential from −0.34 to −1.13 VSCE. It was further found that increase in tool rotational speed from stationary condition up to 200RPM results in enhancement of corrosion resistance; here, the current density reduces from 0.4 to 0.088 μA/cm2 and increase in corrosion potential from − 1.89 to 0.11 VSCE. [ABSTRACT FROM AUTHOR]

Aluminum-based ceramics are used in industry to produce cutting tools that resist extreme mechanical and thermal load conditions during the machining of Ni-based and high-entropy alloys. There is wide field of application also in the aerospace industry. Microtexturing of cutting ceramics reduces contact loads and wear of cutting tools. However, most of the published works are related to the electrical discharge machining of alumina in hydrocarbons, which creates risks for the personnel and equipment due to the formation of chemically unstable dielectric carbides (methanide Al3C4 and acetylenide Al2(C2)3). An alternative approach for wire electrical discharge machining Al2O3 in the water-based dielectric medium using copper tape of 40 µm thickness and TiO2 powder suspension was proposed for the first time. The performance was evaluated by calculating the material removal rate for various combinations of pulse frequency and TiO2 powder concentration. The obtained kerf of 54.16 ± 0.05 µm in depth demonstrated an increasing efficiency of more than 1.5 times with the closest analogs for the workpiece thickness up to 5 mm in height. The comparison of the performance (0.0083–0.0084 mm3/s) with the closest analogs shows that the results may correlate with the electrical properties of the assisting materials. [ABSTRACT FROM AUTHOR]

Aluminum-based ceramics exhibit excellent wear resistance and hot hardness that are suitable for various responsible applications allowing products to work under extreme mechanical and thermal loads (up to 1000 °C). The problem of high-precision forming complex-shaped parts is a known engineering challenge due to the insulating properties of aluminum-containing ceramics and the formation of chemically active carbides in a hydrocarbon medium. The alternative approach for electrical discharge machining non-conductive sintered Al2O3 in the water-based medium using nickel-chrome plasma-vapor-deposed coating of 12 mm, SnO powder suspension (particle diameter of ⌀10 µm, concentration of 150 g/L), and brass wire-tool is proposed. The productivity was evaluated by calculating the material removal rate and discharge gap for various combinations of pulse frequency and duration. The maximal material removal rate of 0.0014 mm3/s was achieved for a pulse frequency of 30 kHz and pulse duration of 1.7–2.5 μs. The recommended value of the interelectrode gap is 48.0 ± 4.9 µm. The possibility of electrical discharge machining aluminum-containing insulating ceramics without using hydrocarbons, carbon and copper-group assisting measures was proposed and shown for the first time. The chemical content of the debris in the interelectrode gap between components of the materials was thermochemically analyzed. [ABSTRACT FROM AUTHOR]

Modern industry is focused on looking for new and effective technologies to manufacture complex shapes from alloys based on nickel and chromium. One of the materials widely used in the chemical and aerospace industry is Hastelloy C-22. This material is difficult to machine by conventional methods, and in many cases, unconventional methods are used to manufacture it, such as electrical discharge machining (EDM). In the EDM process, the material is removed by electrical discharges between a workpiece and a tool electrode. The physical and mechanical properties of the tool electrodes have a direct impact on the process efficiency, machining accuracy, and surface roughness. Currently, there has been a significant increase in the use of graphite as a material for tool electrodes due to the low purchase cost of the raw material, good machinability, and high sublimation temperature. In this work, an experimental investigation of the influence of the grain size of the graphite tool electrode on material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) of Hastelloy C-22 was carried out. Two POCO graphite tool electrodes with a grain size of 1 µm (AF-5) and 10 µm (S-180) were used. Based on the experimental studies, empirical models describing the influence of machining parameters on technological indicators and the condition of the surface texture were determined. The research indicates that graphite with a larger grain provides higher process efficiency with high relative wear of the tool electrode. The lowest surface roughness was obtained for graphite with a smaller grain size (AF-5). The analysis of the machining parameters proves that the discharge current and pulse duration are the main factors determining the MRR and Ra values for both AF-5 and S-180 graphite. The time interval is the dominant parameter with regard to the relative wear of the graphite electrode. [ABSTRACT FROM AUTHOR]

The discharge current waveform affects the processing characteristics and surface integrity by affecting the process of energy input. At present, although the rectangular current waveform is widely used in electrical discharge machining (EDM), there is not enough evidence to prove that it is the most suitable. Therefore, in this study, the influence of the discharge current waveforms on processing characteristics and surface integrity was investigated and compared under similar pulse energy. Three types of discharge current waveforms including rectangular (Rec), triangular (Tri), and trapezoidal (Tra) are used for processing. The material removal amount, surface topography, roughness, phase compositions, white layer thickness, and residual stress were investigated and analyzed. The results showed that Tri could remove the most materials per pulse-on duration, followed by Tra. Compared with Rec, the size of craters and debris on the sample surface produced by the Tri and Tra was larger. The surface roughness and residual stress of samples processed by Tri were the highest. When the discharge current waveform was constant, XRD spectra of samples fabricated by EDM under different pulse energy were almost the same. Compared with Rec, the diffraction peaks of samples produced by Tri and Tra were reduced. When the pulse energy was low, the white layer of samples processed by Rec was thinner than that processed by Tri. This phenomenon was reversed when the pulse energy was high. The white layer thickness of the sample fabricated by Tra was between the samples processed by Rec and Tri regardless of pulse energy. [ABSTRACT FROM AUTHOR]

Highly dense electrically conductive silicon carbide (SiC)–(0, 10, 20, and 30 vol%) titanium boride (TiB2) composites with 10 vol% of Y2O3–AlN additives were fabricated at a relatively low temperature of 1800°C by spark plasma sintering in nitrogen atmosphere. Phase analysis of sintered composites reveals suppressed β→α phase transformation due to low sintering temperature, nitride additives, and nitrogen sintering atmosphere. With increase in TiB2 content, hardness increased from 20.6 to 23.7 GPa and fracture toughness increased from 3.6 to 5.5 MPa m1/2. The electrical conductivity increased to a remarkable 2.72 × 103 (Ω cm)–1 for SiC–30 vol% TiB2 composites due to large amount of conductive reinforcement, additive composition, and sintering in nitrogen atmosphere. The successful electrical discharge machining illustrates potential of the sintered SiC–TiB2 composites toward extending the application regime of conventional SiC‐based ceramics. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is very essential unconventional electrothermal machining process to machine the contour profile of hard materials in modern production industries. The liquid dielectric fluid has been replaced by the gas and minimum quantity of liquid mixed with gas (gas mist) to encourage the green machining processes. The various gases and gas mist have been used as the working fluid in dry and near-dry EDM, respectively. The research-contextual, various dielectric fluids, sustainable and innovative developments, process parameters, machining characteristics, and optimization techniques applied in various dry and near-dry EDM have been illustrated through an extensive literature survey. Future research opportunities in both dry and near-dry EDM have been summarized to promote eco-friendly EDM research activities. [ABSTRACT FROM AUTHOR]

In electrical discharge machining (EDM), the discharge current waveform that determines the process of energy input has an important influence on machining characteristics as the discharge voltage is constant after the dielectric is broken down. In the past, the influence of pulse-on time and current on the surface metamorphic layer under rectangular current waveform has been reported, while the influence of non-rectangular current waveform on the surface metamorphic layer is still elusive. In this study, the difference in the surface metamorphic layer of the workpiece processed by triangular current waveform and rectangular current waveform under the same pulse energy was investigated and analyzed. Compared with rectangular current waveform, surface roughness of the workpiece processed by triangular current waveform was higher. Cracks on the surface of the sample produced by rectangular current waveform always exist from 0.088 to 1.96 mJ. However, it was difficult to observe cracks on the surface of the sample processed by the triangular current waveform when the pulse energy was higher than 0.41 mJ. There is no obvious difference in the intensities of diffraction peaks α-Fe, γ-Fe, and cementite for the samples processed by rectangular current waveform with different discharge energy. However, for the workpiece fabricated by triangular current waveform, the peaks of cementite and γ-Fe increased as the pulse energy increased. When the pulse energy was low, the white layer of the sample processed by rectangular current waveform was thinner than that processed by triangular current waveform. This phenomenon is reversed when the pulse energy is high. [ABSTRACT FROM AUTHOR]

The influences of electrical and non-electrical parameters on surface integrity during the EDM process have been widely researched in past years. However, the effect of the energy input process at the same discharge energy is seldom reported. To select more suitable processing parameters according to the processing requirements, we have studied the influence of the energy input process on processing characteristics and surface properties. Two different energy input modes (high discharge current with short pule-on time (HIST) and low discharge current with long pule-on time (LILT)) are used. When the discharge energy is the same, the HIST mode has a higher material removal amount, while the sample produced by the LILT mode presents a lower surface roughness and residual stress. More surface cracks are detected on the samples processed by the LILT mode, and their dimensions in terms of length and width are greater than that of the HIST mode. The microstructure of the EDM surface is composed of α-Fe, γ-Fe, and cementite. When the discharge energy is higher than 0.24 mJ, the intensities of diffraction peaks γ-Fe and cementite on the EDM workpiece surface produced by the HIST mode are higher. The white layer thickness is related to the discharge energy and its input process. When the discharge energy is lower than 0.51 mJ, the white layer is thinner under the LILT mode. However, the white layer of the EDM sample fabricated by the HIST mode is thinner when the discharge energy is higher than 0.51 mJ. [ABSTRACT FROM AUTHOR]

The dynamical evolution of electrical discharge machining (EDM) has drawn immense research interest. Previous research on mechanism analysis has discussed the deterministic nonlinearity of gap states at pulse-on discharging duration, while describing the pulse-off deionization process separately as a stochastic evolutionary process. In this case, the precise model describing a complete machining process, as well as the optimum performance parameters of EDM, can hardly be determined. The main purpose of this paper is to clarify whether the EDM system can maintain consistency in dynamic characteristics within a discharge interval. A nonlinear self-maintained equivalent model is first established, and two threshold conditions are obtained by the Shilnikov theory. The theoretical results prove that the EDM system could lead to chaos without external excitation. The time series of the deionization process recorded in the EDM experiments are then analyzed to further validate this theoretical conclusion. Qualitative chaotic analyses verify that the autonomous EDM process has chaotic characteristics. Quantitative methods are used to estimate the chaotic feature of the autonomous EDM process. By comparing the quantitative results of the autonomous EDM process with the non-autonomous EDM process, a deduction is further made that the EDM system will evolve towards steady chaos under an autonomous state. [ABSTRACT FROM AUTHOR]

Sinking electrical discharge machining (EDM) is a vital machining technology used in modern mechanical manufacturing. However, the conventional sinking EDM, which utilizes an oil-based working medium, presents disadvantages such as low machining efficiency, harmful gas emissions, and fire hazards. Although researchers have attempted to use pure water as the working medium, pure water cannot replace oil and has not yet been industrially applied as a working medium because of its low machining efficiency and thick surface recast layer. Herein, we propose sustainable and green sinking EDM utilizing foam water (SEDM-FW) as the working medium, a method that uses pressurized foam water, ultrastrong energy discharge, and upward electrode feeding. The proposed method is cost effective, and its machining efficiency is more than three times higher than that of the conventional sinking EDM at the same peak current. The use of foam water instead of oil as the working medium solves environmental pollution problems associated with the conventional sinking EDM. In terms of environmental performance, the SEDM-FW produces gas byproducts that do not contain any harmful components, including 1,3-butadiene and benzene, which are present in the conventional sinking EDM. Compared with using pure water, using foam water as the working medium in conjunction with an appropriate gas-to-liquid ratio can double the machining efficiency, reduce the thickness of the recast layer by more than half, and reduce the size of surface microcracks. Using gas-dominated foam water, surface microcracks can be eliminated, and a zero-thickness recast layer can be achieved. [Display omitted] • A sustainable and green sinking EDM method (SEDM-FW) is proposed. • Foam water is used as the working medium, which replaces conventional oil and pure water. • Gas byproducts of SEDM-FW are completely harmless to humans and environment. • A proper gas-to-liquid ratio has higher MRR, lower REWR, and good surface integrity. • Gas-dominated foam water can eliminate microcracks and achieve zero-thickness recast layers. [ABSTRACT FROM AUTHOR]

Boron carbide (B 4 C) composites containing 0–10 wt.% graphene nanoplatelets (GNPs) were consolidated using hot pressing at 1950 °C for 60 min under 30 MPa in an argon atmosphere. Their electrical discharge machining (EDM) characteristics were evaluated for the first time. Additionally, the effects of GNPs on the microstructure, electrical conductivity, material removal rate (MRR), and surface roughness (R a) of B 4 C composites were investigated. The results show that the B 4 C composite containing 10 wt.% GNPs exhibited the highest electrical conductivity of 4997 S·m−1 because of the formation of GNPs conductive networks. Under a fine machining condition, the MRR of the B 4 C composite was enhanced by 43.5 % (from 6.55 to 9.40 mm3 min−1) compared with that of monolithic B 4 C. Furthermore, the R a decreased to 1.12 μm, which was significantly lower than that of pure B 4 C (2.44 μm). Scanning electron microscope and energy disperse spectroscopy analysis of the EDM surfaces were used to determine that the main material removal mechanisms for B 4 C composites with less than 2 wt.% GNPs were spalling and melting. As the GNPs content increased, B 4 C grain fallout, melting, and evaporation became more dominant. The other mechanisms, including thermal shock and oxidation, are also discussed in detail. [ABSTRACT FROM AUTHOR]

AISI-D6 steel is widely used in the creation of dies and molds. In the present paper, first the electrical discharge machining (EDM) of the aforementioned material is performed with a testing plan of 32 trials. Then, artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were applied to predict the outputs. The effects of some significant operational parameters—specifically pulse on-time (Ton), pulse current (I), and voltage (V)—on the performance measures of EDM processes such as the material removal rate (MRR), tool wear ratio (TWR), and average surface roughness (Ra) are extracted. To lead the process operators, process plans (i.e., parameter–effect correlations) are created. The outcomes exposed the upper values of pulse on-time caused by higher amounts of MRR and Ra, and likewise lower volumes of TWR. Furthermore, growing the pulse current resulted in upper volumes of the material removal rate, tool wear ratio, and surface roughness. Besides, the higher input voltage resulted in a lower amount of MRR, TWR, and Ra. The estimation models developed by using experimental data recounting MRR, TWR, and Ra. The root means the square error was used to determine the error of training models. Furthermore, the estimated outcomes based on the models have been proven with an unseen validation set of experiments. They are found to be in decent agreement with the experimental issues. The investigation shows the powerful learning capability of an ANFIS model and its advantage in terms of modeling complex linear machining processes. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is an unconventional machining process based on removing material by successive electrical discharges. The tool electrode wear must be kept as minimal as possible to produce high-precision components. This scope proposes the development of a new technique for identifying wear on electrodes and its evolution using acoustic emission (AE) signals. Therefore, EDM tests were performed on AISI H13 steel parts with electrolytic copper tool electrodes under different conditions with concomitant AE signal measurements. In these tests, the first one has the following parameters: voltage pulse duration time (te) of 150 μs; the time interval between two successive voltage pulses (to) of 14.84 μs; electrical current of 33 A; and positive polarity electrode. For the second test: duration of the voltage pulse of 2 μs; the time interval between two successive voltage pulses of 4.90 μs; electrical current of 18 A; and negative polarity electrode. In this way, a wear rate 28.3 times higher was obtained in the electrolytic copper electrode in the first test, more aggressive due to its parameters, for the same machining time compared to the second test. Finally, the wear of the tool electrodes was related to the AE signals from machining; initially in this study, the workpiece's mass loss was not verified. These signals were analyzed using the short-time Fourier transform techniques and spectral entropy. The results showed that the signals using the new technique of relation respond to wear and are sensitive to the electrode's wear rate. [ABSTRACT FROM AUTHOR]

This paper proposes a new optimization methodology based on the combination of the response surfaces methodology and the genetic algorithm for the selection of process parameters in electric discharge machining. Machining tests are carried out on a stamping machine under different process parameters. The paper presents a mathematical modeling for the analysis of the effects of machining parameters on the characteristics performance of EDM process when machining AISI 1095 steel. The mathematical models are developed by the response surface methodology (RSM). These models are used to build an optimization model taking into account the effect of various machining parameters. It is observed that the developed models present agreeable error limits when they have been compared with the experimental models. [ABSTRACT FROM AUTHOR]

The efficient removal of material debris by flushing is critical for the performance and the surface quality of the electrical discharge machining (EDM) manufacturing process. The particle concentration alters the thermal, mechanical, and electrical properties of the particle–dielectricum suspension and affects the manufacturing process and the surface quality by inducing high thermal loads. For the first time, we perform a direct particle–fluid simulation of the flushing cycle in a generic EDM cavity using a hierarchical Cartesian sharp-interface cut-cell method. The flow around each debris particle is completely resolved and the heat transfer between the particles and the fluid is taken into account. The rate of material removal and the cooling performance of the flushing mechanism are studied for three-volume loadings. The results show that the flow around the particles has a pronounced impact on the heat transfer between the dielectricum and the workpiece. A particle loading of 14% increases the mean heat transfer by approximately 16%. The particle loading also has a pronounced impact on the rate at which particles are flushed out of the cavity. Increasing the initial volume loading from 6% to 14% decreases the amount of particles that get flushed out of the cavity by 14%. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is the unconventional machining technique used extensively for machining difficult-to-machine materials with lower material removal rate and poor surface roughness. To overcome these drawbacks, synthetic dielectric fluid is replaced with nanoparticle-infused biodegradable dielectric fluid in the machining of Hastelloy material. This paper focusses on the machining performances of Hastelloy in EDM using various concentrations of 0.5, 1 and 1.5 wt% of nano-zirconia dispersed in biodegradable canola oil methyl ester as the dielectric medium, and these characteristics were compared with those of the synthetic dielectric medium. Based on the D-optimal design coupled with cuckoo search algorithm, machining was carried out with various dielectric fluids and their influences on the metal removal rate, surface roughness, surface morphology and surface topography in EDM studied. The results proved that the canola oil methyl ester containing 0.5 wt% of nano-zirconia (C-0.5) had provided good surface finish, better surface topography, smooth surface morphology and high metal removal rate in comparison with the other dielectric fluids used in this study. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is one of the most broadly used non-traditional machining processes. The introduction of the idea of sustainable production and the need to adjust the ISO norms are essential for the assessment of all production methods using the principles of sustainability. The traditional EDM uses kerosene as a dielectric with poor safety and unfriendly environmental consequences. To solve this issue, the substitution of hydrocarbon dielectric is the principal consideration in EDM investigation. This research offers an intensive review of the environment-friendly EDM processes, where the objective is to try dielectric liquids that can be replaced, bypassing traditionally used EDM oil. It is seen that water- and gas-based dielectrics could assume control over synthetic oil in the EDM process. Revolutionary sustainable technologies using water or bio-dielectric have been introduced to rectify sustainability issues and have benefited greatly from the evolution of the EDM operation in terms of efficiency and sustainability. Innovative environmental-friendly EDM processes, which have determined the step of advancement in the field of scientific and mechanical research, are briefly discussed in this article. A blueprint of the forthcoming trends of the research is indicated in the last segment. [ABSTRACT FROM AUTHOR]

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Magnesium and its alloys play a vital role in various applications such as automobile, aircraft, biomedical and military etc. Mg alloys have superior characteristics such as light weight, high strength, good damping capacity and easily castability etc. Eventhough it has attractive range of properties, the machining of magnesium alloys using conventional machining methods is difficult. To overcome that issue, non traditional machining is considered as a potential process. EDM is an electro thermal process extensively used for machining hard materials. In this investigation, the ZE41A magnesium alloy is machined using EDM with copper electrode. In order to improve surface characteristics such as material removal rate (MRR) and surface roughness (SR), various parameters namely current, pulse on time and pulse off time were selected. The regression values of MRR and SR are 97.20% and 99.62% respectively indicating an empirical relationship between the parameters and responses. Pulse off time was found as a significant parameter on the response followed by pulse on time and current. MRR and SR increased with increasing current, pulse on time and pulse off time. At a current of 5A, the produced spark density is high so that the removed quantity of material from the workpiece is high. At a pulse on time of 95 μs, the spark intensity is high affecting the local temperature in the machined zone, and hence MRR increases. SR drastically increases at increasing current. At higher current, large size crater are observed on the machined surface that made the surface rough, and hence SR increases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deterministic cellular lattice structures of IN718 are fabricated through LPBF. • Through-holes EDM drilling is performed on LPBF-fabricated lattice structures. • Machined holes show dimensional variability due to pores, nodes, and lattice defects. • Near-circular through-holes machined by optimizing EDM parameters and electrode positioning. Additive manufactured (AM) metallic lattice structures are being largely explored for different engineering applications. The fastening, implantation, and installation of such lattice structures demand secondary processing. In the current work, through-hole drilling is performed using electrical discharge machining (EDM) on Inconel 718 (IN718) lattice structures fabricated by laser powder bed fusion (LPBF). The challenges in EDM hole drilling have been encountered and uncertainty in the machined holes owing to periodically open pores and nodes in the lattice structures sizes has been identified. Finally, an experimental strategy has been proposed for near-circular hole drilling by design optimization and tool positioning with respect to the cellular structures. [ABSTRACT FROM AUTHOR]