Electrical Discharge Machining Method Research Articles

Assessment of process parameters on modified 316L SS surfaces prepared via hybrid powders mixed EDM

Abstract This study aims to assess the influence of hybrid powders (hydroxyapatite, manganese, copper, and carbon nanotube) mixed electric discharge machining (EDM) and coating process on 316L stainless steel (SS). An efficiently machined, hydrophilic, thin and microporous surface is produced using variable discharge energies and powders weighted percentage suspended in the dielectric medium. The research outcome indicates that the hybrid powders mixed-EDM process synthesised a coating that substitutes the base elements with foreign elements of calcium (Ca), phosphorous (P), copper (Cu), carbon (C), oxygen (O), and manganese (Mn). The surface wettability response of the coating displays a hydrophilic nature with a contact angle of 51.5° and surface energy of 52.9 mJ/m2. The coated surface exhibited a roughness value of 3.201 µm, which is expected to promote osseointegration, and the material removal rate has been enhanced to an optimal value of 100.32 mg/min. The Taguchi design demonstrated that the powder mixing ratio, current intensity, and spark time are the most influential factors in the hybrid powders mixed EDM process. This study determines a novel multiple additives-assisted EDM method to synthesise a coating on 316L SS with potential benefits for biomedical applications.

INVESTIGATION OF THE MACHINING PERFORMANCE OF ALUMINUM–BRONZE ALLOY IN WEDM USING TAGUCHI METHOD

Aluminum–Bronze alloys (Al-10%–Cu-balance) are difficult-to-machine cut alloys. Copper (Cu) metal itself is not suitable for machining. The machining performance of the Aluminum–Bronze alloy sample was investigated by the Wire Electric Discharge Machining (WEDM) method, which is among the non-traditional manufacturing methods used in conductive materials that are difficult to process. The aluminum–bronze sample with a diameter of 20[Formula: see text]mm was cut with 0.18[Formula: see text]mm molybdenum wire electrode. Table feedrate, pulse-on-time and pulse-space were used as experimental parameters. Surface roughness and energy consumption values were measured in WEDM process. According to Taguchi analysis and ANOVA results, it was determined that the pulse-on-time parameter was effective on the surface roughness and the table feedrate parameter was effective on the energy consumption.

EDM machining effectiveness for Ti–6Al–4V alloy using Cu–TiB2 ceramic composite electrode: a parametric evaluation

The study addresses the requirement for better machining of titanium alloy (Ti–6Al–4V) in Electrical Discharge Machining (EDM) with a Cu–TiB2 ceramic composite powder metallurgy electrode. The electrode underwent analysis for relative density, hardness, and microstructure using field emission scanning electron microscopy and X-ray diffraction. Results indicated a relative density of approximately 90.08%, a microhardness of around 142 H V, and an electrical conductivity of 46% IACS. Response Surface Methodology (RSM) was used as Design of Experiment (DoE) technique for this study to investigate the effects of pulse current (Ip), pulse on time (Ton), and discharge voltage (V) on Material Removal Rate (MRR) and Surface Roughness (SR). Analysis of variance (ANNOVA) at a 5% significance level highlights the significant impact of Ip, Ton & V, and the interaction between selected parameter on MRR and SR. Results show a significant influence of pulse current (Ip) and pulse duration (Ton) on both MRR and SR. Rising pulse current correlates with improved MRR, with optimal parameters identified as a pulse current of 15 A, a pulse on time of 150 μs, and a voltage of 50 V. The study also looks into the usage of reverse polarity to improve surface finish compared to typical EDM methods. The use of Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) analyses adds depth to the evaluation of surface formations on the workpiece. EDS analysis indicates the presence of 63.13 wt (%) of boron on the machined work surface, affirming the effectiveness of the developed Cu–TiB2 electrode in machining titanium alloy.

Experimental optimization of machining GH4145 by atomizing discharge ablation milling

Atomizing discharge ablation milling (ADAM) technology is an efficient discharge machining technology derived from the traditional electrical discharge machining (EDM) method, which can be used to efficiently machine hard-to-machine materials such as nickel-based superalloy. In this present, the performance of machining nickel-based superalloy GH4145 by ADAM and Air near-dry EDM were compared, and the experimental results showed that the material removal rate (MRR) obtained by ADAM was nearly double that of the latter. A single-factor experiment were conducted to investigate the effect of electrode rotation speed on ADAM’s processing performance. Subsequently, an orthogonal experimental method was used to design the experiment. The signal-to-noise ratio analysis method was used to systematically study the performance characteristics of ADAM, including the influence of atomization amount, oxygen pressure, discharge current, duty ratio on MRR and tool electrode relative wear rate (TWR). The results showed that discharge current was the most influential processing parameter on MRR and TWR. Finally, the optimal combination of processing process parameters that met the requirements of various processing effect evaluation indicators were obtained and the correctness of the single objective optimization results was verified through experiments.

Micro ECDM process comparison using different tool feed methods of constant gravity and spring-force

Quartz glass has been widely used in multiple frontier fields of science and technology owing to its excellent chemical and mechanical properties, such as optical communication, semiconductor, photovoltaic power, and aerospace. ECDM (electrochemical discharge machining) is a non-traditional material removal process suitable for machining non-conductive materials of high hardness and brittleness. The tool electrode feed method is a key factor affecting the ECDM process. Experimental research was carried out for comparing the conventional gravity feed method and a newly-developed spring-force feed method. Micro tool electrodes of Φ150 µm were fabricated by combining the method of TF-WEDG (tangential feed-wire electrical discharge grinding) and reverse micro EDM (electrical discharge machining). Machined microstructures of blind holes, channels, squares, and patterns were compared by the gravity feed method and the spring-force feed method respectively. The experimental results show that the spring-force feed method can improve the micro ECDM process considering the aspects of dimensional accuracy, overcuts, deteriorated edges, surface topography, and tool wear.

Surface modification by electrical discharge machining: A systematic literature review and bibliometric analysis

In past few decades, the non-traditional machining techniques of electrical discharge machining (EDM) has been developed to machine materials that are difficult to cut. Additionally, the EDM method has also been employed to change the material's surface properties by applying a layer on the workpiece that is up to a few microns thick in order to improve the surface attributes. In past three decades, several numerous investigations on surface modification using EDM have been conducted globally. Present study provides a comprehensive review along with bibliometric investigation of the many approaches used to enhance the surface topology of the materials during the EDM process from 1993 to 2023. Firstly, a brief introduction to EDM-based different surface modification techniques such as electric discharge coating, surface texturing, surface alloying, and powder-mixed EDM has been given. All related documents were acquired from Scopus Core Collection and evaluated using a bibliometric analysis technique. The bibliometric analysis was examined based on the time distribution of articles, geography, top-cited documents, analysis of authors’ keywords, country-wise publications, etc. The result showed that India dominates this research area, followed by China, and there is a growing trend in the number of publications. Further, the influence of EDM parameters, dielectric fluid, tool, and work material etc. has also been discussed. The research work published related to topic has been summarized and resented in tabular format. This review offers interested scholars with a thorough overview of the significant achievements in the subject over the last few decades, including a description of the most relevant studies and their results. Moreover, potential areas for further investigation are emphasized with the goal of revitalize the interest of the worldwide scientific community in advancing this method.

Optimization of PMEDM process parameters for B4C and B4C+SiC reinforced AA7075 composites

MaterialsWith sufficient electrical conductivity can be successfully processed by applying the electrical discharge machining (EDM) method; however, due to the presence of non-conductive particles in composites, which have been produced by adding ceramics particles, problems such as unstable machining, low material removal rate, and high tool wear are observed during the EDM. This study employed powder-mixed electrical discharge machining (PMEDM) by adding electrically conductive nano-size graphite powder into the dielectric liquid to minimize these problems. Moreover, the machinability of AA7075/ B4C and AA7075/ B4C+SiC composites was evaluated using the Taguchi method. The experimental study used L18 orthogonal array (OA) (21 ×32). ANOVA was employed to obtain significant parameters and percent contributions of variable parameters on the material removal rate (MRR). Reinforcement ratio, current and sintering time applied to the workpiece were chosen as variable parameters. The optimum parameters for MRR were obtained at A1B3C3 (reinforcement ratio= 10%, current= 8 A, sintering time=150 min). According to S/N ratio graphs, increasing the reinforcement ratio leads to a decreased MRR. On the contrary, when the applied current increases, MRR increases. Additionally, analysis results show that the discharge current is the most important parameter affecting MRR. In the morphological examinations, it was understood that the amounts of B4C and SiC particles in the composite structure affect the quality of the machined surfaces. It was determined that the surface quality deteriorated with the increase in the amount of SiC and B4C in the composite structure and the increase in the discharge current.

ANALSYS OF DEFECT LAYER IN ELECTRICAL DISCHARGE MACHINING OF NON-CONDUCTIVE CERAMIC

The aim of the research is to describe a new approach for processing non-conductive ceramics. A method of electrical discharge machining with an assisting electrode is presented, which allows the machining of zirconium ceramics. An analysis of the defective layer, i.e., the recast layer and the heat-affected zone, was performed. Two parameters, discharge current and pulse duration, were chosen to study the effects on the thickness of the defect layer. The test results show that increasing the discharge current and pulse duration increases the thickness of the defect layer. This is due to the increase of discharge energy, which causes more heat in the machining zone. Future research can be directed to the analysis of a larger number of test points to see a better dependence between the machining parameters and the thickness of the defect layer.

Effects of non-electrical parameters on the characteristics of discharge craters and machining performance in short electrical arc milling

During electrical discharge machining (EDM), the process parameters greatly influence the discharge characteristics and machining performance, including electrical and non-electrical parameters. As a new EDM method, short electrical arc milling (SEAM) is plagued by frequent short circuits, poor debris removal, and low energy-transfer efficiency. Therefore, this paper investigated the influence of non-electrical parameters (electrode material, working medium, and electrode rotation) on the crater characteristics, machining efficiency, and electrode wear. The micromorphological characteristics of the workpiece were explored. The results suggested that non-electrical parameters compressed and fractured the plasma channels, thus changing the effect of EDM. The air-tap water medium and electrode rotation promoted debris removal and arc breaking, which prevented the arc from ablating the workpiece. When GH4099 alloy was machined with a copper electrode, the workpiece surface quality and machining efficiency were high, and the thickness of the heat-affected zone was small. This work reveals the characteristics of short electric arc discharge and provided a theoretical basis for the efficient and high-quality machining of difficult-to-cut materials by SEAM.

Parameters Optimization of Electrical Discharge Machining Process Using Swarm Intelligence: A Review

Electrical discharge machining (EDM) can use soft tool electrodes to process hard workpieces to achieve “soft against hard”, because it directly uses electrical energy and thermal energy to remove metal materials. Then, it can generate complex features on harder materials and meet the requirements of excellent surface quality. Since EDM involves many process parameters, including electrical parameters, non-electrical parameters, and materials properties, it is essential to optimize its process parameters to obtain good performance. In this direction, the application of the swarm intelligence (SI) technique has become popular. In this paper, the existing literature is comprehensively reviewed, and the application of the SI technique in the optimization of EDM process parameters is summarized. Sinker-EDM (SEDM), wire-EDM (WEDM), and micro-EDM (MEDM) with various hybrid techniques are among the EDM methods considered in this study because of their broad adoption in industrial sections. The fundamental nature of all review articles will assist engineers/workers in determining the process parameters and processing performance, the SI algorithm, and the optimal technique by which to obtain the desired process parameters. In addition, discussions from the perspectives of the similarity, individuality, and complementarity of various SI algorithms are proposed, and necessary outlooks are predicted, which provides references for the high performance of the EDM processes in the future.

Multi-response optimization of machining parameters of Ti-6Al-2Sn-4Zr-2Mo alloy using EDM process through grey relational analysis

Due to its high corrosion resistance and low density, it is tedious to machine high strength materials such as titanium alloy for the manufacture of engineering products related to aerospace, automobiles, and medical applications. In this study, an attempt was made to consider the impact of tool electrodes in the electrical discharge machining method for successful machinability of titanium alloy. High temperatures are used during electrical discharge machining to melt and vaporise the hard titanium alloy. In the current work, an EDM machining method was used to machine a Ti-6Al-2Sn-4Zr-2Mo alloy while using the input parameters of pulse on time, voltage, and current as process parameters. The experiments were carried out based on the workpiece, and surface morphology was performed on the workpiece surface. The process parameters were optimised using the Multi-Response Grey Relation Analysis method, and a major effects plot was created to see how the factors affected the MRR and surface roughness. Surface finish and MRR have been discovered to be directly correlated with discharge current. These are the best process parameters for machining pulse on time (150 s), voltage (60 V), and discharge current (16 A).

Experimental Investigation and Optimization of EDM process in different Paramaters on NICKEL material (nimonic 8A)

Newly prepared Nickel alloy (Nimonic80A As Per ASTM B637 Alloy-N07080) using powder metallurgy is considered in this investigation. In Conventional machining, Nickel alloys produce higher tool wear rate , poor surface Finish, but this can be reduced by Electrical Discharge Machining (EDM) method. Nickel alloy(Nimonic80Aas per ASTM B637 Alloy-N07080) presently used in wide variety of applications such as Automobiles, Aerospace industries, because of their high strength to temperature ratio. In this project, Nickel alloy (Nimonic80A as per ASTM B637 Alloy-N07080) is taken with different types of EDM Properties. Before that Chemical characteristics in addition machinelike possessions as well as to a degree Tensile test,Charpy test are administered on for judgment substance moreover severity of the material plus from that timeforward we acted EDM process by utilizing of TAGUCHI procedure. Results of tests are resolved to select high quality surface finish moreover fastest process for material request.

Current Research Trends in Electrical Discharge Machining : A Review

One of the most widely utilised non-conventional exact material removal procedures is electrical discharge machining (EDM). Hard metals can be moulded using the electrical discharge machining (EDM) method, which uses arc erosion to create deep, intricately formed holes in all types of electroconductive materials. Between the work piece and the electrode, there is a tiny space where erosion pulse discharge takes place. By melting and vaporising the undesired material, this separates the parent metal from the unwanted stuff. The objectives of this new study are the same: to reduce tool wear and achieve enhanced surface quality while reducing metal removal rate. This study discusses the scientific work done from the beginning to the invention of die-sinking EDM, Water in EDM, and dry Electric discharge machining and powder-mixed EDM are also used. in the last ten years. Additionally, a brief description of the EDM research plan going forward is included.

Fatigue crack propagation analysis in an aero-engine turbine disc using computational methods and spin test

This article presents a study on applying the fracture mechanics-based method to predict the fatigue crack growth (FCG) characteristics of the turbine disc in a turboshaft engine. According to the stress analysis results, the electric discharge machining (EDM) method introduced notches for initiating cracks of a specific size into the critical locations of the turbine disc. The FCG of these cracks under cyclic load was predicted utilising a three-dimensional (3D) numerical analysis method and a simplified rectangular plate model with relevant fracture mechanics properties. Meanwhile, the full-scale spin test was performed using a pre-flawed turbine disc under intentional loads at an isothermal temperature. After the test, the crack surface fractography and the quantitative fracture striation analysis revealed the practical crack propagation behaviour. There was a relatively small difference between the experimental results and the 3D finite element method, which indicated the good predictability of FEM for turbine disc crack growth. Furthermore, the rectangular plate models could predict the front stage of steady-state crack growth but were overall conservative due to their inability to precisely calculate the effects of crack growth and structure geometry on the stress intensity factor.

INFLUENCE OF PULSE DURATION ON SURFACE ROUGHNESS IN ASSISTING ELECTRODE ELECTRIC DISCHARGE MACHINING

Electrical discharge machining (EDM) is an unconventional machining process that can machine all electrically conductive materials, regardless of their physical and metallurgical properties. Due to the efficiency of machining modern engineering materials, existing EDM methods are constantly being researched and improved or developed. This paper deals with an innovative method that enables EDM machining of non-conductive ceramic material, named Assisting Electrode Electrical Discharge Machining (AEEDM). It combines electrical discharge machining with a hybrid assisting electrode. The aim of the study is to find the influence of pulse duration on surface roughness. For the set machining conditions, it was found that the surface roughness was increased by increasing the pulse duration. It should be emphasized that the supporting electrode method is used only in the electroerosion of electrically non-conductive materials.

A state-of-the-art review on electric discharge machining of shape memory alloys

Electrical Discharge Machining is among the early non-traditional machining methods. The heart of the EDM process is the thermoelectric energy that exists between the work piece and an electrode. By melting and vaporizing the undesired material in a narrow gap between the work piece and the electrode, a pulse discharge may remove it from the parent metal. In order for the work piece and the electrode to ignite the flame, electrical conductivity is necessary. EDM may be used to develop a range of objects, such as dies and moulds, aeronautical components, and automotive parts. EDM may be used to finish both medical and industrial items. Research trends in EDM are explored in this study, including those in dry EDM machining, ultrasonic vibration, EDM in water, and EDM with powder additives. This paper's purpose is to evaluate the extensive research that has been done to process these shape memory alloys (SMAs) utilizing the concepts of electrical discharge machining (EDM) and related methods. A careful examination and publishing of the numerous studies undertaken in the disciplines of wire EDM, die-sinking EDM, and other EDM variations on different kinds of SMAs. The various theoretical, experimental, modelling, and optimization-based studies that have been done into SMA EDM are also discussed. It was also suggested that choosing the suitable process parameters, tool electrodes, and dielectrics may considerably boost the process overall efficacy.

Direct Observation of Discharge Phenomena in Vibration-Assisted Micro EDM of Array Structures.

The batch mode electrical discharge machining (EDM) method has been developed to improve the throughput and accuracy in fabricating array structures, but the process suffers from insufficient debris removal caused by the complex electrode geometry. Tool vibration has been used to improve flushing conditions, but to date the underlying mechanism of the tool vibration on the micro EDM of array structures remains unclear. This study aimed to investigate the effect of tool vibration on the machining process by direct observation of the discharge phenomena in the discharge gap by using a high-speed camera. Micro EDM experiments using 9 and 25 array electrodes were performed, and the effect of tool vibration on the discharge uniformity and tool wear was evaluated. It was found that tool vibration improved the uniformity of the discharge distribution, increased the machining efficiency, and suppressed the tool wear. The discharges occurred in periodic intervals, and the intensity increased with the amplitude of tool vibration. The results of this study indicate that the vibration parameters determine the discharge period duration and intensity to achieve optimum stability and efficiency of the machining process.

Optimization of hydroxyapatite powder mixed electric discharge machining process to improve modified surface features of 316L stainless steel

Traditional methods for producing 316L steel with a desired roughness and a uniform thin coating for sufficient bioactivity and long-term durability are highly difficult and require post-processing. Electric discharge machining (EDM) is a nontraditional process that can accomplish both machining and coating the surface concurrently. This study provides a thorough examination of the impacts of EDM process parameters on the machining responses, which are significantly necessary for processing 316L steel to reach its full potential. The nano-hydroxyapatite particles added EDM method is used to improve the machining and the surface responses. EDM process parametric optimization is conducted using Taguchi's design to achieve the lowest surface roughness of 2.04 µm and a recast layer thickness of 6.11 µm. As a machinability metric, the greatest material erosion rate (MER) of 20.64 mg/min is achieved. Current intensity, discharge period and hydroxyapatite amount are identified to be important predictors for MER, surface roughness and recast layer thickness. Scanning electron microscope with the energy dispersive X-ray spectrums and atomic force microscopic images validate the machined surface morphology, elemental compositions and surface topography. Errors of the confirmatory tests are less than 10%, showing that the projected solution sets by the grey wolf optimizer are highly accurate. The study shows a thin recast layer with both nano and micro-surface roughness formation, which have a great importance in biomedical applications.

Dual-wafer intergrinding thinning by bipolar-discharge EDM with a capacity-coupled pulse generator considering large gap capacitance and minimization of discharge energy

The noncontact electrical discharge grinding technique has the potential to effectively grind thin, increasingly large-diameter wafers. This study proposes a bipolar electrical discharge machining (bipolar-EDM) method to realize the intergrinding of dual wafers, in which both wafers serve as the working electrode. A capacity-coupled (CC-type) pulse generator generates regular and identical bipolar discharges, ensuring symmetrical and stable removal of both wafers. Thus, both the energy efficiency and wafer thinning yield are doubled. The process characteristics are evaluated through equivalent circuit analysis and experiments, demonstrating that two thinned wafers exhibit high consistency in surface integrity and material removal rate (MRR). Moreover, the dual-wafer system causes an increase in the circuit resistance and gap capacitance, leading to a much lower discharge energy. This is beneficial for precision wafer grinding and thinning by electrical discharge machining (EDM) while keeping damage minimal. As a result, two Φ20 mm 4H–SiC wafers were thinned simultaneously with a maximum thinning rate of 3 μm/min. A mirror-like smooth surface (Ra < 80 nm) was obtained under finishing conditions, demonstrating its capability for precise wafer processing.

Evaluation of the Support Structure Removal Techniques for Additively Manufactured Ti6AL4V Parts

Support structures are required for overhanging surfaces in additive manufacturing to prevent part deformation. However, these support structures are undesirable because they are removed during postprocessing after the part is built. It is critical to remove metal support structures because they can occasionally leave residue on the part. Among the various support-removal techniques, manual removal and wire electrical discharge machining (EDM) are the most frequently used. While most manufacturers recommend the manual method due to its economic benefits, it may be challenging for thin walls, small-scale components, and brittle materials. The purpose of this study is to evaluate and compare these two methods, taking into account both their advantages and disadvantages. The results indicate that while manual support-removal is quick, it results in a degraded surface topography and increased surface roughness due to support tooth remnants and residue. The wire EDM method of removing support resulted in a more uniform surface topography and a superior surface finish. However, as a result of thermal damage, a heat-affected zone developed on the machined surface.