Dry Electrical Discharge Machining Research Articles

Near Dry Powder Mixed Electric Discharge Machining of AA7050 Hybrid Composites Utilizing Composite Tool Materials

Electric Discharge Machining (EDM) is a prominent technique for producing components with complex geometry and intricate shapes. However, productivity depends on the selection of optimal input variables. This research investigates EDM and Near-Dry EDM (NDEDM) on AA7050 hybrid composites, exploring the impact of tool materials, Al2O3 powder concentration, and dielectric fluids on Material Removal Rate (MRR) and Surface Roughness (Ra). NDEDM offers a higher MRR due to localized heating and energy concentration, while hydrocarbon oil EDM provides lower Ra due to cooling and lubrication. Tool material properties, thermal conductivity and bonding strength, affect MRR and TWR. Aluminum composite tools via stir casting display a strong bonding interface, leading to efficient energy transfer and higher MRR, while copper composite tools via friction stir processing exhibit weaker bonding, potentially reducing MRR. Hydrocarbon oil significantly lowers TWR due to effective lubrication and cooling, while near dry EDM results in slightly higher TWR. Al2O3 powder enhances MRR, with an optimal concentration of 1 g/l, while higher concentrations hinder MRR. The presence of Al2O3 powder enhanced the surface quality by reducing the size of the recast layers and producing a smoother surface. Globules, craters, microcracks, pock marks and re-casted layers are the noticeable features spotted on the surface. The results were optimized using the TOPSIS optimization technique and process parameters 32 A current, 30 µs Ton, 3 mm gap distance machined under 3 g/l Al2O3 incorporated hydrocarbon oil dielectric medium using copper composites tool proffers optimal machining performance.

Investigation and Optimization on Parameters of Gas Additive Powder Mixed Near Dry –EDM (GAPMNDEDM) by using Taguchi based- Grey Relational Optimization

The Gas Additive Powder Mix near Dry Electric Discharge Machining (GAPMND-EDM) serves a manufacturing purpose, specifically for cutting hard materials. This involves the removal of material from a workpiece via fusion, ablation, and evaporation caused by the heat energy generated through electric sparks during energy supply. The process offers several advantages in terms of performance and characteristics. This research project aims to optimize key process parameters, including material removal rate, surface roughness, residual stresses, and microhardness. The study employs a methodology that combines the standard deviation-based objective weighting method with GRA (Gray Relational Analysis) optimization to enhance the hybrid GAPMND-EDM process when applied to EN-31 material. Experimental runs were conducted to evaluate the impact of various input factors, such as pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration. The taguchi-based GRA method was utilized for this purpose, and the experimental design followed an L-27 orthogonal array with the assistance of Minitab-19 software. A total of 27 experiments were performed, encompassing diverse combinations of process parameters. Subsequently, an ANOVA (Analysis of Variance) was executed to analyze the influence of pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration on Material Removal Rate (MRR), Surface Roughness (SR), Residual Stress (RS), and Microhardness (MH). The result shows the optimal combination of parameters, denoted as A2B2C2D1, was identified as the preferred configuration.

Preliminary experimental study on a servo control strategy for dry electrical discharge machining

Preliminary experimental study on a servo control strategy for dry electrical discharge machining

Modeling of Dry EDM process parameters during machining of Inconel 718 using artificial neural network

Dry EDM is a modified technique with substituted gaseous medium instead of liquid dielectrics in the usual EDM phase. In this work, dry EDM attempt is made with copper electrode on Inconel 718 material using L27 orthogonal array with compressed air as a dielectric medium. This study takes into account process variables like gas dielectric pressure, pulse current, spark on time, and gap spark voltage. ANN models is developed using Feed-forward back propagation algorithms with trainlm, learngdm, MSE, transig as the training, learning, performance and transfer functions respectively for the Material Removal Rate (MRR), Tool Wear Rate (TWR) and Surface roughness (Ra) as a response characteristics. A good fitness is observed for the trained model. Experimental response values and the ANN predicted values is compared and found that the overall correlation coefficient was 0.94455 which shows good prediction accuracies and effectiveness of the model and ANN technique.

Hybrid Additive and Subtractive Manufacturing Method Using Pulsed Arc Plasma.

In this study, a novel hybrid additive and subtractive manufacturing method using pulsed arc plasma (PAP-HASM) was developed to better integrate additive and subtractive processes. The PAP-HASM process is based on the flexible application of pulsed arc plasma. In this PAP-HASM method, wire arc additive manufacturing using pulsed arc plasma (PAP-WAAM) and dry electrical discharge machining (EDM) milling were used as additive and subtractive techniques, respectively; both are thermal machining processes based on pulsed arc plasma, and both are dry machining techniques requiring no working fluids. The PAP-HASM can be easily realized by only changing the pulsed power supply and tool electrodes. A key technological challenge is that the recast layer on the part surface after dry EDM milling may have a detrimental effect on the component fabricated by PAP-HASM. Here, the hybrid manufacturing method developed in this study was validated with commonly used 316L stainless steel. Preliminary experimental results showed that the PAP-HASM specimens exhibited excellent tensile properties, with an ultimate tensile strength of 539 ± 8 MPa and elongation of 46 ± 4%, which were comparable to the PAP-WAAM specimens. The recast layer on the surface after dry EDM milling has no significant detrimental effect on the mechanical properties of the parts fabricated by PAP-HASM. In addition, compared with components fabricated by PAP-WAAM, those fabricated by PAP-HASM showed significantly better surface roughness.

Experimental investigation into portable near dry EDM

Experimental investigation into portable near dry EDM

Experimental investigation on microhardness, surface roughness, and white layer thickness of dry EDM

In this research, the environment-friendly dry electrical discharge machining (EDM) process is investigated to improve the microhardness, surface finish, and white layer thickness of the machined surfaces using graphite-argon gas as a dielectric medium. The graphite powder, mixed with compressed argon gas, has been used to replace the existing dielectric medium in the EDM process. Gas pressure, discharge current, pulse width, and gap voltage were working as input parameters to reduce surface roughness and enhance the microhardness and white layer thickness. The Taguchi L16 orthogonal array is applied to the design and analysis of the experimental results. The minimum surface roughness (2.23 μm) of the HN31 steel has been attained by increasing the gas pressure up to 1.0 MPa and the minimum values of pulse width (40 μs), gap voltage (40 V), and discharge current (6 A). The maximum microhardness (501.04 HV) has been obtained at 1.2 MPa of gas pressure, 120 μs of pulse width, 60 V of gap voltage, and 18 A of discharge current. The maximum white layer thickness (16.24 μm) is achieved by the maximum values of gas pressure (1.2 MPa), pulse width (160 μs), gap voltage (70 V) and discharge current (18 A). The SEM analysis had been done to reveal the white recast layer thickness and surface roughness of the machined surfaces of the dry EDM process. The SR is increased by the recast layer, pores, and microcracks on the machined surfaces. Finally, the multi-criteria optimization technique: Weight Product Method (WPM) is applied to predict optimum process parameter settings: GP: 1.2 MPa, PW: 120 μs, GV: 50 V, and DC: 18 A to meet the best machining performances (MH = 493.32 HV, WLT = 14.28 μm, and SR = 3.82 μm). The validation tests were done to confirm the predicted results obtained by both the Taguchi and WSM methods.

0D Modeling of Dry-Electrical Discharge Machining Plasma Discharge

Abstract There is a growing interest in developing the dry electrical discharge machining (EDM) process as a sustainable alternative to the conventional liquid dielectric-based EDM process. It is shown that the dry EDM process possesses advantages over the conventional process in terms of thermal damage, recast layer, and tool wear. However, there is a need to increase the productivity of the dry EDM process for its successful adaptation in the industry. This paper presents a dry EDM plasma discharge model with air as the dielectric medium. The model uses global modeling (0D) approach in which equations of mass balance, energy balance, and plasma expansion are solved simultaneously to obtain a time-dependent description of the plasma in terms of its composition, temperature, diameter, and heat flux to electrodes. The model includes reaction kinetics involving 622 reactions and 55 species to determine the air plasma composition. A single discharge dry EDM operation is successfully simulated using the model, and the effects of the interelectrode gap and discharge current on the plasma are studied. An increase in the interelectrode gap decreases the average electron density, plasma temperature, and heat flux. On the other hand, an increase in the discharge current increases the electron density, temperature, and diameter of the plasma linearly, while heat flux to the workpiece increases exponentially. Overall, the model provides an essential tool to study the dry EDM process mechanisms at a fundamental level and devise methods for process improvements.

Multi-performance characteristics optimization in near-dry rotary EDM of AlSiC by weighted principal component analysis

In the current study, electrical discharge machining of particle reinforced aluminium matrix composite (AlSiC) using near-dry conditions is investigated. The investigation has been carried out by using de-ionized water as liquid phase and air as gaseous phase of a two-phase dielectric fluid. The gap between the work material and the tool is supplied with a little amount of de-ionized water droplets at a slow, steady pace using a minimum quantity lubrication (MQL) device. The process parameters included in the study are peak current, duty cycle, pulse-on time, tool rotation and air pressure. MRR (Material removal rate), TWR (Tool wear rate) and HT (Hole Taper) were selected as evaluation criteria. L27 (313) orthogonal array was used to conduct the experiments. The experimental results obtained were used in principal component analysis (PCA). The MPI (multi-response performance index), which combines these principal components and weighted principal component analysis (WPCA), is calculated as overall performance index. The approach is capable of forecasting optimal levels of machining factors. Significant factors and their contribution is determined by ANOVA performed for MPI. To validate the optimum parametric settings confirmatory experiment was conducted. Experimental results show that the responses in near dry rotary EDM process can be successfully improved using the suggested method.

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.

Comparative Analysis of Stationary and Rotary Electrode on Dry EDM in Machining of Hastelloy C276

Dry EDM is a variation of the standard EDM method in which the liquid dielectric is replaced with a gaseous medium during the machining process. This paper presents comparative analysis of stationary and rotary electrode on Dry EDM in machining of Hastelloy C276 using copper EC grade rod as electrode and air as dielectric medium. Solid cylindrical (stationary and rotary) tool electrodes are used, and high-velocity gas is fed between the electrode and the workpiece through it into the discharge gap. The high-velocity gas flow into the gap assists debris clearance and reduces tool and workpiece overheating at the discharge areas. The dry EDM technique is currently known to have reduced tool wear, a smaller discharge gap, fewer residual stresses, a smaller white layer, and a smaller heat-affected zone, in addition to being ecologically friendly. To improve response factors such as material removal rate (MRR), surface roughness (Ra), and tool wear rate (TWR), Taguchi's L9 orthogonal array approach is utilised to design the trials and study the effects of different process parameters. Discharge current (I), pulse on time (Ton), Voltage (V), pressure (P), and tool rotational speed (N) were the varied input parameters. It is observed that the rotary electrode gives better MRR compared to stationary. The analysis of results show that current (I), pulse on time (Ton) and pulse off time (Toff) are the dominant factors that influence MRR and EWR.

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.

Finite Element based Numerical Modelling of Near-Dry EDM with Glycerin-Air Dielectric Mixture

Electrical discharge machining (EDM) is an advanced, non-traditional machining process that is widely employed in sectors such as manufacturing, automotive, aerospace, and medicine. Near-dry EDM is a prospective technology that offers advantages over dry and wet EDM in terms of material removal rate (MRR), tool wear rate (TWR), and surface integrity. A 2D model of the axi-symmetric workpiece based on the Gaussian distribution of the heat flux is used to simulate the single spark in near-dry EDM. The MRR of near-dry EDM is determined at various glycerin flow rates in the glycerin-air combination. The simulation is then performed on the SS304 workpiece with different glycerin flow rates. The results are compared to EDM simulations using N2 and O2 as the dielectric medium. The average MRR of near-dry EDM with an 8 ml/min glycerin flow rate is determined to be 204% higher than that of N2 and 117% higher than that of O2 gas dielectric. When the volumetric ratio of glycerin in the glycerin-air combination increases, the MRR was also found to be increasing. The maximal MRR of near-dry EDM was found to be 129.30703 mm3/min with an 8 ml/min glycerin flow rate and a 0.18 volumetric ratio and a maximal MRR of 144.3407 mm3/min was found with a 15 ml/min glycerin flow rate and a 0.35 volumetric ratio.

Multi objective study in powder mixed near dry electric discharge machining by using utility concept

Powder mixed near dry electric discharge machining is an advanced hybrid form of electric discharge machining method which makes minimum use of dielectric oil and is quite sustainable in machining terms. In this article an approach has been made to optimize the variable parameters such as tool type, metallic powder concentration, dielectric mist pressure, and mist flow rate in order to study their effect along with their range in order to enhancing the machining performance in terms of increased material removal rate (MRR), improved surface finish, improved micro-hardness, reduction of residual stress and tool wear rate. Analysis of variance along with Taguchi L9 methodology was utilized for conducting experiments and it was revealed by the confirmation experiments that by this technique, the optimized results for improved material removal rate, improvement of surface finish, enhanced micro-hardness, reduced residual stress and tool wear rate were 0.63 (mg/s), 0.79 (µm), 249 (HV), 286 (MPa) and 1.07 (mg/min) respectively. The optimized values were obtained at Tool diameter (3mm), flow rate of mist (15 ml/min), concentration of metallic powder (8 gm/l) and mist pressure (0.5 MPa) of dielectric medium.

Optimization of Dry Electrical Discharge Machining of Stainless Steel using Big Data Analytics

Big data (datasets accessible through the Internet) coupled with machine learning arrangements constitute big data analytics, which is heavily resource-depended and creates inequality-only large organizations can sustain or utilize big data analytics, and medium and small organizations fall behind. This article presents a novel inequality-free big data analytics for process planning in medium and small enterprises. Big data, search mechanism, control and evaluation variables relevant datasets, uncertainty quantification using possibility distributions, and decision rules are the components of the proposed analytics. This article reports the characteristics of the analytics applied to optimizing dry electrical discharge machining conditions of stainless steel.

Novel Advances in Machine Tools, Tool Electrodes and Processes for High-Performance and High-Precision EDM

High-performance electrical discharge machining (EDM) is a key technology for manufacturing high-precision components in a broad range of industrially relevant applications. Formation of debris in the working gap leads to arcing and short-circuits on the surface as well as related inaccuracies and process instabilities. Despite decades of research in the field of EDM excessive tool wear and limited process performance are still challenging. In order to overcome highly complex state-of-the-art challenges, dedicated processes, machine tools, peripheral systems, software, tool electrodes and technologies for the application of alternative dielectric fluids have been developed. Within this work novel advances in the development of a sophisticated dry EDM machine tool, including generator and process control technology based on open architecture, open source software, and commonly available machine tool components, are presented. Solutions for challenges regarding remaining debris and gas bubbles as well as related arc discharge and short-circuit pulses in sinking EDM are presented by new flushing methods, technologies and devices. A new system for inverted pressure flushing of a dielectric fluid in ED-drilling enables a highly efficient removal of debris and gas bubbles through the interior channels of the tool electrode. A new multi-fluidic spindle system for EDM provides the ability to use performance- and material-related application of gaseous, near-dry and liquid dielectric fluids sequentially within a single machining process. Recent advances in tool electrode design, tool electrode material application, modification and production have led to essential process improvements. A helical tool electrode design significantly improved flushing conditions and related material removal rate in ED-drilling. Modification of ED-drilling tool electrode surfaces by thermal oxidation of copper reveals a promising approach to minimize ineffective discharges. Application of a specific mesophase-pitch carbon fiber with a diameter of df = 10 µm using a new process and handling technology enabled drilling holes with a diameter of dh = 25 µm. Next to the shown advances in EDM, efficient development of new process technologies could be enabled by using a specially adapted natural analogue algorithm software tool.

An extensive review on sustainable developments of dry and near-dry electrical discharge machining processes

Abstract Electrical discharge machining (EDM) is very essential unconventional electro-thermal 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.

Simulation and experimental investigation of performance characteristics of dry and near dry EDM process

ABSTRACT In many industrial applications, necessity of new age materials; however some typical alloys like spring steel material are used in critical sector such as defence, aerospace, and automobile. To work on spring steel material, there are several difficulties such as hard to cut, low material removal rate, and high energy consumption. The EDM is critical thermal evacuation process. This paper presents the result of experimentation and simulation carried out on a spring steel material by varying current, gap voltage, cycle time and pressure. The experimental results are verified by developing a thermal-electrical model of workpiece material using ANSYS workbench. Transient thermal analysis is used to simulate the electric discharge machining. The finite element method (FEM) analysis includes spark radius variation and temperature profile formation by electric discharge. It is found that the dielectric fluid pressure is closely related to the discharge environment, such as debris concentration and fluid viscosity. Further, it is found that distilled water provides more stability to plasma channel in near dry electric discharge machining (NDEDM) compared to dry electric discharge machining (DEDM). From the results obtained, it is concluded that the material removal rate is affected by dielectric medium properties viz. dielectric strength, dielectric constant and thermal conductivity.

Comparative Analysis of Dry-EDM and Conventional EDM in machining of Hastelloy

Dry EDM may be a modification of the traditional electrical discharge machining (EDM) process during which the liquid dielectric is replaced by a gaseous medium. High velocity gas is supplied through it into the discharge gap. The flow of high velocity gas into the gap facilitates removal of debris and prevents excessive heating of the tool and work piece at the discharge spots. it's now known that aside from being an environment–friendly process, other advantages of the dry EDM process are low tool wear, lower discharge gap, lower residual stresses, smaller white layer and smaller heat affected zone.[1]
 Keeping literature review into consideration, during this research, an effort has been made by selecting compressed gas as a dielectric medium, with Hastelloy as a work piece material and copper as a tool electrode. Conventional experiments were also performed. Experiments are performed using Taguchi DoE orthogonal array to watch and analysis the consequences of various process parameters to optimize the response variables like material removal rate (MRR) and gear wear rate (TWR).

Experimental investigation and performance enhancements characteristics of gaseous assisted powder mixed near dry electric discharge machining

Gaseous assisted powder mixed near dry EDM (GAPMND-EDM) is one of the recent hybrid technologies, which not only enhance the machining performance, but at the same time, high quality products with better surface quality characteristics can also be achieved. In this study, the response parameters were material removal rate, surface finish, micro hardness and residual stress. It was found that the maximum material removal rate (MRR 3.379 mg/min) was achieved with combination of (dielectric) oxygen gas with graphite powder while lowest surface roughness (SR 1.11 μm) was found to be with dielectric argon gas with graphite additives. Highest micro hardness (MH) and lowest residual stress (RS) was 820.30 Vickers hardness number (VHN) and 229 MPa found with dielectric combination of zinc additives with argon gas.