Electro-discharge Machining Research Articles

Reactive spark plasma sintering of an electrically conductive B4C-SiC-ZrB2 composite with enhanced mechanical properties

Ternary B4C-SiC-ZrB2 ceramics with eutectic compositions were prepared in situ by reactive spark plasma sintering at 1600–1800 °C. The two-step sintering, including an in situ reaction 2ZrSi2 + 5B4C+ 3 C= 4B4C+ 4SiC+ 2ZrB2 at 1600 °C and sintering at 1800 °C, is superior to combined one-step sintering at 1800 °C. The as-sintered 40B4C-40SiC-20ZrB2 composites (sample 16R18) had grain sizes of microns with a density over 97%. The Vickers hardness, bending strength and fracture toughness of the ternary ceramic reached 28.6 GPa, 631 MPa and 5.50 MPa m1/2 respectively. Crack deflection and branching were ascribed to improved fracture toughness. The elongated plate-like ZrB2 grains not only had toughening effects but also helped to lower the percolation threshold of the electrical conductivity. The 16R18 sample possessed an electrical conductivity of 5.38 × 104 S/m, owing to the tiny conductive ZrB2 grains with aspect ratios of 3–4, which is beneficial for the electro-discharge machining of the B4C-SiC based composites.

Characterization and Microstructure of Recycled Eroded Particles from Die-Sink Electro Discharge Machining of H11 Alloy for Applicability in Additive Manufacturing

Different waste streams from electro discharge machining (EDM) were investigated for an upcycled usage in processes for additive manufacturing (AM). These erosion sludges accumulate in filter cartridges and at the bottom of machining basins. The enclosed particles were extracted, sieved and investigated via laser diffraction, dynamic image analysis, scanning electron microscopy, optical emission spectroscopy, elemental analysis and flowability measurements. Additionally, thermal, crystallographic and metallographic investigations as well as X-ray micro-computed tomography (µ-CT) were utilized for the characterization of particle and material properties. In general, eroded powders fulfill the requirements for AM regarding particle size and shape very well, which is confirmed in morphological investigations and powder flow characteristics showing similar properties as the H11 AM reference material. The chemical composition of the powders is equal to the machined H11 alloy, except for the high carbon content. Carbon is entrapped in the iron lattice originating from pyrolysis of the present dielectric fluid and the graphite electrode during rapid solidification, which leads to a transition from martensite to cementite structures. This change is observed in the microstructure of powders, in which acicular primary cementite and austenite are present. After remelting with slow heating and cooling rates the microstructure changed to ledeburite II with retained austenite and martensitic phases. The pore size and shape distributions obtained by µ-CT measurements showed a pore formation in the compact sample. These results provide a fundament of major properties as well as handling and recycling suggestions for eroded particles enclosed in waste sludges.Graphical

Utilizing multiple criteria decision-making optimization methods to machine LM25Al/VC material under electro-discharge machining processes

In this work, sparking electro-discharge machining (EDM) process parameters are optimized by using multiple criteria decision-making (MCDM) methods. The work piece utilized for the investigation was LM25 aluminum alloy reinforced with Vanadium carbide (VC), processed through a stir casting technique. The EDM process parameters that have been considered in this work are by peak current, pulse-on-time, and pulse-off-time, with the effects of each variable and their combinations on the performance metrics of EDM like material removal rate, electrode wearing rate, and surface roughness. In this study, three MCDM methodologies were applied to evaluate EDM performance. Then, the obtained MCDM scores were compared using two different objective verification mechanisms. In this case, the VIKOR technique delivered the best-desired results relative to TOPSIS method, and factorial analyzing method. Also, the factorial method is simpler than the other methods, though it produced nearly identical results as the sophisticated MDCM method.

A Novel Physically Guided Data Fusion Prediction Model for Micro-EDM Drilling

Accurate prediction of Electro-Discharge Machining (EDM) results is crucial for industrial applications, aiming to achieve high-performance and cost-efficient machining. However, both the current physical model and the standard Artificial Neural Network (ANN) model exhibit inherent limitations, failing to fully meet the accurate requirements for predicting EDM machining results. In addition, Micro-EDM Drilling can lead to the distortion of the macroscopic shape of machining pits under different input conditions, rendering the use of only the volume of machining pits as the evaluation index insufficient to express the complete morphological information. In this study, we propose a novel hybrid prediction model that combines the strengths of both physical and data-driven models to simultaneously predict Material Removal Rate (MRR) and shape parameters. Our experiment demonstrates that the hybrid model achieves a maximum prediction error of 4.92% for MRR and 5.28% for shape parameters, showcasing excellent prediction accuracy and stability compared to the physical model and the standard ANN model.

INVESTIGATION OF ELECTROEROSION MACHINING PERFORMANCE OF METAL MATRIX COMPOSITE MATERIALS PRODUCED USING STIR AND INDIRECT SQUEEZE METHOD

In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 [Formula: see text]s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. Based on the ANOVA results, the [Formula: see text]2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively.

Powder-Mixed Micro-Electro-Discharge Machining-Induced Surface Modification of Titanium Alloy for Antibacterial Properties

The powder-mixed electro-discharge machining (PM-EDM) technique has shown its advantages in forming surfaces and depositing elements on the machined surface. Moreover, using hydroxyapatite (HA) powder in PM-EDM enhances the biocompatibility of the implant’s surfaces. Ti-6Al-4V alloy has tremendous advantages in biocompatibility over other metallic biomaterials in bone replacement surgeries. However, the increasing demand for orthopedical implants is leading to a more significant number of implant surgeries, increasing the number of patients with failed implants. A significant portion of implant failures are due to bacterial inflammation. Despite that, there is a lack of current research investigating the antibacterial properties of Ti-6Al-4V alloys. This paper focuses on studying the performance of HA PMEDM on Ti-6Al-4V alloy and its effects on antibacterial properties. By changing the capacitance (1 nF, 10 nF and 100 nF), gap voltage (90 V, 100 V and 110 V) and HA powder concentration (0 g/L, 5 g/L and 10 g/L), machining performance metrics such as material removal rate (MRR), overcut, crater size and hardness were examined through the HA PM micro-EDM (PM-μ-EDM) technique. Furthermore, the surface roughness, contact angle, and antibacterial properties of HA PM micro-wire EDM (PM-μ-WEDM)-treated surfaces were evaluated. The antibacterial tests were conducted for Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis bacteria. The key results showed a correlation between the discharge energy and powder concentration with the antibacterial properties of the modified surfaces. The modified surfaces exhibited reduced biofilm formation under low discharge energy and a 0 g/L powder concentration, resulting in a 0.273 μm roughness. This pattern persisted with high discharge energy and a 10 g/L powder concentration, where the roughness measured 1.832 μm. Therefore, it is possible to optimize the antibacterial properties of the surface through its roughness.

EXPERIMENTAL INVESTIGATION AND PARAMETRIC OPTIMIZATION OF ELECTRO DISCHARGE MACHINING FOR TI-5553 ALLOY USING GREY RELATION ANALYSIS COUPLED WITH TAGUCHI METHOD

In this paper, the machinability aspects of Ti-5553 have been experimentally investigated during Electro-Discharge Machining using three different geometrical shapes of copper electrodes i.e. cylindrical, triangular, and square. TIMETAL (Ti-5553) is a titanium-based alloy extensively used for special aerospace and marine applications due to its high strength and higher hardenability. By changing each of the aforementioned process parameters at three distinct levels, experiments based on the [Formula: see text] orthogonal array (OA) design of the experiment (DOE) were carried out. The machining performance has been carried out by utilizing different input parameters i.e. current, pulse off time ([Formula: see text]), flushing pressure ([Formula: see text]), tool shape ([Formula: see text]), and voltage (V) to examine machining performance characteristics like material removal rate (MRR), tool wear rate (TWR), surface roughness (Ra), white layer thickness (WLT), and surface crack density (SCD). Surface integrity in contents of surface morphology and surface topography is discussed herein. In this MRR, TWR, and Ra have been optimized by using a methodology (combining Grey relational analysis method and Taguchi’s philosophy) and found the optimal parameters that will have more MRR and less TWR, Ra. Later SCD and WLT were investigated by employing the optimal setting (A3, B2, C2, D2, E1, F3) and arbitrary setting (A3, B2, C1, D3, E3, F2) and concluded that SCD and WLT are less by utilizing optimal settings for machining as compared to arbitrary settings. Among all three different geometrical shapes of copper electrodes, the cylindrical tool has been found to be the best suitable tool for machine Ti-5553.

Approach towards green manufacturing in Maglev EDM using different biodegradable dielectrics at variable discharge conditions

The urge to implement eco-friendly approach for modern manufacturing techniques has assisted in eliminating the hazardous effect of the undesirable byproducts released into the atmosphere. In electro-discharge machining (EDM) process, the hydrocarbon oil degradation releases various toxic gases and non-biodegradable residuals as byproducts. Several bio-dielectrics have been implemented to overcome such setbacks as an economical replacement to conventional hydrocarbon oil dielectrics. The current research demonstrates a green Maglev EDM operation on Ti-6Al-4V alloy using neem oil and canola oil as bio-dielectrics compared with EDM oil. Maglev EDM utilizes novel bipolar linear self-servo strategy for tool positioning which generates consistent machining stability by unique magnetic repulsive force balance action. The performance characteristics of all the dielectrics have been examined through machining rate (MR), tool wear rate (TWR), consumed specific energy (SE), area roughness parameters and surface morphology. The results were compared for respective bio-dielectric at variable discharge voltages (VD) i.e. 22 V, 25 V and 28 V, whereas the discharge current (ID) varied within (220-250 mA). The performance assessment depicts (25 to 28) % lower SE consumption in neem oil and (35 to 37)% in canola oil as compared to EDM oil. The surface morphology assessment portrays lower deformities and better uniformity using bio-dielectrics with huge potential for selective surface modification.

Fatigue behaviour of additive manufactured Nb-48Ti alloy parts from powders produced by Plasma Atomization (PA) and Hydride-Dehydride (HDH) process

Fatigue behaviour of bcc Nb-48 wt%Ti (Ti-36at%Nb) alloy parts processed by Laser Powder Bed Fusion (L-PBF) using as raw material two different types of powders, spherical powder produced by Plasma Atomization (PA) and irregularly shaped powder produced by Hydride-Dehydride (HDH) process, are compared. Laser power and scanning speed were selected to obtain rods with porosity below 0.5 vol%. All rods were produced using the same scanning strategy (chessboard with shift). The building platforms were heat treated for stress relieving at 650 °C for two hours before removing the rods using wire electro-discharge machining. The heat-traded rods were machined to obtain specimens for rotate bending fatigue tests, and S-N curves were plotted. Fatigue behaviour for PA and HDH sets were similar but with higher dispersed results for the specimens produced from the HDH powder. The fracture was nucleated in porosities near the machined sample surface, mostly on lack-of-fusion type pores. The fatigue cracks propagated in a “zigzag” mode with peaks and valleys parallel to the L-PBF building direction (BD) in both sets. One of the analysed samples, produced from HDH powder and with a lower fatigue life than average, showed a significantly higher number of pores, indicating the existence of a laser process parameter yet to be controlled.

Thermo-Mechanical Treatment for Reducing the Wear Rate of CuCrZr Tool Electrodes during Electro-Discharge Machining.

The research presented in this paper focused on optimising the process of unconventional plastic forming by hydrostatic extrusion (HE) with post-processing heat treatment of a copper alloy (CuCrZr) for electro-discharge machining (EDM) applications. The treatment was carried out in such a way as to obtain a material with an improved microstructure, characterised by a significant increase in hardness and strength while maintaining a high electrical conductivity, thus achieving the main goal of reducing electrode wear in the EDM process. As part of the research, a material with an ultrafine-grained structure was obtained with an average grain size of d2 = 320 nm and a much higher strength of UTS = 645 MPa compared to the material in the initial state (UTS = 413 MPa). The post-processing treatment (ageing) allowed us to obtain a material with a high electrical conductivity after the HE process, at 78% IACS. The electrodes made of CuCrZr subjected to HE had a reduced electrical discharge wear in relation to electrodes made of the initial material. The best results were obtained for electrodes made of the material subjected to a five-stage HE process combined with ageing at 480 °C for 1 h. The electrical discharge wear in these electrodes was reduced by more than 50% compared to electrodes made of non-deformed copper.

Study of Wire-Cut Electro-Discharge Machining of Heat-Resistant Nickel Alloys.

This paper presents an analysis and theoretical model for assessing the quality and accuracy of wire-cut electro-discharge machining (WEDM) of products made from novel heat-resistant nickel alloys such as CrNi56KVMTYB. It is observed that WEDM processing of Ni alloy led to high surface roughness for the thick specimens, and electrical parameters such as pulse duration for the selected range depict an insignificant role in the value of surface roughness. On the other hand, the cut width of the machined surface decreases as the pulse duration increases, while the cut width is elevated for thick workpieces. Secondary discharges developed in WEDM have negative effects that cause sludge adhering and deterioration in the quality and productivity of processing. The regression model is developed to predict the surface roughness and cut width of machined surfaces, which holds significant importance in modern engineering. The workpiece is examined for surface integrity and material deposition. It is observed that an increase in the height of the specimen leads to the occurrence of secondary discharges, which in turn results in the formation of cracks on the surfaces of high-temperature nickel alloys. These cracks have a detrimental effect on the performance of critical products made from next-generation heat-resistant nickel alloys.

Metrological Assessment of Microtextured EDM Electrodes Generated by Additive Manufacturing and Electroforming

Surface engineering makes use of functional and aesthetic textures to meet different needs in the development of new products, with high-value enriched features. At present, the use of additive manufacturing is bringing many advantages in its integration into advanced hybrid manufacturing processes. The direct application of textures on 3D models is a viable, fast and sustainable solution in many of these technologies by reducing the consumption of resources in materials and energy, of the additional processes that have been commonly applied in these applications.One of the processes that allows texturization of materials with great hardness is sinker electro discharge machining. This process, although slow, allows to obtain textures in small dimensions with very high precision, difficult to achieve by conventional processes. However, one of the aspects that make it a slow and expensive process is the manufacture of electrodes, especially those with complex geometries.Therefore, work is being done to solve this aspect, combining the additive technology of stereolithography by mask (MSLA) and the electroforming process to generate micro-textured copper electrodes with some structured and bioinspired textures. The model parts are generated with the textures in MSLA, which are then metallized on the functional surfaces before being introduced into the electrolytic bath to generate the electroforms with the appropriate thickness. This work presents the results of the metrological assessment from he CAD modeling to the electroeroded part, including the generated model part and the electrode made from it. This work is being developed in the Integrated and Advanced Manufacturing research group of the University of Las Palmas de Gran Canaria and in collaboration with the Engineering and Materials and Manufacturing Technology research group of the University of Cadiz.

Effect of microstructure refinement of pure copper on improving the performance of electrodes in electro discharge machining (EDM)

The paper presents an analysis of the impact of plastic deformation using hydrostatic extrusion (HE) on the structural, mechanical and functional properties of pure copper for use as electrodes in the process of electro discharge machining (EDM). As part of the research, copper was subjected to the HE process with the maximum cumulative true strain equal to ɛcum = 3.89 obtained in 5 stages. The result was, a refinement of the microstructure with the grains elongated in the direction of extrusion, with a cross-sectional size of d2 = 228 nm. As the obtained material can be potentially used in the process of electro discharge machining, the copper specimens after the HE process were subjected to a comprehensive analysis to determine the mechanical, physical and functional properties of the material. A significant increase in strength (UTS) and yield strength (YS) of the HE-processed copper was obtained, reaching respectively UTS = 464 MPa and YS = 456 MPa at the maximum strain of ɛ = 3.89. Despite the clear strain-induced strengthening of the material, a very high electrical conductivity of not less than 97% was obtained. The electrodes made of copper after HE process have reduced erosion wear while maintaining a comparable or better quality of the machined surface. The best results were obtained for finish machining, where the electrical discharge wear was lower by 60% compared to the electrode made of non-processed copper. In addition, an improvement in the surface quality after the EDM process by 25% was observed when using the HE-processed electrodes.

Experimental investigation on EDM of aluminium alloy (Al 2014) using diatomite powder-mixed dielectric fluid based on Taguchi methodology

One of the most crucial factors to consider in electro-discharge machining (EDM) is the choice for right machining factors since these factors affect crucial properties like material removal rate (MRR) and tool wear rate (TWR), compared to other factors. In current study, a diatomite powder material mixed dielectric fluid is utilised to machine Aluminum Alloy in order to boost the dielectric fluid's electrical conducting capacity, expand the Al2014 workpiece and Cu electrode gap, and easily expel removed material. This increases the MRR and decreases the rate of tool wear. Additionally, a L9 orthogonal array (OA) that adopts the Taguchi methodology was used in this study to conduct a number of trials, and analysis of variance (ANOVA) was used to scientifically evaluate the outcomes. To define the technological qualities stated above, the primary machining parameters voltage (V), pulse-on interval (Ton), pulse-off interval (Toff) and current (I) were selected. The results show that the current is the most important variable, with MRR increasing from 0.981 mm3/min to 1.8 mm3/min when the current is increased from 14 A to 18 A.

Simultaneous electrochemical and electrodischarge machining process: An approach to sustainable manufacturing

Manufacturing of Net Finished Shape (NFS) microholes in Inconel 718 materials with faster machining rate can offer significant benefits in terms of reduced waste, improved efficiency, and lower production costs, which are essential for sustainable manufacturing. However, the existing manufacturing method, namely electrochemical machining (ECM), results in slow machining with uncontrolled dissolution, leading to increase production time, energy consumption, and carbon emission associated with the manufacturing process. The current manuscript investigates the reason attributes for these problems through potentiodynamic polarization test. Subsequently, a new machining process known as Simultaneous electrochemical and electrodischarge machining (SECEDM) has been proposed. This frugal manufacturing-based machining process offers high machining rate (MR) and better overall hole circularity (OHC) through the synergistic effect of anodic dissolution and electrochemical discharges. The obtained results reveal that the SECEDM process offers nearly 261 % and 141 % higher MR and 1.23 % and 3.78 % better OHC than electrochemical machining (ECM) and electrodischarge machining (EDM), respectively. Moreover, SECEDM outperforms the simultaneous micro-EDM and micro-ECM process (SEDCM) process by seven times in machining rate and promotes localized dissolution than ECM. Overall, SECEDM's benefits, including its high machining rate, superior surface quality, sustainability, eco-friendliness, and elimination of the need for secondary finishing processes, make it an ideal candidate for the next-generation manufacturing process.

GENERATION OF EFFUSION HOLES ON ULTRA-HIGH TEMPERATURE ALLOY BY MICRO ELECTRO-DISCHARGE MACHINING PROCESS

Fabrication of surface features like effusion holes on ultra-high temperature (UHT) alloys with micro electro-discharge machining ([Formula: see text]-EDM) is a very convolute strategy. Due to the exceptional mechanical properties and resistance to ease brittle transformation at elevated temperatures, UHT alloys are being widely used in hot sections of aero engines. This research tailored the existing capabilities of [Formula: see text]-EDM setup by employing a copper-tungsten (Cu-W) hybrid tool electrode which has been rarely reported. This research addresses investigations, predictive modeling, and optimization during [Formula: see text]-EDM of UHT alloy, namely Inconel 718. For experimentation, the factors like inter-electrodes gap (IEG), current ([Formula: see text]), and pulse on/off time ([Formula: see text]on, [Formula: see text]off) were considered as input variables to analyze the responses like overcut (OC), tool wear rate (TWR), material removal rate (MRR), and diametric alterations in between the top and bottom shape of holes’ feature (DE). The multi-objective desirability-based artificial bee colony optimization (MOABC) projected optimal parametric settings of 5.276 A, 16.389 [Formula: see text]s, 1.77 [Formula: see text]s, and 50 [Formula: see text]m for [Formula: see text], [Formula: see text]on, [Formula: see text]off, and IEG, respectively. These settings provide MRR, TWR, OC, and DE solutions of 0.001479, −0.00038, 0.030239, and 0.047048 mm, respectively. Further, the confirmation test has been performed to validate the optimal solution. The results supported the ideal settings with error values of 0.03177, 1.31578, 0.05863, and 0.04704 for MRR, TWR, OC, and DE, respectively. Distinctive diagnostic tests assessed by several statistical parameters ([Formula: see text], [Formula: see text], [Formula: see text]2, AD-P values) confirmed that the accuracy of developed models for prediction of various performance characteristics has high degree of resemblance with experimental results and the adequacy as well as accuracy of models is also demonstrated. Moreover, the surface morphology has also been scrutinized by microscopical observation to perceive the consequences of the electro-discharge phenomenon on both electrodes. Overall, the research comprises experimentation, surface integrity study, and parametric optimization followed by a confirmation test to perform the betterment of the current [Formula: see text]-EDM approach.

Назначение рациональных режимов электроэрозионной обработки деталей из титанового сплава ВТ5 на основе решения тепловой задачи о перемещении границы фазового превращения материала

The paper presents results of theoretical studies of the VT5 titanium alloy machinability by the electrodischarge machining method based on solving the thermal problem of the material phase transformation boundary displacement (Stefan problem). It proposes a method for determining parameters of electrical pulses for the VT5 alloy electrodischarge machining in order to increase the process productivity; recommendations are provided for that purpose. Density of the heat flux and its duration were determined necessary for implementation of the VT5 alloy electrodischarge machining process. Dependences were established of the minimum value of the heat flux pulse duration, when the VT5 alloy electrodischarge machining process was possible, and of maximum value of the heat flux pulse duration ensuring maximum removal of the VT5 alloy from the workpiece in one pulse, on the heat flux density. It is shown that for the maximum productivity of the VT5 alloy electrodischarge machining at the heat flux density used, it is necessary to assign effective duration of such a flux. Dependences of the heat flux effective duration on its density were established. Besides, to assign rational modes of VT5 ally electrodischarge machining, relationships were established and provided between the VT5 alloy machinability curves (dependences of the material penetration depth on the pulse duration) and other materials, including those for which rational modes are currently defined

Experimental Study of Electro Discharge Machining (EDM) on Mild Steel (E-250) using Copper Electrode

Abstract: Electro-discharge machining is used for machining different types of hard materials which are electrically conductive and these materials are particularly challenging to manufacture using any other machining method. In electro-discharge machining electrical energy is transformed into thermal energy which is approximately 8000 to 12000 degrees Celsius and due to high thermal energy material melting and vaporising. In electro-discharge machining, three types of electrode materials are used which are copper, brass and graphite, Of all three materials, graphite has the highest electrical conductivity and brass has the lowest electrical conductivity. Electro-discharge machining process suitable for generating complex shapes and profiles. In this paper, a Copper electrode was used for machining mild steel (E-250) and analysed the MRR and Ra with a variation of discharge current keeping other variables constant and studying the consequence of different discharge currents on MRR and Ra.

A Review on the Usage of Different Optimization Techniques for Wire Electro Discharge Machining of Stainless Steels

Wire electrical discharge machining (WEDM) is a non-traditional metal cutting procedure and the overall cutting process is contactless between the wire and work material. A plasma channel is created by the electrical energy between work piece and wire, which convert the electrical energy into thermal energy and the temperature rises (8000°C to 12000°C). Due to this mechanism, metal is melted from the upper surface of work piece. Generally difficult to machine material is used to cut in WEDM. However, stainless steel (SS) is one of them, it is a metal alloy, which is mixed with steel and other elements such as chromium (Cr), nickel (Ni), molybdenum (Mo), silicon (Si), carbon (C), nitrogen (N2), and manganese (Mn) etc. SS has some excellent properties, such as high durability, high tensile strength, and corrosion resistant etc. Due to these properties SS is mainly used in automobile industries, biogas tank, combustion chamber and petrochemical industries etc. The present paper discussed about the machining of different SS grades in WEDM and effect of several input parameters (such as pulse on time (Ton), pulse off time (Toff), servo voltage (SV), wire feed (WF) etc.) on response parameters (such as material removal rate (MRR), surface roughness (SR), kerf width (KW) etc.). The review paper also reports the uses of different optimization techniques (such as taguchi technique (TT), response surface method (RSM), gray relational analysis (GRA) etc.) on various SS grades for optimizing the response parameters on the basis of different input variables. Furthermore, the research shows how to vary the value of output responses corresponding to input parameters value. Keywords: WEDM; stainless steels; input variables; output variables; optimization techniques.

Thermal modeling and experimentation on discharge energy distribution and plasma flushing for a single discharge in EDM of D2 steel

An electrical discharge forms a crater on the workpiece surface in the electro-discharge machining. The geometry of the molten cavity is determined by the energy parameters (gap voltage, discharge current, and pulse-on-time), the plasma channel radius, and the energy fraction coming to the workpiece. The plasma flushing efficiency determines the crater geometry with respect to the molten cavity. This work attempted to develop a thermo-physical model to express plasma radius, energy fraction, and plasma flushing efficiency as a function of all three energy parameters: gap voltage, discharge current, and pulse on time. Plasma flushing efficiency is calculated from crater dimensions and recast layer thickness. The plasma radius and energy fraction are estimated by inverse-FEM using measured crater radius, crater depth, and recast-layer-thickness values. The expressions for plasma radius, energy fraction, and plasma flushing efficiency are estimated from the regression equations obtained from the designed data set using the Taguchi method. Validation shows that the error found when predicting the crater radius, crater depth, and recast layer thickness is under 10.71%, 8.84%, and 12.65%, respectively.