Electrode Wear Research Articles

Machinability of tool steels machined by electric-discharge machining

SKD11 has been a widely used tool steel for cold works for many years while DC53 tool steel is intently developed to replace SKD11. In this paper, the machinability of these two tool steels was compared in terms of material removal rate (MRR), electrode wear ratio (EWR), and arithmetic mean of value of roughness (Ra) of the specimen machined by electric-discharge machining. The machining variables involved were electric-discharge time and electric-discharge peak current. The machining electrode was made from a copper alloy. Results show that both electric-discharge time and electric-discharge peak current had an influential effect on MRR, EWR, and Ra of both tool steels. MRR of SKD11 was significantly higher than that of DC53 while DC53 caused higher EWR than SKD11. It was found that SKD11 provided a better surface finish than DC53. Empirical models for MRR, EWR, and Ra were also presented in this paper.

Optimizing Main Process Parameters When Conducting Powder-Mixed Electrical Discharge Machining of Hardened 90CrSi

In the current study, an optimization process of powder-mixed electrical discharge machining (PMEDM) process when machining cylindrically shaped parts made of hardened 90CrSi steel is reported. In this study, SiC powder was mixed into the Diel MS 7000 dielectric solution. Additionally, graphite was chosen as the electrode material. The multi-objective functions were minimizing the surface roughness (SR) and electrode wear rate (EWR) and maximizing the material removal rate (MRR). The used input parameters of the optimization process included the powder concentration, the pulse-on time, the pulse-off time, the pulse current, and the servo voltage. A combination between the Taguchi method and the grey relation analysis (GRA) method with the support of Minitab R19 software was used to design the experiment and analyze the results. It was found that the optimal set of process parameters that can satisfy the above responses are Cp of 0.5 g/L, Ton of 8 µs, Toff of 8 µs, IP of 5 A, and SV of 4 V.

Surface alloying characteristics of WS2/Cu composite electrodes deposited on an aluminum alloy by electrical discharge coating

Electrical discharge machining (EDM) is a widely used non machining technique for machining difficult-to-machine materials. Electro discharge coating (EDC) has been utilized to convert the surface of workpieces using standard electro discharge equipment by transferring electrode material to the workpiece using reverse polarity. Nowadays there is an increasing demand for lightweight materials such as aluminum (Al) alloys are widely used in aerospace as well as in automobile components due to reduction in weight to improve performance and efficiency. Nevertheless, the surface qualities such as hardness and wear resistance, of aluminium alloy are insufficient to meet the needs of a wide range of applications. As a result, the current research looked into the EDC of aluminium alloy utilizing a green compact WS2/Cu electrode to alter the surface properties. Experiments were designed utilizing a response surface approach and a central composite rotatable design. The following significant EDC variables current, pulse on time, and pulse off time, determine the coating characteristics such as deposition rate (DR) and electrode wear rate (EWR). The most significant variables were determined using analysis of variance. A scanning electron microscope was used to explore various surface morphology that occurred during EDC. Energy-dispersive spectroscopy measurements were taken to validate the successful deposition of several elements on the workpiece surface.

A NOVEL METHOD FOR SELECTING THE OPTIMAL EDM PROCESS FOR HASTELLOY B2 USING THE MODIFIED-ADDITIVE RATIO ASSESSMENT METHOD (M-ARAS) BASED ADAPTIVE NEURO FUZZY INFERENCE SYSTEM (ANFIS)

Electrode wear and metal removal exhibited nonlinear behavior in the Electrical Discharge Machining (EDM) of Hastelloy B2 plate. Hence, mathematical modeling was used to solve this problem. The hole size, pulse duration, duty cycle, and current were selected as inputs. Squareness and taper angle were considered as responses. Therefore, the Modified-Additive Ratio Assessment Method (M-ARAS) based Adaptive Neuro Fuzzy Inference System (ANFIS) method was used to find the optimum EDM process parameters. The overall analysis showed that the M-ARAS-based ANFIS algorithm provided a good fit for optimization of the process parameters and could be used for further multi-objective optimization problems.

The Corrosion and Wear Behaviors of a Medium-Carbon Bainitic Steel Treated by Boro-Austempering Process

The effects of boro-austempering treatment on growth kinetics of borided layers, microstructure, and properties in a medium-carbon bainitic steel were investigated. The microstructure, distribution in coatings, corrosion, and wear properties of boro-austempered steels were characterized by a microscope, field-emission electron probe micro analyzer, scanning vibrating electrode technique system and wear resistance machine. The results show that the corrosion resistance of steels in different corrosive mediums was significantly enhanced by boro-austempering treatment. In addition, the wear performance of borided layers was improved by more than two times compared to bainitic substrates, proving a better wear property of samples treated through the boro-austempering route. The solubility of carbon and silicon in borides is very little. In addition, the dual-phase coating of FeB and Fe2B was observed, and the internal stress induced during the growth of Fe2B and FeB was almost eliminated. The preferential crystallographic growth directions of Fe2B and FeB are [001] and [010], respectively, which belongs to the (100) plane. Finally, the kinetics equation d2 = 0.125·t of the borided layers at 1223 K was established.

Sustainability and recent trends in micro- electric discharge machining (μ-EDM): A state-of-the-art review

In the era of miniature machining, micro Electrical -discharge machining (A thermal energy based materials removal process) is the most recognized non- conventional machining approaches which has the ability to generate complex 2D & 3D shapes on difficult to machine materials in a short time while maintaining high feature quality. Micro-EDM is a noncontact machining process that produces mould cavity and deep holes with less metallurgical losses, stress free and miniaturized features through careful regulation of the electrical and non-electrical process parameters. Input parameters such as current, voltage, and pulse on time, pulse off time and Duty factor play an imperative role to achieve good feature quality. This progressive review of micro–electrical discharge machining studies latest machinable composite materials (conductive), dielectric fluids, issues of surface integrity and various optimization techniques with the perspective of sustainability (i.e. high energy consumption, electrode wear, generation of hazardous dielectric waste, toxic emissions and fire hazard). A brief note on future research trends has been included in the last section. Moreover, recent applications and advantages of micro-EDM machining processes are also presented in this study.

Influence of die-sinking EDM parameters on machining characteristics of alloy 625 and alloy 718: A comparative analysis

In current exploration, a die-sinking EDM technique on two various Ni based alloy materials (Alloy 625, Alloy 718) were planned to optimize numerous performance attributes depends on Taguchi method. Nickel based Super alloy like Alloy 625 and Alloy 718 are mostly used in aerospace, marine, nuclear industries due to its remarkable chemical and mechanical properties. Experimentation have been proposed by Taguchi’s design to see impact of four input process machining factors like pulse on time, off time, current and tool rotation on material removal rate, electrode wear rate, average surface roughness and overcut. A combined route of optimization of satisfaction function with Taguchi method was used for the multiple performances optimization. The optimum and most cogent parametric setting for machining was obtained at: [pulse on time = 100 µs, pulse off time = 50 µs, current = 17A, tool rotation = 825 rpm] for alloy 625; [pulse on time = 300 µs, pulse off time = 75 µs, current = 14A, tool rotation = 925 rpm] for alloy 718.

Machine-vision-based electrode wear analysis for closed loop wire EDM process control

The purpose of this study was to develop a closed-loop machine vision system for wire electrical discharge machining (EDM) process control. Excessive wire wear leading to wire breakage is the primary cause of wire EDM process failures. Such process interruptions are undesirable because they affect cost efficiency, surface quality, and process sustainability. The developed system monitors wire wear using an image-processing algorithm and suggests parametric changes according to the severity of the wire wear. Microscopic images of the wire electrode coming out from the machining zone are fed to the system as raw images. In the proposed method, the images are pre-processed and enhanced to obtain a binary image that is used to compute the wire wear ratio (WWR). The input parameters that are adjusted to recover from the unstable conditions that cause excessive wire wear are pulse off time, servo voltage, and wire feed rate. The algorithm successfully predicted wire breakage events. In addition, the alternative parametric settings proposed by the control algorithm were successful in reducing the wire wear to safe limits, thereby preventing wire breakage interruptions.

Discriminant Analysis-based Parametric Study of an Electrical Discharge Machining Process

This paper deals with the application of discriminant analysis in an electrical discharge machining (EDM) process to determine the comparative contribution of each of its input parameters on the measured responses. It also identifies the most significant EDM process parameters influencing those responses. For this process, voltage, current, pulse-on time and pulse-off time are considered as the input parameters, whereas, material removal rate, electrode wear rate and surface roughness are the responses. Based on the past and simulated experimental data, both simultaneous and step-wise estimations are carried out for each of the three responses showing the relationships between the EDM process parameters and the considered responses. It is observed that in both these estimations, pulse-off time, current and pulse-on time respectively evolve out as the most significant parameters for material removal rate, electrode wear rate and surface roughness. Step-wise estimation identifies voltage as the least significant input parameter for all these responses. The developed discriminant functions, which can also help in predicting the responses, are finally cross-validated.

Experimental investigation into tool wear behaviour of line-array tool electrode during the electrochemical discharge micromilling process

A tool-workpiece gap during the electrochemical discharge machining (ECDM) process is a critical parameter for successfully fabricating microchannels using line-array tool electrodes. Tool wear during the ECDM process increases the tool-workpiece gap and result in non-uniform array microchannel depths or intermittent machining due to reduced heat flux transferred into the workpiece. Hence, proper selection of a tool material that results in uniform tool-tips height/tool-workpiece gap for a longer machining time is essential, especially for the line-array tool electrodes. In this article, the tool wear behaviour of four different materials, i.e., brass, SS304, molybdenum, and tungsten, during fabrication of longer (>15 mm) and deeper (>200 μm) array microchannels using multi-pass ECDM process is reported. The tool wear behaviour at varying machining time/pass numbers was investigated, keeping all other process parameters constant. The experimental results found that the brass electrode's wear rate was relatively faster, and the line-array tool electrode becomes unusable for the ECDM process after 15 min of total machining time. The wear behaviour of molybdenum and tungsten tool materials was similar and resulted in intermittent or no microchannels formation after 35 min of machining time. At the electrolyte-air interface, necking of the tips and subsequent breaking at different machining times was observed for the brass, molybdenum, and tungsten tool materials. Comparatively uniform tips height, microchannel depths, and negligible necking were observed for the SS304 tool electrode after 65 min of machining time. Therefore, SS304 is a suitable tool material for fabricating longer and deeper array microchannels using the multi-pass ECDM process. Moreover, the fabrication of a dual serpentine flow field was demonstrated in the glass workpiece using customized SS304 line-array tool electrodes.

Improving the precision of micro-EDM for blind holes in titanium alloy by fixed reference axial compensation

Abstract During the electrical discharge machining (EDM) process, the tool electrode wear is inevitable, which affects the process precision of the micro-hole. In the present experimental investigation, a fixed reference axial compensation (FRAC) method is proposed to enhance the machining precision of micro-hole. The effect of pulse power, compensation methods, and electrode materials on the depth and roundness factor of micro-hole are explored. The experiment results show that the FRAC method can realize the accurate compensation and reach the expected depth hole processing. When the FRAC is used, the depth deviation is less than 0.43%, and the minimum difference from the expected depth is only 0.106 µm. In addition, the micro-holes of tungsten steel and brass electrodes machine by the FRAC method were close to the expected depth, the difference from the expected depth less than 0.7%, but the bottom of micro-hole produced a cone. However, compared to tungsten steel and brass electrodes, the copper electrode has a better processing performance, the roundness factor is up to 79.8%. When the long-pulse power supply is applied, the expected depth of 400–1,600 µm blind holes with a better processing shape, and the phenomenon of the cone at the bottom are not apparent. Therefore, the proposed FRAC method can be utilized in many high-end manufacturing fields to improve the precision of the micro-hole for micro features.

Novel carbon nanotubes reinforced copper composite electrode for improved performance of electric discharge machining

Composite electrode fabrication is an effective strategy to improve the performance of the Electric Discharge Machining (EDM) process. In this work, a new copper/carbon nanotube (Cu/CNT) metal matrix composite electrode at a different volume fraction of CNT (0.35%, 0.70% and 1.05%) is developed using a spark plasma sintering (SPS) method. The real-time functional performance of the developed electrode on the EDM machining is also examined by changing the EDM process parameters (discharge current, pulse-on time and voltage). The composite electrode characterization results indicated that as the percentage of CNT increases from 0.35 to 1.05 vol%, the density reduced and electrical resistivity increased due to the rise in porosity. Performance review of CNT-infused electrodes during EDM machining revealed a higher Material removal rate (MRR) and good surface finish than the Cu electrodes due to high discharge energy and enlargement in the spark gap. However, Cu/CNT electrodes wore out faster than Cu electrodes by 90%, possibly due to the reduction in thermal conductivity induced by porosity effects. Comprehensively, although the addition of CNT affected the mechanical attributes of the electrode, it offered significantly better output (MRR and Surface finish) than the Cu electrode with limitations on electrode wear.

Suggested Research Trends in the Area of Micro-EDM-Study of Some Parameters Affecting Micro-EDM.

This paper provides an overall view of the current research in micro-electrical discharge machining (micro-EDM or µEDM) and looks into the present understanding of the material removing mechanism and the common approach for electrode material selection and its limitations. Based on experimental data, the authors present an analysis of different materials’ properties which have an influence on the electrodes’ wear ratio and energy distribution during the spark. The experiments performed in micro-EDM conditions reveal that properties such as electron work function and electrical resistivity strongly correlate with the discharge energy ratio. The electrode wear ratio, on the other hand, is strongly influenced by the atomic bonding energy and was found to be related to the tensile modulus. The proposed correlation functions characterized the data with a high determination coefficient exceeding 99%.

EDM of titanium foam: electrode wear rate, oversize, and MRR

ABSTRACT This article intends to give the prospect of machining Ti foam using electrical discharge machining (EDM) process. Closed-cell titanium foam with average cell size of 5 μm and pure brass are selected as workpiece and tool electrode material, respectively. Two different shapes of tool electrode, hollow and chamfer shaped electrode, are selected for this study. The EDM input factors such as discharge time, current, and discharge voltage are selected as input measures; electrode wear rate, oversize, and MRR are taken as outcome measures. Current demonstrates major influence on electrode wear rate compared to discharge time and discharge voltage. A linear regression model is proposed to predict the wear of electrode for varying blends of input process variables. The proposed model predicts electrode wear at R2 value of 81.5% and 75.8% for hollow and chamfered electrode, respectively. The wear features of machined tool electrode and oversize are analyzed using the microscopic images. The micrograph reveals that hollow electrode experience severe inner edge wear, whereas chamfered electrode undergoes more front wear. The chamfered electrode produce hole with oversize of 0.43% and 0.4% at entry and exit, respectively. Maximum MRR is obtained using hollow electrode.

Electrode wear pattern during EDM milling of Inconel 718

Electrode wear pattern during EDM milling of Inconel 718

Multi-Performance Optimization in Electrical Discharge Machining of Al2O3 Ceramics Using Taguchi Base AHP Weighted TOPSIS Method

The main application of electrical discharge machining in ceramic processing is limited to conductive ceramics. However, the most commonly used non-conductive potteries in modern industry, such as aluminum oxide (Al2O3), also reveal the limitations of choosing a suitable process. In this study, Taguchi based TOPSIS coupled with AHP weight method to optimize the machining parameters of EDM on Al2O3 leads to better multi-performance. The results showed that the technique is suitable for tackling multi-performance machining parameter optimization. The adhesive foil had a significant impact on material removal rate, electrode wear rate, and surface roughness, according to the findings. In addition, the response graph of relative closeness is used to determine the optimal combination levels of machining parameters. A confirmation test revealed a good agreement between predicted and experimental preference values at an optimum combination of the input parameters. The suggested experimental and statistical technique is a simple, practical, and reliable methodology for optimizing EDM process parameters on Al2O3 ceramics. This approach might be utilized to optimize and improve additional process parameters in the future.

Optimization of electrical discharge machining processing for ceramics using grey-taguchi system

Electrical discharge machining (EDM) is one of the importantly non-traditional processing technologies employed for ceramics’ surface processing. Modeling and optimization of the EDM process are essentially applied to find and obtain the optimal values of the responses for materials having smaller surface roughness, higher removing rate of materials, lower electrode wear rate. In this study, the Grey-Taguchi system with AHP weighting was applied in order to optimize the multi-responses of the EDM processing for ceramics. When the EDM processing was used in the ZrO2 ceramics for adhesive metal foils, the multi-response gray relational grade for the optimal level of machining parameter was 0.2685, which was higher than those using the initial experimental conditions. This study has proven that using the Grey-Taguchi system method with AHP weighting to find a model with a highly efficient standard for optimizing differently advanced machining processes is profitable.

Influence of Different Tool Electrode Materials on Electrochemical Discharge Machining Performances.

Electrochemical discharge machining (ECDM) is an emerging method for developing micro-channels in conductive or non-conductive materials. In order to machine the materials, it uses a combination of chemical and thermal energy. The tool electrode’s arrangement is crucial for channeling these energies from the tool electrode to the work material. As a consequence, tool electrode optimization and analysis are crucial for efficiently utilizing energies during ECDM and ensuring machining accuracy. The main motive of this study is to experimentally investigate the influence of different electrode materials, namely titanium alloy (TC4), stainless steel (SS304), brass, and copper–tungsten (CuW) alloys (W70Cu30, W80Cu20, W90Cu10), on electrodes’ electrical properties, and to select an appropriate electrode in the ECDM process. The material removal rate (MRR), electrode wear ratio (EWR), overcut (OC), and surface defects are the measurements considered. The electrical conductivity and thermal conductivity of electrodes have been identified as analytical issues for optimal machining efficiency. Moreover, electrical conductivity has been shown to influence the MRR, whereas thermal conductivity has a greater impact on the EWR, as characterized by TC4, SS304, brass, and W80Cu20 electrodes. After that, comparison experiments with three CuW electrodes (W70Cu30, W80Cu20, and W90Cu10) are carried out, with the W70Cu30 electrode appearing to be the best in terms of the ECDM process. After reviewing the research outcomes, it was determined that the W70Cu30 electrode fits best in the ECDM process, with a 70 μg/s MRR, 8.1% EWR, and 0.05 mm OC. Therefore, the W70Cu30 electrode is discovered to have the best operational efficiency and productivity with performance measures in ECDM out of the six electrodes.

Experimental Study During Electrical Discharge Machining of Reinforced Carbon Fiber Plastic Material

Abstract: The proper selection of machining conditions and machining parameter is an important aspect, before going to machine a carbon-fiber composite material by Die sinking electrical discharge machining (EDM). Because these conditions will determine such important characteristics as; Material removal rate (MRR), Electrode wears rate (EWR), and Surface roughness (R). The purpose of this work is to determine the optimal values of machining parameters of electrical discharge machine, while machining carbon-fiber-composite with copper electrode. The work has been based on the affect of four design factors: pulse current(Ip) supplied by power supply system of electrical discharge machine (EDM), pulse-on-time(TON), gap voltage(Vg) and duty cycle () on such characteristic like material removal rate (MRR), electrode wear rate(EWR), and surface roughness(Ra) on work-piece surface. This work has been done by means of the technique of design of experiment (DOE), which provides us to perform the above-mentioned analysis with small number of experiments. In this work, a L9 orthogonal array is used to design the experiment. The adequate selection of machining parameters is very important in manufacturing system, because these parameters determine the surface quality and dimensional accuracy of the manufactured part. The optimal setting of the parameters are determined through experiments planned, conducted and analyzed using the Taguchi method. It is found that material removal rate (MRR) reduces substantially, within the region of experimentation, if the parameters are set at their lowest values, while the parameters set at their highest values increases electrode wear rate (EWR). Keywords: EDM, Material removal rate, Surface roughness, Tool wear rate,

Treatment of textile industry effluents by Electro-Coagulation and Electro-Fenton processes using solar energy: A comparative study

The discharge of textile wastewater into the ecosystem is a dramatic source of pollution, eutrophication, and unaesthetic disturbance in aquatic life. The present work aimed at the treatment of the polluted water from the Industrial Textile Company “SITEX” in Ksar Hallal town (Tunisia) using two alternative processes namely Electro-coagulation (EC), and Electro-Fenton (EF). The experiments were carried out with and without Sparging air (SA). Electricity used was provided by solar energy through photovoltaic panels. Results showed that the effluent discoloration reached 100% with all processes after 280 min of treatment. These processes without (SA) were able to reach Chemical Oxygen Demand (COD) degradation until 80% and 85%, respectively. Total Organic Carbon (TOC) reached the same degradation returns. Treatment by EC and EF with (SA) reduced the COD to about 97% and 92%, respectively. TOC reached the same values. The economic Studies of electric energy consumption (SEEC) were observed in both conditions (with and without SA). The wear of electrodes was minimized, and their lifetimes were extended with SA.