Use Of Electrical Discharge Machining Research Articles

PERFORMANCE EVALUATION AND ECONOMIC ASSESSMENT IN ELECTRICAL DISCHARGE MACHINING OF SS316 USING GRAPHITE POWDER DISPERSED IN BIODEGRADABLE PALM OIL DIELECTRIC

In today’s rapidly evolving manufacturing industry, researchers and engineers are constantly seeking innovative methods to improve machining processes. One such area of interest is the use of electrical discharge machining (EDM) for difficult-to-machine metals like SS316. This research compares the performance and economic aspects of traditional EDM and powder-mixed EDM when machining SS316 using copper electrode. Graphite powder dispersed in biodegradable palm oil is investigated as a dielectric media with the aim of enhancing EDM performance. According to the findings, the analysis of the cutting performance of different machinability aspects revealed that using graphite powder mixed with palm oil as a dielectric in EDM outperformed conventional EDM relating to material removal, surface finish, surface hardness, electrode wear rate and hole overcut. The flushing condition and unique properties of graphite powder and palm oil, such as cooling, and thermal conductivity, contributed to the improved performance observed in EDM processes. These findings highlight the potential of graphite powder mixed with palm oil as a promising alternative dielectric in EDM, offering enhanced machining capabilities and improved surface quality. The total machining expenditure per part under PMEDM (INR 505.50) is lowered by 9.2% than expenditure under conventional EDM (INR 525). The surface microhardness of the machined component attained using graphite powder-mixed EDM is enhanced in comparison to that achieved using standard EDM due to the creation of a carbon-rich re-solidified layer.

Parametric Study of Die Sinking EDM of H13 Steel using Taguchi Techniques

As for H13 die steel, it is distinguished by a high hardness and a unique surface characteristics that must be created during machining using non-standard methods. One of such non conventional manufacturing techniques involving the use of Electrical Discharge Machining (EDM) for machining complex or hard material parts. It indicates that EDM has progressed from a series of a tool and die process to an alternative micro-scale application machining process. The paper is aimed at elaborating mathematical models defining the link between the MRR and SR to measured input parameters (current, pulse-on time, pulse-off time, and Reference voltage) in hot work steel EDM. With a L9 orthogonal involving four variables at three levels were used. The values of the model quality factors analyzed by the ANOVA procedure show that the selected mathematical models describe the process performance within successfully studied range with high level of precision. To determine the optimal condition, Taguchi method was used to measure the performance impact of different process parameters and find out best mixing. Minitab V 21 software has been used for the analysis and explanations. A good agreement between experimental value and the predicted one was found.

A systematic study to achieve cleaner and sustainable manufacturing process by using bio-degradable dielectrics

Inconel 600 is widely used in aeronautical and aerospace industry owing to its excellent mechanical, wear and corrosion characteristics. This high strength alloy requires a special machining environment which justifies the use of Electric Discharge Machining (EDM). However, low cutting rate, which accounts for the productivity aspect, and emission of toxic fumes generated by thermal breakdown of kerosene dielectric currently limit the use of EDM. Moreover, since EDM is an energy intensive machining process, industry has a stringent emphasis to make this process sustainable and eco-friendly. In this context, the potentiality of six bio-degradable dielectrics was comprehensively investigated here for the first time ever to achieve cleaner and sustainable production of Inconel 600. Each biodegradable dielectric was coupled to four electrode materials to find the best tool-dielectric combinations for the EDM processing of this Ni-based super alloy. The responses were defined considering the three key ingredients of sustainability: i.e. productivity (assessed in terms of material removal rate and tool wear ratio), quality (expressed in terms of surface finish and dimensional deviation) and power consumption (expressed in terms of specific energy consumption). Experimentation was performed with a full factorial design taking dielectric type and electrode material as input variables. The EDM configuration including amla oil as dielectric and brass electrode was the best in terms of maximum MRR (19.8 mm3/min), 560% better than the standard EDM configuration including the same brass tool and kerosene dielectric. The lowest surface roughness SR (quality aspect) was obtained by the EDM configuration including a brass electrode and the sunflower oil dielectric: surface quality improved by 30.6% with respect to standard EDM using the same electrode and kerosene dielectric. Considering the specific energy consumption, the EDM setup with brass electrode and amla oil dielectric was 6.6 times more efficient than standard EDM with the same electrode and kerosene dielectric. The combination of coconut dielectric and Cu electrode results in a 5.4 times lower tool wear ratio than the traditional dielectric. In terms of achieving a better dimensional control, graphite electrode is a preferred choice against olive oil dielectric. Based on the measured values for EDM responses, it was revealed that relative percentage of carbon dioxide emissions reduces by 83.95% if amla oil is used in comparison to the CO2 emissions noted for standard kerosene oil considering brass as electrode. Finally, an optimal combination of the best biodegradable dielectric fluid and electrode material to satisfy all performance indicators was proposed through MOGA technique. Experimental data were properly fitted by using artificial neural networks. The EDM setup with copper electrode and amla oil dielectric achieved the best global performance with respect to all responses.

Analyzing micromachining errors in EDM of Inconel 600 using various biodegradable dielectrics

Inconel 600 is a Ni-based superalloy having exclusive properties like high strength and stability in harsh conditions. However, its accurate machining is challenging via conventional cutting methodologies. As a result, the use of electric discharge machining is common in cutting Inconel 600 precisely. But the intrinsic issue of overcut associated with traditional EDM limits its appreciation in cutting Ni-based alloy. Moreover, conventional dielectric oil used in EDM releases hazardous fumes and gases that put the operator’s health at risk. Therefore, in this study, six different biodegradable dielectrics have been investigated for their potential in controlling the dimensional overcut, which have yet to be evaluated thoroughly. The performance of biodegradable dielectrics (canola, amla, olive, sunflower, coconut, and mustard oil) against four types of electrode materials has been evaluated using full factorial design in the EDM of Inconel 600. Experimental findings are analyzed with statistical tests and optical/scanning electron microscopic evidence. The experimental results indicated that canola dielectric yield the smallest dimensional overcut. However, combination of sunflower oil and copper electrode proved as second premier case to reduce the overcut. Compared to the conventionally used kerosene oil, the biodegradable dielectrics (canola and sunflower) display a 63% and 1.2-folds reduction in overcut.

Reducing the geometrical machining errors incurred during die repair and maintenance through electric discharge machining (EDM)

The importance of geometrical accuracy can never be overruled in dies and molds which governs the dimensional precision of the parts being manufactured. The continuous use of such tooling requires repair and maintenance. Among the different processes used to upkeep the dimensional consistency of the tooling, machining is essentially required in most cases. The intricacy of the dies and molds’ cavities requires the use of electric discharge machining (EDM). However, in EDM it is challenging to develop control over the machined dimensions owing to the inherent issues of overcut/undercut. This aspect was not comprehensively investigated so far which is the core focus of this research. Three electrode materials, namely, copper, graphite, and tungsten carbide, which belong to the category of metals, nonmetals, and ceramics, respectively, have been compared for the said perspective on the comprehensive list of parametric variables. The results revealed that the average value of the axial errors is 2.5 times lesser in comparison to lateral dimensional errors. In the case of lateral dimensional errors, the electrode of graphite has proved to be a promising choice in comparison to the other two types of electrode materials, namely, copper and tungsten carbide. The copper electrode is noticed to be the most appealing option for reducing axial error (A.E). The mean A.E obtained with Cu electrode is 80.9% and 47.6% lower than that achieved in case graphite and tungsten carbide, respectively. Furthermore, the optimal parametric combination based on 7 variables has also been proposed using desirability analyses whose validity is proved during confirmation trials.

Tribological characterization of a hip prosthesis in Si3N4-TiN ceramic composite made with Electrical Discharge Machining (EDM)

In this work, the friction and wear behavior in hip prosthesis made of Si3N4-TiN ceramic composite were evaluated by tribological tests in order to estimate the prosthesis life. The innovation consists in the use of Electrical Discharge Machining (EDM) for the realization of the hip prosthesis. This was allowed using TiN as a dopant of the ceramic matrix which confer electrical conductivity properties to the composite, necessary in order to use the EDM. The Coefficient of Friction (CoF) and Wear Rate (WR) were evaluated through experimental tribological tests using a tribometer with Pin on Disk (PoD) configuration. The experimental results were used for the calibration of the Archard wear model adopted to simulate the wear process between pin and disk. Finally, after calibrating the wear model, numerical analysis was performed to evaluate the wear of the material and the life cycle of the hip prosthesis.

A Comprehensive Analysis of the Effect of Graphene-Based Dielectric for Sustainable Electric Discharge Machining of Ti-6Al-4V.

Titanium alloys, especially Ti-6Al-4V, which is considered a difficult-to-cut material, bears numerous applications in aerospace and biomedical sectors. The criticality of the accurate formation of the machined cavity for the said applications and properties of Ti-6Al-4V accentuated the use of electric discharge machining (EDM). However, the issues of lower material removal rate (MRR) and tool wear (TWR) discouraged the use of EDM. These inherent issues hold a pivotal role regarding the sustainable machining of Ti-alloy. Therefore, in this research the potentiality of kerosene-based dielectric, having graphene nanoparticles, is comprehensively examined for the sustainable EDM of Ti-6Al-4V, which was not focused upon yet. Experimentation was performed under Taguchi’s design (L18) with three types of electrodes, namely Aluminum, Brass and Copper. In total, 36 experiments were conducted, of which 18 were with graphene-mixed dielectric and the remaining were with kerosene. Experimental results reveal that the brass electrode with negative tool polarity yields higher MRR for both types of dielectrics. The maximum MRR (7.602 mm3/min) achieved with graphene mixed dielectric is 64.5% greater as compared to that obtained with kerosene (4.621 mm3/min). Moreover, the minimum TWR obtained for graphene-based dielectric, i.e., 0.17 mg/min is approximately 1.5 times less than that achieved with kerosene.

Experimental investigation of heat pipe thermal performance with microgrooves fabricated by wire electrical discharge machining

This work presents the use of electrical discharge machining (EDM) technology for manufacturing of three different types of axial microgrooves in heat pipes. This specific process, called wire electrical discharge machining (wire-EDM), allows the fabrication of microgrooves on the inner wall of a heat pipe with accuracy. Different from other capillary structures, such as composite wick and screen mesh, the material is removed from the pipe?s container in order to conceive the capillary structure, which contributes with the mass reduction of the passive two-phase heat transfer device. The heat pipes were manufactured from a straight copper pipe with the external diameter of 9.45 mm, the inner diameter of 6.20 mm, and a total length of 200 mm. Three types of axial microgrooves were manufactured for constant width (35 ?m) and varying the depth (from 30-48 ?m), and thickness (from 35-70 ?m). The number of microgrooves was also varied from 21-32 microgrooves. Water was used as the working fluid and the loading filling ratio was 60% of the evaporator volume. The condenser was cooled by air forced convection, the adiabatic section was insulated and the evaporator was heated by an electrical resistor and it was insulated from the environment with aeronautic thermal insulation. The thermal performance of the heat pipes are analyzed based on experimental results, so the heat pipes were tested at the horizontal and different inclinations under different low heat loads (from 5-50 W or a heat flux from 0.21-2.10 W/cm2). The experimental results showed that the axial microgrooves manufactured by the wire-EDM process worked satisfactorily in all analyzed cases and microgrooves of Type 1 showed a better thermal performance when compared with the others.

Electrical discharge dressing of honing stones

Honing processes require a systematic preparation and a regeneration of the honing tool to guarantee a sufficient cutting behaviour and prevent unintended wear of the tool. These dressing processes are particularly important for the regeneration of the macro- and microscopic topography of the honing stones. The established method of manual shaping subsequent to a cylindrical grinding process demands a high skill level, a great amount of non-productive time and is not reproducible.In this paper the preparation of honing stones by use of electrical discharge machining (EDM) is presented. The aim is to ensure an automatic, systematic and reproducible process of resetting the bond of honing stones. Different tool electrode materials were analysed systematically for two different bond specifications of the honing stones. EDM process parameters were studied within a design of experiments (DoE) strategy and a subsequent effect analysis to assure the identification of most appropriate EDM process parameters. After this procedure various cycles of long-stroke honing processes were carried out. As a result, the new approach makes it possible to prepare honing stones with reproducible sharpness and macroscopic topography within an automated process. The dressing time td was reduced by 88 % compared to the established method.

Application of the method of electroerosion treatment to improve the quality of the treated surface

Intensive use of electrical discharge machining is currently determined by the very dynamic development of domestic engineering. The use of electrical discharge machining helps us to achieve the desired results, namely high machining accuracy, low surface roughness and low dependence of performance on the mechanical properties of the processed materials. Thus, the study of processes and tools of electrical discharge machining to improve the quality of machined parts is one of the urgent tasks.

Повышение надежности работы тяговых электродвигателей локомотивов за счет применения электроискровой обработки коллекторных пластин

Повышение надежности работы тяговых электродвигателей локомотивов за счет применения электроискровой обработки коллекторных пластин

Investigations of Effect of Rotary EDM Electrode on Machining Performance of Al6061 Alloy

Electric Discharge Machining is an essential process which is being used for machining desired shape using electrical discharges which creates sparks. There will be electrodes subjected to electric voltage and which are separated by a dielectric liquid. Removing of material will be due to the continuous and rapid current discharges between two electrodes.. The spark is very carefully controlled and localized so that it only affects the surface of the material. Usually in order to prevent the defects which are arising due to the conventional machining, the Electric Discharge Machining (EDM) machining is preferred. Also intricate and complicated shapes can be machined effectively by use of Electric Discharge Machining (EDM). The EDM process usually does not affect the heat treat below the surface. This research work focus on the design and fabrication of rotary EDM tool for machining Al6061alloy and investigation of effect of rotary tool on surface finish, material removal rate and tool wear rate. Also the effect of machining parameters of EDM such as pulse on & off time, current on material Removal Rate (MRR), Surface Roughness (SR) and Electrode wear rate (EWR) have studied. Al6061 alloy can be used for marine and offshore applications by reinforcing some other elements. The investigations have revealed that MRR (material removal rate), surface roughness (Ra) have been improved with the reduction in the tool wear rate (TWR) when the tool is rotating instead of stationary. It was clear that as rotary speed of the tool is increasing the material removal rate is increasing with the reduction of surface finish and tool wear rate.

Effects of melt-pool geometry on microstructure structural damage behavior for single crystal superalloys in rapid solidification process

Electro-machining surface stochastic failure is one of the main factors which limit the use of electrical discharge machining in hot end of aeronautics and astronautics. This study proposes the recast layer (RL) failure prediction model and analyses the effect of unit melt-pool geometry on recast layer structural stability in single crystal by analyzing cellular-dendrite microstructure around ring layer. Both model calculation and experimental results show that melt-pool geometry parameters-radius-depth ratio and tangent angle directly influence ring RL thermal structural stability. Smaller radius-depth ratio range and larger tangent angle (on (1 0 0) substrate) can significantly improve RL performance or even avoid high temperature service structural damage. For certain undesirable melt-pool geometry, the RL damage crack location has selectivity on specific secondary orientation. High temperature oxidation, crack initiation and propagation mode together influence RL failure modes in high temperature atmospheric environment. Electro-machining surface reliability can be effectively evaluated with the prediction model, and the geometry parameters can be used to provide efficient data for surface structure design.

A comparative investigation on hybrid EDM for drilling small deep holes

For the use of electrical discharge machining (EDM) to drill small, deep holes, many studies have shown that tool electrode vibration and rotation and pump forced flushing can improve machining efficiency or quality. However, these factors are usually studied separately. In this study, a hybrid, rotary, ultrasonic EDM system was developed that used these three methods simultaneously. A comparative investigation on different combinations of the three methods was conducted for drilling small, deep holes in Inconel 718 and 41Cr4 workpieces. Results showed that, compared with other combinations for precision drilling under low discharge currents, combinations including these three methods simultaneously achieved more stable machining and higher material removal rates. In addition, the applied current greatly influenced hole depth and the effects of ultrasonics. When a high discharge current was applied, the electrode vibration contribution appeared weak.

Micromachining of a High-Density Current-Conducting Ceramic with the Use of Electrical-Discharge Machining. Part 2

Production features of micromachining ceramic workpieces using electrical-discharge machining are studied. The effect of pulse duration, breakdown voltage, voltage gain factor, peak current strength, and working voltage for electrical-discharge machining of VOK71 ceramic workpieces on roughness at the bottom of a channel and electrode-tool end wear are established. A mechanism is proposed for surface formation with electrical-discharge machining of current-conducting ceramic and recommendations are formulated for improving micromachining efficiency for components of this material.

Influence of urea content blended with deionized water in the process of nitriding using electrical discharge machining on AISI 4140 steel

The process of nitriding with electrical discharges makes use of electrical discharge machining (EDM) machines. Nitrogen is supplied by a dielectric fluid comprised of distilled water or deionized and urea solution (CH4N2O). The underlying objective of this study was to investigate the influence connected to the amount of urea diluted in deionized water during the nitriding process of AISI 4140 steel. The tests were performed using a sinker EDM machine. As a tool electrode, the authors used an electrolytic copper cylinder, and as workpiece electrodes, they used cylindrical AISI 4140 steel. Samples of deionized water were used as a dielectric fluid and urea was added at different concentrations. The results showed the progressive loss of dielectric strength with the addition of different amounts of urea, mixed to the water. There was also a noticeable change in the kinetics of the plasma channel formation. Urea quantities higher than 10 g/l did not produce correct plasma arc formation. Variations in urea content did not significantly change in the morphology of the machined surface, the thickness of the nitrided layer, the type of nitrides formed, or the final hardness of the enriched surfaces. However, the increase in the amount of urea caused the loss of dielectric strength of the fluid with a consequent decrease in the material removal rate and therefore, the best material removal rate (MRR) was found when machined at a lower urea content level.

Micromachining of a High-Density Current-Conducting Ceramic With the Use of Electrical-Discharge Machining. Part 1

This article discusses technological aspects of the micromachining of semifinished products made of a high-density electrically conducting ceramic with the use of electrical discharge machining (EDM). It is established that an increase in pulse frequency during the EDM cutting of channels in semifinished products made of an oxide-carbide ceramic is accompanied by a decrease in the dimensions of the channel’s profile and the productivity of the machining operation, an increase in the roughness of the channel bottom, and an increase in wear of the tool-electrode.

Nano Graphite Powder Assisted Electric Discharge Machining Characteristics of ZM21 Magnesium Alloy

Magnesium alloys are used in many applications, particularly in orthopaedic implants are very difficult to machine by conventional processes because of their complex 3D structure and limited slip system at room temperature. Hence there is an inherent need for alternative processes for machining such intricate profiles. Electric Discharge Machining is growing rapidly in tool rooms, die shops and even in general shop floors of modern industries to facilitate complex machining for difficult-to-machine materials and provide better surface integrity. Therefore, the use of electric discharge machining on ZM21 magnesium alloy is attempted in this paper. Nanographite powder is added for machining zone to enhance the electrical conductivity of EDM oil by way it improves the machining performance. Machining parameters such as the current, pulse on time and pulse off time were process parameters to explore their effects on the material removal rate and tool wear rate. It is observed that, an increased material removal rate was due to the enhanced electrical and thermal conductivity of the EDM oil.

EXPERIMENTAL INVESTIGATION OF RECAST LAYER FORMATION ON THE SURFACE OF Ti-6Al-4V TITANIUM ALLOY DURING EDM PROCESS (machining carried out at lower range of machining parameters)

A b s t r a c t The recast layer forms during the machining of Ti-6Al-4V titanium alloy carried out with a use of electrical discharge machining (EDM). The paper presents the description of EDM process carried out at lower range of machining parameters also the formation process of recast layer. The recast layer was analyzed using scanning electron microscopy and 3D viewer image. The performed experiments involved application of copper and graphite electrode with positive polarity. In order to analyze the results, the authors used design of experiment (DOE) method – Taguchi technique (L18) with mixedlevel design. The influence of peak current (A), servo voltage (V), pulse on time (Ton) and pulse off time (Toff) on the recast layer was described in the article.

Characterization of electric discharge machining, subsequent etching and shot-peening as a surface treatment for orthopedic implants

Presented work aims at multi-method characterization of combined surface treatment of Ti–6Al–4V alloy for biomedical use. Surface treatment consists of consequent use of electric discharge machining (EDM), acid etching and shot peening. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. Acid etching by strong Kroll's reagent is capable of removing surface layer of transformed material created by EDM. Acid etching also creates partly nanostructured surface and significantly contributes to the enhanced proliferation of the bone cells. The cell growth could be positively affected by the superimposed bone-inspired structure of the surface with the morphological features in macro-, micro- and nano-range. Shot peening significantly improves poor fatigue performance after EDM. Final fatigue performance is comparable to benchmark electropolished material without any adverse surface effect. The proposed three-step surface treatment is a low-cost process capable of producing material that is applicable in orthopedics.