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This research paper explores the impact of electrical discharge machining process parameters, including current, pulse‐on time (Ton), and pulse‐off time (Toff), on the material removal rate (MRR) and surface roughness (SR) during the fabrication of aluminum silicon dioxide (Al7075–SiO2) composites. The Al7075–SiO2 composites were produced through stir casting, incorporating 10% by weight of SiO2 reinforcements with an average particle size of 54 µm. To systematically investigate the process parameters' effects, Taguchi's L9 orthogonal array was implemented in the design of experiments. Subsequently, the experimental data underwent analysis of variance (ANOVA) for thorough analysis. The response table for MRR and SR demonstrated that the current significantly influenced both responses (MRR and SR). The ANOVA results provided valuable insights into the percentage contribution of each parameter to the responses. Through the analysis, the optimal control variable settings for achieving the highest MRR were identified as a current of 3 A, a pulse‐on time of 1500 µs, and a pulse‐off time of 1 µs. Conversely, to attain the lowest SR, the ideal control variable settings were determined to be a current of 1 A, a pulse‐on time of 500 µs, and a pulse‐off time of 1 µs. Results also suggest that the error was within admissible range of 5% and the percentage contribution of the current (70.19%) had the largest effect on MRR. [ABSTRACT FROM AUTHOR]

Conventional drilling of carbon fibre–reinforced plastic (CFRP) presents significant challenges due to the material's abrasive nature and anisotropic properties, leading to tool wear, delamination, and surface damage. To address these challenges, this study pioneers the use of wire electrical discharge machining (WEDM) to evaluate the drilling performance of thick CFRP lay-up configurations mainly unidirectional and multidirectional, marking the first application of WEDM for CFRP drilling. The study evaluates material removal rate (MRR), delamination factor (DF), and surface damage while employing an analytical solution to estimate surface temperature and heat conduction in the laminates. An eight-full factorial experimental design was employed, involving variations in ignition current (3 A and 5 A) and pulse-off time (4 µs and 8 µs). The findings revealed that the multidirectional lay-up achieved an MRR of 2.85 mm3/min, significantly outperforming the unidirectional lay-up's MRR of 0.95 mm3/min, representing a 300% increase at 5 A and 4 µs. However, the increase in discharge energy led to surface damage such as delamination, frayed fibres, and irregular circularity, especially evident in the unidirectional lay-up. For delamination, the multidirectional lay-up had the highest top DF of 1.4 at 5 A and 6 µs, while the unidirectional lay-up achieved the peak bottom DF of 1.24 at the same levels. While none of the parameters significantly affected the responses, the current exhibited the highest contribution ratios. Analytical predictions of the thermal distribution indicated a 45-µm delamination length at the laminate surface and depth, aligning closely with experimental predictions of 30–50 µm. [ABSTRACT FROM AUTHOR]

Dense silicon carbide (SiC) composites with 0–30 vol% (ZrN-TiB 2) were fabricated by using liquid phase spark plasma sintering at a relatively lower sintering temperature (1800 °C) and shorter holding time (5 min). The effects of co-addition of ZrN and TiB 2 on densification, mechanical properties, and electrical conductivity of SiC ceramics were investigated. The reinforcement significantly enhanced density of sintered composites, while the phase analysis and microstructure confirm the suppression of β→α phase transformation in the SiC matrix. The fracture toughness ranged from 4.1 to 4.6 MPa·m0.5, hardness from 19.5 to 20.3 GPa, and electrical conductivity from 4.85 ×101 to 1.25 ×103 (Ω·cm)−1. Incorporating conductive reinforcements and nitrogen additives enhanced electrical conductivity. Successful wire-EDM cutting of SiC-ZrN-TiB 2 composites demonstrate the feasible alternative to conventional machining of non-oxide ceramics with a maximum material removal rate of 8.54 mm2/min. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the discharge energy distribution during Powder Mixed Electrical Discharge Machining (PMEDM) at different values of pulse duration, peak current and powder concentration. A finite element method (FEM) based numerical model has been developed to estimate the power distribution factor by reverse simulation. The developed model has been used for determining the fraction of discharge energy distributed to the electrodes. The model and experimental values of total fraction of discharge energy are in close agreement with the error varying between 0.47 % to 14.04 % for tool and 0.82 % to 9.82 % for workpiece. Parametric influence on components of discharge energy has also been discussed. • Study of discharge energy distribution during graphite powder mixed EDM. • Determination of power distribution factor using reverse simulation approach. • Development of FEM model using COMSOL Multiphysics. • Powder concentration, pulse duration, peak current are the process variables. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V alloy due to high mechanical properties and high corrosion resistance is widely used in the manufacture of biomedical devices, including hip articulations, screws and dental implants. For proper implant performance in the long run, a rapid reaction between the bone and implant should be performed, which depends on the surface properties of the layer doped on the surface of the implant. The surface coating is therefore considered to be the underlying factor in the attenuation of such occurrences. This research aims to assess the modified surface of Ti-6Al-4V by the mixed electric discharge (EDM) process of β-tricalcium phosphate powder to detect potential bioimplants. One of the features of this coating process is the location of the base titanium layer containing β-tricalcium phosphate, thereby improving the substrate properties. For investigating the surface morphology, distribution and dispersion of elements on the modified surface, field emission scanning electron microscope (FE-SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) tests were used. Morphological features have shown that porous surface topography just like natural bone is coated on the surface of Ti-6Al-4V alloy using the AM-EDM process. EDS and XRD examinations showed the coated layer compositions from Ti kα, V, Al, Ca and P and also formation of the biocompatible phases such as Ca 2 P 2 O 7 andCa OH 2 on the surface of Ti-6Al-4V, which caused the better biocompatibility of the alloy, creation of an antibacterial agent for periodical injuries and also improvement of the bone formation on the alloy surface. The results also showed that the size of the resin thickness was 35 micrometers, which contained nanoparticles of tricalcium phosphate, as well as an excellent metallurgical substrate with a strong bond between the substrate and the coating. In this research, the effects of input parameters, such as spark energy and powder concentration on output parameters, including material removal rate, surface roughness and surface hardness, were studied. The results showed that this method has a positive effect on the reduction in the material removal rate, roughness and hardness of the surface of the workpiece. Due to the dispersion of β-tricalcium phosphate particles, the surface roughness diminishes during the electric discharge process. Also, the highest material removal rate occurred in 21 A, the pulse duration of 50 μs and the concentration of 8 g/L, and minimal surface roughness occurred in 6 A, the pulse duration of 100 μs and the concentration of 4 g/L. The hardness of the surface deposited with β-tricalcium phosphate powder is 348 VH, which is 1.75 times more than the original surface. The reason is that the hard oxide is deposited on the surface of the workpiece. [ABSTRACT FROM AUTHOR]

Sustainability is vital in manufacturing industries for the fabricating products with economic, social and environmental attention. The current study uses stir casting fabricating methodology to manufacture aluminium LM25 alloy reinforced with 7.5 wt.% Silicon Carbide (SiC) and 2.5 wt.% Titanium Oxide (TiO2) hybrid metal matrix composite (HMMC). The microstructural and energy dispersive spectroscopy (EDS) analysis is supported to confirm hybrid reinforcement's existence and even distribution in the aluminium matrix. The Vicker's hardness of 110.25 HV is measured for the manufactured composite. The machinability behaviour of the fabricated HMMC is studied using electrical discharge machining (EDM) to achieve the optimum material removal rate (MRR) and surface roughness (SR) through Taguchi integrated grey relational analysis (TGRA). To get the best machining results, the impact of machining process variables such as pulse on time (Ton), current (I), and voltage (V) was examined. To determine the importance of process variables on the machining responses, analysis of variance (ANOVA) was also conducted. The optimum machining process variables were revealed concerning the machining process variables such as pulse on time 100 μs, current 6 A, and voltage 25 V. ANOVA analysis confirmed that the current with a percentage significance of 71.52%, is the most important EDM machining process variable followed by pulse on time and voltage. Further, the machined surface is examined through a hi-resolution scanning electron microscope (HRSEM) and 3D optical profilometer. The formation of a white layer, craters and bubbles on the machined area are observed for varying machining conditions. The fabricated HMMC can be utilized in the automobile applications such as pistons, brake discs, gears and cylinders. [ABSTRACT FROM AUTHOR]

The electrical discharge machining is very successful and generally recognized for producing complicated shapes and small openings with exceptional precision. The objective of this study is to assess the impact of different electrical discharge machining parameters on the attributes of the machining process. The evaluation of the machining process was conducted based on the workpiece's material removal rate, the rate at which the electrodes wear, and the level of surface roughness. Simultaneously achieving a high material removal rate, low electrode wear rate, and high surface roughness is not possible with a specific combination of approaches due to their contradicting nature. Frequently, it is necessary to independently apply many measures instantaneously in order to assess their impact on various responses. This research investigates the machining of high carbon high chromium steel making use of electrical discharge machining with aluminum, copper, and graphite electrodes. The study focuses on the impact of different current intensities on the rate of material removal, electrode wear, and surface roughness. The experimental results demonstrate that the highest material removal rate (mmcubicmin−1) is achieved at a current density of 12 A when using a copper electrode (54.67), as opposed to aluminum electrode (22.91) and graphite electrode (29.43). [ABSTRACT FROM AUTHOR]

In the electrical discharge machining process (EDM), quantities of discharge craters randomly scatter the workpiece surface. However, the formation mechanism of the discharge crater has not been fully understood, which affects the application of EDM technology. In the paper, a thermal-fluid coupling model was proposed to elucidate the crater formation dynamics process utilizing COMSOL Multiphysics software. The temperature distribution, fluid flow velocity, and more changes in the crater were analyzed, aiming to deepen the understanding of the formation mechanism of the discharge crater in the EDM process. Through the comparison of experimental results and numerical simulation results, it was found that a little of the material is eroded by vaporization, while a lot of material is eroded mainly by melting. In addition, the material removal process is continuously eroded after the end of discharge due to the residual heat and the flow of molten material. Moreover, the effect of pulse on-time and peak current on the temperature field and flow field was solved. Through the experiments and numerical simulations, it was shown that the simulation results are consistent with the experimental results, verifying the applicability of the thermal-fluid coupling model in demonstrating the mechanisms of crater formation in the EDM process. [ABSTRACT FROM AUTHOR]

Electrical discharge grinding technology (EDGT) is an efficient and high precision method for machining RB-SiC ceramic materials. In this paper, the mechanism of material removal in EDGT is deeply analyzed, and the formation mechanism of surface topography under different material removal regimes affected by grinding depth is discussed. A three-dimensional heat conduction analysis model in the process of single pulse discharge was established, and the temperature field distribution in RB-SiC ceramic material under different discharge energy was obtained by numerical calculation. It is found that the simulated crater radius and depth increase with the increase of the discharge time, and the material removal amount gradually increases, but the growth rate gradually decreases. In order to give full play to the advantages of EDGT, the discharge energy and grinding depth were optimized according to the material removal mechanism. Finally, RB-SiC ceramic machining experiments were carried out using the optimized machining parameters, and a smooth surface with few discharge craters was obtained. It is found that the grinding scratches on the material surface are mainly plastic grinding, and the material surface roughness is 0.443 μm. The research results of this paper can provide guidance for engineering practice of ductile grinding RB-SiC ceramic materials. [ABSTRACT FROM AUTHOR]

Electrical Discharge Machining (EDM) process is considered as one of the ultimate famously process used in the components production like tools of surgical, dies, punch and aerospace. The EDM technique perform on the control of loss metal principle according to power as thermal-electric through the electrode and blank piece. Alloy steel (X210) was selected as a workpiece, whereas copper electrodes selected by in different angled electrodes (0°, 22.5°, 45°, 67.5°, and 90°). The technique of composite design (CCD) was applied in this work and accomplish (ANOVA) was concluded to consider the highly important variables. The experimental results show that the material removal rate is accelerate at highest value using Angle of Electrode (E A 67.5°) and (I 30A). Electrode Wear Rate (EWR) can be attained using (E A 22.5°) and (I 20A).Thickness of White Layer (WLT) is increased at (E A 22.5°) with enlarge current at maximum magnitude (30 A), minimize WLT is obviously at (E A 45°) and current is (15A). An optimization technique was utilize to conclude of optimal parameters at maximize MRR and consequently reduce EWR. The optimum values for the responses such as MRR and EWR with optimum value are gained with the following parameters: (E A 22.5°), (I 27), (P-on299) and (P-off 50). [ABSTRACT FROM AUTHOR]

Being a manufacturing process based on thermal material removal, it has been known for decades that Electrical Discharge Machining (EDM) affects the properties of surface layers of machined workpieces, notably by inducing residual stresses. These stresses are undesirable as they can contribute to crack formation in ED machined parts in on-load operation. Thus, their minimization is preferable. In this research the influence of different combinations of EDM parameters (namely discharge duration and discharge current) on characteristics of residual stresses is studied and compared. However, industrial ED machining usually consists of a sequence of process regimes that each represents a thermal load for the material and consequently each causes an individual profile of residual stress. Therefore, the resulting effect of these combined loads is also investigated. The findings contribute to the knowledge of the process signature of Electrical Discharge Machining as well as they allow for improved planning of industrial EDM processes. [ABSTRACT FROM AUTHOR]

Porous metal materials are widely used in heat-absorbing, biomedical parts and other fields because of their excellent mechanical properties and biocompatibility. Further applications of porous metal materials are inseparable from secondary precision machining. However, traditional cutting methods tend to compromise the original porosity of the material surface. Electrical discharge machining (EDM) is a type of non-conventional machining method which is more preferable to overcome these defects. In the present study, the main target is to investigate the effect of four input electrical machining parameters (current, frequency, efficiency and gap voltage) on the five output responses (material removal rate (MRR), electrode wear, surface roughness (SR), noise and time consumption value of environmental particulate matter (PM2.5)) when electrical discharge machining porous 316L stainless steel and compared with that of pure 316L stainless steel. The Taguchi method was employed to determine the relationship between electrical discharge machining parameters and output responses. The analysis of variance (ANOVA) was used to evaluate the effect of input parameters on output responses. The effects of electrical machining parameters on above responses were analyzed by main effects, and the order of influence was obtained, respectively. Finally, the surface morphology was observed by scanning electron microscope (SEM), and the effect of electrical machining parameters on the characteristics and formation of machined surface of porous stainless steel was mainly analyzed. [ABSTRACT FROM AUTHOR]

An enclosed microgroove is a vital surface microstructure that is difficult to prepare on the surfaces of difficult-to-machine electrically conductive materials using conventional methods. Electrical discharge machining (EDM) is suitable for this task. It is obtained primarily through layer-by-layer scanning EDM with micro-column electrodes or reciprocating EDM with foil electrodes. However, owing to the small cross-sectional size of the electrodes, a stable machining process is challenging to achieve, which seriously reduces the machining efficiency. To solve these problems, this study proposed ultrasonic vibration-assisted EDM using a laminated electrode possessed strong anti-interference properties for enclosed microgrooves. The effects of ultrasonic vibration on the EDM of microgrooves with single foil and laminated electrodes were investigated. The results show that ultrasonic vibration could improve the machining efficiency of the two types of electrodes and significantly improve the profile quality of the microgrooves prepared using laminated electrodes. When the amplitude was 3 μm and the frequency was 30 kHz, the bottom sidewall corner radius of microgrooves machined by brass foils in laminated electrodes was 28 μm, the width, depth, and roughness of microgrooves machined by copper foils in laminated electrodes were approximately 78 μm, 229 μm and 0.7 μm, the material removal rate was 0.0072 mm3/min. Based on the optimized parameters, inverted “convex” microgrooves with fine consistency were successfully prepared using laminated electrodes on Ti–6Al–4V alloy surfaces. The machining time was reduced by 40% for each microgroove compared with using the single foil electrode. This study provides a new method for preparing complex microgrooves.

Abstract Wire electrical discharge machining (WEDM) is one of the most important non-traditional machining methods that is widely used in various industries. The present research work is concerned with the influences of process variables on quality of machined specimen obtained from WEDM process. The process parameters to manufacture mold structure included wire feed speed, wire tension and generator power, and in the current research, the effects of these variables on the aim factors, namely dimensional accuracy, hardness and roughness of product surface have been investigated, simultaneously. In order to obtain the optimal experiment, the multi-objective optimization with discrete solution area has been employed. Method based on the removal effects of criteria (MEREC) and weighted aggregates sum product assessment (WASPAS) techniques have been used with the aim of weighting the objective functions and discovering the best practical experiment. In the following, the regression analysis has been employed to study the effects of variables on response factors. A good correlation between the results gained from two analysis methods was observed. Based on MEREC-WASPAS hybrid technique, the weights of roughness, hardness and dimensional accuracy of machined part were calculated to about 89%, 9% and 2%, respectively. In the selected optimal experiment, the amount of wire feed speed, wire tension and generator power variables were considered to, in turn, 2 cm/s, 2.5 kg, and 10%.

Electrode wear (EW) during the electrical discharge machining (EDM) process determines surface topography accuracy. In this paper, an automatic evaluation method is proposed by integrating image segmentation and three-dimensional (3D) registration (IS-3DR) to evaluate the EW more accurately. First, the original two-dimensional (2D) image and the 3D point cloud were derived from a laser microscope image, and the 2D worn area was determined by automatic recognition and segmentation. Then, 3D registration between the 3D point cloud and the 2D worn area was utilized to qualitatively define the 3D EW area. Finally, the 3D EW volume was obtained quantitatively through micro-element calculation based on the 3D EW area and the shape fitting of the original electrode. The results showed that the intersection over union (IOU) of image segmentation was higher than 97.5%, compared with the manually labeled image segmentation method. Compared with IS-3DR, the random error of the two-dimensional evaluation method could reach 27.08%, indicating higher reliability and stability of IS-3DR. The EDM experiment was carried out to investigate the effect of parameters on EW. The experimental results showed that the effects of current and servo voltage were most significant, followed by pulse width. [ABSTRACT FROM AUTHOR]

In electrical discharge machining (EDM), it is a much more effective method to improve working characteristics by changing the input process of pulse energy. However, it has not been investigated enough whether pulse form is the most adequate or not. In this study, the effect of superimposed pulse current waveform and its parameter on surface integrity was investigated. The surface topography, roughness, microstructure, white layer thickness, and residual stress were analyzed and discussed. Moreover, the material removal rate was also tested and compared. The results show that with the backward movement of the superimposed pulse current, the material removal rate and surface roughness decrease, while the white layer thickness, residual stress, and surface defects increase. The current waveform has little influence on microstructure. Under the same pulse discharge energy and pulse-on time, the samples processed by superimposed pulse current waveform instead of rectangular current waveform can obtain a thinner white layer, lower residual stress, fewer surface defects, and high surface roughness. With the increase of superimposed pulse-on time and current, the surface integrity becomes worse due to the increase of pulse energy. This paper provides a guide to the development and selection of EDM discharge current waveforms in EDM. [ABSTRACT FROM AUTHOR]

High electrical conductivity and low thermal conductivity are beneficial for the electrical discharge machining performance of ceramics. In this work, B 4 C–TiB 2 composites were prepared by spark plasma sintering of B 4 C–TiC–B powder mixture. The chemical reaction between TiC and B, together with subsequent selective matrix grain growth, expelled small in-situ generated TiB 2 grains to form conductive interlayers around large B 4 C grains. The unique microstructure significantly enhances the electrical conductivity of B 4 C–TiB 2 composites, especially at low TiB 2 content, while the ultrafine in-situ formed TiB 2 grains endow the composites with low thermal conductivity. The effects of TiB 2 content on the microstructure, mechanical properties, thermal & electrical conductivity of the composites were investigated. B 4 C–20 vol% TiB 2 composite exhibits excellent comprehensive performance, including a relative density, Vickers hardness, flexural strength, fracture toughness, room electrical and thermal conductivity of 98.6%, 28.15 GPa, 656 MPa, 5.46 MPa⋅m1/2, 1.08 × 105 S/m and 19.37 W/m⋅K, respectively. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC) and its composites are typically associated with high hardness and high wear resistance, posing challenges in conventional machining processes like turning. To address the machining difficulties of WC-Co, electrical discharge turning (EDT) was proposed. The rotational speed in EDT is a key factor influencing the machining results; however, conflicting reports exist about its impact on the EDT process. Therefore, the effect of rotational speed on three different machining regimes, including roughing, semi-finishing, and finishing, was investigated using energy-dispersive X-ray spectroscopy (EDX), SEM, and roughness tests. Additionally, elemental mapping was applied to illustrate the element distribution on the machined surface. The results indicated that increasing the rotational speed led to a 10% to 17% decrease in the recast layer thickness and a 14% to 54% reduction in the surface roughness (Ra). [ABSTRACT FROM AUTHOR]

The main objective of research work to investigates the effects of various process parameters on the material removal rate, kerf width, surface roughness and the dimensional accuracy of Inconel 718 workpiece subjected to wire electrical discharge machining (WEDM). The input parameters of this study were wire speed, wire tension and flushing rate. The individual as well as interacting effect of process parameters on surface roughness, kerf width and dimensional accuracy. It was found that, in order to minimize the diameter error for circular cuts, the flushing rate, wire speed and wire tension should all be held at maximum values. The wire tension and wire speed both exhibited an insignificant effect on the surface roughness. The dimensional accuracy of the machined holes decreased with increasing wire tension and in order to achieve maximum material removal rate, wire tension and wire speed must be around 1400–1600 gf and at 8 m/min respectively. The flushing rates over 5 L/min had a negligible effect on the material removal rate. The highest kerf width and material removal rate were obtained at medium values of wire tension (1400–1600 gf) and wire speed (8 m/min). The lowest diameter error is achieved in a combination of maximum flushing rate, wire speed and wire tension. Factors such as circularity, cylindricity and hole diameter were closely examined in order to gain a deeper understanding of their influence on dimensional accuracy. [ABSTRACT FROM AUTHOR]

The exploration of Electrical Discharge Machining (EDM) with coated electrodes represents a relatively novel research avenue, thereby yielding limited published research outcomes. The choice of coating material plays a pivotal role in the EDM machining process, and alterations in coating materials can directly influence the adjustment of technological parameters in EDM. Consequently, research dedicated to optimizing these technological parameters for EDM employing coated electrodes is of paramount importance, and it promises to advance the practical implementation of this cutting-edge technique. In this study, we systematically investigate the technological parameters for EDM employing a copper-coated aluminum electrode in the context of Ti-6Al-4V machining. Our research outcomes are framed within a multi-objective optimization paradigm, with a focus on Material Removal Rate (MRR) and Surface Roughness (SR) as vital quality indicators. To address the intricate multi-objective optimization challenge, we have harnessed the combined power of the Taguchi methodology and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The amalgamation of these techniques enables us to navigate the complexities of EDM parameter optimization effectively. Our findings reveal that the most favorable process parameters entail a configuration of U=40V, I=40 A, Ton=1000μs, resulting in an MRR of 0.028mg/min and an SR of 7.56μm. These optimized parameters exemplify a substantial enhancement in machining efficiency and surface quality when utilizing coated electrodes. Moreover, our study scrutinizes the quality of the machined surface under optimal conditions with coated electrodes. We employ the TOPSIS method as a proficient solution for this endeavor, offering a straightforward approach to this intricate calculation process. [ABSTRACT FROM AUTHOR]

This study investigates the performance of deep cryogenically treated brass (CuZn25Al5) electrodes in the die-sink EDM process. Two different cryogenic treatment durations, 6 h and 12 h, were applied to 8 mm diameter electrodes, and their effects were compared to untreated electrodes. The machining tests were conducted under moderate and aggressive conditions. In the machining tests, the 6-h cryo-treated electrode exhibited a 16.8% increase in material removal rate (MRR) under moderate conditions and a 19.7% increase under aggressive conditions compared to the reference electrode. The 12-h cryo-treated electrode showed similar MRR values to the reference electrode but improved tool wear resistance by 9.4% under moderate conditions. The kerf angle was minimized, indicating better hole verticality, in the 6-h cryo-treated electrode group. The improvement in machining performance was attributed to the enhancement in electrical conductivity of the electrodes, which increased by 28% for the 6-h cryo-treated electrode and 20% for the 12-h cryo-treated electrode. X-ray diffraction (XRD) analysis revealed shifts in peak positions and possible phase transformations due to cryogenic treatment. Surface roughness measurements showed improved surface conditions in the cryo-treated electrodes under aggressive conditions. The results indicate that cryogenic treatment enhances MRR, reduces tool wear, and improves surface quality in die-sink EDM. These improvements are attributed to increased electrical conductivity and changes in the internal structure of the brass electrode. [ABSTRACT FROM AUTHOR]

Micro electrical discharge drilling (ED-drilling) is a machining method used to make micro holes in hard-to-cut materials. The RC-discharge generator is often used because it creates a short and strong discharge spark. However, this method has issues such as current oscillation between tool electrode and workpiece, causing polarity changes that increase tool wear, and a low material removal rate due to long spark delay time. Furthermore, micro ED-drilling results in a large taper angle due to second discharge sparks created by debris in the narrow gap. To address these issues, the effect of adding graphite powder to the working fluid was studied. The graphite powder in kerosene created a bridge effect that reduced tool wear and taper angle, while improving MRR and surface roughness. The electrical conditions were not changed, and the machining process was improved by only altering the working fluid without modifying the existing system. [ABSTRACT FROM AUTHOR]

Electrical discharge drilling of blind holes has been a challenging task due to the inherent difficulties in removing debris from the discharging gap. This paper investigates the working mechanism and effects of new stepped electrodes which are used in conjunction with injection flushing in drilling deep blind holes. A series of theoretical simulations and comparative experiments were conducted using cylindrical electrodes and two types of stepped electrodes. Pulse waveforms were captured to analyse the discharge status. Surface topography and machining quality were analysed using scanning electron microscope (SEM) images. The machining performance was evaluated by studying the material removal rate (MRR) and tool wear ratio (TWR). Experiment results show that internal flushing caused the debris to circulate in the machining zone and led to abnormal discharges, disrupting the formation of the plasma channel. The MRR was increased by 75% and 82% when using cylindrical electrodes with pressures of 120 psi and 40 psi, respectively. In contrast, the MRR with injection flushing was about 80% of that without injection flushing when using stepped electrodes. Regardless of the type of electrode, the application of injection flushing resulted in the increase in the maximum effective machining depth. [ABSTRACT FROM AUTHOR]

The demand for carbon fiber reinforced plastics (CFRP), classified as functional resins, has increased for micromachined products that are manufactured using lathes and used in the medical field. However, the problems with machining CFRP include the occurrence of burrs and deterioration of the finished dimensions owing to the significant tool wear caused by the carbon fiber. To turn CFRP and maintain high dimensional accuracy, the authors proposed a novel combination of conventional turning and electrical discharge-assisted turning (EDAT). In this study, the capability to control the machinability of EDAT under low-voltage conditions was experimentally investigated. The relationship between the discharge voltage, frequency, and depth of discharge influence of the carbon fibers was clarified. [ABSTRACT FROM AUTHOR]

Conventional machining of Ti6Al4V parts with complex shapes is often a tough task due to its low thermal conductivity and its high strength-to-density ratio. Thus, electrical discharge machining (EDM) comes as a better alternative that surpasses these manufacturing difficulties. In this work, a coupled thermo-mechanical model was built using the FEM software package Abaqus to estimate the sublayers final microstructure of a Ti6Al4V machined workpiece. The proposed numerical model aims to replicate a single-spark electrical discharge machining process. Phase transformations kinetic laws of the biphasic titanium alloy and heat flux distribution subroutines were implemented. XRD analysis, metallurgical sample preparation and optical microscope imaging were performed to investigate electrical discharge machining effects on Ti6Al4V part and to validate the numerical proposed model. Close agreement was found between experimental investigation results and numerical outcomes. The numerical model considers the remaining amount of 10% of β phase redeposited at the end of the discharge phase additionally to the martensitic phase α'. [ABSTRACT FROM AUTHOR]

In this work, fuzzy model was developed that predicts response parameters and surface properties of an electrical discharge machined Zircaloy-2. Taguchi L18 mixed design was used to perform the experiments using different process parameters (polarity, pulse-on-time, pulse-off-time, tool electrode material, and peak current). Material removal rate (MRR) and tool wear rate (TWR) were chosen as machining response parameters, whereas number of particles (NoP) and the percentage particle area (PPA) for surface properties of EDMed surface. Digital image processing tool was used to evaluate the surface properties. Fuzzy-Sugeno (FS)-model was developed to predict MRR, TWR, NoP, and PPA. Model accuracy was found to be 94% for MRR and TWR, and 92% for NoP and PPA. Maximum MRR 1.53 × 10−3 mm3/min found when machining was performed using graphite tool with negative polarity. Fuzzy Sugeno-GRA method was successfully implemented to predict optimal response corresponding to high value of GRG. [ABSTRACT FROM AUTHOR]

A global manufacturing community is dedicatedly striving to implement the concept of NetZero in precision cutting of difficult-to-machine materials, specifically, Inconel 617 (IN617) with due consideration to environmental protocols. The fast strain hardening issue of the said alloy during conventional processing rationalizes the application of electric discharge machining (EDM). However, EDM has been criticized for its high energy consumption and limited cutting efficiency. Moreover, conventional dielectric (kerosene) employed in EDM has drastic environmental and operator health concerns. To address the abovementioned issues, waste cooking oil (WCO) has been employed in this study which enhances the reusability of resources and minimizes the cost of the dielectric. Making the process sustainable is imperative along with continuously escalating scarcity of engineering resources. Therefore, the potential of shallow and deep cryogenically treated electrodes (SCT and DCT) has been comprehensively examined against nanofilled WCO to achieve the aforementioned objective. Three different concentrations of powder (Cp) and surfactant (Cs) to uplift the machining responses are investigated through a detailed parametric experimental design. Core machining factors such as material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) are examined through optical and electron microscopy studies and 3D surface profilometry. Hereafter, machining factors are modelled using the artificial neural network (ANN) technique. An exceptional improvement of 80%, 25.3%, and 75.16% has been achieved in MRR, SR, and SEC respectively using nanopowder-mixed WCO against SCT brass compared to the responses' values obtained against conventionally used kerosene. Furthermore, compared to kerosene, the maximum CO2 reduction of 79.97 ± 11.2% is achieved with WCO. [ABSTRACT FROM AUTHOR]

In the electric discharge machining process, the material is separated from the surface of the work piece by an electric spark, and in the presence of the dielectric material and tool electrode, changes are made on the surface of the work piece. In this project, we investigated the effect of dielectric material and brass tool electrode diffusion on the surface of carbon steel workpiece by means of quantmetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The effect of the parameters such as electric current intensity (I), pulse on time (ton), pulse off time (toff) and machining time (τ) on the composition of work peace, microstructure and electrochemical corrosion of machined work peace, were investigated. The results of quantmetric analysis showed that with the increase of machining parameters, the amount of diffused copper (from brass tool electrode) and carbon (from pyrolysis of flashing dielectric material) on the surface of machined carbon steel was increased. X-ray diffraction results confirmed that the formation of different phases such as Fe1.92C0.08, Cu4, Cu2 and Fe2 on the surface of workpiece, which was accordance with the quantmetric results. Electrochemical studies showed that during the EDM process, the electrochemical corrosion resistance was increased. [ABSTRACT FROM AUTHOR]

The use of additive technology—in particular, selective laser melting (SLM)—in producing wire electrodes for electrical discharge machining is considered. By this means it is possible to produce electrodes of high precision and complex geometry, with distinctive properties. In addition, the results of topological optimization in electrode design are presented. Topological optimization permits the production of wire electrodes that are more efficient in the given operating conditions. It is shown that, on the basis of additive technology and optimized electrode geometry with internal supply channels for dielectric liquid, the removal of sludge from the machining area may be improved, with consequent stabilization of the machining process. [ABSTRACT FROM AUTHOR]

In the electric discharge machining process, the material is separated from the surface of the work piece by an electric spark, and in the presence of the dielectric material and tool electrode, changes are made on the surface of the work piece. In this project, we investigated the effect of dielectric material and brass tool electrode diffusion on the surface of carbon steel workpiece by means of quantmetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The effect of the parameters such as electric current intensity (I), pulse on time (ton), pulse off time (toff) and machining time (τ) on the composition of work peace, microstructure and electrochemical corrosion of machined work peace, were investigated. The results of quantmetric analysis showed that with the increase of machining parameters, the amount of diffused copper (from brass tool electrode) and carbon (from pyrolysis of flashing dielectric material) on the surface of machined carbon steel was increased. X-ray diffraction results confirmed that the formation of different phases such as Fe1.92C0.08, Cu4, Cu2 and Fe2 on the surface of workpiece, which was accordance with the quantmetric results. Electrochemical studies showed that during the EDM process, the electrochemical corrosion resistance was increased.

Electrode wear during electrical discharge machining (EDM) is inevitable, and tool electrodes of different materials exhibit different wear rates. Unlike a single-material tool electrode, for a laminated electrode consisting of various material foils (LE-VMF), the components suffer from significantly different amounts of wear and also influence each other in EDM, however, the form and cause of the wear are not clear. Thus, the LE-VMFs including symmetric and asymmetric LE-VMFs were prepared and used in EDM in this paper. The wear of foils in LE-VMFs and their mutual influence during the EDM process were investigated through experiments. The wear forms of a single foil electrode and a foil of the same material in the LE-VMF were also compared. The experimental results show that copper foil with a lower wear rate had a protective effect on an adjacent brass foil with a larger wear rate in the LE-VMF, while the protective effect of the brass foil in the symmetric LE-VMF was larger than that in the asymmetric LE-VMF. The closer the distance from the copper foil, the stronger was the protection effect and the smaller was the wear. In addition, the working surface of the brass foil in the LE-VMF did not show any concavity-like wear in the middle region of its thickness after EDM, as was the case for the single brass foil electrode, even if the thickness of the brass foil was greater than 150 μm.

The present work focuses on the impact of expanded graphite (EG) nano-powder along with spark-on-duration (Ton) and spark-off-duration (Toff), and current as factors on increasing material removal rate (MRR), reduction of surface roughness (SR), tool wear rate (TWR), dimensional deviation (DD), and surface defects for Ni55.8Ti. Taguchi’s design having 4 factors at 3 levels was employed to perform the experimental trials. ANOVA has successfully validated the developed regression equations. EDM factors of PC, Toff, current, and Toff were found to be the largest contributing factors with the involvement of 76.91 %, 38.40 %, 34.36 %, and 44.54 % for MRR, TWR, SR, and DD respectively. TLBO algorithm was used in the present work to tackle the conflicting situation and to optimize the response variables. The simultaneous optimization conducted through the Teaching-learning-based optimization technique has yielded optimal parameters setting of Ton at 7 µs, Toff at 5 µs, PC at 1.5 g/L, and current at 10 A by giving optimal response values at MRR of 42.82 mm3/min, TWR of 0.4039 mm3/min, SR of 3.71 µm, and DD of 92.65 µm. Lastly, Scanning electron microscopy was utilized to check EG nano-powder significance on the machined parts' surface morphology.

Understanding and optimizing mechanical manufacturing processes is essential for sustainable industrial development. Among unconventional machining methods, electrical discharge machining (EDM) distinguishes itself by its capability to remove material through successive electrical discharges submerged in a dielectric fluid. EDM encompasses intricate phenomena influenced by machine parameters, dielectric choice, and the materials involved. Unlike conventional machining, EDM operates with the tool electrode in close proximity to, but not in physical contact with, the workpiece, achieving material removal through localized overheating. This study focuses on monitoring EDM phenomena during the machining of AISI H13 steel, exploring variations in machining parameters and electrode materials (electrolytic copper and graphite). Acoustic emission (AE) signals and machine learning (ML) are employed for experimental characterization and data analysis. Spectral entropy is applied to AE signals, quantifying inherent signal uncertainty. The findings reveal remarkable accuracy (97.7%) and underscore the superior control achieved with graphite electrodes in managing machining phenomena compared to electrolytic copper electrodes. [ABSTRACT FROM AUTHOR]

When electric discharge machining (EDM) is used to process Al2O3-TiC ceramics, it is difficult to obtain an optimal production efficiency and tool wear rate. As the target demand of processing largely relies on the process parameters, it is pertinent to conduct an in-depth study on the process parameters. In this study, the effects of certain technological parameters on the properties of EDM Al2O3-TiC ceramic materials were assessed and a mixed 2–3 horizontal orthogonal test method was designed. The rules of machining polarity, inter-electrode voltage, peak current, gain, pulse frequency, pulse width, inter-electrode gap and electrode length loss, electrode profile loss, material removal rate were studied. The effect of process parameters on process performance was determined by range analysis. In addition, the analysis of variance revealed that machining polarity has a significant effect on the electrode loss while the electrode voltage and peak current significantly influenced the material removal rate. The optimal parameter combination was determined as negative machining polarity, 130 V inter-electrode voltage, 50 A peak current, 45 gain, 150 Hz pulse frequency, 1.0 μs pulse width, and 40 μs inter-electrode gap. [ABSTRACT FROM AUTHOR]

When utilizing electrical discharge machining (EDM) for processing, the processing efficiency and quality will be significantly impacted, if the electrocorrosion residues in the gap flow field cannot be discharged in time. Numerical simulation is considered an effective means to simulate the flow field of EDM gaps. Based on simulation, this study investigates the processing time, depth, current, and dielectric (kerosene, water, and sunflower seed oil), on the movement of electrocorrosion residues within the dielectric. The simulation results demonstrate that an increase in processing time, current, or depth leads to a decrease in the escape rate of corrosion residues from the discharge gap. Compared with kerosene and sunflower seed oil, water has a higher residue escape rate, but the actual processing effect is not ideal. The escape rate of sunflower seed oil at any time was higher than that of kerosene,the highest was higher than 25%, and the average was higher than 22.21%. Sunflower seed oil can be used as a renewable dielectric to replace kerosene. Subsequently, verification experiments are conducted based on simulation results that demonstrate that the discrete phase model (DPM) fluid simulation exhibits excellent coupling with actual processing conditions. [ABSTRACT FROM AUTHOR]

The present work focuses on the impact of expanded graphite (EG) nano-powder along with spark-on-duration (T on) and spark-off-duration (T off), and current as factors on increasing material removal rate (MRR), reduction of surface roughness (SR), tool wear rate (TWR), dimensional deviation (DD), and surface defects for Ni 55.8 Ti. Taguchi's design having 4 factors at 3 levels was employed to perform the experimental trials. ANOVA has successfully validated the developed regression equations. EDM factors of PC, T off , current, and T off were found to be the largest contributing factors with the involvement of 76.91 %, 38.40 %, 34.36 %, and 44.54 % for MRR, TWR, SR, and DD respectively. TLBO algorithm was used in the present work to tackle the conflicting situation and to optimize the response variables. The simultaneous optimization conducted through the Teaching-learning-based optimization technique has yielded optimal parameters setting of T on at 7 µs, T off at 5 µs, PC at 1.5 g/L, and current at 10 A by giving optimal response values at MRR of 42.82 mm3/min, TWR of 0.4039 mm3/min, SR of 3.71 µm, and DD of 92.65 µm. Lastly, Scanning electron microscopy was utilized to check EG nano-powder significance on the machined parts' surface morphology. [ABSTRACT FROM AUTHOR]

Surface formation in electrical discharge machining (EDM) involves melting, evaporation, re-solidification and crater overlapping. However, almost all existing models concerning surface formation in EDM only consider the thermal process and ignore hydrodynamic phenomena during machining. Herein, a novel three-dimensional thermo-hydraulic coupling model incorporating the arbitrary Lagrangian–Eulerian scheme was developed to address the above problem. The model comprehensively considered the surface deformation caused by melt flow, temperature-dependent material properties, phase changes and the effects of practical forces on melt pools to simulate surface formation on an anodic workpiece at a discharge current of 2 A. Simulation results demonstrate that during single-pulse discharge, molten material flowed radially to the crater periphery. The radial melt flow was driven by evaporation recoil pressure and thermocapillary force. The effect of evaporation recoil pressure on melt flow was gradually counteracted by that of surface tension after discharge ignition, and thermocapillary force became the dominant factor that maintained the existence of bulges around craters. During multiple discharges, the bulges generated by different discharges underwent superposition owing to the flow of molten material and subsequently formed surface peaks. The simulation results also provide the measurements of crater diameter, surface roughness and recast layer thickness, which are consistent with experimental results. The proposed modelling method can provide a useful reference for further investigations on surface integrity in EDM with minimal computing resource requirements. • A novel 3D thermo-hydraulic coupling surface formation model for EDM was proposed. • The effects of evaporation recoil pressure and thermocapillary force on melt pool dynamics in EDM were investigated. • Simulation results of multiple discharges show good consistency with experiment results concerning surface properties. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) and electrochemical machining (ECM) are two typical unconventional processing methods for fabricating difficult-to-cut materials. Surfaces machined by EDM generally contain recast layers, whereas ECM owns low machining accuracy. EDM–ECM hybrid machining can suppress their shortcomings and combine their advantages. The working fluid is vital to realizing the combination of EDM and ECM. Conventional EDM–ECM hybrid machining commonly adopts water-based fluid, which can meet the requirements of hybrid micro-, small-hole, and milling machining. However, water-based fluid hardly maintains the stable sinking EDM that possesses a relatively large machining area and a closed machining gap; thus, it is unsuitable for hybrid sinking machining. The lack of appropriate fluid seriously hinders the promotion and application of EDM–ECM hybrid sinking machining. Here, a novel bi-characteristic fluid water-in-oil (W/O) nanoemulsion that combines electrical insulation and conductive properties is proposed, and an electrical discharge and electrochemical hybrid sinking machining (EDCSM) using W/O nanoemulsion is developed. The composition parameters (salt concentration, water content) of the W/O nanoemulsion and electric parameters (open voltage, pulse frequency) are investigated. Material removal mechanisms are also discussed. Results show that the material removal mechanisms and the strength of EDM and ECM in EDCSM can be manipulated by adjusting the investigated crucial parameters. EDCSM using W/O nanoemulsion can achieve a high-quality machined surface and good machining accuracy, demonstrating its superiority and potential in the field of sinking machining. [ABSTRACT FROM AUTHOR]

The electrode is an important component of electrical discharge machining (EDM), playing an important role in machining efficiency, surface quality and geometric accuracy. In this work, a new method combining equal channel angular pressing (ECAP), deep cryogenic treatment (DCT) and aging treatment (AT) was proposed. The ultrafine-grained Cu-0.5%Cr electrode has high strength and high electrical conductivity through this process, so as to improve the machining characteristics in EDM. The surface roughness (Ra), the workpiece corner sharpness (WCS), and the electrode wear rate (EWR) were investigated. The results showed that the treatment of the electrode with 4 passes of ECAP + DCT (12h) + AT (550℃ × 1h) can reduce the EWR and WCS by 63.6% and 49.7%, respectively. It also contributed to the enhancement of electrical conductivity and microhardness of the Cu-0.5%Cr electrode by ECAP + DCT + AT. Meanwhile, it revealed that the processing of the Cu-0.5%Cr electrode resulted in the excellent machined surface quality (Ra was reduced by 53.5%) which was confirmed by the results of the scanning electron microscopy (SEM). The ultrafine-grained Cu-0.5%Cr electrode with an excellent combination of strength and electrical conductivity has an outstanding EDM performance. [ABSTRACT FROM AUTHOR]

Micro drilling using Electrical Discharge Machining (MD-EDM) has emerged as a prominent technique in precision manufacturing, offering the capability to create small and intricate holes. This study focuses on investigating the influence of input process parameters on nickel-based superalloy (Ni3 (Ti, Al)) material, while the electrode materials studied are copper, aluminum and tungsten, with varying electrode diameters of 0.4 mm, 0.5 mm and 0.6 mm. The research encompasses an L9-orthogonal array (L9-OA) in which the Machining Voltage, Peak Current (IP), Pulse off time (Poff) and Servo Standard Voltage (SVR) are varied. Three levels of Machining Voltage (4 volts, 6 volts and 8 volts) and IP are selected. Moreover, scanning electron microscope (SEM) imaging is employed to observe and analyze the morphological characteristics of the drilled holes. The experimental results reveal that the choice of electrode material and diameter significantly influences the SR of the drilled holes. Copper electrodes demonstrate the lowest SR, followed by tungsten and aluminum electrodes. Smaller electrode diameters result in improved surface finish due to reduced discharge energy concentration. Additionally, increasing the Machining Voltage leads to larger discharge energy and heat, resulting in increased SR. SEM imaging demonstrates distinct differences in hole morphology based on the electrode material and diameter, with copper electrodes producing cleaner and more precise holes with minimal recast layer formation compared to aluminum and tungsten electrodes. The influence of Machining Voltage is observed through the presence of craters and debris in higher voltage conditions. [ABSTRACT FROM AUTHOR]

High specific strength and good fatigue limit are the key properties to watch out during development of aerospace components. Aluminum composites are proven high specific strength materials especially graphene embedded composites worth a mention in this context. While, surface finish is an eminent parameter affecting fatigue strength of a component showcasing the importance of machining technique employed to transform a fabricated bulk into finished product. Current study, therefore emphasizes on electrical discharge machining (EDM) of aluminum composites embedded with graphene nanoplatelets (1.5 wt.%) fabricated through a hybrid approach of blending solid and liquid metallurgical routes. Further, mathematical and neurological forecast models are developed to individually predict the machining response variables namely surface roughness (SR), material removal rate (MRR) and tool wear rate (TWR). Among machining parameters current (I), pulse on-time (Ton), pulse off-time (Toff) and flushing pressure (P) considered; Ton is noted to greatly influence the surface quality of composite while TWR and MRR are affected by current during ANOVA analysis. On comparative understanding of forecast models, neurological models outperform quadratic non-linear mathematical models where accuracy of prediction achieved by developed artificial neural network (ANN) model is 96% for surface roughness. The error performance plots, error histograms and overall fit plots depict a marginal over-fit neurological model. However, significantly high coefficient of correlation (R) of 99% possessed by ANN model illustrates their potential in forecasting response parameters. [ABSTRACT FROM AUTHOR]