Electrical Discharge Machining Research Articles

Experimental investigation on optimizing wire-cut EDM process parameters of hybrid MMC(AA7475/ZrO2/Gr) using artificial neural network

Abstract Wire cut Electrical discharge machining (WCEDM) is a widely used method for machining complex shapes in advanced materials like metal matrix composites (MMCs) and hybrid metal matrix composites (HMMCs). To address these challenges, this study focusses on the wire-cut EDM (WCEDM) process of a workpiece made from zirconium dioxide and graphite-reinforced aluminium alloy 7475 with a molybdenum electrode. The effects of input process variables such as peak current (IP), pulse-on-time (TON), and flushing pressure (PF) on the output response features are investigated. These output responses include material removal rate (MRR), surface roughness (SR), and wire wear ratio (WWR). To optimise the process parameters, the Taguchi design technique is used. An artificial neural network (ANN) with a feed-forward back propagation architecture is utilised to find the best fit for the optimisation challenges. ANN predicted the results with an accuracy of 97.81% for MRR, 97.95 % for SR and 95.865% for WWR. The results reveal that the WCEDM of AA7475/ZrO2/Gr with a molybdenum electrode achieved minimal WWR and SR, while maximizing the MRR.

Taguchi optimization of Wire EDM process parameters for machining LM5 aluminium alloy.

LM5 alloy is suitable for metal castings for marine and aesthetic uses due to its admirable resistance to corrosion. In order to make intricate shapes in the LM5 alloy, this study intends to assess the impact of Wire Electric Discharge Machining process variables, like Pulse on Time (Ton), Pulse off Time (Toff), Gap Voltage (GV) and Wire Feed (WF) on responses like Material Removal Rate (MRR), Surface Roughness (SR), and Kerf Width (Kw). The LM5 aluminium alloy plate was produced through stir casting process. SEM, EDAX and XRD images confirm the LM5 Al alloy's microstructure and crystal structure. WEDM studies were conducted using design of experiments approach based on L9 orthogonal array and analysed using Taguchi's Signal to Noise Ratio (S/N) analysis. Pulse on Time has the greatest statistical effects on MRR (68.25%), SR (79.46%) and kerf (81.97%). In order to assess the surface integrity of the WEDM machined surfaces, the SEM study on the topography was conducted using the optimum surface roughness process variables: Ton 110 μs, Toff 50 μs, GV 40 V, and WF 9 m/min. SEM images show the recast layer and its thickness. The average absolute error for MRR is 1.69%, SR is 3.89% and kerf is 0.88%, based on mathematical (linear regression) models. The Taguchi's Signal to Noise ratio analysis is the most appropriate for single objective optimization of responses.

Processing of silicon carbide particulate reinforced aluminum alloy composites using rotary electrochemical discharge machining

ABSTRACT As a kind of metal matrix composites, silicon carbide particulate reinforced aluminum alloy composites (SiCp/Al) have been widely applied in numerous fields. However, it is still difficult to process this composite material with electrical discharge machining (EDM) at present. To address this problem, this study introduces a novel rotary electrochemical discharge – chemical composite machining (RECDM-CM) method. This method uses rotating electrodes and workpieces to improve the flushing effect of working medium and utilizes the electrolysis to reduce the recast layer thickness. The chemical reaction between sodium carbonate (Na2CO3) and aluminum oxide (Al2O3) at high temperatures is used to remove the non-conductive Al2O3 in this composite machining. Rotary electrochemical discharge – chemical composite machining is used to process silicon carbide particulate reinforced AA2009 aluminum alloy composites with the silicon carbide volume fraction of 55%. The experimental results reveal that the material removal rate (MRR) of rotary electrochemical discharge – chemical composite machining is 5.2 times that of rotary electrical discharge machining, and its relative tool wear rate (RTWR) is 37.42% of rotary electrical discharge machining. The recast layer thickness is reduced to less than 13 μm via rotary electrochemical discharge – chemical composite machining.

3D Binder-Free Mo@CoO Electrodes Directly Manufactured in One Step via Electric Discharge Machining for In-Plane Microsupercapacitor Application

Cobalt oxide-based in-plane microsupercapacitors (IPMSCs) stand out as a favorable choice for various applications in energy sources for the Internet of Things (IoT) and other microelectronic devices due to their abundant natural resources and high theoretical specific capacitance. However, the low electronic conductivity of cobalt oxide greatly hinders its further application in energy storage devices. Herein, a new manufacturing method of electric discharging machining (EDM), which is simple, safe, efficient, and environment-friendly, has been developed for synthesizing Mo-doped and oxygen-vacancy-enriched Co-CoO (Mo@Co-CoO) integrated microelectrodes for efficiently constructing Mo@Co-CoO IPMSCs with customized structures in a single step for the first time. The Mo@Co-CoO IPMSCs with three loops (IPMSCs3) exhibited a maximum areal capacitance of 30.4 mF cm−2 at 2 mV s−1. Moreover, the Mo@Co-CoO IPMSCs3 showed good capacitive behavior at a super-high scanning rate of 100 V s−1, which is around 500–1000 times higher than most reported CoO-based electrodes. It is important to note that the IPMSCs were fabricated using a one-step EDM process without any assistance of other material processing techniques, toxic chemicals, low conductivity binders, exceptional current collectors, and conductive fillers. This novel fabrication method developed in this research opens a new avenue to simplify material synthesis, providing a novel way for realizing intelligent, digital, and green manufacturing of various metal oxide materials, microelectrodes, and microdevices.

Experimental study of the effects of the ultrasonic peening treatment on residual stress, surface hardness, and hardness depth of parts cut with wire EDM

Experimental study of the effects of the ultrasonic peening treatment on residual stress, surface hardness, and hardness depth of parts cut with wire EDM

Comparative Studies on Performance of 3D-Printed Metal Electrode and Conventional Electrode in Electrical discharge Machining on Ti-alloy

Comparative Studies on Performance of 3D-Printed Metal Electrode and Conventional Electrode in Electrical discharge Machining on Ti-alloy

Influence of different wire materials on the machining of Albromet W130 by WEDM

Wire Electrical Discharge Machining (WEDM) is an unconventional machining technology, widely spread in different sectors of many industries. The machining uses periodically repeating electrical impulses, which allows all materials with at least a minimum electrical conductivity to be machined. The machining tool is a thin wire that can be made of many different materials. Wire electrode material requirements vary from industry to industry. This study aimed to increase the efficiency of WEDM through an analysis of the influence of the type of wire material on the machining of Albromet W130 copper alloy. The analysis comprised a molybdenum, brass and a copper wire of a 0.25 mm diameter and a Box-Behnken design of experiment totalling 42 rounds. The design of experiment results analysis covered cutting speed, machined surfaces’ topography and morphology, and the subsurface layer condition. Furthermore, an analysis of the wire electrodes used in the experiment was carried out. The highest cutting speed was achieved using a copper wire and the lowest R a values were achieved in samples machined with a molybdenum wire.

Parametric analysis of electrical discharge machining on AA6061 with a WC–Cu composite electrode

The AA6061 aluminium alloy surface characteristics presented in this study were obtained after it was machined using die sinking electro discharge machining (EDM) with a composite electrode developed through powder metallurgy. Machining was performed using negative polarity. In order to obtain optimum material removal rate (MRR) and surface roughness (SR), the research has been carried out, and EDM parameters like voltage, current and pulse on time were optimized using the response surface methodology that integrates the central composite design. The parameter interaction effects on EDM machined surface characteristics were studied with the aid of ANOVA. It was determined from model that the regression for MRR and SR were 98.6% and 98.3% respectively, means empirical model is considered sufficient. It was observed that increased MRR and SR were observed in the condition of increased current, but MRR and SR decreased at increased voltage and pulse on time. This could be due to strengthened ionization temperature that increased MRR with acceptable SR. The microstructure of the machine was assessed using microscopic evaluation. The increased current contributed to the formation of a recast layer and debris which hinders the machining process and reduces MRR. The experimental results show that the maximum MRR of 0.087 mg/min and minimum SR of 1.893 µm were achieved. Additionally, the use of WC–Cu composite electrodes led to an increase in hardness from 65 HV to 78 HV in the machined region. It is concluded that WC–Cu composite electrodes typically result in higher hardness, improved MRR and better SR for the AA6061 alloy compared to conventional Cu electrodes.

Electro-discharge deposition of zinc powder on 316L stainless steel: Synthesis, deposition rate, and characterization

This study investigated the potential of powder-mixed electrical discharge machining (PM-EDM) to deposit metallic powder, specifically zinc powder, on 316L stainless steel (316L SS). This study aimed to evaluate the effect of zinc (Zn) deposition on 316L SS for oil and gas application. Minitab 19 software was employed to design the experiments using screening DOE option and to analyse and model the results through screening response optimiser from Minitab 19 software. Surface morphology, microstructure and coating thickness were examined through field-emission scanning electron microscopy (FESEM) and scanning electron microscope (SEM). The results suggested an improvement in the coating thickness with an increase in powder concentration and discharge current. An average coating thickness of 91.47 μm was achieved in samples fabricated at 20 g/L powder concentration. X-ray diffraction analysis revealed the formation of hard carbides, such as Cr3C2 and TiC, on the PM-EDMed 316L SS surface. Further characterisation through energy-dispersive X-ray spectroscopy confirmed the deposition of both the tool electrode and Zn powder particles. The adhesion test confirmed that all specimens failed under 100% adhesive failure. The hydrophobicity analysis confirmed that the coated surfaces are hydrophobic. Significant improvement has been established for microhardness, wear resistance and corrosion performance. Screening results revealed that discharge current, pulse-on time, and powder concentration were the most significant parameters. The average predicted errors of 2.055%, 6.782%, and 2.396% for material deposition rate, tool wear rate, and surface roughness were achieved, respectively. These affirmed the excellent reproducibility of the model developed. This study presents a methodology for the formation of carbide- and oxide-based coatings specifically for oil and gas applications (flanges and connectors).

The Influence of the Gap Phenomenon on the Occurrence of Consecutive Discharges in WEDM Through High-Speed Video Camera Observation

The Wire Electrical Discharge Machining (WEDM) process is an accurate method for manufacturing high-added-value components for industry. Continuous developments in the process have resulted in specialized machines used in sectors such as aerospace and biomedical engineering. However, some fundamental aspects of the discharge process remain unresolved. This work aims to study the influence of discharge location and bubble expansion on the occurrence of subsequent discharges. A high-speed video camera observation system was constructed to capture images of each discharge. From the acquired images, an algorithm was devised to determine the discharge location based on grayscale analysis. Moreover, the voltage and current waveforms of the discharges and the framing signals of the high-speed video camera were then obtained using an oscilloscope. Synchronizing the observation images and signals allowed for calculating the delay time for each single discharge. The results indicate that most of the discharges occurred near the boundary of the bubble and during bubble expansion. This finding has been observed for a variety of machining conditions and can be explained by the effect of the debris particles concentrated at the bubble boundary. This study provides useful information for better understanding the discharge process in WEDM.

Machining performance analysis of wire-EDM for machining of titanium alloy using multi-objective optimization and machine learning approach

This study investigates the multi-objective optimization of process parameters in wire electrical discharge machining (WEDM) using titanium alloy grade 5 and zinc-coated brass microwire. The novelty lies in the comprehensive investigation of the effects of varying pulse on time (Ton), wire tension (WT), and wire feed rate (WF) on output responses, including surface roughness (SR), surface crack density (SCD), corner diameter (CD), and kerf width (KW). The Box-Behnken design, a sophisticated response surface methodology (RSM) technique, is employed to efficiently explore the complex relationships and interdependencies between these input and output parameters. The study's novel approach incorporates machine learning algorithms, including decision tree, light gradient boosting machine (LightGBM) and random forest, to predict the characteristics of the laser-cut components based on the input parameters. The contour plots generated provide valuable insights into the underlying patterns and associations between input and output features, aiding in the understanding of the WEDM process. The results reveal that the optimized values for SR, SCD, CD, and KW are obtained at specific machining conditions: Ton of 10 μs, WF of 3.79 m/min, and WT of 8 gf. Among the machine learning algorithms employed, random forest outperforms the others in predicting KW, SR, SCD and CD, exhibiting significantly lower mean squared error (MSE) and mean absolute error (MAE) values. This study contributes to the field of WEDM by providing a comprehensive analysis, incorporating advanced experimental design techniques and machine learning algorithms, which can aid in process optimization and quality control in manufacturing applications.

A study on the machinability of DMLS In718 alloy using an electro-spark machining process

ABSTRACT The direct metal laser sintering process is used to develop the nickel base superalloy DMLS In718 for the experimentation. The DMLS In718 alloy is evaluated to ensure the metallurgical qualities and mechanical properties. Microstructure of the DMLS In718 alloy is anisotropic in nature and the hatch bands are clear to infer. The hardness of the DMLS In718 is 275 Hv which equivalent to the commercially available inconel718 material. the mechanical strength and density of the DMLS In718 alloy is justifiable to the commercial material. The machining studies are performed with electro spark erosion process to report on surface quality, kerf taper and material removal rate. the minimum pulse on time has produced a fine surface quality compared to the maximum process condition. The surface topography in terms of oxide scale and recast layers are identified during to inefficient process conditions. This paper was an opportunity to deliberate the machining quality of the wire electro spark process.

Green dielectric exploration: spectrographic analysis and technical feasibility of vegetable oils in EDM via PIV, TOPSIS, and MOORA evaluation methods

Achieving a sustainable dielectric medium for Electrical Discharge Machining (EDM) has now drawn the attention of researchers and industries alike. Increased awareness among the Government and NGOs paved the way for the manufacturing industries to move towards a green environment and sustainability in the production process. To search for sustainable dielectric, 5 different types of oils viz., Jatropha, coconut, groundnut, sunflower, and EDM 4 oil (conventional oil) are experimented in this paper and revealed its suitability of potential replacement for the conventional dielectric. The properties such as viscosity, density, flash point, electrical conductivity, and BDV (Break down Voltage) are tested as per the standards. Since the number of output response is more than, Multi Attribute Decision Making (MADM) algorithms namely PIV, TOPSIS, and MOORA are used for the ranking and optimization. Entropy weight method is adopted to endow criteria weight to each of the MADM techniques. Jatropha oil has been ascertained to be rank 1 followed by groundnut, coconut, sunflower, and EDM 4 oil. Subsequently, the Gas Chromatography & Mass Spectrometry (GC–MS) analysis has revealed the quantitative constituents present in Jatropha as well as remaining oils. Furthermore GC–MS analysis reports that the retention time of Jatropha (43.042 min) is relatively longer than other oils except coconut oil, to release Ricinoleic acids. Groundnut and EDM 4 oils took relatively less retention time to release the alkanes. Machining performance was also conducted with the obtained dielectric and compared with conventional type oil (EDM 4 oil).

Low temperature machining advantages for sintered NdFeB magnets: A comparative experimental study of WAWJ with laser and WEDM

Sintered NdFeB magnets exhibit excellent magnetic properties and high reliability, making them widely used in fields such as new energy vehicles and electronic communications. However, NdFeB magnets have a low Curie temperature and poor thermal stability. Common machining methods such as laser cutting and EDM (Electrical Discharge Machining) often involve cutting temperatures in the hundreds or even thousands of degrees Celsius, leading to defects such as melting and cracks on the magnet surface. These defects degrade the surface quality and magnetic properties of the magnet. To avoid thermal damage to the magnet during processing, WAWJ (Wet Abrasive Waterjet) cutting was employed on sintered NdFeB. Experimental results indicate that at an ambient temperature of 4.5 °C, the maximum cutting temperature remains below 50 °C, with an average cutting temperature below 25 °C. No heat-affected zones or oxidation layers are exhibited on the cutting surface of the magnet. Jet pressure is identified as the primary factor influencing the maximum cutting temperature, accounting for 96.13 %. With jet pressure increasing from 200 MPa to 280 MPa, the maximum cutting temperature rises from 38.7 °C to 47.9 °C. Furthermore, to validate the necessity of low-temperature cutting for NdFeB magnets, WEDM (Wire Electrical Discharge Machining) and laser cutting were employed on sintered NdFeB magnets. The cutting surfaces of both methods exhibit defects such as cracks, craters, and melting. Compared to the original magnet surface, no significant changes in elemental content were observed on the WAWJ-cut surface. Under high-temperature conditions, the oxidation rate increased, leading to a 18.9 % and 19.8 % increase in oxygen content on the WEDM and laser machined surfaces, respectively. Some neodymium (Nd) and iron (Fe) elements exist in the form of oxides such as FeO and Nd2O3, resulting in loss of magnetism. Moreover, the presence of oxides reduces the continuity of magnetic phases, adversely affecting the magnetic properties of the magnet.

Comparative Analysis of Simultaneous Electrochemical and Electrodischarge Machining Process

Abstract Recent advances have established electrochemical discharge machining (ECDM) as an effective alternative to electrical discharge machining (EDM) for producing microholes in conductive materials. However, ECDM leaves nonuniform layers, including recast layers and heat-affected zones, rendering it unsuitable for materials vital to aerospace, defence, and biomedical applications. To address this issue, the present work investigates a novel electrochemical machining (ECM)-based frugal engineering process known as simultaneous electrochemical and electrodischarge machining (SECEDM) for microhole fabrication. To evaluate the process effectiveness, the machining results of the SECEDM process were compared with ECDM, EDM, and ECM. The obtained results present the fundamental distinction between the process mechanism of SECEDM and ECDM. SECEDM has been reported to produce microholes with improved machined surfaces characterized by their freedom from recast layer and ECDM-induced defects. Moreover, SECEDM facilitated meticulously controlled high-speed anodic dissolution of work material, surpassing the material removal rate (MRR) achieved through ultrasonic-assisted ECDM (U-ECDM), ECM, and EDM processes by 2.67, 4.2, and 6.2 times, respectively. Furthermore, the substantial 67.72% and 68.82% reduction in the average machined hole diameter than ECM and U-ECDM, respectively, with a noteworthy 13.69% enhancement in average roundness error achieved while maintaining the repeatability accuracy with an accuracy range within ±0.009 mm through SECEDM process underscore SECEDM's accuracy and repeatability. In addition, lower surface roughness by 31.6% and 68% compared to ECM and EDM, along with reduced carbon and oxygen content as examined through energy dispersive X-ray (EDX) analysis, signifies the SECEDM process efficiency in microfabrication.

Tool wear prediction in broaching based on tool geometry

Abstract The aircraft engine is a safety-critical part of an aircraft. Constructive modifications resulting in ecological and economic improvements of the engine lead to necessary changes in manufacturing processes. The turbine discs in the low-pressure section are made of temperature resistant nickel-based superalloys. For the connection of the turbine blades with the disc, fir-tree slots are machined by broaching. The broaching process achieves high geometrical accuracy as well as process reliable rim zone properties. Alternative manufacturing processes such as milling or wire electrical discharge machining are still the subject of research in many applications and do not yet achieve the required process reliability. Especially in finishing operations, tool geometry is complex. In previous research work, the local rake angle and, as a result, the acting cutting force were determined analytically and empirically. Based on these results, the relationship between tool geometry, cutting force, and tool wear will be investigated in this work to enable a cutting length dependent prediction of tool wear. The aim of this work is a model-based prediction of tool wear for a given cutting length and a previously unknown tool geometry. For this purpose, a method was developed to predict tool wear using empirical test data as well as internal machine data. With the results of this work, it is not only possible to identify critical points on newly developed broaching tools by maxima of the cutting force, but also to predict wear locally, depending on the cutting length.

Determination of the Optimum Conditions for Machining NiTi Shape Memory Alloys by Electrical Discharge Machining

Determination of the Optimum Conditions for Machining NiTi Shape Memory Alloys by Electrical Discharge Machining

Enhancing of Material Removal Rate and Surface Roughness in Wire EDM Process using Grey Relational Analysis

Enhancing of Material Removal Rate and Surface Roughness in Wire EDM Process using Grey Relational Analysis

Enhanced machining of Al 10%SiCmicro 1%SiCnano hybrid composite using rotary tool rotary workpiece EDM with bio dielectrics and treated tools

A sustainable approach was proposed to address environmental pollution, carbon footprint and economic efficiency challenges in Electrical Discharge Machining (EDM). This approach involved the use of Bio-dielectric such as biodiesel and Bio fuel (distilled water with 10% ethanol). The EDM process performance was further optimized by experimenting with both electrodes’ rotation (i.e., in same direction, opposite direction, no rotation) and the use of treated tools (no treatment, heat treatment, cryogenic treatment). Biodiesel as a bio-dielectric showed promise by delivering the highest Material Removal Rate (MRR) and the lowest Tool Wear Rate (TWR). Bio-fuel (distilled water with 10% ethanol) resulted in the lowest Surface Roughness (SR) and cleaner machined surface with least carbon deposition. Additionally, electrode rotation improved flushing and enhanced performance parameters, with opposite direction rotation yielding the highest MRR and the lowest SR. However, no rotation of electrodes resulted in the lowest TWR. The use of treated tools, specifically heat-treated and cryogenically treated tools, also improved performance and reduced energy consumption, with cryogenic treatment providing the highest MRR, heat treatment giving least SR, and no treatment providing least TWR. Certain interactions between factors significantly impacted performance parameters. Grey relational analysis revealed that using distilled water with 10% ethanol as a dielectric, employing cryogenically treated copper tools, and having no rotation of both electrodes yielded the best performance parameters.

Assessment of Wire Offset While Machining EN-24 on WEDM

Wire offset is the dimensional shift that is experienced while machining a job on Wire-EDM machine. This modeling of wire offset during machining of EN-24 (EN is Euro Norm) was performed implementing Response Surface Methodology (RSM). Factors under consideration are peak current, on duration and off duration of pulse. Scanning Electron Microscopy was later performed for measurement of dimensional shift experienced under various machining conditions. The difference of programmed width and actual width obtained revealed the wire offset of the machined specimen. The tests revealed that Wire-EDM (Wire-Electro Discharge Machine) variables and Wire Offset can be modelled using Quadratic equations. ANOVA (Analysis of Variance) depicted that quadratic term of peak current is crucial parameter for Wire offset trailed by off duration. Keeping medium level of electrical parameters will lead to lower wire offset. Further model validation was performed and the residual error for Wire Offset was found to be 2.43% which suggest the competence of the present model.