Conventional Copper Electrodes Research Articles

Multi-Channel Electrical Discharge Machining of Ti-6Al-4V Enabled by Semiconductor Potential Differences

Titanium alloys are difficult to machine using conventional metal cutting methods due to their low thermal conductivity and high chemical reactivity. This study explores the new multi-channel discharge machining of Ti-6Al-4V using silicon electrodes, leveraging their internal resistivity to generate potential differences for multi-channel discharges. To investigate the underlying machining mechanism, the equivalent circuit model was developed and a theoretical simulation was carried out. Comparative experiments with silicon and conventional copper electrodes under identical parameters were also conducted to analyze discharge waveforms, material removal rate, surface quality, and heat-affected zones (HAZ). The results demonstrate that the bulk resistance of silicon is the main mechanism for generating multi-channel discharges. This process efficiently disperses the discharge energy of the single discharge pulse, resulting in smaller craters, smoother machined surfaces, and shallower recast layers and HAZ.

Metal-free flexible triboelectric nanogenerator based on bifunctional carbon fiber for mechanical energy harvesting and human activity monitoring

Conductive electrodes in triboelectric nanogenerators (TENGs) typically use metal-based materials. However, such devices have limited flexibility and challenges in humid environments. To overcome this issue, we present a metal-free flexible TENG made from bifunctional carbon fiber paper that serves as both a conductive electrode and an efficient tribo-positive friction layer. The electrical performance of carbon fiber paper-based TENG (CFP-TENG) at 3 Hz demonstrated a peak-to-peak voltage of 109.1 V, a current of 10.8 μA, and a power density of ∼ 0.093 W/m2 at 7 MΩ external resistance. A 20 µF capacitor is also charged, and 38 light-emitting diodes (LEDs) arranged in the letter 'DGU' can be lighted. The CFP-TENG device's high flexibility allows it to sustain 12,000 repeated mechanical contact-separation cycles and fold, twist, and roll the device without degrading performance. In addition, the hydrophobic characteristic of carbon fiber ensures the improved moisture resistance of the CFP-TENG device compared to conventional copper electrodes. Furthermore, the CFP-TENG is successfully integrated into various human joints as a self-powered motion sensor for tracking real-time human activity monitoring, including finger motion detection, arm motion, walking, and running activities. A metal-free TENG based on bifunctional carbon fibers paves the way for energy- harvesting solutions and self-powered biomedical sensors.

Multi-channel electrical discharge machining of titanium alloy Ti-6Al-4V with semiconductor electrodes

Titanium alloys are extensively used in aerospace and medical engineering owing to their exceptional mechanical properties and biocompatibility. For a long time, the low thermal conductivity of titanium alloys has made them difficult to machine with conventional approaches. Electrical discharge machining (EDM) is a nonconventional method for machining difficult-to-cut materials. However, it is not possible to achieve high-quality surface finish while simultaneously maintain high machining efficiency. This paper introduced a new EDM approach to obtain high surface quality in machining titanium alloy Ti-6Al-4V with discrete semiconductor electrodes by utilising a new multi-channel discharge principle to disperse the discharge energy. To explore the dissimilarities in discharge characteristics between semiconductor electrodes and traditional copper electrodes, continuous discharge waveforms of both electrodes were compared. Through modelling the discharge equivalent circuit and analysing workpiece surface using scanning electron microscopy (SEM), it was discovered that, due to the unique electrical properties of the semiconductor, it is possible for semiconductor electrodes to form multiple discharge channels. The outcomes reveal that the utilization of semiconductor electrodes can disperse discharge energy and enhance surface quality without sacrificing material removal rate compared to the use of conventional copper electrodes.

Machinability of SUPERNI-800 during PMEDM using the Taguchi method

Abstract EDM is the most popular machining method used in industry to machine hard metals and alloys and many researchers try to explore the applications of EDM process. They are trying to optimize the machining characteristics of difficult to machine materials from the literature reviewed, it is observed that considerable research work has been done on various aspects of electrical discharge machining and abrasive EDM of Inconel 718 and Titanium-based alloy. But less literature is available in the study EDM of Superni-800 is a versatile alloy that is widely used for nuclear industries, petrochemical industries, furnace equipment, etc. There is a need to investigate the machining of this material with different powders by varying different machining parameters such. In the current test study, blind holes were machined using BM-processed copper-titanium electrodes and a conventional copper electrode during the discharge of the Superni-800. The test design and variation analysis were implemented to understand the effects, contribution, importance, and optimal mechanical configuration, i.e. polarity, peak current, of the process investigation., Separation voltage in electrode type, pulse time, and material removal rate (MRR) and wear rate (WR). Significant parameters affecting the decisiveness of the machine were explored and the optimal size of the combination of machine parameters for MRR and WR was determined. A K-D powder metal has been found to give higher MRR and WR with a processed electrode, resulting in better mechanical performance than the Superni-800. The results were verified by a confirmatory test.

Tubular hollow fibre electrodes for CO2 reduction made from copper aluminum alloy with drastically increased intrinsic porosity

Electrochemical reduction of CO2 to higher-order hydrocarbon products offers a significant contribution to the challenge of a circular economy. In the pursuit of better copper metal catalyst, it was early on realized that increasing productivity of copper catalysts systems is reliant on high surface area per volume. Tubular gas diffusion electrodes offer such properties. In this work, we present a methodology to fabricate tubular hollow fibre copper electrodes with drastically increased intrinsic porosity. Our described method utilizes a standard dealloying process of copper aluminium particles to induce an intra-particle nanoporosity. The specific surface area increases from 0.126 m2 g−1 before dealloying to 6.194 m2 g−1 after dealloying. In comparison to conventional planar copper electrodes and literature data from conventional copper hollow fibres, the intra-particle porosity leads to a drastically increase in electrochemical activity. Electrochemical measurements reveal increased current densities at low over-potentials in comparison to conventional copper electrodes under identical experimental conditions emphasizing the significant impact of the porosity on the electrode performance. The presented method can be easily transferred to other alloy particles, highlighting its versatility for electrode fabrication.

Resistance ceramic-filled annular welding of thin steel sheets

To meet the requirements of automobiles for high-strength steel welding and thin-sheet welding, a composite ceramic-filled annular electrode (A-electrode) was designed by controlling welding energy distribution. By embedding a circular non-conductive ceramic rod in the center of a conventional copper electrode, the welding heat changed from centralization in the center of the nugget of traditional spot welding to a more dispersed annular distribution. As a result, an annular nugget that corresponds to the annular copper end face was formed. Given the energy dispersion, a higher current was required to bond the sheets by the A-electrode than that by a traditional electrode. However, the indentation depth on the surface of the nugget decreased effectively. The stress distribution indicated that the stress was concentrated at the edge of the nugget under the load, and the unconnected part in the middle did not affect the strength. The size of the annular nugget was designed by adjusting the structure of the A-electrode. The strength of the nugget could be improved by forming a large nugget area.

Micro-hardness evaluation for surface alloying of H11 die steel with Cu–Cr–Ni powder metallurgy tool in electrical discharge machining

Electrical discharge machining is a non-conventional material removal process; recently, efforts have been made to use it as a surface alloying/modifying method. This study investigates and compares the micro-hardness of the surface machined by electrical discharge machining process using composite tool electrode (copper–chromium–nickel) manufactured by powder metallurgy and conventional copper tool. Design of experiment is used to find the best level of process parameters in order to achieve high micro-hardness. The machined surfaces are subsequently analyzed using different techniques like scanning electron microscopy, X-ray diffraction and energy-dispersive spectroscopy to ascertain the surface characteristics. Results indicate that the micro-hardness of the alloyed surface formed by powder metallurgy tool electrode is improved by 96.3% as compared to base material and 65.7% as compared to the surface machined by conventional copper electrode. Energy-dispersive spectroscopy of the surface machined using powder metallurgy electrode confirms significant material migration from tool and dielectric to the machined surface. The X-ray diffraction shows the formation of cementite (Fe3C), intermetallic compound of iron, chromium and nickel (FeCrNi) and chromium carbide (Cr7C3) on the surface machined using powder metallurgy electrode.

Dual-topography electrical discharge machining of titanium to improve biocompatibility

Abstract Surface modifications of titanium are widespread in an effort to improve the osseointegration capabilities of the metal for orthopaedic and dental applications. Here, electrical discharge machining (EDM) was used to create modified, notably, dual-topography surfaces on titanium. By swapping conventional copper electrodes for a titanium electrode and water dielectric, modified surfaces free of trace element contaminants were produced. Three surfaces were produced by varying the peak currents at 10 A, 29 A and a uniquely hierarchical multi-current combination of 29 A followed by 2.4 A. The physicochemical properties of these surfaces were analyzed by scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), and Auger Spectroscopy. These revealed the topography of the modified surfaces and a titanium oxide layer that was markedly thicker on the EDM samples compared to controls. In vitro cell testing was carried out with osteoblast-like MC3T3-E1 cells. Cell differentiation was increased in all EDM modified surfaces compared to controls and early differentiation was promoted on the dual-topography surface. The present study suggests the promise of dual-topography surfaces created using EDM for implant applications.

Nanostructured cupric oxide electrode: An alternative to amperometric detection of carbohydrates in anion-exchange chromatography

In this paper, a new and low cost copper/cupric oxide nanostructured electrode is presented as an alternative to the amperometric detection of carbohydrates in high-performance anion exchange chromatography. The modified copper electrodes were prepared by a simple and fast method which resulted in the obtainment of homogeneously distributed nanostructures adhered to the surface with controlled chemical nature. The results, when compared to conventional copper electrodes, exhibited considerable improvements in analytical results, including: 1) Better repeatability in consecutive glucose detections, in which the percent relative standard deviation improved from 15.1% to 0.279%. 2) Significant improvements in the stability of the baseline and a decrease of the stabilization time, going from several hours to approximately 15 min. 3) Considerable increase in the sensitivity towards glucose, from 5.02 nA min mg L−1 to 25.5 nA min mg L−1. 4) Improvements in the detectability with limits as low as 1.09 pmol. 5) Wide working range of concentrations (1 × 10−2 to 1 × 104 mg L−1). 6) Good linearity with correlation coefficients greater than 0.998. 7) Possibility of detecting different molecules of carbohydrates (lactose, maltose, sucrose cellobiose, sorbitol, fructose, glucose, galactose, manose, arabitol, xylose, ribose and arabnose). In comparison to the electrode that is more employed for this type of application (gold electrode), the low cost, the possibility of detection at constant potential and the equivalent detection limits presented by the new electrode material introduced in this work emerge as characteristics that make this material a powerful alternative considering the detection of carbohydrates in anion exchange chromatography.

Impact of Powder Metallurgy Electrode in Electric Discharge Machining of H-13 Steel

Electric discharge machining (EDM) widely used mostly in the tool and die industry and the material normally used as electrode are copper, tungsten, graphite, copper tungsten and copper chromium alloys. In the present work, Electric discharge machining was carried on H-13 workpiece using powder metallurgy electrodes of copper chromium (CuCr) and conventional copper electrode. The input parameters selected in the study were current, voltage, duty cycle and retract distance. The output parameters were material removal rate, tool wear rate, surface roughness and overcut. Experimental results show that CuCr powder metallurgy electrode gives best results for MRR. Also CuCr powder metallurgy electrodes gives better results for overcut as compare to conventional copper electrode. It has been seen that electrode type is significant factor for all output parameters.

Surface Quality Modification Using Powder Metallurgy Processed CuW Electrode During Electric Discharge Machining of Inconel 718

Use of powder metallurgy processed (PM) electrode in electrical discharge machining (EDM) has emerged as an alternate tooling option with a view to impart improved surface properties to the work surface. Preliminary investigation with CuW PM electrode using Taguchi method was done on Inconel 718 to obtain best parameter settings for higher the better surface roughness. In the present work surface micro hardness study and X-ray diffraction (XRD) analysis was performed on the machined surface at the best parameter setting and comparison was done with the surface machined using conventional copper electrode. It was observed that the micro hardness of the machined surface was improved from 380.9 HV of the base metal to 496.7 HV of the surface machined with powder metallurgy processed electrode. XRD analysis revealed the formation of Fe2W3C6 phase on the machined surface causing remarkable improvement in the surface micro hardness.

Influence of Welding Parameters in Substrate/Coating of Galvanized Sheets Using Resistance Spot Welding

The main objective of this work is to propose an optimization of welding parameters through the process of resistance spot welding, applied to Interstitial Free (IF) steel sheets in order to increase the life of conventional copper electrodes. The methodology consisted of using a weld tester in order to ensure the accuracy of values. The main parameters selected through a survey of the weldability were: force, time and welding current. To evaluate the resistance of the weld and the electrode wear, mechanical tests were performed like tensile-shear, cross-tension, peel test and microhardness. A microstructural evaluation by optical microscopy (OM) and scanning electron microscopy (SEM) was made. The results show reducing the thickness of the coating in the weld region and macro and microstructures were observed. Through the tensile-shear and cross-tension tests were verified using electrodes caps up to 1250 points with acceptable welds. The microhardness test results indicated significant hardness increase in weld nugget elucidated by differences in microconstituents evaluated by OM and SEM. The methodology used for parameter selection has highlighted an optimal combination with 200kgf electrodes force, 9cy welding time and 7.8 kA welding current, in overlap IF steel sheets with 0.75mm of thickness, thereby increasing the lifetime of the electrode and ensures a better quality of welds and the consequent reduction of energy applied to the weld process.

Study of ultrasonic assisted cryogenically cooled EDM process using sintered (Cu–TiC) tooltip

In most EDM operations, the maximum contribution in the total operation cost is the tool cost. Electrode wear is a major problem in EDM process. Therefore, in this paper, the process performance of sintered copper (Cu)–titanium carbide (TiC) electrode tip in ultrasonic assisted cryogenically cooled electrical discharge machining (UACEDM) has been studied. The performance parameters studied in this paper are electrode wear ratio (EWR), material removal rate (MRR), surface roughness (SR), out of roundness and surface integrity. The process parameters considered in this study are discharge current, pulse on time, duty cycle and gap voltage. Cermet was fabricated, having copper content of 75% and titanium carbide content of 25%, by mixing, pressing, and sintering. The performance of the newly formed cermet electrode tip is compared with conventional copper electrode tip for UACEDM process and analyzed. It has been observed that EWR and out of roundness decreases when cermet electrode tip is used as compared to conventional tooltip. It has also been observed that MRR and SR increase when cermet tooltip is used. The surface cracks density and crack width on workpiece machined by cermet tooltip have been found to be lesser as compared to the specimen machined by conventional tooltip.

Performance analysis of Cu-B<SUB align="right">4C metal matrix composite as an EDM electrode

Performance of electrode materials is one of the important factors that determine the quality of the machined component and the cost involved in the operation of electro discharge machining (EDM) process. Low electrode wear resistance in graphite and copper electrodes necessitated the development of sintered composite electrodes for EDM operation. In this paper, authors attempted to develop a new copper-based metal matrix composite (Cu-B4C) to get an optimum combination of wear resistance, electrical and thermal conductivity. Here the copper-boron carbide composite was developed through powder metallurgy route and EDM experiments were carried out using mild steel specimen. Copper composite with 40% boron carbide reinforcement exhibits better metal removal rate (MRR) and tool removal rate (TRR) compared to conventional copper electrode. SEM and XRD results show the surface modification and formation of boron, B4C reinforced layer on the surface of mild steel work piece when machined with composite electrode.

Development of Thick-GEMs for a GEM-TPC Tracker

A Time Projection Chamber (TPC) with Thick Gas Electron Multipliers (TGEMs) has been developed for an inner tracker of the J-PARC E15 experiment, a deeply-bound kaonic nuclear states search experiment. The TPC has a cylindrical design with an inner diameter of 170 mm, an outer diameter of 280 mm, and a drift length of 300 mm filled with P10 gas (90:10 argon-methane) at atmospheric pressure. A TGEM is used for the amplification of the TPC in order to realize a self-supporting structure in a limited space. We use a double TGEM structure and the maximal effective gain of more than 104 is achieved with 100 × 100 mm TGEM prototypes. Moreover, we have been developing a resistive-electrode TGEM (RETGEM) with graphite electrodes, which has the advantage of being fully spark-protected. The results of our recent studies on the TGEM prototypes with conventional copper electrodes, the RETGEM with graphite electrodes, and the newly developed hybrid-RETGEM with copper and graphite electrodes are discussed.

Optimisation of electrical discharge machining process with CuW powder metallurgy electrode using grey relation theory

In this paper, an attempt has been made to correlate the usefulness of powder metallurgy (PM) electrodes in electrical discharge machining (EDM). This paper explains the same with the help of experimentation on AISID2 steel in kerosene with CuW (25% Cu and 75% W) PM electrode. An L18 orthogonal array was used to identify the effect of process parameters (viz. electrode material, duty cycle, flushing pressure and current) on the performance characteristics i.e., material removal rate surface roughness and surface hardness. A grey relation grade obtained from the grey relation analysis is used to solve the EDM process with multiple performance characteristics. Experimental results have shown that electric discharge machining process performance can be improved efficiently through this approach. It is found that copper tungsten PM electrode gives better multi-objective performance than conventional copper electrode.

Surface modified long-life electrode for resistance spot welding of Zn-coated steel

In order to increase the life of conventional copper electrodes in resistance spot welding of Zn-coated sheet steel, a multi-layer Ni/(TiC P/Ni)/Ni composite coating was deposited onto the copper electrode top surface by electro-spark deposition. Scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and micro-hardness tests were employed to characterize the microstructure and property of the coating. The results showed that the copper electrodes with a dense Ni/(TiC P/Ni)/Ni coating slightly increased the resistance of the weld system and hence the welding current could be reduced to produce a weld with the same button size as that made by uncoated electrodes at a high welding current. The coating was gradually cracked during welding under the action of welding force, forming Ni/(TiC P/Ni)/Ni composite islands which were strongly adherent to and further, punched into copper substrate. The coating could significantly reduce the alloying between copper electrode substrate and molten Zn. As a result, coated electrode showed a much longer life than an uncoated electrode even though the welding current for coated electrode was lower than that for uncoated one.

The Potential of Plating Techniques in the Development of Rapid EDM Tooling

Electrodischarge machining (EDM) is a widely used process in the manufacturing of mould cavities for plastic products. EDM work typically accounts for a large portion of overall production time. A major cost and time element of EDM is electrode production, which can account for more than 50% of the total machining costs. A large complex electrode profile, which is very difficult to produce through machining and is also time consuming, can be easily produced using the rapid prototyping (RP) technique. The direct laser sintering of metal powders is a widely established RP process that can be employed for the rapid production of EDM electrodes. In this study, the above-mentioned technique has been employed. The powder mixture used in this process consists of copper, tin, nickel and phosphorus. An infra-red (IR) 200 W CO 2 laser is used to sinter the powdered metals layer-by-layer in order to form solid electrodes. Electroless copper and copper plating are then employed to improve the surface finishing and the conductivity of the sintered electrode as it deposits a uniform thickness of metal onto the substrate by chemical reaction, without building up at the edges and corners, and achieves unique physical characteristics. The performance of the newly developed electrode is very similar to that of conventional copper electrodes. It is found that integration of RP and electroless plating techniques can be a potential means of the rapid production of EDM electrodes at low cost.