Search Results (27)

Wire electrical discharge machining (WEDM) is widely used for the precision cutting of difficult-to-machine materials, including nickel-based superalloys. Wire electrode wear, however, remains a practical limitation, because it affects process stability, wire consumption, and machining cost. This work examines the wear behaviour of a gamma-phase Cu₅Zn₈-coated copper-core wire electrode (Elecut X, ø 0.25 mm) during the WEDM of Inconel 718 using direct gravimetric measurement. A 3³ full factorial experiment was carried out with three electrical parameters: pulse-on time (A), pulse-off time (B), and servo reference voltage (Aj). The discharge process was monitored with an oscilloscope so that measurements only started after the programmed pulse-off time had been reached. Electrode wear was evaluated as the mass loss Δm of 4 m wire segments after 5 min cutting intervals on a Charmilles Robofil 310 machine, and factor significance was assessed by analysis of variance (ANOVA). Pulse-on time was the dominant factor, accounting for 88.45% of the total variation in Δm, followed by servo reference voltage and pulse-off time. SEM/EDS examination showed material transfer from the Inconel 718 workpiece to the worn electrode surface, with local nickel content reaching 16.84 wt.% on the frontal face of the most worn sample. The results provide a quantitative basis for reducing wire consumption during the WEDM of Inconel 718 while recognising the trade-off with cutting productivity. Full article

This study utilized a twisted wire rotating arc cladding method to in situ fabricate a Fe-containing multi-principal element alloy (HPEA) coating derived from NiCrCoTiMo stranded wire on 45 steel (equivalent to AISI 1045 steel). The macroscopic morphology, microstructure, mechanical properties, and electrochemical corrosion behavior of the prepared coatings were examined. The coating exhibited no visible cracks or pores and displayed a dual-phase face-centered cubic (FCC) + body-centered cubic (BCC) structure, with an average grain size of 78 μm for the FCC phase and 1 μm for the BCC phase. The microhardness of the coating is approximately 381.3 HV_0.1. Compared to 45 steel, the coating’s coefficient of friction (COF) decreased from 0.6265 to 0.5125, representing an 18.2% reduction. The calculated wear rate of the coating was 1.47 × 10⁻⁵ mm³/N·m, approximately six times lower than that of 45 steel (8.93 × 10⁻⁵ mm³/N·m). Electrochemical testing revealed that the coating’s open-circuit potential (OCP) was −0.405 V vs. the saturated calomel electrode (SCE), with a corrosion potential (E_corr) of −0.556 V vs. SCE and a corrosion current density (I_corr) of 4.458 × 10⁻⁶ A/cm². In comparison, 45 steel exhibited an OCP of −0.582 V vs. SCE, with corrosion parameters of E_corr = −0.840 V vs. SCE and I_corr = 1.302 × 10⁻⁵ A/cm². These results demonstrate the superior corrosion resistance and wear performance of the coating, underscoring its potential for applications in challenging environments that demand enhanced material durability. Full article

The high strength and light weight of aluminum matrix composites have made them the material of choice for many engineering applications. Snail shells and other bio-reinforcements offer a potential substitute for conventional ceramic reinforcements. However, the inherent difficulty in machining Aluminum Matrix Composites (AMCs) stems from the presence of reinforcing particles. This study investigates the machinability of aluminum matrix composites (AMCs) reinforced with Physella Acuta snail shell (PAS) particles using Wire Electrical Discharge Machining (WEDM) with a zinc-coated brass wire electrode. The primary objective is to determine how various input elements affect process conditions to achieve the desired surface quality. In order to do this, the Random Decision Forest approach was employed. Scanning Electron Microscopy (SEM) evaluation revealed the presence of microvoids, surface defects, deep craters, and crack propagation. It was found that the random forest method had an F1-score of 0.94, a recall of 0.96, and a precision of 0.97. The optimized parameters yielded an MRR of 0.5 mm³/min, SR of 2.14 µm, and EWR of 0.017. Full article

Research on the WEDM process has traditionally focused on analyzing discharge initiation, material removal mechanisms and surface formation from the perspective of the machined part. However, the same phenomena also affect the tool, namely the wire electrode. A comprehensive understanding of the process requires to examine how these effects impact the electrode itself, particularly in terms of wear. Despite its significance, electrode wear in WEDM is not a topic frequently addressed in the literature. The most common method for evaluating wear involves determining the wire wear ratio (WWR), based on the electrode’s weight before and after machining. However, this approach does not provide insight into changes in the microstructure of the electrode surface. This study presents an alternative approach to interpreting wire electrode wear, using surface roughness parameters in relation to the surface texture of the machined workpiece. Measurements were conducted using an optical focus variation microscope. The influence of selected process parameters—including discharge current I_p, pulse-off time t_off and workpiece height h—on selected surface roughness parameters was investigated. The experimental tests were carried out for three alloys representing distinct material groups: 42CrMo4 steel, Inconel 718 nickel alloy, and Ti6Al4V titanium alloy. The results were compared with the roughness parameters of the corresponding machined surfaces. The presented interpretation of the key factors affecting the electrode surface condition after WEDM serves as an initial step in a broader research initiative. It lays the foundation for further studies on wire electrode wear and the development of new wear assessment parameters such as the electrode wear index based on surface texture parameters. Full article

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

Intermetallic compounds from the Fe-Al system are attracting increasing attention due to their outstanding properties, including excellent mechanical performance, low density, corrosion, and oxidation resistance, as well as resistance to sulfidation, carburization, and wear at elevated temperatures. These unique characteristics make Fe-Al intermetallics promising candidates for high-temperature and harsh environmental applications. However, challenges such as brittleness and low plasticity have hindered their broader use. By exploring the impact of spray conditions on coating properties, this study contributes to enhancing the performance and functionality of Fe-Al coatings in industrial applications, where durability and resistance to extreme conditions are essential. This article presents the results of research on the production of composite coatings from the Fe-Al system with in situ fabricated intermetallic phases. For this purpose, arc spraying in an inert gas was used. The coating manufacturing process was carried out by simultaneously melting two different electrode filler wires, aluminum and steel, in a stream of argon. The obtained coatings were subjected to tests of roughness, adhesion to the substrate, and microstructure. It was shown that both the roughness and adhesion to the substrate of coatings sprayed in air are higher than those sprayed in argon. The increase in roughness results from the greater oxidation of coatings sprayed in air, while better adhesion is the result of the formation of coatings at a higher temperature. Metallographic studies have shown that during the spraying process, the in situ synthesis of intermetallic phases occurred. The results showed the local occurrence of intermetallic phases from the Fe-Al system. Among the two dominant phases, i.e., Al and the Fe alloy, there are also the following phases: FeAl₃, FeAl₂, and Fe₂Al₅. Furthermore, in layers sprayed in an inert atmosphere, the share of oxides is small. Full article

This study aims to optimize the Wire Electrical Discharge Machining (EDM) process parameters for aluminum 6061 alloy reinforced with Mg and MoS₂ using the Box–Behnken (BBD) design and the non-dominated sorting genetic (NSGA-II) algorithm. The objective is to enhance the machining efficiency and quality of the composite material. The Box–Behnken (BBD) design was utilized to design a set of experiments with varying levels of process parameters, comprising pulse-on time, servo volt, and current. The material removal rate and surface roughness were considered as machining responses for optimization. These responses were measured and used to develop a mathematical model. The NSGA-II, a multi-objective optimization algorithm, was then applied to search for the optimal combination of process parameters that simultaneously maximizes the material removal rate and minimizes the electrode wear rate and surface roughness. The algorithm generated and evolved a set of Pareto-optimal solutions, providing a trade-off between conflicting objectives. The results of the optimization process were analyzed to identify the optimal process parameters that lead to improved machining performance. The study revealed optimal Wire Electrical Discharge Machining (WEDM) parameters for Al6061/Mg/MoS₂ composites using NSGA-II. The optimized parameters, including a pulse-on time (Ton) of 105 µs, servo voltage (SV) of 35 V, and peak current (PC) of 31 A, resulted in a Material Removal Rate (MRR) of 7.51 mm³/min and a surface roughness (SR) of 1.97 µm. This represents a 15% improvement in the MRR and a 20% reduction in the SR compared to non-optimized settings, demonstrating the efficiency of the BBD-NSGA-II approach. Full article

Oxide layers on the surface of the aluminum alloys D16 and AMg6 and on arc coatings sprayed with electrode wires made of the alloys D16 and AMg6 were synthesized using plasma electrolytic oxidation (PEO). The microstructure, phase composition and micro-hardness of the PEO layers were studied. In addition to the two main phases (α-Al₂O₃ and γ-Al₂O₃), a small amount of a metastable crystalized Al_2.427O_3.64 phase was found in their structure. A comparison was made of the wear resistance and friction coefficients of the synthesized PEO layers during friction tests in pairs with other PEO layers, a galvanic chromium coating, cast iron, steels and bronze of the BrC30 type. The results of the friction tests for the various PEO layers on aluminum alloys in tribo-contact with high-hardness elements made of hardened or chrome-plated steel justify the possibility of their use in a friction pair. We experimentally showed the influence of glycerin additive in motor oil 15W30 on the change in the friction coefficient of the PEO layers synthesized on the aluminum alloys and on the arc-sprayed coatings on their surfaces in tribocouples with hardened steel. Full article

Fe-Mn-Cr-Ni alloys like Citomangan, delivered in the form of powders, tubular wires, and coated electrodes, are intended for welding deposition operations to create wear-resistant layers. Their main characteristic is their high capacity for surface mechanical work-hardening under high shock loads, along with high toughness and wear resistance. In order to increase the resistance to cavitation erosion, hardfacing of Duplex stainless steel X2CrNiMoN22-5-3 with Citomangan alloy was performed using a new welding technique, namely one that uses a universal TIG source adapted for manual welding with a coated electrode in pulsed current. Cavitation tests were conducted in accordance with the requirements of ASTM G32—2016 standard. Comparing the characteristic cavitation erosion parameters of the manganese austenitic layer, deposited by this new welding technique, with those of the reference steel, highlights an 8–11 times increase in its resistance to cavitation erosion. Metallographic investigations by optical microscopy and scanning electron microscopy (SEM), as well as hardness measurements, were carried out to understand the cavitation phenomena. Full article

The present research focuses on the machining of grade 2 titanium material using the Wire Electric Discharge Machining (WEDM) process by means of L₁₆ Orthogonal Array (OA). This study investigates numerous process parameters, including pulse on time, current, pulse off time, voltage, bed speed and flush rate. The voltage and flush rate were kept constant throughout the experiment, while the other four parameters were varied for the machining process. In this study, a 0.18 mm molybdenum wire was utilized as the electrode material. Initially, this research aimed to optimize the process parameters to discern their impact on machining characteristics (Surface Roughness and Electrode Wear) as well as on machining performance (Acoustic Emission Signals). Subsequently, simpler functional relationship plots were generated between these parameters to recognize the potential information about the machining characteristics and machining performance. The straightforward approach lacks the capability to furnish information regarding the condition of the material (Surface Roughness), the tool (Electrode Wear) and the signals (Acoustic Emission). Hence, to estimate the experimental values the numerical tools viz., Group Method of Data Handling (GMDH) and Artificial Neural Network (ANN) were used. Upon comparing the predictive performance of ANN and GMDH, it became evident that the ANN’s predictions using 70% of the data for training displayed a higher correlation with the experimental values compared to the GMDH. Full article

Nowadays, due to the carcinogenic effects of chrome, replacing the hard chromium used for hydraulic components like rods and cylinders is becoming increasingly requested. Thermally sprayed coatings are a solution to the problem; however, proper understanding and characterisation of their tribological behaviour are essential for the successful exploitation of surface engineering. Thus, the main aim of this study is to evaluate the abrasive wear characteristics of two metal sprayed layers, tungsten carbide (WC) deposited through the high-velocity oxygen fuel coating (HVOF) method and Fe alloy coating deposited through thermal spraying with an electric arc with a wire-electrode G3Si1, and compare the results with those of an electrochemically deposited hard chromium layer. Their wear resistance is then related to their hardness. The results highlight the tribological performances of the thermally sprayed coatings. The HVOF WC10Co4Cr coating has a wear coefficient and a material wear volume that are hundreds of times lower than those of the other two coatings. Full article

In the midst of the COVID-19 pandemic, new requirements for clean air supply are introduced for heating, ventilation, and air conditioning (HVAC) systems. One way for HVAC systems to efficiently remove airborne viruses is by filtering them. Unlike disposable filters that require repeated purchases of consumables, the electrostatic precipitator (ESP) is an alternative option without the drawback of reduced dust collection efficiency in high-efficiency particulate air (HEPA) filters due to dust buildup. The majority of viruses have a diameter ranging from 0.1 μm to 5 μm. This study proposed a two-stage ESP, which charged airborne viruses and particles via positive electrode ionization wire and collected them on a collecting plate with high voltage. Numerical simulations were conducted and revealed a continuous decrease in collection efficiencies between 0.1 μm and 0.5 μm, followed by a consistent increase from 0.5 μm to 1 μm. For particles larger than 1 μm, collection efficiencies exceeding 90% were easily achieved with the equipment used in this study. Previous studies have demonstrated that the collection efficiency of suspended particles is influenced by both the ESP voltage and turbulent flow at this stage. To improve the collection efficiency of aerosols ranging from 0.1 μm to 1 μm, this study used a multi-objective genetic algorithm (MOGA) in combination with numerical simulations to obtain the optimal parameter combination of ionization voltage and flow speed. The particle collection performance of the ESP was examined under the Japan Electrical Manufacturers’ Association (JEMA) standards and showed consistent collection performance throughout the experiment. Moreover, after its design was optimized, the precipitator collected aerosols ranging from 0.1 μm to 3 μm, demonstrating an efficiency of over 95%. With such high collection efficiency, the proposed ESP can effectively filter airborne particles as efficiently as an N95 respirator, eliminating the need to wear a mask in a building and preventing the spread of droplet infectious diseases such as COVID-19 (0.08 μm–0.16 μm). Full article

Background: This study aimed to investigate the effects of different shoulder orthoses on the neuromuscular activity of superficial and deep shoulder muscles during activities of daily living (ADL) and physiotherapeutic exercises. Methods: Ten participants with healthy shoulders (31 ± 3 years, 23.1 ± 3.8 kg/m²) were randomized to receive a “shoulder sling”, an “abduction pillow” and a “variably adjustable orthosis” on the dominant side. With each orthosis, they completed seven ADL with and four physiotherapeutic exercises without wearing the orthoses. An electromyographic system was used to record the neuromuscular activity of three superficial (trapezius, deltoid, pectoralis major) and two deep shoulder muscles (infraspinatus, supraspinatus) using surface and intramuscular fine-wire electrodes. Results: The neuromuscular activity differs between the orthoses during ADL (p ≤ 0.045), whereby the “variably adjustable orthosis” mostly showed the highest activation levels associated with the worst subjective wearing comfort rated on a visual analog scale. In addition, differences exist between the physiotherapeutic exercises (p ≤ 0.006) demonstrating the highest activations of the infra- and supraspinatus muscles for assistive elevation and wipe across a table, middle for pendulum and lowest for continuous passive motion exercises. Conclusions: The neuromuscular activity of superficial and deep shoulder muscles differs between the orthoses during ADL and also between the physiotherapeutic exercises. Full article

In order to study the effect of element B on the corrosion resistance of stainless steel-based flux cored wire surfacing alloy, a stainless steel surfacing layer was prepared on the surface of carbon steel plate by melt electrode gas shielded welding, and then the microstructure, electrochemical corrosion resistance, and wear resistance of the surfacing layer were analyzed. The results show that the surfacing layer of surfacing alloy presents M₂B and Fe₃(C, B) phases based on austenite. Boride formed in deposited metal has good corrosion resistance. Therefore, adding the proper amount of B can significantly improve the corrosion resistance of the surfacing layer. When the boron content is 2%, the corrosion resistance is the best. The minimum self-corrosion current density is 1.75766 × 10⁻¹¹ mA·cm², and the maximum self-corrosion potential is −0.254438 V. Maximum impedance curve radius. At this time, the wear resistance of the surfacing layer is also the best. Full article

Electrode material used in wire electric discharge machining (WEDM/wire EDM) plays a vital role in determining the machined component quality. In particular, when machining hard materials like nickel titanium/NiTi (NiTiNOL) shape memory alloy, the quality of electrode material is important as it may have adverse effects on the surface properties of the alloy. Different electrode materials give different performances, as each electrode material is made up of different conductivity, compositions and tensile strength. Therefore, detailed experimental studies have been carried out to understand the effect of diffusion annealed coated wires (X-type and A-type) on NiTiNOL SMA during the wire EDM process. The tool wear rate and surface roughness responses have been studied for both the electrode materials against different wire EDM variables such as pulse time, pause time, wire feed and spark gap set voltage. The impact of these process parameters on the stated output responses has been analyzed and further surface and subsurface analysis of the machined component has been carried out to understand the impact of diffusion annealed electrode materials during the wire EDM process. The investigation reveals that an A-type diffusion annealed coated wire is found to be most suitable in terms of tool wear rate, surface roughness and surface integrity during machining of NiTiNOL shape memory alloy compared to X-type and traditional brass-based electrode materials. Surface topographical properties were studied using confocal microscopic analysis and scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS) analysis. The subsurface analysis like microhardness and recast layer thickness was also studied for both the wires against different machining conditions. Full article