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This article presents a review on some important recent research, development, and innovations related to the nonconventional machining of glass material. Nonconventional machining processes were identified suitable for machining of glass, years ago, and from then to now various technological developments have made nonconventional machining a viable alternate to the conventional machining of glass material. In this article, we have mainly focused on three important nonconventional machining processes, namely, last cutting, ultrasonic machining, and electrochemical discharge machining (ECDM). Novel aspects, effects of process parameters, and salient features are discussed. Mainly, previous five years' work is reviewed. This review finally ends with a conclusion and important future research directions. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) offers a superior technology for manufacturing hard-cutting metals such as modified Inconel 718 (IN718). However, in many cases, poor surface quality arises because of the specific dissolution characteristics of the material, hindering further application of the process. Vibration-assisted ECM (VA-ECM) has been proposed in the hope of solving the problem by oscillating the cathode. A multiphysics model was developed for pulsed ECM (PECM) and VA-ECM. Systematic experiments were performed to clarify the mechanism of cathode oscillation on surface quality and verify the computational results. With 20 Hz vibration frequency and 25% duty cycle, the surface roughness reaches 0.39 µm, show that higher oscillation frequency and lower duty cycle are effective in improving surface quality. Finally, dissolution models of modified IN718 under PECM and VA-ECM are proposed. By oscillating the cathode, electrolyte fluctuation is enhanced, electrolytic products are removed effectively, the surface quality is improved significantly. [ABSTRACT FROM AUTHOR]

Inconel-625 is a high-performance nickel-based superalloy which offers exceptional properties such as extensive resistance to corrosion, high strength-to-weight ratio, hardness, and impressive heat tolerance. Machining precise holes with required dimensional accuracy is challenging in Inconel-625 using conventional drilling processes. The investigation aims to improve the quality characteristics of hole machined on Inconel-625 by using the abrasive aqua jet drilling (AAJD) process. The influence of jet pressure ( J P ), table feed ( T F ), mass flow rate ( M FR ) and gap distance ( G D ) on the erosion rate ( E R ), surface roughness ( R a ), circularity error (CIerror) and striation zone ( S Z N ) are investigated. The weighted principal component analysis (WPCA)-based response surface methodology (WPC-RSM) is employed to analyze and optimize process parameters. The optimal parameter settings ( J P -300 MPa, G D -1.5 mm, T F -64 mm/min, M FR -0.55 kg/min) are observed to produce substantial improvement in response. Comparing initial and optimal conditions, the surface roughness ( R a ) is decreased by 10.15% from 3.25 μ m to 2.92 μ m. The CIerror and S Z N are also reduced by 38.02% and 12.74%, respectively. The erosion rate ( E R ) is improved by 8.79% with the optimal settings. J P is found to be the most influential parameter, followed by M FR . Scanning electron microscopy (SEM) pictures and 3D roughness plots are used in the surface topography analysis. [ABSTRACT FROM AUTHOR]

High efficiency, high quality and green machining of single crystal silicon carbide (SiC) is an important issue in the third-generation semiconductor industry. In this paper, a novel machining method for single crystal SiC based on tribo-oxidation is proposed. The formula and preparation process of polysaccharide bonded soft abrasive tool were designed. Dry machining of C-face of 4H–SiC substrate was carried out with the prepared environmentally friendly abrasive tool sample. The material removal mechanism of the proposed machining method was preliminarily analyzed, and the material removal rate, surface roughness and subsurface residual stress were studied. The experimental results show that the maximum material removal rate of 4H–SiC can reach 1.03 μm/min with a corresponding average surface roughness of S a 0.816 nm. The machined surface has no brittle flaw, and subsurface residual compressive stress exists with a maximum value of 58.9 MPa. The material removal mainly attributed to the active oxidation of SiC surface induced by the friction between alumina abrasives and SiC substrate. The proposed machining method has potential application value in thinning of SiC wafers. [ABSTRACT FROM AUTHOR]

Nitinol alloy is widely utilized across various industries due to its special properties. In this paper, the compound effects of two kinds of energy fields on material removal rate (MRR), hole wall quality, machining accuracy, and recast layer in ultrasonic combined magnetic field assisted EDM (UV-MFEDM were studied and analyzed. In addition, the influence of magnetic field intensity on the efficiency and accuracy of micro-hole machining is analyzed systematically. The results show that the surface quality of the micropore is significantly improved, the MRR is increased by 31.6%, the taper of the micropore is reduced by nearly 30%, the overcut diameter is reduced by nearly 23%, the recast layer is more uniform and the thickness of the recast layer is reduced by nearly half. Appropriate magnetic field intensity proves beneficial for improving micro-hole machining efficiency while reducing both taper angle and diameter overcut of micro-holes. [ABSTRACT FROM AUTHOR]

This article investigates the effects of mixing different alkaline electrolytes on the geometrical features created by the ECDM. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) were mixed in varying volumetric proportions. Effect of critical process parameters on the depth and width of the microchannels and the associated tool wear was investigated. Pure NaOH electrolyte has resulted in the highest depth compared to the pure KOH electrolyte. Process mechanism behind the role of mixed electrolytes on the opening sizes and depths of microchannels is explained. Higher material removal by the NaOH electrolyte was due to the larger number of sodium (Na+) ions in the electrolyte, resulting in more aggressive electrochemical discharge; however, it also resulted in severe tool wear. Mixed electrolytes with a KOH yielded lower width and low tool wear. Increasing the volumetric proportion of KOH in the mixed electrolyte gradually decreased the machining depth, width, and tool wear. [ABSTRACT FROM AUTHOR]

AbstractThis article introduces a novel model reconstruction method for machining turbine blades damaged in service and repaired via additive manufacturing (AM). Addressing the lack of a model for damaged parts crucial for precise adaptive machining, the method involves model registration and construction. Initially, the AM-repaired blade is aligned with a theoretical CAD model through rough registration using Principal Component Analysis (PCA), followed by precise alignment within the blade profile’s tolerance zone. The model construction employs the minimum curve energy principle to ensure seamless integration with undamaged areas and adherence to profile tolerance constraints. The interfacial profile curve between the undamaged and AM-repaired areas is used as the original curve to construct the curves in the AM-repaired area. The reconstructed curves are modified with a double constraint of being smooth and minimum occupation of the theoretical model tolerance zone. The efficacy of this method is validated through a case study. The repaired blade showed deviations from −0.101 mm to 0.115 mm, within profile tolerances, and a surface smoothness difference of less than 6.41 μm between the damaged and undamaged sections. This method significantly improves the precision and efficiency of turbine blade repair, offering substantial benefits for the turbomachinery manufacturing industry. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses (BMGs) are growing in popularity prominently due to their potential in micro-electromechanical systems (MEMSs) and aerospace applications. BMGs have unique mechanical properties, i.e., high strength, hardness, modulus of elasticity, and wear resistance, due to their disordered atomic structure. Due to their unique mechanical properties and amorphous structures, machining of BMGs remains a challenge. This paper aims to carry out a detailed literature review on various aspects of the machining of bulk metallic glasses using both conventional and non-conventional processes, including experimental approaches, modeling, statistical findings, challenges, and guidelines for machining this difficult-to-machine material. Conventional machining processes were found to be challenging for machining bulk metallic glasses due to their high hardness, brittleness, and tendency to convert their amorphous structure into a crystalline structure, especially at the machined surface and sub-surface. Although their high electrical conductivity makes them suitable for machining by non-conventional processes, they impose new challenges such as heat-affected zones and crystallization. Therefore, the successful machining of BMGs requires more in-depth analysis of cutting forces, tool wear, burr formation, surface finish, recast layers or heat-affected zones, crystallization, and mechanical property changes among different varieties of BMGs. This review paper provides guidelines emerging from in-depth analysis of previous studies, as well as offering directions for future research in the machining of BMGs. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to develop observation techniques and processing technology for the electrochemical discharge machining (ECDM) of sapphire wafers. To measure the effect of gas-film thickness, discharge-spark conditions, and droplet sliding frequency on machining quality and efficiency in ECDM, this research utilized high-speed cameras to observe the gas film thickness and formation of the gas film during ECDM. Additionally, this study observed the machining-gap phenomena during ECDM. The formation mechanism and machining characteristics of the gas film were understood through experiments. The machining parameters included the liquid level, working voltage, rotation speed, and duty factor. This study analyzed and discussed the effect of each machining parameter on the gas-film thickness, current, electrode consumption, and droplet sliding frequency. Moreover, this study aimed to obtain optimized machining parameters to overcome the difficulty of machining sapphire. The experimental results indicated that utilizing a high-speed camera to capture the phenomena between electrodes during electrochemical discharge could effectively observe the gas-film thickness and the coverage of the gas film. A higher bubble coalescence rate enhanced the machining capability and reduced the lateral discharge. Therefore, this study could obtain better machining-hole depths through observation and analysis to improve gas-film stability and machining capability. This study demonstrated that a liquid level of 700 µm, a working voltage of 48 V, a duty factor of 50%, and a tool electrode rotational speed of 200 rpm could achieve a hole depth of 86.7 µm and a hole diameter of 129.5 µm. [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining (ECDM) micro-milling exhibits enormous machining potential in manufacturing metal microstructures. In this paper, a novel sinking ECDM micro-milling using glycol-based electrolyte is proposed for the high-quality fabrication of metal micro-channel structures. Firstly, a novel combined process is developed for the simple and efficient preparation of micro-electrode. With the proposed method, a micro-electrode with 91.1 μm in diameter and 21.2:1 in aspect ratio is successfully machined in 47.2 minutes. Secondly, experimental research on ECDM micro-milling machining of micro-channels in glycol-based electrolyte is carried out using the fabricated micro-electrode. Experimental results show that the machined voltage significantly affects the machining quality of micro-channels. Wear analysis reveals that the bottom geometry of the micro-electrode exhibits equal wear along the axis direction with processing times increasing, and a constant length compensation strategy (1.52 μm/mm) is adopted. Finally, an S-shaped micro-channel without recast layers (Ra 0.093 μm) was successfully fabricated. [ABSTRACT FROM AUTHOR]

The electrochemical machining process involves electrical and chemical processes while removing materials from the workpiece. Electrochemical machining (ECM) lacks accurate models for predicting the shape and material removal rate during the ECM process. This limits the ability to optimise the process and predict the final product geometry, which is crucial for industrial applications. This research mainly focused on the modelling and simulation of material removal from the workpiece using COMSOL Multiphysics software. This research involves developing a mathematical model that describes ECM's electrical, chemical, and mechanical interactions. The model is based on electrochemistry, fluid dynamics, and solid mechanics principles and will be solved using numerical simulation techniques. Various workpiece materials considered in this investigation include Aluminium, Nickel, Stainless Steel, and Tungsten, whereas copper is electrode material. The effects of the various parameters, such as workpiece materials, the voltage applied during machining, and electrolyte conductivity on the material removal rate are being investigated. In addition, the shape of the machined workpiece is also predicted. The results of this research provide a deeper understanding of the underlying physics of the ECM process and lead to the development of more accurate models for predicting the shape and material removal rate during ECM. [ABSTRACT FROM AUTHOR]

With escalating demand for machinability, economical production, health, and environment-related aspects are pushing the present industrial units to drop the usage of harmful-cutting fluid in machining. However, the adaption of this approach for machining difficult-to-cut materials does not ensure favourable outcomes of the tool performance, surface qualities, etc., as friction and heat seriously disturb machining efficiency. This study is focused on near-dry machining employing recently developed hybrid nanofluids-based lubrication in the machining of AISI 52,100 steel. Hexagonal boron nitride (hBN) and silicon carbide (SiC) nanoparticles are added to the lubrication oil to enhance the performance of the Minimum Quantity Lubrication (MQL) system. Taguchi's method-based Grey relational analysis (GRA) is used for the concurrent optimisation of the tool flank wear and surface roughness. The best parametric setting for the multi-response is achieved as: a lubricant flow rate of 150 ml/h, depth of cut of 0.2 mm, and nanofluid with 0.8 wt % of hBN and 0.2 wt % of SiC nanoparticles. The confirmation experimentation concluded that the multi-response factor is enhanced by 2.48% at the optimum setting with the mean values of TFW and SR as 84 and 0.36 µm, respectively. [ABSTRACT FROM AUTHOR]

Zirconia is a ceramic material having a wide range of applications in industries owing to its excellent properties like high strength-to-weight ratio, biocompatibility, insulating, high wear, thermal resistance, and chemical stability over conventional materials. These properties pose a significant challenge for machining at the micro-level with considerable accuracy and preciseness. The ECDM is a low-cost hybrid machining technique with great potential to machine such materials. Barely any simulated or numerical work has been available for machining zirconia material through the ECDM process. In this study, a finite element model (FEM) is developed to predict the material removal rate (MRR) of the zirconia material using the temperature distribution plots through the electrochemical discharge machining process (ECDM) for different parametric conditions using a single spark mechanism. The simulation results reveal the increase of 316.9 µg in MRR by increasing electrolytic concentration from 15% to 30% wt. However, a small error was found between simulated and experimental results, which might be due to the assumptions during the study. This study will provide new guidelines during the processing of zirconia material for predicting the material removal rate for future manufacturing engineers. [ABSTRACT FROM AUTHOR]

Modular hobs are tools with very complex geometry. Regardless of the material of the gear wheels, they determine the accuracy of the gears made in the hobbing machining process. Gears are made of various, often innovative materials depending on the requirements. Sometimes, the materials are characterised by very high hardness (over 65 HRC). The mathematical basis for describing the faces of a hob presented in the article allows for modifying the rack profile shaping the gear wheel's teeth. The model's universality makes it possible to perform numerical simulations of the influence of individual parameters of the hob creation process (geometry of the grinding wheels and their setting in the shaping process) on the profile of the rake and flank surfaces. The cutting edge (rack edge) is the locus of points belonging to both of these surfaces and thus directly impacts the accuracy of the gear wheel that is shaped in the hobbing process. The article summarises the authors' long-term cooperation with the industry, resulting in a series of articles devoted to hobs. The issues presented in the article are significant to the machinery industry and hob manufacturers. [ABSTRACT FROM AUTHOR]

This article investigates the feasibility of producing an in-situ micro tool rod using micro-electrochemical spark machining (µ-ECSM) technology. The study included the examination of both electrical factors (such as voltage and duty factor) and non-electrical factors (such as electrolyte concentration and spindle speed) as the input parameters for the machining process. The responses measured in the study were the reduction in tool diameter and the surface roughness of the micro tool produced. The potassium hydroxide solution is used as a working fluid. The results indicate that voltage is the most crucial factor that influences micro tool fabrication. The utmost reduction in tool diameter, measuring 279.5 µm, occurred when utilizing machining parameters of 35V, 30%, 4 wt.%, and 600 rpm. Meanwhile, the lowest surface roughness for the micro tool was 3.42 µm, achieved with machining parameters of 35V, 10%, 4 wt.%, and 600 rpm. Additionally, the impact of machining settings on the micro tool electrode is covered. [ABSTRACT FROM AUTHOR]

The Nickel-Iron alloy Supra50 is one of the commonly used materials for manufacturing aeronautical parts and is resistant to excessive thermal stress. Due to its low coefficient of expansion, this material can guarantee dimensional stability at high temperatures while also offering mechanical characteristics like those of stainless steel. However, several works in the literature demonstrate that the Nickel-Iron alloy Supra50 has low machinability due to low thermal conductivity and work hardening. These main qualities, with its magnetic characteristics, qualified it for the manufacture of components for solenoid valves in aircraft. Despite its performance, obtaining Supra50 parts by machining presents difficulties. Indeed, faced with tight dimensional and geometric tolerances, manufacturers must invest in means and methods that converge to an agreement between cost and quality that ensures the efficiency of the machining process. This research work aims to analyze the effect of machining strategies and the tool feed rate on surface roughness by using an experimental approach in a Fe-Ni-based alloy-Supra50 surfacing operation with a flat end-mill tool. This study addresses a gap in the literature, focusing on the unique challenges posed by Supra 50 machining. It was demonstrated that the feed rate strongly affects surface roughness. In other hand, it was demonstrated that the machining strategy sweep gives the minimum of arithmetic mean height of the surface (Sa), compared to other analyzed machining strategies, such as mono-directional sweep and spiral sweep. All experimental results were demonstrated in sequence with other literature works on Fe-Ni-based alloy machining. [ABSTRACT FROM AUTHOR]

Introduction: The demand for improved small arms ammunition has led to exploring advanced materials and manufacturing techniques. This research investigates the machining characteristics of CM and WNF alloy bullets, aiming to enhance ballistic performance and durability. Methods: Bullet profile-making trials were conducted to evaluate the impact of machining parameters such as cutting speed and feed. The study also considered variables including surface roughness, cutting temperature, and hardness, alongside a detailed morphological analysis, The evaluation utilized an orthogonal array and MCDM approach, incorporating the TOPSISmethod for decision-making processes. Results: The findings reveal that WNF alloy bullets exhibit 3.01% to 27.95% lower machining temperatures, 24.88%-61.85% reduced surface roughness, and 19.45%-34% higher microhardness compared to CM bullets. Moreover, CM bullets demonstrated higher machining temperatures, resulting in 47.53% increased tool flank wear. WNF bullets showed a 24.89% reduction in crater wear and a 38.23% decrease in compressive residual stress in bullet profiles, indicating superior machining performance. Discussion: The superior machining performance of WNF alloy bullets suggests their potential to improve the ballistic performance and durability of small arms ammunition. The reduced tool wear and favorable machining parameters highlight WNF alloy's advantages for military and defense applications. A ballistic impact analysis using a finite element method (FEM) model in Abaqus software further supports the potential of WNF alloy bullets, providing a solid foundation for future advancements in bullet manufacturing technologies. [ABSTRACT FROM AUTHOR]

Injection moulds are crucial to produce plastic and lightweight metal components. One primary associated challenge is that these may suffer from different types of failures, such as wear and/or cracking, due to the extreme temperatures (T), thermal cycles, and pressures involved in the production process. According to the intended geometry and respective needs, mould manufacturing can be performed with conventional or non-conventional processes. This work focuses on three foremost alloys: AMPCO® (CuBe alloy), INVAR-36® (Fe-Ni alloys, Fe-Ni36), and heat-treated (HT) steels. An insight into the manufacturing processes' limitations of these kinds of materials will be made, and solutions for more effective machining will be presented by reviewing other published works from the last decade. The main objective is to provide a concise and comprehensive review of the most recent investigations of these alloys' manufacturing processes and present the machinability challenges from other authors, discovering the prospects for future work and contributing to the endeavours of the injection mould industry. This review highlighted the imperative for more extensive research and development in targeted domains. [ABSTRACT FROM AUTHOR]

Build-up-edge (BUE), high-temperature machining and tool wear (TW) are some of the problems associated with difficult-to-machine materials for high-temperature applications, contributing significantly to high-cost manufacturing and poor tool life (TL) management. A detailed review of non-traditional machining processes that ease the machinability of INCONEL®, decrease manufacturing costs and suppress assembly complications is thus of paramount significance. Progress taken within the field of INCONEL® non-conventional processes from 2016 to 2023, the most recent solutions found in the industry, and the prospects from researchers have been analysed and presented. In ensuing research, it was quickly noticeable that some techniques are yet to be intensely exploited. Non-conventional INCONEL® machining processes have characteristics that can effectively increase the mechanical properties of the produced components without tool-workpiece contact, posing significant advantages over traditional manufacturing. [ABSTRACT FROM AUTHOR]

Glass vias are emerging as a favourable option for radiofrequency-based micro-electromechanical system packaging. For the micromachining of glass, electrochemical discharge machining (ECDM) could be the most suitable technique if issues pertaining to the process stability are addressed thoroughly. The electrolyte temperature has immense influence on the viscosity and conductivity of the electrolyte, which percolate the stability of the ECDM process. Therefore, this article investigates the effects of the electrolyte temperature and applied voltage on the performance characteristics of ECDM for the micromachining of borosilicate glass. The machining rate (MR) and hole overcut (HOC) of the machined microholes are considered as performance characteristics. A 3D thermal-based finite element model (FEM) was developed for the thermal analysis in the machining zone. In the thermal analysis, the heat flux by thermal discharge was assumed to have Gaussian distribution, and accordingly, temperature profiles in the thermal zone were analyzed by controlling the electrolyte temperature and voltage at various levels. Further processing of temperature profiles in the thermal zone was utilized in the estimation of MR and HOC. Electrostatic-based FEM was utilized to assess the intensity of the electric field in the proximity of the tool electrode to analyze the probable locations of thermal discharge and its impact on the geometrical characteristics of the machined microholes. The simulation outcomes were validated experimentally, and show good agreement. A field emission electron microscope with energy dispersive spectroscopy was used for the characterization of the machined surface to observe the effect of the electrolyte temperature. [ABSTRACT FROM AUTHOR]

The engine casing components operate in high-temperature and high-pressure environments. Process holes are drilled when defects occur. Welding is employed in the repair of process holes as a process for permanently joining materials. The traditional welding method relies on padding, which results in poor back formation of process holes. Additionally, the shape of the process holes imposes high requirements on the size of the droplet transition. The conventional approach of adjusting a welding current makes it difficult to achieve stable droplet transition and precise formation of small holes. It poses a challenge for the robotic welding process. To deal with this problem, the influence of the high-frequency vibration GTAW process on the directional transition of molten droplets is studied. The molten droplet directional transition process is developed. The impact of vibration energy on the molten pool is reduced. Welding repair experiments for process holes are successfully conducted. When the frequency is 3 Hz, the transition of droplets changes from a continuous one-droplet transition to a discontinuous liquid bridge transition. The residual height and mechanical properties of the repaired area are tested. The experimental results indicated that the residual height after dual-side repair is ≤0.7 mm. The X-ray and fluorescent penetration tests have a 100% first-pass qualification rate. The repaired area demonstrates a hardness of 480 HV and a room-temperature tensile strength of 1069 MPa. The repair process requirements for the casing are met. [ABSTRACT FROM AUTHOR]

In the recent development of high-performance gas turbine engine, there is a tendency to design the cooling holes in order to improve the heat transfer and cooling efficiency. Titanium alloy is the most preferred material for these blades. It is hard material, and hence, the traditional drilling is not appropriate for "Ti" alloy. This research presents the design and optimization required to manufacture contoured holes on a titanium-based superalloy using hybrid electrochemical machining (ECM) under different operating conditions. The circular holes are developed and are analyzed by ANOVA. The experimental results are further optimized using a Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method. The voltage (V), feed rate (f1), and feed rate (f2) were identified as the most influencing factors which are further used for stepped circular hole machining. A design of the experiment is also optimized using the TOPSIS method. The obtained experimental results are verified using a SEM analysis to confirm the uniformity of the machined surfaces and the inverse relationship of the overcut with the increasing values of the voltages and feed rates. Optimal machining conditions for the stepped hole machining were determined for voltage 18 V, feed rate "f1" at 0.8 mm/min, and feed rate "f2" at 1.35 mm/min. [ABSTRACT FROM AUTHOR]

Fabrication of surface features like effusion holes on ultra-high temperature (UHT) alloys with micro electro-discharge machining (μ -EDM) is a very convolute strategy. Due to the exceptional mechanical properties and resistance to ease brittle transformation at elevated temperatures, UHT alloys are being widely used in hot sections of aero engines. This research tailored the existing capabilities of μ -EDM setup by employing a copper-tungsten (Cu-W) hybrid tool electrode which has been rarely reported. This research addresses investigations, predictive modeling, and optimization during μ -EDM of UHT alloy, namely Inconel 718. For experimentation, the factors like inter-electrodes gap (IEG), current (I), and pulse on/off time (T on, T off) were considered as input variables to analyze the responses like overcut (OC), tool wear rate (TWR), material removal rate (MRR), and diametric alterations in between the top and bottom shape of holes' feature (DE). The multi-objective desirability-based artificial bee colony optimization (MOABC) projected optimal parametric settings of 5.276 A, 16.389 μ s, 1.77 μ s, and 50 μ m for I , T on, T off, and IEG, respectively. These settings provide MRR, TWR, OC, and DE solutions of 0.001479, −0.00038, 0.030239, and 0.047048 mm, respectively. Further, the confirmation test has been performed to validate the optimal solution. The results supported the ideal settings with error values of 0.03177, 1.31578, 0.05863, and 0.04704 for MRR, TWR, OC, and DE, respectively. Distinctive diagnostic tests assessed by several statistical parameters (P , F , R 2, AD-P values) confirmed that the accuracy of developed models for prediction of various performance characteristics has high degree of resemblance with experimental results and the adequacy as well as accuracy of models is also demonstrated. Moreover, the surface morphology has also been scrutinized by microscopical observation to perceive the consequences of the electro-discharge phenomenon on both electrodes. Overall, the research comprises experimentation, surface integrity study, and parametric optimization followed by a confirmation test to perform the betterment of the current μ -EDM approach. [ABSTRACT FROM AUTHOR]

Owing to its non-conducting nature, Through Glass Vias (TGV) is a new paradigm to reduce the losses in high-frequency transmission systems. However, due to brittleness and non-conducting nature, micro-machining of glass is challenging. In the backdrop of limitations of the existing processes, Electro-chemical Discharge Machining (ECDM) is an evolutionary micro-machining process for brittle and non-conducting materials, like glass. ECDM is a hybrid of electro-chemical and electro-discharge processes. During machining in ECDM, poor flushing coupled with poor replenishment of electrolyte deteriorates the Energy Utilization Behavior (EUB), particularly in hydrodynamic regime. Therefore, the present article deals with a novel approach (using a magnetic stirrer) of Temperature-assisted ECDM (termed as T-ECDM) to improve the energy utilization behavior in the micro-machining of borosilicate glass. The T-ECDM approach has the capability to control the temperature and stirring rate of the electrolyte. The Machining Rate (MR) as well as Aspect Ratio (AR) of micro-hole are considered as the desirable performance indicator, while Tool Wear Ratio (TWR) and Heat-Affected Zone (HAZ) are considered undesirable performance indicator of EUB. The experimental investigation indicated the improvement in Overall Energy Utilization Index (OEUI) by T-ECDM as compared to ECDM. The morphological, composition analysis, and surface profiles of micro-hole witnessed the improved flushing and etching in T-ECDM than ECDM that resulted in better surface finish of the micro-hole. It implies better energy utilization behavior in terms of surface characteristics also. [ABSTRACT FROM AUTHOR]

Improving material removal rate and surface quality are the key issues in macro-electrolyte jet machining. The current density of the workpiece surface significantly influences material removal rate and surface quality. A novel tool with the rear-end tilted is proposed to increase the current density of the workpiece surface. The flow field simulation results demonstrate that, in comparison with standard tools, the tool with the rear-end tilted not only enables the rear-end contact with electrolyte but also enhances the rear-end electrolyte flow rate. The electric field simulation results showed that, in comparison with standard tools, the tool with the rear-end tilted enabled the rear-end to participate in the electrochemical dissolution of the workpiece surface and increased the current density of the workpiece surface. The experimental results show that the material removal rate of the workpiece is increased by 27 % and the surface roughness Ra is reduced from 6.71 μm to 2.52 μm by tools with a rear-end tilt angle of 15° compared with the standard tool. In addition, when a tool with a rear-end tilt angle of 15° is used to process the plane structure, the protrusion phenomenon of tool marks at the intersection of parallel trajectories with a step-over of 9.25 mm is the smallest, with a protrusion phenomenon of 0.092 mm. • An appropriate tilt angle of the tool rear-end enables the tool rear-end to contact the electrolyte and engage in the electrochemical dissolution of the workpiece surface, thereby improving the current density of the workpiece surface. • The experimental results show that compared with standard tools, tools with a rear-end tilt angle of 15° increase the workpiece MRR by 27 %, and the workpiece surface roughness Ra decreases from 6.71 μm to 2.52 μm. • When a tool with a rear-end tilt angle of 15° is used to process the plane structure, the protrusion phenomenon of tool marks at the intersection of parallel trajectories with a step-over of 9.25 mm is the smallest, with a protrusion phenomenon of 0.092 mm. [ABSTRACT FROM AUTHOR]

Unconventional machining methods include electrochemical micromachining (EMM). EMM is suitable for hard and difficult-to-cut materials used in the manufacture of special forms of machine parts used in aeronautics and hydro pneumatic machinery. As a result of a set of electrical, mechanical and chemical parameters, the EMM process is a very complex process. The analytical modeling of the method is therefore difficult. The artificial neural network (ANN) significantly simplifies the relationship between input and output parameters due to the large number of measurements required. With a set of data containing very different machining parameter choices, the neural network was trained. This paper presents the results obtained for predicting certain output parameters. The ANN is used in this paper to determine the model for parameter optimization. To represent the relationship between machining rate (MR), overcut (OC) and input parameters, an ANN model has been established that adapts the Levenberg-Marquardt algorithm and Bayesian regularization (LMABR). The model is shown to be efficient, and optimized machining parameter improves the MR and OC. [ABSTRACT FROM AUTHOR]

The machining of extremely hard material in conventional machining requires high energy. Therefore stress-free, burr-free, and high-accuracy machining technique like Electro Chemical Micro Machining (ECMM) with extra features is recommended. To improve efficiency, various electrolytes such as Magnet Associated Electrolytes (MGAE), Metal Particle Mixed Electrolytes (MPME), and Carbon Pellets Mixed Electrolytes (CPME) are employed. The micro-holes were drilled over the work material MONEL 400 alloy. The parameters for the studies are electrolyte type, concentration (g/l), machining voltage (V), and duty cycle (%). The responses of ECMM are estimated through material removal rate (MRR) in μm/sec and overcut in μm. The results are optimized using Multi-objective optimization based on ratio analysis (MOORA) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR). Both techniques produce the same optimal parameter, 18th experiment CPME, 50% duty cycle, 11 V machining voltage, and 28 g/l electrolyte concentration. It is the best optimal parameter solution for machining. According to the ANOVA table of both, the type of electrolyte plays a 62.6% and 60.37% contribution, respectively, to machining performance. Furthermore, the scanning electron microscope (SEM) image analysis perused on the micro holes to extend the effect of different electrolytes on machining surfaces. [ABSTRACT FROM AUTHOR]

This work investigates the combination of wire electrical discharge machining (Wire EDM) and wire electrochemical machining (Wire ECM) in a single medium to obtain good surface quality and dimensional accuracy without sacrificing productivity. The experimental setup is evaluated with respect to the deviations in the profile accuracy and surface roughness. The developed strategy is validated and findings suggest that Wire ECM requires an accurate starting contour, obtained by first preparing the surface using Wire EDM. Results indicate the feasibility of the hybrid platform, combining the good accuracy (5 µm) and good surface finish (< 0.5 µm Ra) of either process. [ABSTRACT FROM AUTHOR]

Nonconventional machining processes like Electrochemical micromachining (ECMM) provide better surface finish without thermal and mechanical defects on the workpiece surface, which is generally found in other processes like electron beam machining (EBM), electric discharge machining (EDM), plasma arc machining (PAM), electrochemical spark machining (ECSM) and laser beam machining (LBM) processes, etc. ECMM process is well recognized for the production of µ-channels, high aspect ratio µ-holes, and other complex microstructures on hard-to-cut elements like copper, stainless steel, titanium, and other superalloys, which find wide application in the space of MEMS, automotive, aviation, biomedical and electronics with requisite surface finish. Moreover, hybrid ECMM processes are capable of machining novel materials which may not be otherwise possible using traditional manufacturing techniques. This review includes details of the µ-ECM process capabilities, hybrid machining processes, and current research trends in the ECMM field with an emphasis on machining of miniaturized parts used in various industries. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is a contemporary electrochemical energy-based machining practice that has widely been attempted for the productive processing of a vast range of typical engineering materials, namely, composites and difficult-to-process advanced materials. In the present work, an attempt has been made to critically review and report the previously investigated studies and research in the domain of machining numerous materials with electrochemical machining and its other allied methods. This work also deeply explores the various theoretical, experimental, modeling-based, and optimization-related research studies carried out in the broad domain of ECM for finding out the most effective and conclusive outcomes with the overall process improvement with the support and quality selection of machine, tool materials, electrolyte flow, and some other operating parameters. While shifting from macro- to micro-electrochemical machining, numerous investigations have been reported in the literature that have been targeted to enhance the overall machining performance and the measures. Among the numerous acquirable modifications in assisted ECM as employed in research and developments and industries, vibration-assisted ECM has been revealed as a more sturdily established ECM variation as compared to other explored versions such as abrasive Jet-ECM, magnetic-assisted ECM, and laser-assisted ECM. Furthermore, the in-depth discussion about jet-assisted ECM and wire ECM has also been reported, along with the considerations of several impactful process inputs. The concluding section of this article explores the several developments made in wire and micro-ECM processes and layouts the issues and directions for further research. [ABSTRACT FROM AUTHOR]

This study examined the impact of vibration-assisted drilling (VAD) on hole quality and residual stress in Ti-6Al-4V ELI (Extra Low Interstitials) material. Ti-6Al-4V ELI possesses excellent mechanical properties but presents challenges in machining, including chip evacuation, burr formation, and elevated cutting temperatures. VAD, particularly low-frequency vibration-assisted drilling (LF-VAD), has been explored as a potential solution to address these issues. The research compares LF-VAD with conventional drilling (CD) under various cutting and cooling conditions. LF-VAD exhibits higher maximum thrust forces under specific conditions, which result in accelerated tool wear. However, it also demonstrates lower RMS (root mean square) forces compared to CD, offering better control over chip formation, reduced burr formation, and improved surface roughness within the hole. Furthermore, LF-VAD generates greater compressive residual stresses on the hole's inner surface compared to CD, suggesting enhanced fatigue performance. These findings indicate that LF-VAD holds promise for improving the hole's surface characteristics, fatigue life, and overall component durability in Ti-6Al-4V machining applications. [ABSTRACT FROM AUTHOR]

For electrochemical machining (ECM) to be stable and accurate, the electrolytic flow field is essential. To improve the flow field, numerous studies have been conducted. This review study offers various enhancements to aero engine blade flow approaches. This report illustrates three different flow field models: one where the solution of electrolyte is introduced at the starting and trailing edges, another proposal that takes into account the effect of gravity on bubbles according to the bubble dynamics analysis, and the final one that uses electrochemical trepanning as a method of machining to create a radial blade via a constant area. Combining modelling and investigations, the suggested methods were assessed. The outcomes of the investigation demonstrate the suitability and applicability of these flow patterns for producing aero engine parts. [ABSTRACT FROM AUTHOR]

Electrochemical machining was performed on two cemented carbides with different compositions using unipolar and bipolar short-pulse voltages to investigate the effects of the composition and pulse conditions on the machining characteristics. In the case of cemented carbides with high cobalt and low tungsten carbide (WC) contents, machining progressed even when a unipolar voltage was used. This is believed to be due to the dissolution of the binder, that is, Co, which causes the WC and WO3 particles to drop out. Machining progressed more easily when a bipolar voltage was used than when a unipolar voltage was used. This is attributed to the effective removal of WO3. The unevenness of the machined surface was also reduced with bipolar voltage. The negative pulse duration had to be sufficiently but appropriately long, because too long a duration increased the wear of the tool electrode. Even when bipolar pulse voltages were used, similar to the machining of general materials, a shorter positive pulse duration resulted in more precise machining. However, in the case of cemented carbide with low Co and high WC contents, the removal did not progress when a unipolar pulse voltage was applied. On the other hand, the machining progressed when a bipolar voltage was applied. However, if the positive pulse duration was excessively long, the amount of removal decreased. This is believed to be because the longer positive pulse duration increased the amount of WO3 generated, thereby inhibiting the current flow. Therefore, it is necessary to set an appropriate positive pulse duration to avoid the excessive production of WO3. [ABSTRACT FROM AUTHOR]

Due to its extremely high optical uniformity and excellent hot stability, glass–ceramic serves as a key material for ultraprecision imaging of lithography lens, and low‐deformation machining is of significance for achieving high‐quality surface. Aiming at controllable processing, the annealing of different nanoscratches on glass–ceramic was investigated for revealing the mechanism of material removal and damage repair. The volume change of the single‐pass nanoscratch under various normal loads and sliding velocities before and after the annealing was calculated for quantifying the contribution of shear flow, densification, and residual stress to the material removal, respectively. It is found that ductile removal under high normal load or low sliding velocity is dominated by shear flow, thereby improving removal efficiency and reducing machining deformation and defects caused by densification and residual stress. The changes of microstructures beneath the scratches before and after annealing further reveal that the excess processing energy will be absorbed in glass–crystal interface and form micro‐cracks on crystal surface. For comparison, brittle removal under variable cycles was simulated by multi‐pass nanoscratches, and it reveals that the shear flow ratio raises gradually with the increase of cycle number. These findings provide theoretical guidance for ultraprecision processing of glass–ceramic surfaces. [ABSTRACT FROM AUTHOR]

Electrochemical micromachining (ECMM) is an important machining process for machining materials susceptible to produce burrs during contact machining process. In this research copper plate of thickness 2mm and tool electrode of 464pm were machined through ECMM process under the sodium nitrate electrolyte (NaNO3). The tool electrode is coated with ceramic material and prevent stray current and chemical attack. The control factors namely, voltage, electrolyte concentration and duty cycle are varied on machining time and overcut. Higher voltage of 12V takes 1 minute to complete the through hole and the use of ceramic coated tool produces good arc on the circumference of the micro-hole and 65% reduction of overcut. The suitable range of electrolyte concentration for reduced machining time is 24 to 26g/lit. As per TOPSIS analysis, 10V, 24g/lit and 65% duty cycle and 11V, 24g/lit and 75% are the best optimal combinations. ANOVA results show that voltage and electrolyte concentration are the most significant factors with 57.73% and 28.83% contribution, respectively. [ABSTRACT FROM AUTHOR]

The effect of graphite powder on the machining characteristics in graphite-powder-mixed electrochemical discharge machining of microholes was still not clear. How the discharge mechanism changed with the addition of graphite powder into the electrolyte, which further led to changes in the morphology of the machined holes, remained to be revealed. In this study, a series of microhole machining experiments were conducted in glass. Comparisons of the discharge energy, microhole entrance diameter, hole taper, and tool electrode morphology after machining were made when machining in the electrolytes with and without graphite powder. Experimental results revealed that there were a lot of small pulse currents distributed on the current waveform when machining with the graphite-powder-mixed electrolyte. The average discharge energy of the small pulse current was 2.8 times as much as that of the general electrochemical discharge. After introducing graphite powder into the electrolyte, the entrance diameter of the hole became larger when the hole depth was deeper than 200 μm. The HAZ width increased with increasing hole depth at the voltage of 37–41 V, while it decreased at the voltage of 43 V. A reduction in hole taper angle with a range of 0.5° to 2.3° was achieved. In addition, after machining in electrolytes with and without graphite powder, the tool electrode surfaces showed different morphologies due to different discharges. [ABSTRACT FROM AUTHOR]

In the recent past, through the exact patterning and refinement of the microstructure, cryogenic treatment considerably improves the mechanical properties of the materials. Cryo-processing improves dimensional stability and wear resistance in aerospace, tool, and die industries. The impact of cryogenically treating wire electrodes on WEDM performance parameters are investigated in this work. Utilizing various wire electrodes, including molybdenum, deep cryo-treated, and untreated brass wire, analysis was done on the machining performance, including MRR, SF, and KW. The experimental results show cryogenically treated wire has advantages over untreated, including better surface quality, a higher material removal rate (MRR), and increased conductivity. Cryogenic treatment of wire electrodes reduces residual stress and improves atomic bonding, improving WEDM machining performance. Cryogenically treated wire improved MRR by 4.48% and 1.64% over molybdenum and plain brass wire, respectively. Plain brass wire had a superior surface finish than cryogenic-treated and molybdenum wire by 1.15% and 2.20%, respectively. [ABSTRACT FROM AUTHOR]

Reducing pulse duration is the sole effective strategy to improve the processing accuracy in ultra-short pulse electrochemical microfabrication. High cost and unsuitability in practical production also restrain its development. This study aims to propose a method based on sinusoidal signals with variable resistance. The bilayer capacitor cannot be fully charged to achieve a transient machining state. An equivalent circuit differential equation is established, and the resistance becomes an effective parameter to control the machining accuracy. The experimental result shows that the machining accuracy increases significantly with the increase in resistance. The approach is applied to machine microstructures and achieves sub-micron scale accuracy on a pure nickel sheet. The same superior machining accuracy can be obtained by machining microstructures on hard-to-cut superalloy plates. [ABSTRACT FROM AUTHOR]

Gamma titanium-aluminum intermetallic compounds (γ-TiAl) have an important application significance in the field of aero-engines owing to their excellent mechanical properties (e.g., high-temperature resistance and high toughness). Grinding as an important method was used to realize the high efficiency and precise machining for difficult-to-cut materials. However, the machining defects (e.g., adhesion, cracks, and even burns) were confronted on the machined surface of γ-TiAl materials under high grinding force and temperature loads. In this case, the new machining methods combined with ultrasonic vibration and high-efficiency deep grinding technology were proposed to improve the machining quality and efficiency. Comparative trials of ultrasonic vibration-assisted high-efficiency deep grinding (UVHEDG) and high-efficiency deep grinding (HEDG) were carried out to study the grinding performance, in terms of the grinding force, grinding temperature, specific grinding energy, and machining surface quality. Results show that UVHEDG possesses the lower grinding force and temperature by 38.69% and 39.05% compared with HEDG, respectively. In addition, the employment of ultrasonic vibrations contributes to maintaining the abrasive sharpness, and thus, the specific grinding energy is reduced by 23.95%. Ground surface roughness can be reduced by 19.53%, and the grinding surface quality is effectively improved due to the lubrication effect and track overlap effect under ultrasonic vibration. [ABSTRACT FROM AUTHOR]

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There are two main ways of carrying out the electrical discharge machining of the insulating ceramics: changing the electrical and chemical properties of ceramics due to additives in producing composites/nanocomposites and changing the electrical and chemical properties in the interelectrode gap. This review summarizes and analyzes the current data on the machinability in water suspension and hydrocarbons depending on the electrical properties of the ceramic composites and assisting means such as coating and powder. There are provided the existing approaches and original methods for solving the global problem of the electrical discharge machining of insulating ceramics, suggesting further development of the existing methods since, up to now, the experimental research is non-systemic. The dependencies of the machinability on the electrical properties of conductive ceramic composites, the specific electrical resistance of the assisting coating, and the assisting powder's band gap and concentration for machining insulating ceramics are revealed. The higher the electrical conductivity, the higher the machinability of ceramic composites, and the lower the band gap, the higher the machinability for insulating ceramics. Two technological gaps were revealed in the powder's concentration that can be a particular case of logarithmic decrement of attenuation. The proposed approach suggests using assisting powder with the lower band gap. [ABSTRACT FROM AUTHOR]

Turning is a drastically favoured machining process for producing cylindrical components with required dimensions. Prediction of chip formation is essential when damages caused by chips are into consideration during machining. A high amount of residual stresses are generated in the machined component due to a large number of forces and temperature distribution during machining. The scope of this paper is to investigate the percentage of residual stresses induced in a component during the dry micro turning process. Hence, in this work, Inconel 718, A2024-T351, and AISI D2 (62HRC) are selected as a workpiece materials and WC as tool material, simultaneously comparison studies of chip morphology have been carried out. Also, cutting speed and power consumption were investigated experimentally by opting varied tool rake angles (positive, negative, and zero) and a depth of cut. Residual stresses, nose wear, and chip morphology were found experimentally while machining Inconel 718. From the simulation and experimental results obtained, one can adopt a suitable tool rake angle to minimise power consumption during the micro turning process which leads to a sustainable machining process. [ABSTRACT FROM AUTHOR]

This study investigated the machining characteristics of two shapes of diamond grit – coated tools used in grinding-aided electrochemical discharge machining for optical glass drilling. The effects of roundness, machining accuracy, surface roughness, and tool wear under various machining depths and electrode rotating speeds were explored, and the bubble generation mechanism and its effects on the discharge current waveform and electrochemical discharge reaction were observed. This study revealed that the bubbles generated in the gaps between diamond particles combine with each other to form a stable bubble film. Owing to differences in bubble generation mechanisms, the discharging waveform of the diamond grit – coated tool was more stable than that of tools without diamond grit – coated. It is known from the experimental results that the diamond grit – coated ball end mill in this method minimized shape roundness errors, machining time and the fracture of the exit edge. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present scenario, electrochemical arc machining (ECAM) (hybrid of electric discharge erosion and electrochemical dissolution) is an evolving procedure for difficulty in machining the materials due to constraints of existing processes. This research aims to investigate the machinability of Ni 5 5. 7 Ti alloy through electrochemical arc drilling using molybdenum electrode. Electrolyte concentration (ethanol with ethylene glycol and sodium chloride), supply voltage, and tool rotation are considered as the variable factors to evaluate the ECAM performance characteristics in drilling blind hole operation concerning overcut (OC), tool wear rate (TWR) and materials removal rate (MRR). Consequently, response surface methodology is implemented for predictive modeling of various performance characteristics. Finally, multi-objective optimization through desirability function approach (DFA) has produced a set of optimal parameters to improve the productivity along with the accuracy, which is the prime requirement for the industrial applicability of the ECAM process. Results demonstrated that supply voltage is the influential key factor for improvement of machining rate. Scanning electron microscope (SEM) photographs revealed the development of heat affected zone (HAZ), white layer, melted droplet, craters, re-solidified material, ridge-rich surface and voids as well as cavities around the end-boundary surfaces of a blind hole. Composition analysis through energy dispersive spectroscopy (EDS) indicated the oxygen content on the machined surface because electrolyte breakdown causes oxidation to take place at elevated temperatures across the machining zone. Moreover, carbide precipitation like TiC was found in the melting zone of the drilled hole, as revealed by X-ray diffraction (XRD) analyses, which has the affinity to reduce the SMA properties in HAZ. [ABSTRACT FROM AUTHOR]