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High-precision surface of 201 stainless steel obtained by electrochemical micro-machining without or with magnetic field-assisted was studied by combining experiments and simulations. The results demonstrated that the surface roughness of the samples was reduced to 0.40 μm after 18 min electrochemical micro-machining. Besides, the introduction of the magnetic field further improved the surface accuracy and reduced it to 0.20 μm. At the same machining time, the magnetic field-assisted electrochemical micro-machining provided lower surface roughness, which indicated that the magnetic field had a favorable impact on the improvement of machining efficiency. Additionally, the distribution characteristics of magnetic induction lines in the machining gap were also discussed. When the magnetic induction lines were approximately parallel to the anode surface and perpendicular to the electric field, the processing efficiency was further improved. The simulation results showed that the current density on the anode surface and the mass transfer rate of the electrolyte were enhanced by the existence of the magnetic field, which accelerated the electrochemical reaction behavior. The external permanent magnet contributed magnetohydrodynamic force during electrochemical micro-machining promoting the occurrence of magnetohydrodynamic convection. Consequently, the charge and the mass transfer in electrolyte was expedited, indicating the improvement of processing efficiency. [ABSTRACT FROM AUTHOR]

Visual examination of the surface topography, in conjunction with the other sensors, may confirm the existence of chatter. Online chatter detection during real machining operations is possible with the use of sensors, and the presence of noise in their output and restricted bandwidth are the major drawbacks of these sensors. Productivity drops and manufacturing costs go up when there is a lot of chatter in the machining process. In the present paper, an integrated spindle tool system is modeled using finite element method with Timoshenko beam theory including rotational and shear deformation effects. To maximize the average stable depth of cut in an end milling process while simultaneously minimizing the chatter vibration levels, real time and offline strategies have been investigated. Machining experiments performed on Al6061-alloy specimens provide an empirical confirmation of the stability boundaries. The surface topography methods such as scanning electron microscope (SEM) and optical microscope images along with vibration levels are considered, to identify chatter marks under various machining conditions, which helps to assure cutting process stability. Stability lobe diagrams are plotted with these derived conditions and observed at an incremental level in the axial depths of the cut. The methodology shown in this paper improves the machining stability of the end milling with the reduction in the tool tip vibrations. [ABSTRACT FROM AUTHOR]

Tool condition monitoring is an important basis to ensure workpiece quality and machining efficiency. It is also a key factor in improving machining efficiency, ensuring machining accuracy. Therefore, a new method for predicting tool wear based on DenseNet-ResNet-GRU is proposed. Firstly, statistical theory and an improved wavelet threshold denoising method are used to improve the signal quality. In addition, the asymptotic semi-soft threshold function is applied to reduce the noise of the cutting force signal. Secondly, DenseNet, ResNet, and GRU (gate recurrent unit) deep learning networks are integrated to create a new tool wear prediction model to realize the nonlinear mapping relationship between the tool wear amount and the cutting force characteristic. Finally, the tool wear prediction model is verified by high-strength steel experiment. The experimental results verify the accuracy and reliability of the method, which has a better training effect and higher prediction accuracy compared with the CNN-GRU model. [ABSTRACT FROM AUTHOR]

In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 μ s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be L 2 L 1 L 1 , L 3 L 1 L 1 , L 1 L 3 L 3 , and L 1 L 1 L 2 , respectively. Based on the ANOVA results, the R 2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively. [ABSTRACT FROM AUTHOR]

For nickel (Ni) superalloys, including Inconel 738, electrochemical machining (ECM) is commonly used. However, the mechanisms behind ECM surface flattening and improved surface quality have not been fully elucidated, and the relationship between corrosion and ECM is weakly established without microstructural correlation. To bridge this knowledge gap, we have systematically investigated the electrochemical dissolution behavior of wrought Inconel 738 superalloy in the selected NaNO3 solution and narrowed down the optimal ECM parameters (i.e., 12 V, 0.8 mm/min, and 0.8 MPa). The results show that the precipitates and secondary phases of the Inconel 738 superalloy dominate the final surface quality and the ECM efficiency. Importantly, we have confirmed that a core–shell precipitate phase with shell-layer Ti and Mo enrichment remains on the surface even after the 12 V ECM, limiting the final roughness. This novel finding clarifies why the morphology differs under two representative conditions (i.e., anodic dissolution at 1.3 V, 1500 s and optimal ECM with 12 V, 0.8 mm/min, and 0.8 MPa), and how the core–shell precipitates evolve during the non-equilibrium 12-V ECM condition leads to a totally different flattening process. This ECM analysis method, with solid electrochemical theory and detailed microstructural investigation, reveals the microstructure-dependent ECM flattening mechanisms at precipitate scale and demonstrates how the microstructures influence the ECM processing quality. This novel finding plays a guiding role in improving the quality of ECM processing, shows great value for various industrial applications, and helps strategically break the current surface roughness limit. [ABSTRACT FROM AUTHOR]

Electrochemical micro-Machining (ECMM) is best suited for machining micro level profiles as it provides several advantages like better precision, less wear and machinability of wide range of materials. Micro level holes in Stainless Steel 316 are generally present in surgical equipment like syringe, suction tips and surgical suture etc. Using various levels of process parameters like voltage, electrolyte concentration, frequency and duty cycle, electrochemical micro machining was performed using untreated and cryogenic treated electrodes and its effect on various response parameters while machining Stainless Steel 316 are studied. From the results obtained, the cryogenic treated tool electrode had a high MRR, 9.8 % of lower overcut, 11.2 % of lower conicity and 3.8 % 0f higher circularity compared to untreated tool electrode because the treated tool has high electrical conductance, high corrosion resistance and smaller grain size. The optimized values for Cryogenic Treated tool was achieved when applied voltage was 10V, electrolyte concentration was 30 g/L, frequency was 50 Hz and duty cycle was 33 %. [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]

In this review, recent advances regarding the integration of machine learning into electrochemical analysis are overviewed, focusing on the strategies to increase the analytical context of electrochemical data for enhanced machine learning applications. While information-rich electrochemical data offer great potential for machine learning applications, limitations arise when sensors struggle to identify or quantitatively detect target substances in a complex matrix of non-target substances. Advanced machine learning techniques are crucial, but equally important is the development of methods to ensure that electrochemical systems can generate data with reasonable variations across different targets or the different concentrations of a single target. We discuss five strategies developed for building such electrochemical systems, employed in the steps of preparing sensing electrodes, recording signals, and analyzing data. In addition, we explore approaches for acquiring and augmenting the datasets used to train and validate machine learning models. Through these insights, we aim to inspire researchers to fully leverage the potential of machine learning in electroanalytical science. [ABSTRACT FROM AUTHOR]

Grinding of silicon nitride ceramics has been seen the existence of processing problems such as low processing efficiency and high grinding forces. In response to the problem, this paper mainly analyzes the processing mechanism of the laser-assisted grinding process, simulates the grinding process of a single abrasive grain grinding the surface of the silicon nitride microgroove through the coupled simulation of the smooth particle hydrodynamics (SPH), and finite element method (FEM), and analyzes the change of the material removal process with the grinding force and the depth of damage. The simulation results show that the grinding force and damage depth are significantly reduced when the abrasive grain cuts in the position of microgroove proximity due to the change of microstructure on the crack extension direction. An indentation experiment was carried out on silicon nitride ceramics, when the indenter was pressed in the closer position of the microgroove, the diagonal crack of the indentation would be extended to the side of the microgroove, which showed reasonable agreement with simulation results. It also proved that the laser heat source had a softening effect on the material. Two kinds of microgroove surfaces with different groove spacings were designed, and the laser-induced surfaces were subject to grinding experiments. The experimental results show that compared with the non-groove surface, the micro-grooved surface can significantly reduce the grinding force and improve the machining efficiency, and modifying the parameters of the grinding process can impact the effectiveness of laser-assisted grinding in reducing grinding force. [ABSTRACT FROM AUTHOR]

Extrusion tapping (ET) poses a technical difficulty when processing internal threads with large depth, small diameter, and high-precision blind hole. In addition, conventional ET (CET) of Ti-6Al-4V small internal blind-hole threads with large length-to-diameter ratio is challenging given its small elastic modulus, large deformation resistance and easy cracking in cold forming. To this end, a novel longitudinal–torsional ultrasonic vibration–extrusion tapping (LT-UVET) is proposed to address the technical problem of these threads. On the basis of ultrasonic longitudinal–torsional vibration characteristics, the motion trajectory equations of LT-UVET were deduced. The motion model of LT-UVET was established, and the intermittent extrusion law and force state between the tap extrusion edge and the processed material were explored and studied. Furthermore, tapping experiments were conducted to compare the differences in torque, thread quality, microhardness, and tap wear obtained by CET and LT-UVET. The influence of different tapping speeds on the thread was studied through singlefactor experiment. According to experimental findings, the maximum tapping torque was reduced by 9 %–26 % compared with CET. Moreover, the surface integrity and the profile of the thread were improved. The overall microhardness of threads increased by 3 %–17 %. The wear area of the tap lobes in LT-UVET is reduced by 65 % compared with that of CET. Therefore, the introduction of longitudinal–torsional ultrasonic vibration into the extrusion zone enhances the machinability of Ti-6Al-4V, which in turn improves the quality of extruded threads and increases the efficiency of thread machining. [ABSTRACT FROM AUTHOR]

The lubricating medium of the aerostatic spindle is gas, with relatively low rigidity, which is easy to cause rotor offset and additional vibration under the action of external load, thus affecting the processing accuracy of the spindle. To solve the problem of unbalanced vibration of the spindle, a new type of controllable radial aerostatic bearing is designed by combining piezoelectric ceramics, which use the inverse piezoelectric effect of piezoelectric ceramics to squeeze the air film to produce corresponding control force, and the radial unbalanced vibration of the spindle is suppressed. A bearing–rotor–piezoelectric ceramic coupling model was established, and the control method of feedforward combined with feedback was used to reduce the hysteresis characteristics of piezoelectric ceramics. On this basis, the sliding mode controller of the entire system, and through research, it is found that the sliding mode controller based on the extended observer has the best vibration suppression effect compared with other sliding mode controllers in the article; this research results can improve the rotation accuracy of the spindle system and the machining accuracy of ultra-precision machine tools. [ABSTRACT FROM AUTHOR]

Manufacturing internal splines with complex structures in high-hardness materials poses challenges in conventional machining processes. This paper introduced a new electrochemical machining (ECM) method using an assembled tool cathode with a cathode working teeth sheet with circumferential vibration for efficient and stable shaping of involute internal splines of intricate high-hardness components. A detailed design of the assembled tool cathode is presented, accompanied by flow field simulations analysing electrolyte distribution during circumferential vibration. A specific experimental system, fixture, and a used electrolyte filter module were constructed for spline ECM experiments. The results show that with the cathode feed rate of 2.7 mm/min, and the circumferential vibration frequency of 80 Hz, the involute internal spline profiles were successfully shaped with higher precision and efficiency with less appropriate allowance. • A novel ECM approach featuring an assembled tool cathode, equipped with teeth that vibrate circumferentially, is introduced for enhanced machining. • Circumferential vibration of the cathode is shown to improve electrolyte distribution in the area where tooth roots are machined, facilitating better machining outcomes. • An experimental ECM system for spline machining, complete with a dedicated fixture and a module for filtering used electrolyte, has been developed. • Utilizing a cathode feed rate of 2.7 mm/min and a vibration frequency of 80 Hz, precise involute internal spline profiles are achieved with minimized excess material. [ABSTRACT FROM AUTHOR]

GH4169 alloy/Inconel 718 is extensively utilized in aerospace manufacturing due to its excellent high temperature mechanical properties. Micro-structuring on the workpiece surface can enhance its properties further. Through-mask electrochemical micromachining (TMEMM) is a promising and potential processing method for nickel-based superalloys. It can effectively solve the problem that traditional processing methods are difficult to achieve large-scale, high-precision and efficiency processing of surface micro-structure. This study explores the feasibility of electrochemical machining (ECM) for GH4169 using roll-print mask electrochemical machining with a linear cathode. Electrochemical dissolution characteristics of GH4169 alloy were analyzed in various electrolyte solutions and concentrations. Key parameters including cathode sizes, applied voltage and corrosion time were studied in the roll-print mask electrochemical machining. A qualitative model for micro-pit formation on GH4169 was established. Optimal parameters were determined through experiments: 300 μm mask hole and cathode size, 10 wt% NaNO3 electrolyte, 12 V voltage, 6 s corrosion time. The results demonstrate that the micro-pits with a diameter of 402.3 μm, depth of 92.8 μm and etch factor (EF) of 1.81 show an excellent profile and localization. [ABSTRACT FROM AUTHOR]

During the machining process, problems such as tool wear, high temperature, force distribution, and surface quality deterioration must be fully understood. Control of these problems with experimental studies and numerical analyses is important in ensuring dimensional accuracy and surface integrity of the cutting tool, workpiece, and also the finished product. The aim of this study is to investigate the effects of machining parameters on chip morphology, residual stresses and tool wear in turning operations of ASTM-F75 CoCrMo alloy experimentally and by finite element method (FEM) simulation. The study was carried out at three different feed rates (0.1, 0.2, 0.3 mm/rev) and at a constant cutting speed of 80 m/min both experimentally on a CNC turning machine and with FEM simulation. From the obtained results, the formation of cracks and adhesions on the surfaces of the chip were observed due to the increase of the feed rate. According to the orthogonal cutting model, chip height ratio (Gs) and tooth pitch (Pc) values of saw-tooth chips supported each other with measurements taken from both FEM images and experimental images. With the increase of the forward speed, the Gs ratio decreased, while the Pc increased. In addition, microscopic images obtained from the cutting tool also showed that the rate of crater wear gradually increased with increasing feed rate. As a result, it is seen that machining parameters have a significant effect on cutting tool and chip morphology in CoCrMo ASTM-F75 alloy turning. [ABSTRACT FROM AUTHOR]

Machining of silica glass is a challenging task due to its physical properties like brittleness, electrically insulated, etc. Although with the use of electrochemical discharge, it is possible to make holes and channels in silica glass, but the generation of spark discharge and removal of materials is a complex phenomenon in the electrochemical discharge process. Several research works were carried out previously to control the spark discharge as well as machining accuracy using rotational tool, the addition of ultrasonic vibration, including a magnetic field, and the use of different electrolytes, etc. A novel tool feeding technique i.e. using a horizontal tool and vertically upward tool feeding technique was used during milling on glass. The effects of voltage, the tool feed rate (TFR) and the concentration of electrolyte on the material removal rate and machining quality were studied in this work. The machined channel was examined under an optical measuring microscope as well as scanning electron microscope. The machining surface was also observed using a coherence correlation interferometry image to analyze in-depth surface topography of machined channels. Material removal rate and Ra value of the bottom layer were measured. The material removal rate of 6.097 µg/min was noticed at 25 wt% of electrolyte concentration, 40 µm/s of TFR and 45 V of applied voltage. The bottom layer's surface roughness (Ra) was found as low as 0.222 µm (Ra) at parametric conditions of 40 V, 40 µm/s TFR, and 15 wt% electrolyte concentration by employing the developed novel tool feeding technique. [ABSTRACT FROM AUTHOR]

The electrochemical discharge machining (ECDM) is an advanced and promising technology for fabricating micro structures. This method is effectively applicable for non-conductive hard and brittle materials micromachining, such as glass and ceramics. However, the ceramics high melting point and intense heat exchange effects during microchannel fabrication lead to the easy dissipation of thermal energy and the difficulty in processing. To address this issue and expanded the ECDM processing range. This paper dedicated to the investigation of the material removal mechanism and process characteristics for the alumina ceramic surfaces microchannels preparation. Firstly, this study explained the difference of the ECDM critical applied voltage and gas film generation mechanism by analyzing the volt-ampere characteristic curve of 20 wt% NaOH electrolyte with a tool immersed depth of 2 mm and 10 mm respectively. Then, a thermal removal finite element model (FEM) for ECDM was developed. The heat cumulative and intermittent cooling effects applied on the alumina ceramic surface dominated the materiel removal. Additionally, it can be found that the microchannel machining accuracy and bottom surface quality depended on the Gaussian heat source characteristics, gas film formation mechanism, heat accumulation effect, and temperatures spatial and temporal distribution. And a series of single factor experiments for evaluating the parametric studies such as the effect of discharge frequency, applied voltage, duty ratio and tool feed rate on the fabricated microchannel performance are executed. Finally, the complex three-dimensional structures of cross microchannel grid and zigzag microchannel array with variable depth were successfully fabricated on aluminum oxide ceramic surface. Notably, the results highlighted and enriched the ECDM stability, consistency and applicability for alumina ceramic surface microchannel fabrication. [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]

Owing to the incapability of the existing techniques, Electrochemical Spark Machining (ECSM) is transpiring to micro machine the glass for potential applications in micro domain. However, in ECSM, the bubble accumulation and poor flushing lead to the generation of a non-uniform gas film, resulting in the deterioration of Hole Circularity (HC) and Surface Roughness (SR). Therefore, present communication is an attempt toward the concept of Rotary-Magnet assisted ECSM (RM-ECSM) to produce the micro holes in the borosilicate glass with better quality characteristics (higher HC and lower SR), which are required for better performance of glass vias in RF-MEMS. The evolutionary algorithm and Machine Learning (ML) have been adopted for optimization. From optimization, the values of optimal input parameters were obtained as follows: Applied voltage = 43.46 V; Electrolyte-temperature = 45.93 ֯ C; Pulse on time = 3.28 ms; Magnetic rotation = 551 rpm with corresponding values of HC and SR as 79.28% and 3 um respectively. Finally, these outcomes were validated by Levenberg-Marquardt algorithm (ML). [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining (ECDM) is a micro-machining hybrid technique that utilizes electrical discharge and electrochemical machining principles. However, the issue of insufficient electrolyte in the hydrodynamic region hinders the continuation of the machining action. Although ultrasonic tool vibrations have been used to overcome this problem to some extent, the excessive mechanical energy produced by high-amplitude tool vibration may lead to surface crack formations. As a result, the present work employs two flushing improvement methods, namely the ultrasonic vibrations and magnetic filed assistances, in the ECDM process. A comparative study has been performed to identify the effect of the magnetic field on discharge quality. The material removal rate and depth of penetration were increased by 11% and 24%, respectively, and the observed reduction in hole overcut and taper angle was around 35% and 50%, respectively. Optical microscope images quantified improvement in dimensional accuracy and decreased HAZ area. [ABSTRACT FROM AUTHOR]

Higher accuracy and meticulousness are highly demandable in modern industrial field during micro-machining performances by electrochemical discharge machining (ECDM) process. The paper deals with the experimental fuzzy logic control (FLC) analysis as well as artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) analysis during micro-channel fabrication on silica glass. A comparative analysis of FLC, ANN as well as ANFIS has been performed and experimental error prediction has been propounded to estimate minimum error possibilities such as mean absolute error (MAE), root mean square error (RMSE) and regression value (R). Computational time training dataset, minimum sample size and prediction time are also illustrated in this paper. In this paper, ANN, FLC and ANFIS models are analyzed for tool wear rate (TWR) and heat-affected zone (HAZ). 3D Rule Viewer and regression analysis as well as validation of test results and characteristics graph between performances with number of epochs of ANN model also are included in this paper for TWR and HAZ. Influence of process parameters like voltage, duty ratio, pulse frequency and electrolyte concentration on Surface Viewer of TWR and HAZ is also illustrated. It is found that ANFIS has great effectiveness of prediction of error during micro-ECDM process. [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]

The grain size effect is an important factor in determining the material removal behavior of polycrystalline silicon (p-Si). In the present study, to improve the understanding of nanoscale machining of p-Si, we performed molecular dynamics simulation of nanometric cutting on a p-Si workpiece and discussed the grain size effect on material removal behavior and subsurface damage formation. The simulation results indicate that when cutting on the polycrystal workpiece, the material removal process becomes unstable compared with single crystals. Higher removal efficiency, less elastic recovery and higher frictional coefficient are observed as the average grain size decreases. In the subsurface workpiece, when the grain size decreases, slip along grain boundaries merges as a nonnegligible process of the plastic deformation and suppresses the elastic deformation ahead of the cutting tool. It is also revealed that when cutting on a polycrystal workpiece with smaller grains, the average stress decreases while the workpiece temperature increases due to the impediment of heat transfer by grain boundaries. These results could provide a fundamental understanding in the material deformation mechanism of p-Si during nanoscale machining. [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]

Surface defect detection is a critical task in the manufacturing industry to ensure product quality and machining efficiency. Image-based precise defect detection faces significant challenges due to defects lacking fixed shapes and the detection being heavily influenced by lighting conditions. Addressing the efficiency demands of defect detection algorithms, often deployed on embedded devices, and the highly imbalanced pixel ratio between foreground and background images, this paper introduces a multi-scale fusion staged U-shaped convolutional neural network (DEU-Net). The network provides segmentation results for defect anomalies while indicating the probability of defect presence. It enables the model to train with fewer parameters, a crucial requirement for practical applications. The proposed model achieves an MIoU of 66.94 and an F1 score of 74.89 with lower Params (36.675) and Flops (19.714). Comparative analysis with FCN, U-Net, Deeplab v3+, U-Net++, Attention U-Net, and Trans U-Net demonstrates the superiority of the proposed approach in surface defect detection. [ABSTRACT FROM AUTHOR]

Quartz crystals are the most widely used material in resonant sensors, owing to their excellent piezoelectric and mechanical properties. With the development of portable and wearable devices, higher processing efficiency and geometrical precision are required. Wet etching has been proven to be the most efficient etching method for large-scale production of quartz devices, and many wet etching approaches have been developed over the years. However, until now, there has been no systematic review of quartz crystal etching in liquid phase environments. Therefore, this article provides a comprehensive review of the development of wet etching processes and the achievements of the latest research in this field, covering conventional wet etching, additive etching, laser-induced backside wet etching, electrochemical etching, and electrochemical discharge machining. For each technique, a brief overview of its characteristics is provided, associated problems are described, and possible solutions are discussed. This review should provide an essential reference and guidance for the future development of processing strategies for the manufacture of quartz crystal devices. ARTICLE HIGHLIGHTS: ● Different etching techniques for quartz crystals in liquid-phase environments are systematically summarized, and etching principles, characteristics, and future development trends are described. ● Progress in wet etching of quartz crystals over many years is reviewed, as well as the latest research results, providing a comprehensive overview of the historical development of this technique. ● In recent years, more attention has been paid to the etching of quartz glass rather than quartz crystal. This is the first systematic review of the etching of quartz crystals in a liquid-phase environment, and should provide inspiration for the further development of quartz crystal processing. [ABSTRACT FROM AUTHOR]

Shaped cathode electrochemical machining is often used to process array microgrooves on difficult-to-machine materials because of its great flexibility. Unlike the single-groove structure, the current density distribution varies greatly during machining of array microgrooves, which is mainly dependent on the sheet cathode array offset (SCAO). This study establishes and validates a mathematical model based on SCAO for the stray-current density, U, and ton. Then the end gap and side gap are modeled. Next, through simulation, the current density distribution at various SCAO is examined. It has been discovered that when the SCAO grows, the current density distribution becomes more uniform, and the stray-current density becomes milder. The array microgrooves having high quality and high density can be fabricated at a SCAO of 1.4 mm. Additionally, the experiments show that quality and efficiency can be ensured under the optimal parameters. [ABSTRACT FROM AUTHOR]

This review article presents the current status of various micromachining techniques used to create microfeatures in alumina ceramic. Alumina has emerged as an advanced substrate in various radio-frequency communication and automotive packaging applications due to its superior electrical resistivity, lower dielectric loss, higher wear resistance, and dimensional stability at high temperatures. However, creating complex-shaped microfeatures in alumina is challenging due to its hard and brittle nature. Traditional contact-based methods fail to create microsized shapes in alumina; thus, the researchers are exploring novel machining methods, like abrasive, thermal, chemical, and hybrid micromachining processes. This review article comprehensively summarizes various micromachining methods used to create microfeatures in alumina ceramics. The mechanism, unique features, pros/cons, novelty, and applications of ultrasonic machining, laser ablation, electrochemical discharge machining, abrasive-jet machining, etc., are presented. The associated processing challenges in various alumina micromachining and the potential remedies to produce high-quality alumina microparts for microelectronics applications are discussed. [ABSTRACT FROM AUTHOR]

This research discusses the effect of typical characteristic dimensions of electrodes on electric arc electrochemical composite machining (EAECM). The flow rate and debris removal capability of electrodes with different characteristic dimensions were investigated by flow field simulation. Single-factor machining experiments were conducted. The discharge characteristics, process indicators and machined surfaces of electrodes were analyzed it was found that the tubular electrode has a demarcation phenomenon that affects the surface quality. The results indicate that the use of electrodes with large inner diameters is favorable to improve the surface consistency. The use of electrodes with small outer diameters improves the overall surface quality but increases the electrode wear. Finally, the fracture mechanism of thin-walled electrodes was revealed by stress field simulations and experiments. In conclusion, in order to improve the machining effect of EAECM, large-diameter (inner and outer diameter) electrodes with wall thickness greater than 2 mm should be selected. [ABSTRACT FROM AUTHOR]

Owing to the challenges faced during conventional machining of Titanium (Ti) alloys due to their low thermal conductivity and high chemical reaction, non-conventional machining techniques are used. Electrical Discharge Machining (EDM) is a promising solution that can precisely machine hard materials into intricate geometries but faces lower material removal rate, higher tool wear rate, and poor surface quality. In this research work, the effect of sub-zero treatments on EDM electrodes was investigated, and experimental investigations were conducted to identify the impact of sub-zero treated electrodes during EDM of Ti-6Al-4V under different discharge energy regimes. Peak Current, Pulse-On-Time and Gap Voltage were varied in 3 levels to evaluate the effect on MRR and TWR. A comprehensive study on EDMed surfaces has been assessed using the morphological and metallurgical observations from SEM micrographs, EDAX and XRD patterns. Sub-zero treated electrodes outperformed the Untreated (UT) electrodes regarding erosion rates and surface quality. [ABSTRACT FROM AUTHOR]

Graphite powder mixed electrochemical discharge machining (GPM-ECDM) is an effective technique for micromachining of hard and brittle nonconductive materials. To reveal the mechanisms of discharge and material removal in GPM-ECDM the voltage and current signals obtained in the electrolyte with and without graphite powder were experimentally investigated, and it was observed that there were two types of discharges in the GPM-ECDM. The influences of adding graphite powder to the electrolyte on the machining of microcraters and microgrooves were studied. The analysis of the machining results revealed that the workpiece material was removed by both the general electrochemical discharge and the discharge occurring on the graphite powder. Compared to the machined surface obtained in conventional electrolyte, the surface roughness decreased by 30–56% when using the graphite powder mixed electrolytes with particle diameters of 1 μm or 18 μm. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) of the inner surface of cylindrical workpiece (WP) with an eccentric rotating cylinder tool-electrode (TE) is studied theoretically using a new mathematical model. The proposed model uses a moving coordinate system bound to the rotating WP. In this case, only the variation in the position of TE center during its orbital movement is taken into account. In addition, for convenient solution and analysis of results, the mathematical model was presented in the dimensionless form in order to reduce the number of parameters. The local one-dimensional approximation is used to calculate the distribution of the current density. It enables determining the distribution of the current density not from the solution of Laplace's equation, but using a simple analytical equation. Three dimensionless parameters are proposed to characterize the properties of the workpiece material, the electrolyte solution and working conditions, and also the dimensions of the electrodes and the rate of their relative motion. These parameters are used in the numerical solution and analysis of the results. The obtained relationship between the accuracy and productivity of ECM with an eccentric rotating TE can be used to optimize the process. The error in the shape of workpiece surface is analyzed within the proposed model. The relation between the error of machining and the minimum interelectrode gap is revealed. A two-stage ECM scheme is proposed to reduce the shape error. [ABSTRACT FROM AUTHOR]

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

Purpose: The purpose of this study is analysis of deformation and vibrations of turbine blades produced by high electrolyte pressure during electrochemical machining. Design/methodology/approach: An experimental setup was designed, experiments were conducted and the obtained results were compared with the finite element results. The deformations were measured according to various flow rates of electrolyte. In finite element calculations, the pressure distribution created by the electrolyte on the blade surface was obtained in the ANSYS® (A finite element analysis software) Fluent software and transferred to the static structural where the deformation analysis was carried out. Three different parameters were examined, namely blade thickness, blade material and electrolyte pressure on blade disk caused by mass flow rate. The deformation results were compared with the gap distances between cathode and anode. Findings: Large deformations were obtained at the free end of the blade and the most curved part of it. The appropriate pressure values for the electrolyte to be used in the production of blisk blades were proposed numerically. It has been determined that high pressure applications are not suitable for gap distance lower than 0.5 mm. Originality/value: When the literature is examined, it is required that the high speed flow of the electrolyte is desired in order to remove the parts that are separated from the anode from the machining area during electrochemical machining. However, the electrolyte flowing at high speeds causes high pressure in the blisk blades, excessive deformation and vibration of the machined part, and as a result, contact of the anode with the cathode. This study provides important findings for smooth electro chemical machining at high electrolyte flows. [ABSTRACT FROM AUTHOR]

This document discusses the advancements in material science and the challenges they pose for the machining industry. It highlights the unique difficulties in machining materials such as superalloys, memory alloys, and composite materials, and explores innovative machining methods to address these challenges. The document also presents a special issue that showcases the latest research and breakthroughs in advanced machining technologies. It includes contributions on topics such as design theory for specific materials, optimization of cutting parameters, durability of forging tools, and the impact of various factors on the machining process. The document concludes by expressing gratitude to the authors, reviewers, and publisher involved in the special issue. [Extracted from the article]

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]

In the realm of microfluidics, a critical issue prevails: The commercially available flow sensors are situated external to the microfluidic chip, resulting in an inherent deficiency of precise operational insights. Applications such as biochemistry, drug development, single cell analyses, gradient generators, biomedical devices and proactive healthcare demand dependable data for broader utilization. In the present work, we introduce a microfluidic flow sensor designed to gauge electrolyte flow rates on-chip inside a microchannel by measuring electrochemical resistance of electrolytic bubbles within a circuit comprising electrolytic fluid and inter-digitated electrodes. This sensor design features a Si wafer substrate with micropatterned Ti/Pt electrodes bonded to a polydimethylsiloxane (PDMS) microchannel using oxygen plasma. The sensor has been characterized for electrolytic fluid (0.1 M NaCl), 600 μ m wide microchannel, 0–500 μ l/min range of flow, 3V dc power input, and 25 ∘ C room temperature conditions. Sensor response has been compared for electrolyte concentrations (0.1 M to 0.4 M NaCl), channel width (400–1200 μ m), and input power (1–5 V) corresponding to a given flow rate. The sensor 3 σ resolution calculated from calibration curve is observed to be 5 μ l/min for lower flow rates (0–100 μ l/min) and 100 μ l/min for higher flow rates (100–500 μ l/min). The limit of detection (LoD) of the sensor is 1 μ l/min. An algorithm based on the trapezoidal rule enabling flow rate prediction within 5 s has been implemented. The proposed flow sensor works over a broad range of flow rates, although with different sensitivity, presenting a novel method employing the electrolysis bubble size and volume for flow rate detection. [ABSTRACT FROM AUTHOR]

Roundness error plays an important role of rotating parts in engineering fields and it has a significant influence on the machining quality and accuracy during electrochemical machining (ECM) process. The precision ECM could be processed only if the initial roundness error is decreased or eliminated and the inter-electrode gap (IEG) becomes steady after reaching an equilibrium state. However, a constant voltage is generally used in ECM process. And a long time and a large allowance are required to level the profile error of workblank if the initial profile error is large. In this study, the focus herein is on the acceleration of the leveling process of the rotary workpiece. A counter-rotating electrochemical machining (CRECM) process method with a variable voltage is proposed to improve the leveling ability. For a rotary workpiece with elliptical contours, the machining voltage can be dynamically adjusted based on the IEG through the approximate regulation of sine waves according to modeling-based analysis. The method aims to improve the leveling ability by expanding the difference in the magnitude of electric current between the high and low points on the profile of the anode workpiece under different voltages. The results of experiments confirmed that the proposed method significantly reduced the leveling time from 36 to 7 min (by 81%), and the depth of dissolution of the highest point on the profile from 1.68 to 0.45 mm while reducing the roundness error from 0.5 to 0.05 mm. The leveling ratio increased from 0.26 to 0.99. [ABSTRACT FROM AUTHOR]

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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]

Inconel 718's exceptional strength and corrosion resistance make it a versatile superalloy widely adopted in diverse industries, attesting to its reliability. Electrochemical machining (ECM) further enhances its suitability for intricate part fabrication, ensuring complex shapes, dimensional accuracy, stress-free results, and minimal thermal damage. Thus, this research endeavors to conduct a novel investigation into the electrochemical machining (ECM) of the superalloy Inconel 718. The study focuses on unraveling the intricate influence of key input process parameters—namely, electrolytic concentration, tool feed rate, and voltage—on critical response variables such as surface roughness (SR), material removal rate (MRR), and radial overcut (RO) in the machining process. The powerful tool, response surface methodology (RSM), is used for understanding and optimizing complex systems by developing mathematical models that describe the relationships between input and response variables. Under a 95% confidence level, analysis of variance (ANOVA) suggests that electrolyte concentration, voltage, and tool feed rate are the most important factors influencing the response characteristics. Moreover, the incorporation of ANN modeling and the MOGA-ANN optimization algorithm introduces a novel and comprehensive approach to determining the optimal machining parameters. It considers multiple objectives simultaneously, considering the trade-offs between them, and provides a set of solutions that achieve the desired balance between MRR, SR, and RO. Confirmation experiments are carried out, and the absolute percentage errors between experimental and optimized values are assessed. The detailed surface topography and elemental mapping were performed using a scanning electron microscope (SEM). The nano/micro particles of Inconel 718 metal powder, obtained from ECM sludge/cakes, along with the released hydrogen byproducts, offer promising opportunities for recycling and various applications. These materials can be effectively utilized in powder metallurgy products, leading to enhanced cost efficiency. [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]