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Thin-walled micro-holes are frequently used in aerospace components to achieve specific functions, such as heat dissipation and filtration. However, traditional manufacturing technologies face difficulties in achieving precision machining of these holes due to deformation caused by cutting force or heat. Laser machining is a highly flexible and efficient advanced processing technology that aims to achieve precise machining of thin-walled holes. However, it is important to note that the thermal energy generated by the laser can cause deformation of the thin walls. To address these issues, this paper proposes a process that combines laser and backside electrochemical composite machining. The model for laser electrochemical composite processing after through-hole formation suggests that the laser's temperature rise effect on the electrolyte can significantly enhance the efficiency of electrochemical processing. Furthermore, the laser exerts a micro-zone stirring effect on the electrolyte in the processed micro-zone, which promotes the liquid-phase mass transfer process during the electrochemical reaction. Furthermore, a one-way experiment was conducted to investigate the effects of the main laser parameters on the processing results. The results indicated that higher laser power, as well as lower laser frequency and scanning speed, significantly reduced the edge damage and pore taper of the processed micro-holes. The language used is clear, concise, and objective, adhering to a formal register and avoiding biased or ornamental language. Technical terms are consistently used and explained when first introduced. The text is grammatically correct and free from spelling and punctuation errors. Furthermore, this process has significantly reduced the oxygen content and surface roughness of the sidewalls of the micro-holes. [ABSTRACT FROM AUTHOR]

The low-cost, high-quality, and high-efficiency machining of the large-thickness ruled surface structure of difficult-to-machine materials, such as turbine disc mortise and blade tenon in aircraft engines, is still a great challenge for existing machining technology. Electrochemical cutting with radial electrolyte flushing emerges as a solution. This method involves using tube electrodes with array jet-flow holes to spray electrolyte radially into the machining gap, effectively cutting the workpiece. It promises not only the inherited benefits of wire electrochemical machining, like flexibility and no heat-affected layers, but also the capability to machine large thicknesses efficiently. Nevertheless, the technique faces a hurdle: the inconsistency in the surface topography due to the electrolyte flow field in the machined slit, impacting the machining quality. To address this, the method has been enhanced with axial supplementary electrolyte flushing. Simulation and experimental results indicate that this addition improves electrolyte flow in the machined slit, ensuring the electrolyte's renewal, which in turn rectifies the issue of inconsistent surface quality and enhances cutting quality without compromising efficiency. Optimization of the nozzle diameter and flow rate for the axial flushing has led to significant advancements. For instance, a fir-tree-shaped turbine disc mortise was precisely cut into a 20-mm-thick Inconel 718 plate at a feed rate of 5 µm/s, achieving a surface roughness of Ra 0.95 µm. [ABSTRACT FROM AUTHOR]

Silicon carbide particle reinforced aluminum matrix composites (SiCp/Al), combine the properties of aluminum matrix materials and reinforced silicon carbide (SiC) particles, finding widespread application in aerospace, optics, and electronics. The increased hardness and electrochemical inertness of SiC particles present significant challenges in their processing. This research investigates the impact of photocatalytic processes on machining accuracy in electrochemical processing (ECM). The dissolution characteristics of SiCp/Al during ECM and photocatalytic-assisted electrochemical machining (PAECM) were analyzed with varying electrolyte compositions, using polarization curves and oxidation–reduction potential (ORP). Validation of improved machining accuracy and surface quality in PAECM was achieved through no-feeding machining. According to theoretical principles and laboratory analyses of the workpiece surface, it was found that PAECM, through its photocatalytic reaction, generated more oxides, blocked stray currents and stray corrosion effectively, and attained accuracy in profile creation. Through a comparative analysis it revealed that PAECM exhibited smoother profiles and reduced Overcut Ratio (OCR) in hole and groove machining compared to ECM, particularly in groove machining. Adjusting machining gaps as well as reducing abrasive particle size in PAECM influenced groove depth and width, which achieved optimal morphology with a 0.4 mm gap and a 2–3 nm abrasive particle size, resulting in a 370 μm depth. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC-Co) with a cobalt binder has been widely used in industrial application. Through their high wear resistance and hardness, which make it a challenge to machine. Electrochemical discharge machining (ECDM) is a newly developed hybrid technique used to machine conductive and nonconductive materials. Tungsten carbide machining is an area that needs more investigation. In this study, different types of electrolytes have been tested in the electrochemical machining of tungsten carbide. It has been concluded that tungsten carbide was successfully machined with electrolytes that were either neutral salts or a combination of neutral salts and hydroxides, the highest material removal rate achieved was (0.09250 g/min), and the average surface roughness achieved in this work was measured at (Ra 0.9275 µm). However, deposition took place on the surface of machined tungsten carbide when the samples were treated with sodium hydroxide and potassium hydroxide. EDX analysis of successfully machined tungsten carbide samples reveal the presence of carbon (C) due to diffusion from the base material and oxygen (O), most likely due to oxidation brought on by the high temperatures utilized. Scanning electron microscopy confirmed that the machined surfaces had craters, pores, restricted microcracks, and re-deposited melt particles, among other things. [ABSTRACT FROM AUTHOR]

Aircraft parts are often designed as thin-walled structures to reduce the weight of the aircraft. However, thin-walled structures are prone to deformation during the milling process, leading to a decrease in machining accuracy. To address this problem, a method combining milling and electrochemical machining, known as electrolytic milling, is proposed to minimize deformation and enhance the accuracy of thin-walled parts. The factors that affect the machining accuracy of electrolytic milling were analysed, and a model for predicting the thickness of the material removed was established. Electrolytic milling experiments were designed, and the model was solved. Based on the built model, the influences of feed rate, spindle speed, radial cutting depth, voltage and electrolyte concentration on material removal thickness were investigated. Compared with the milling method, the electrolytic milling method can improve the machining accuracy of thin-walled parts. Electrolytic milling experiments were conducted on box-shaped parts to verify the reliability of the proposed method. [ABSTRACT FROM AUTHOR]

Aiming at the difficult problem that the ability of ECM error correction is limited by the noncontact machining mechanism and the change of machining gap is difficult to be measured in real time, a method is proposed to realize the enhanced adaptive correction of radial circular runout error by online voltage regulation so as to realize the improvement of the efficiency of the correction of ECM error under the conditions of smaller removal amount and normal machining gap. Taking the eccentricity error of the eccentric bushing parts as the radial circular runout error, adopting the equivalent resistance between poles (real-time voltage/real-time current) to indicate the machining gap, and taking the change of the equivalent resistance as the basis for real-time voltage adjustment, the mathematical model for the correction of the radial circular runout error is established. Comparison experiments between enhanced adaptive machining and constant pressure machining are carried out to verify the effectiveness of enhanced adaptive machining in correcting radial circular runout error. The efficiency of radial circular runout error correction by enhanced adaptive machining is improved by 60.0%, and the average workpiece removal is saved by about 40.7% compared to constant pressure machining at the same time. The experimental results of radial circular runout error after machining are in accordance with the expected results of the mathematical model. Through mathematical modeling and experimental research, it is confirmed that regulating the machining voltage to achieve enhanced adaptive correction of radial circular runout error can effectively improve the error correction accuracy and efficiency of difficult-to-machine rotary parts, and it is an effective method to solve the problem of radial circular runout error correction of eccentric parts. [ABSTRACT FROM AUTHOR]

Thin-walled plates are extensively used in the aerospace industry due to their lightweight properties. However, their low rigidity makes them susceptible to deformation and chatter during traditional machining processes, which increases machining complexity and reduces both quality and efficiency. Therefore, this paper proposes an electrochemical machining method involving the use of a rotating body with complex structured windows as the cathode, enabling pure rolling motion on the workpiece surface. Through the action of an electrolyte and an external power supply, the material is removed from the machined surface layer by layer in the form of ions, thus facilitating the manufacture of complex thin-walled plates. Based on the principles of this method, a kinematics model was established to determine the relative position relationship between the cathode and anode during machining. Additionally, an electric field model and a material dissolution model were established to analyze the electric potential distribution and simulate the process of material removal. The simulation results indicate that the trajectory of the cathode windows forms a "V" shape, with the taper angle being independent of the window angle, but decreasing as the cathode diameter increases. Furthermore, it was observed that the use of an insulation coating can effectively reduce stray corrosion on convex structures of the workpiece surface. Based on these simulation results, electrochemical machining experiments were conducted on nickel-based GH4169 plates measuring 600 × 96 mm with a thickness of 3 mm. The results demonstrate that the average thickness of machined workpieces is 1.1 mm, with a thickness error of 0.12 mm. Meanwhile, the surface roughness Ra is 0.778 μm, with a material removal rate reaching 1.01 cm3/min (8271.9 mg/min). Therefore, electrochemical machining proves to be an effective method for manufacturing thin-walled plates. [ABSTRACT FROM AUTHOR]

Industrial robot electrochemical milling has an important application prospect in efficient and precise machining of hard-to-cut part materials due to its advantages of high flexibility and strong sensing ability and is now becoming a hot spot in the research of new electrochemical machining technology. However, the weak stiffness and low accuracy problems of industrial robots themselves can create errors in the normal clearance in electrochemical milling machining. The inter-electrode gap (IEG) directly affects the process performance of electrochemical machining in terms of machining accuracy and surface quality. To reduce the effect of robot trajectory error on the interpolar gap, real-time compensation control of the machining gap is required. In this paper, we propose an industrial robot electrochemical milling normal motion error correction control system with a gap control strategy that is based on the coupled multi-physical field theory for averaging and solving the machining conductivity. The machining current is measured in real time, the current fluctuation is converted into a normal error compensation amount, and the end-effector accomplishes the error amount compensation for the machining gap. The response performance of the gap control system is simulated and analyzed, the experimental platform is designed and constructed, and finally, to verify the effectiveness of the machining gap control servo system, the plane workpiece machining experiments are carried out, and the experimental results surface that the method can effectively control the gap fluctuation in robotic electrochemical milling within a small range, and ultimately improve the machining accuracy and surface quality of the parts, which proves that the method can improve the machining accuracy of robotic electrochemical milling. [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining (ECDM) is an essential process for microstructure fabrication of difficult-to-machine materials. Currently, there are various kinds of ECDM, and plasma-assisted electrochemical machining (PA-ECM) is a new and promising ECDM proposed in recent years. However, the differences between electrolytic plasma discharge and conventional spark discharge are unclear. Therefore, this study aims to systematically explain the evolvement mechanism and characteristics of these two kinds of discharge. From the phenomenology, the electrolytic plasma discharge is saffron color determined by electrolyte and wrapped at the entire immersion surface of the tool electrode, while the spark discharge is white color and only excited at the end of the tool electrode. Electrolytic plasma discharge is generated preferentially to spark discharge and easily transforms to spark discharge in high electric field strength such as large applied voltage or small inter-electrode gap. The discharge energy and emission spectrum of spark discharge are more significant than that of electrolytic plasma discharge. Especially, the electrolytic plasma discharge does not cause any tool electrode wear due to the low discharge energy (discharge current of about 0.5 A), and the resulted surface of the workpiece is smooth. On the contrary, the spark discharge energy is high (discharge current about 9 A), which causes noticeable tool electrode wear and leaves discharge craters and thermal damage on the workpiece surface. Considering the obvious flushing effect of bubble flow during plasma ignition, PA-ECM is an ideal method for functional surface micro-dimple array fabrication without using tube central spray and workpiece mask. [ABSTRACT FROM AUTHOR]

In this work, the application of three different Machine Learning algorithms, random forest (RF), support vector machine (SVM), and artificial neural network (ANN), to accurately classify ultra-low concentrations of Δ9-tetrahydrocannabinol in biological fluids such as saliva was successfully demonstrated. In doing so, experimental data consisting of the voltammetry signals of 0, 2, and 5 ng/mL of Δ9-tetrahydrocannabinol (THC) in synthetic and human saliva was employed. The dataset consists of person-to-person saliva variation and experimental variabilities in the procedure and artifacts. The results showed that RF was the most robust ML technique to classify different concentration levels of THC in the presence of a variety of variabilities in the experimental data, with an average training accuracy of 96% and an average testing accuracy of 87%. On the other hand, SVM and ANN models were susceptible to incoherencies in the experimental data. [ABSTRACT FROM AUTHOR]

Silicon wafers find applications in manufacturing large-scale micro-components widely available in consumer-based electronic devices. The milling-electrochemical spark micromachining (Milling-ECSMM) process is popular nowadays as an advanced micromanufacturing process for creating microchannels and several other geometric features. This paper presents a parametric effect of voltage, tool rotation, electrolyte concentration, and duty cycle on MRR, Ra, and TWR, using a tungsten carbide (WC) two-fluted flat-end milling cutter. The experimental model was developed using response surface methodology (RSM), and parametric multi-objective optimization was carried out using desirability function analysis (DFA) and genetic algorithm (GA). SEM and optical images were taken to identify the surface quality of the machined microchannel. The optimal combination of parameters obtained from GA as 90 V, 13 rpm, 64 g/l, and 40% DC gives better convergence and multi-objective response for MRR, TWR, and Ra as 0.409 mg/min, 0.0428 mg/min, and 0.572 µm, respectively. [ABSTRACT FROM AUTHOR]

Counter-rotating electrochemical machining (CRECM) stands out as an efficient and cost-effective method for machining aero-engine casings. To maintain stability in the CRECM process equilibrium state, continuous feeding of the cathode tool is essential. However, this continuous feeding approach with single direction of rotation may result in poor roundness and reduced machining accuracy. This paper aims to analyze the sources and rules of roundness error and asymmetry in CRECM. Based on simulation results, a method involving periodic reverse rotation of electrodes with continuous feeding is proposed for CRECM. This approach aims to mitigate the cumulative machining error, thereby significantly improving machining accuracy. Experimental results validate the efficacy of the proposed method at a rotation speed of 0.2 rpm. The roundness error is markedly reduced from 0.19 mm to 0.04 mm, resulting in a more symmetric convex structure. Additionally, the sidewall taper angle is reduced from 14.5 degrees to 6.4 degrees. This underscores the effectiveness of the proposed method in enhancing machining accuracy. [ABSTRACT FROM AUTHOR]

Jet electrochemical micromilling (JEMM) exhibits significant potential for high-efficiency and high-quality machining of titanium alloy microstructures. However, during the JEMM process, the machined surface of the workpiece inevitably experiences stray current attacks at low current levels. Due to the formation of a dense passive film on the surface of the titanium alloy under electrochemical action, stray corrosion occurs on the machined surface. Hence, the electrochemical dissolution behavior of titanium alloys at low current densities directly impacts both machining efficiency and quality. This study first analyzed the effects of electrolyte composition and current density on the transpassive potential, breakdown of the passive film, current efficiency, and the dissolved surface on Ti-6Al-4V. The transpassive potential and electrochemical impedance of Ti-6Al-4V were found to be lower in NaCl solution than in NaNO3 solution. In addition, lower current densities enabled higher current efficiency and resulted in a more uniform and flat dissolution surface. Subsequent experiments used these two solutions for JEMM of complex-shaped microstructures on Ti-6Al-4V. The findings demonstrated that, compared to the NaNO3 solution, the use of NaCl solution increases the material removal rate by approximately 30%, enhances the aspect ratio by about 26%, and reduces surface roughness by roughly 58%. This indicates that employing NaCl solution can lead to superior machining efficiency and quality. [ABSTRACT FROM AUTHOR]

The efficient and cost-effective preparation of masks has always been a challenging issue in mask-based electrochemical machining. In this paper, an electrochemical machining process of micro-textures is proposed using hard particle masks such as titanium and zirconia particles. Numerical simulations were conducted to analyze the formation mechanisms of micro-protrusion structures with insulating and conductive hard particle masks, followed by experimental verification of the process. The results indicate that when the hard particles are electrically insulating, metal material preferentially dissolves at the center of the particle gap, and the dissolution then expands over time in depth and towards the particle contact points. Conversely, using the conductive particles as the masks, such as titanium particles, dissolution initially occurs in a ring region centered at the contact point between the hard particle and the anode, with a radius approximately one-quarter of the chosen particle's diameter (200 μm), and then continues to expand outward. [ABSTRACT FROM AUTHOR]

Aircraft engine blades are produced through various techniques, one of which is precise electrochemical machining (ECM), commonly applied in the aerospace, automotive, and electromechanical industries. This method achieves machining accuracy ranging from 0.1 to 0.3 mm. However, components with complex shapes still require grinding and polishing. During the grinding of aircraft blades, achieving high precision and maintaining strict dimensional control are essential. This involves monitoring the thickness of the blade at key cross-sections, as well as the radii of the leading and trailing edges, chord lengths, twist angles, and more. The paper introduces a developed robotic blade grinding process featuring iterative laser measurement of geometric parameters. A custom measuring device with laser heads was designed, calibrated, and tested for repeatability. The measurement data were then used to determine the blade feed rate and machining path via a fuzzy logic decision system. The proposed method was validated on a series of PT6 aircraft engine blades in collaboration with Pratt and Whitney Rzeszów. [ABSTRACT FROM AUTHOR]

This research paper presents an innovative approach to fabricating enhanced-quality hierarchical surface micro-textures on Ti6Al4V alloy by synergistically employing in situ electrical discharge machining (EDM) and electrochemical machining (ECM) processes. The hierarchical structure encompasses three levels: a primary level at a few hundred micrometers, a secondary level at a few tens of micrometers, and a ternary level at sub-micrometer scales. Despite the precision achieved in generating the primary-level texture through EDM using a chemically patterned tool, inherent thermal damages and surface defects, such as micro-craters and irregularities, pose challenges. Unlike usual ex situ chemical or electrochemical post-processing methods, this study introduces in situ ECM post-processing (ECM) with the same patterned tool. This approach enhances the quality of EDMed surfaces without compromising geometrical accuracy, offering anisotropic dissolution along the feature depth. To ensure geometrical accuracy, an experimentally validated finite element method-based transient numerical simulation model is developed. This model accurately predicts the evolution of the feature profile during the ECM operation. Furthermore, ECM with a fluoride ion–containing electrolyte introduces additional secondary and ternary levels of hierarchical textures. Fluoride ions play a pivotal role in augmenting material removal during ECM, particularly in areas around micro-crevices and pores, shaping the secondary-level texture. [ABSTRACT FROM AUTHOR]

In electrochemical discharge machining (ECDM), continuous renewal of electrolyte between the tool electrode and the workpiece guarantees stable discharge machining. Proposed in this paper is Porous-electrode ECDM (p-ECDM) using a tool electrode made of porous material containing micrometer pores. The rough surface of the porous electrode promotes electrolyte regeneration between the electrodes to produce a stable and relatively thin gas film. At the same time, the internal connected micropores are used to provide controlled gas flow to the processing area, reduce the energy consumption of electrolytic bubbles, and improve the discharge energy to achieve efficient ECDM processing. Experimental results indicate that compared with a solid electrode, the porous electrode has faster electrolyte renewal, smaller bubble volume, more-stable voltage characteristics, 22.55% less overcut, a 4.7% smaller heat-affected zone, and better deep hole processing ability. Experimental results for p-ECDM assisted by controlled airflow demonstrate a 54.23% increase in the material removal rate. [ABSTRACT FROM AUTHOR]

GH4169 alloy, a nickel-based superalloy known for its excellent high temperature resistance, corrosion resistance, mechanical properties, and high-temperature tribological properties, is widely used in industrial applications, such as in gas turbines for space shuttles and rocket engines. This study addresses the issue of electrolyte product residue in the electrochemical machining process of a GH4169 alloy by utilizing a C6H5Na3O7-containing NaNO3 new mixed electrolyte. Comparative investigations of the electrochemical behavior and electrolyte product removal mechanisms at different concentrations of C6H5Na3O7 additive in NaNO3 solutions were conducted. The effects of additives, applied voltage, and the rotating speed of the cathode tool on the processing performance of micro-pit arrays on a GH4169 alloy were analyzed. The results indicate that the mixed solution containing C6H5Na3O7 significantly improves the localization and geometric morphology of the micro-pits compared to a single NaNO3 solution. The optimal electrochemical machining parameters were identified as 0.5 wt% C6H5Na3O7 + 10 wt% NaNO3 mixed electrolyte, 12 V applied voltage, and 0.1 r/min rotating speed of the cathode tool. Under these conditions, high-quality micro-pit arrays with an average diameter of 405.85 μm, an average depth of 87.5 μm, and an etch factor (EF) of 1.67 were successfully fabricated, exhibiting excellent morphology, localization, and consistency. [ABSTRACT FROM AUTHOR]

Detecting urea is crucial for diagnosing related health conditions and ensuring timely medical intervention. The addition of machine learning (ML) technologies has completely changed the field of biochemical sensing, providing enhanced accuracy and reliability. In the present work, an ML-assisted screen-printed, flexible, electrochemical, non-enzymatic biosensor was proposed to quantify urea concentrations. For the detection of urea, the biosensor was modified with a multi-walled carbon nanotube-zinc oxide (MWCNT-ZnO) nanocomposite functionalized with copper oxide (CuO) micro-flowers (MFs). Further, the CuO-MFs were synthesized using a standard sol-gel approach, and the obtained particles were subjected to various characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectroscopy. The sensor's performance for urea detection was evaluated by assessing the dependence of peak currents on analyte concentration using cyclic voltammetry (CV) at different scan rates of 50, 75, and 100 mV/s. The designed non-enzymatic biosensor showed an acceptable linear range of operation of 0.5–8 mM, and the limit of detection (LoD) observed was 78.479 nM, which is well aligned with the urea concentration found in human blood and exhibits a good sensitivity of 117.98 mA mM−1 cm−2. Additionally, different regression-based ML models were applied to determine CV parameters to predict urea concentrations experimentally. ML significantly improves the accuracy and reliability of screen-printed biosensors, enabling accurate predictions of urea levels. Finally, the combination of ML and biosensor design emphasizes not only the high sensitivity and accuracy of the sensor but also its potential for complex non-enzymatic urea detection applications. Future advancements in accurate biochemical sensing technologies are made possible by this strong and dependable methodology. [ABSTRACT FROM AUTHOR]

The potential of micro electrochemical slotting is significant due to its adaptability and usefulness across diverse manufacturing applications. This technique holds potential, particularly for handling advanced engineering materials like superalloys, with a focus on applications requiring high strength, i.e., micro-cutting for gas-turbine parts, biomedical applications, etc. With this view, this article has been attempted to explore the influence of various considered machining factors, namely as; applied potential difference, tool feed rate (TFR), pulse supply, and modes of tool insulation on the performance measures, i.e. material removal rate (MRR) and surface roughness (Ra) while attempting micro-slotting in Nimonic-263 superalloy work samples. The entire experimentation was conducted on the in-house fabricated 3-axis micro-electrochemical setup designed for performing various complex machining operations at a miniature scale. Furthermore, this study has also been focused toward investigating the impact of varying the electrical conductivity by employing different tool materials (i.e. copper and SS304) on the process characteristics measured. The observed effects of the tool electrode's conductivity have also been expressed and supported by performing the simulation for electric field distribution using COMSOL Multiphysics software. The experimental results have revealed that the process input variables remarkably influence MRR and Ra, mainly applied voltage and TFR. The best values of MRR and Ra attained with SS304 and copper tool electrodes were 1.521 mg/min and 0.721 mg/min, and 0.038 µm and 0.029 µm, correspondingly. The microstructure analysis has further been conducted on machined micro-slotted work samples that provided detailed insights into various surface integrity aspects, which are essential for microdevice applications. [ABSTRACT FROM AUTHOR]

The development of wire electrochemical spark machining setup is always challenging in the form of industrial viable for machining advanced engineering materials such as polymer nanocomposites, quartz, glass, ceramics, etc. Because of some drawbacks associated with it, like irregularity in kerf width, poor surface finish, no spark formed at high wire velocity, wire breaking at high voltage, etc. In the present work, a newly developed hybrid machining process that is reversible motion-wire electrochemical spark machining (RM-WECSM) has been developed for curve profile cutting, especially on non-conducting workpieces such as aluminum oxide epoxy nanocomposite of 3.5 mm thickness. The effect of NaOH concentration, applied voltage, reversible wire velocity, pulse on-and-off time, on material removal rate and average surface roughness have been studied using a one-parameter-at-a-time approach. Sparking occurred from the electrolyte surface to 10 mm above the electrolyte surface to cut the workpiece. The spark length is equal to the workpiece thickness. A continuous, stable spark has been formed at a high reversible wire velocity (19.8 m/min). Simultaneously, self-electrolyte flow has been generated, due to which melted materials have been washed out of the cut-surface and provided the smooth (1.987 µm) cut-surface of the workpiece. The maximum MRR is found as 1.63 mg/min. Thermal cracks, heat-affected zones and recast layers were not found on the curve cut-surface, and it was analyzed by a field emission scanning electron microscope. [ABSTRACT FROM AUTHOR]

In this installment of the "Looking at Patent Law" series, we present a case study of the prosecution events of U.S. Patent No. 10,357,839; "Method for Electrochemical Machining using Sympathetic Waveform Interactions". The subject invention aligns with the technical interests of several divisions of The Electrochemical Society (ECS), including Corrosion (CORR), Industrial Electrochemistry and Electrochemical Engineering (IE&EE) and Physical and Analytical Electrochemistry (PAE). Additionally, the case introduces ECS members to an emerging technology of interest to industry. The case study begins with a brief synopsis of the background of the invention followed by 1) summary of several drawings and the specification of the invention, 2) inventor assignment and power of attorney designations, 3) submission of the Invention Disclosure Statement (IDS) and associated Duty of Candor, 4) summary of the non-final office action rejecting the patent application for obviousness, and 5) applicant response and allowance of the patent application. The case study illustrates the use of adding limitations from the dependent claims and the specification to the independent claim to overcome an obviousness rejection. In addition, the case illustrates an applicant initiated nonpublication exception to the eighteen month publication rule. With this case study, we hope to de-mystify the patent prosecution process and better prepare electrochemical and solid-state scientists, engineers and technologists to interact with their patent counsel regarding their inventions. [ABSTRACT FROM AUTHOR]

In this work, a newly discovered biomedical grade Magnesium–Lithium–Strontium (Mg–Li–Sr) alloy is machined using electrochemical machining technology. Two main output constraints employed on the research project to evaluate machinability are surface roughness (Ra) and material removal rate (MRR). Changing feed rate (FR), current, electrolyte concentration (EC), and voltage is required in order to carry out experimental experiments. The trials were designed using the Taguchi method. The ANOVA findings show that current is the most significant factor, after voltage as the most significant input parameter in regulating Ra and MRR. The ideal parameter configuration for the CRITIC-linked Deng's similarity approach method was 5 V, 1 A of current, 0.4 mm/min of FR, and 20 g/l of EC. The final product was a 0.0323 mm/min MRR and a 2.61 μm surface roughness. Furthermore, the response variables are anticipated using the adaptive neuro-fuzzy Inference System, which finally results in predictions that are very similar to the experimental results. [ABSTRACT FROM AUTHOR]

A new eddy current sensor with planar coils designed for noncontact distance measurement was applied in the inter electrode gap detection in the electrochemical machining (ECM). The sensor consists of two micro electroforming planar coils (driver coil and sensitive coil) stacked on the magnetic core. The magnetic model of the detection principle was built, and a new micro motion system was developed as a test and machining platform also. The size of the sensor was: Φ5 mm × 1.5 mm. The results show that the sensor is compact enough to nondestructively assess the electrode gap distance and could be easily integrated into a tool cathode for real-time electrolytic machining gap detection. [ABSTRACT FROM AUTHOR]

The removal of metal in the form of sludge can be termed an ECM process, having primary salient features consisting of the tool, workpiece, power supply and electrolyte solution. ECM is a potential nontraditional machining process that includes too many factors contributing to process performance. Therefore, obtaining optimal factor combinations for higher efficiency is complex. In this research work, machining parameters are voltage, powder concentration and electrolyte concentration, based on which material removal rate (MRR) and surface roughness (SR) are derived. Regression analysis, signal-to-noise ratios and analysis of variance (ANOVA) are performed to determine the optimal levels and to examine the effects of machining parameters on MRR and SR. The results derived from the experiments noticed that the MRR decreases when the voltage level is increased and surface roughness decreases for the applied voltage. In case of an increase in powder concentration, MRR decreases from range 4 to 6 and further reduces to 6–8. In case of SR, it additionally decreases on the maximum level of powder concentration. In electrolyte concentration, the MRR decreases on the increment of electrolyte and increases after a short period of time; simultaneously SR is increased from range value 10–20 and decreased with a maximum level 20–30 of NaCl solution. A comparison of MOORA-PCA and TOPSIS-PCA demonstrates the superiority of TOPSIS over MOORA technique. Statistical results (95% confidence level) indicate that the voltage, powder concentration, and electrolyte concentration affect the surface roughness by 69.50%, 8.67% and 14.59% in the electrochemical machining of d3 die steel. Therefore, the optimum combination of process parameters corresponding to voltage: 45 V, powder concentration: 4 g/L, and electrolyte concentration: 10 NaCl/L, respectively, were found to yield the desired result. The prediction accuracy of the TOPSIS-PCA hybrid approach model is found better than MOORA-PCA technique. [ABSTRACT FROM AUTHOR]

Electro-discharge machining (EDM) has been extensively employed for machining hard alloys, and its simulations have been widely conducted using finite element analysis (FEA). However, the majority of mesh-based models depended on forecasting the crater profile only based on the temperature gradient, without offering detailed data regarding the machined material properties. It is crucial to understand the behaviour of the machined material in order to accurately assess the flushing efficiency, analyse the wear on the electrode, and examine the interaction between the debris generated during machining and the remaining workpiece. This is done to ensure that no recast material is left behind after the EDM process. For the first time, a meshless smoothed particle hydrodynamics multi-phase model was implemented to gain practical insights and comprehensively understand a very intricate phenomenon that occurs within a very short time. Additionally, this approach is utilised to investigate the characteristics of the materials being machined. We utilised our SPH model to simulate both the capacitance- and transistor-based EDM of Ti–6Al–4V and AISI304 steel. Our simulation considered the temperature-dependent thermal properties and latent heats of the materials. The accuracy of our model was confirmed by comparing its results with experimental, analytical, and finite element analysis (FEA) results. The machined material was observed during its removal from the surface, and the dimensions of the resulting crater, as well as its aspect ratio and the rate at which the material was removed, were predicted with an error ranging from 2 to 22%. This error is far lower than that of the typical finite element (FE) prediction. This model lays the groundwork for a more complex model that will more accurately represent EDM and other similar manufacturing processes. [ABSTRACT FROM AUTHOR]

Glass is a widely used material in key fields such as Micro-Electro-Mechanical Systems (MEMS) due to its excellent properties. The existing non-traditional glass machining methods have problems such as high pollution, difficult operation, and poor sustainability, this article utilizes the effective combination of electrochemical discharge machining and grinding (named electrochemical discharge grinding, ECDG), by using NaHCO 3 solution as electrolyte to achieve green machining. Utilizing ultrasonic vibration and multi-hole tube electrode to achieve precise and stable machining. Modeling and simulation analysis were conducted on the material removal rate and grinding force during the machining process, which profoundly revealed the joint improvement mechanism of spark discharge and ultrasonic vibration on grinding quality. First, a single factor experiment was used to preliminarily determine the machining threshold. Second, the Plackett-Burman experiment was used to screen key machining parameters. Then, Box-Behnken experiment was conducted on key machining parameters, and multi-objective and multi-factor optimization was performed to obtain the optimal combination of machining parameters. Compared with normal ECDG with cylindrical grinding electrode, the overcut is reduced by 8.3 %, the edge damage is reduced by 17.5 % and the surface roughness value is reduced by 70.6 %. Finally, by using the optimized combination of machining parameters, high-quality and stable machining of typical microchannel structures was achieved. The milling depth of the microchannel is 400 µm. The machining width is 1175 ± 5 µm. The surface roughness of the measurement area is 0.375 µm. The green, high-quality and stable machining of micro glass micro components further demonstrates the potential application of this compound technology. [Display omitted] [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]

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]

Zirconium alloys possess excellent wear resistance, which ensures the durability and longevity of the components, making them widely used in medical and other fields. To enhance the functionality of these materials, it is often necessary to fabricate functional microstructures on their surfaces. Electrochemical machining (ECM) techniques demonstrate excellent machining performance for these metals, particularly in the processing of microstructures on complex curved surfaces. However, ECM often faces challenges due to the fluid nature of the electrolyte, resulting in low machining accuracy and localization. This paper proposes a novel method for fabricating complex patterned microstructures using a maskless electrochemical direct writing technique with a polyacrylamide (PAM) polymer electrolyte. By leveraging the non-Newtonian properties of PAM, this method effectively confines the electrolyte to specific areas, thus addressing the issue of poor localization in traditional ECM and reducing stray corrosion. To elucidate the electrochemical removal mechanism of Zr702 in the presence of PAM, polarization curves, viscosity characteristics, and current efficiency parameters were analyzed. Additionally, an experimental study was conducted using a custom-designed nozzle structure. The results showed that the PAM electrolyte could effectively reduce the E F , positively impacting machining accuracy and localization. By controlling the nozzle's motion trajectory, complex microstructures were successfully fabricated through direct writing, demonstrating promising application prospects. [ABSTRACT FROM AUTHOR]

Bearing steel (GCr15) is widely used in key parts of mechanical transmission for its excellent mechanical properties. Electrochemical machining (ECM) is a potential method for machining GCr15, as the machining process is the electrochemical dissolution of GCr15 regardless of its high hardness (>50 HRC). In ECM, NaNO3 solution is a popular electrolyte, as it has the ability to help in the nonlinear dissolution of many metallic alloy materials, making it useful for precision machining. However, due to high carbon content of GCr15, the electrochemical dissolution of GCr15 is unique, and there is always a black layer with high roughness on the machined surface, reducing the surface quality. In order to improve the electrochemical machining of GCr15 with a high surface quality, the surface characteristics of GCr15 in ECM were investigated. The anodic polarisation curve in the NaNO3 electrolyte was measured and electrochemical dissolution experiments were conducted with different current densities. SEM, XRD, and XPS were employed to analyse the surface morphology and composition formed on the machined surface at different current densities. The initial results showed that there were two parts (black part and bright part) formed on the machined surface when a short circuit occurred, and the test results suggested that the black part contained a mass of Fe3O4 while the bright part was composed of mainly Fe and Fe3C. Further investigation uncovered that a black flocculent layer (Fe3O4) always formed in a low current density (32 A/cm2) with high roughness. With the current density increased, the amount of black flocculent layer was reduced, and Fe3C particles appeared on the machined surface. When the current density reached 81 A/cm2, the entire flocculent oxide layer was removed, only some spherical Fe3C particles were inserted on the machined surface, and the roughness was reduced from Ra7.743 μm to Ra1.783 μm. In addition, due to exposed Fe3C particles on the machined surface, the corrosion resistance of the machined surface was significantly improved. Finally, circular arc grooves of high quality were well manufactured with current density of 81 A/cm2 in NaNO3 electrolyte. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is one of the most ideal machining methods for difficult-to-cut material of U71Mn alloy. Therefore, it is vital to obtain the electrochemical characteristics of the material. In this paper, these characteristics are measured with an electrochemical station, and a series of experiments are conducted to verify them. The electrolyte solutions of 15 wt.% NaNO3 and 15 wt.% NaCl are selected for the experiments. The polarization experimental results indicate a broader range of passive regions in the NaNO3 electrolyte solution compared with that in the NaCl. This means that a higher voltage is required to break down the passive film in ECM experiments. Meanwhile, the current efficiency of the alloy is measured in 15 wt.% NaNO3 and 15 wt.% NaCl. The results indicate that the current efficiency of U71Mn alloy in NaCl electrolyte solution is higher than that in NaNO3 electrolyte solution. The electrochemical characteristics of U71Mn alloy are verified with a series of single-factor experiments, and reasonable machining parameters are obtained. The suitable range of machining voltage is 10 to 20 V, and the range of inter-electrode gap is 0.1 to 0.2 mm in these two electrolyte solutions. Finally, multi-parameter experiments are carried out in these two electrolyte solutions to obtain machining samples. The experimental results show that 15 wt.% NaNO3 proved to be a better electrolyte solution for U71Mn alloy, the surface roughness (SR) of the workpiece is Sa 0.72 μm, and the material removal rate (MRR) is 0.096 g/min. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) technology holds significant potential for applications in high accuracy engineering and manufacturing. To confine the electrolyte region during ECM and mitigate the effects of reaction products and heat generation, an electrolyte suction tool has been proposed. However, the complex electric field distribution on the anode surface during the application of pulse voltage, limits the further utilization of ECM with suction tool. A multi-physics simulation model is established to calculate the region of electrolyte confinement by the suction tool, current density distribution within the electrolyte region, and material removal. The model considers the combined effects of polarization and double layer, and all key parameters are calibrated through classical electrochemical testing experiments rather than fitted based on the predicted results. This study elucidates the transient response of current density on the anode surface during the application of pulse voltage. The simulation accuracy is validated by comparing experimental and simulated current waveforms, as well as material removal profiles under different pulse parameters and electrode shapes. This research is of great significance for improving surface precision and controllability of complex structures in ECM with suction tool, promoting its further application in the field of precision machining. • Establish a multi-physics field coupled simulation for ECM with electrolyte suction tool. • Calibrate all key parameters through classical electrochemical testing experiments. • Elucidate the transient response of Faraday current density on the anode surface during pulse voltage. • Elucidate the material removal mechanism under the combined effects of polarization and double layer. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses (BMGs) have excellent mechanical properties, however, it is still challenging to process high-qualtiy BMG structures for their widespread engineering applications. In this work, electrochemical machining (ECM) is adopted to process various small BMG structures with high geometrical precision and surface quality. Firstly, the electrochemical dissolution behavior of a Zr 57 Cu 20 Al 10 Ni 8 Ti 5 (at.%) BMG in NaNO 3 , H 3 PO 4 , NaCl, and HCl solutions was investigated and discussed. The results shown that obvious corrosion occurred in HCl and NaCl solutions, while mass by-products and pitting corrosion on the workpiece surface in NaCl solution affect the corrosion continuity and surface quality. Therefore, the HCl solution is selected as the electrolyte for the following ECM process. Secondly, the effects of machining parameters on the ECM performance of BMG workpieces were investigated, where the optimal machining performance was achieved with an electrolyte of 0.1 mol/L HCl, a cathode feed rate of 3 μm/s, a machining voltage of 10 V, and a duty cycle of 15%. Finally, a small round hole with a roughness (Ra) of about 0.2 μm, a sidewall taper of less than 2.83°, and a relative error of diameters of 2.1% was obtained. Another square structure (0.899 mm × 0.891 mm) with high geometrical precision and surface quality was also achieved by the optimal parameters, which validates the feasibility to machine small BMG structures using the ECM technique with its optimal parameters. [Display omitted] • The electrochemical dissolution behavior in four solutions was investigated. • HCl solution was selected as a suitable electrolyte for the ECM process. • The effects of machining parameters on ECM performance were investigated. • Optimal processing parameters for the ECM of Zr57 BMG were obtained. • Typical small BMG structures were fabricated. [ABSTRACT FROM AUTHOR]

Thin-walled annular parts are widely used in the aerospace industry. There are some irregular island structures with non-periodic distribution on the inner surfaces of annular parts, which poses a significant challenge to manufacture such annular parts using conventional mechanical methods. Electrochemical machining (ECM) has exhibited good prospects for manufacturing thin-walled annular parts, with the advantages of no tool wear, no processing deformation and a high material removal rate. However, there is little research related to fabricate convex structures on the inner surfaces of annular parts, although ECM is vital to the machining of thin-walled annular parts. In this study, a flexible cathode tool was used to machine irregular convex structures on the inner surfaces of annular parts via co-rotating ECM. The complex motion of the cathode tool and conductive slider was simulated using matrix equations, and the digital simulation of the material removal process was realized based on matrix equations and Faraday's law. Based on the mathematical model, a design method for a flexible cathode tool was developed, and three main parameters were determined: the position of the window, radius of the cathode, and width of the window. Comparative experiments were performed using the flexible and conventional cathode tools. The results showed that the selective removal of convex structures was achieved by using the flexible cathode tool. The insulated sheet needed to be attached to the position where the convex structure was retained. An aero-engine casing with many irregular island structures on the inner surface was successfully machined. The height of the fabricated island structure is 6 mm. The sidewall thickness of the aero-engine casing is 1.2 mm. Therefore, co-rotating ECM with a flexible cathode tool offers excellent machining ability for irregular island structures on the inner surfaces of annular parts. [Display omitted] • Co-rotating electrochemical machining using a flexible cathode tool is proposed to machine structures on the inner surface of annular parts. • Based on the mathematical model of the material removal process, a design method for a flexible cathode tool is proposed. • The selective retention of island structures is achieved by adding a movable conductive slider in a conventional cathode window. • An aero-engine casing with many irregular island structures on the inner surface is successfully machined. [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]

In order to shorten the cathode design cycle, reduce design cost and improve forming accuracy for all-metal screw drill stator electrochemical machining (ECM), this paper proposed a precision forming cathode design method based on particle swarm optimization BP neural network (PSO-BP). The cathode design algorithm model of all-metal screw drill stator electrochemical machining was established, completed the camber feed cathode design. By using self-developed large scale horizontal CNC electrochemical machining equipment, under the condition of voltage 19 V, electrolyte 15%NaCl, electrolyte temperature 35 ± 1℃, electrolyte inlet pressure 1.6 MPa, and feed speed 10 mm/min, the stable and reliable electrochemical machining processing of the 4-m length of 38CrMoAlA all-metal screw drill stator was completed. The contour forming accuracy is ± 0.03 mm, and the surface roughness is Ra0.848 μm. Research showed that it is an efficient and feasible method to design the electrochemical machining camber feed cathode of all-metal screw drill stator using PSO-BP neural network. [ABSTRACT FROM AUTHOR]

In order to solve the problems of easily distorted and poor surface quality in machining aluminum alloy thin-walled internal spiral deep hole parts, a precision-forming electrochemical machining (ECM) method was proposed. In this paper, the physical model of the pull-type downstream and pull-type countercurrent cathode was established, and the simulation study on the flow field of two kinds of cathode gap was carried out. The inclination angle of the cathode liquid supply hole was optimized. The simulation results showed that the flow rate of the pull-type downstream cathode electrolyte is 21% higher than the pull-type countercurrent cathode, and the flow field is more uniform when the inclination angle of the cathode liquid supply hole is 30°. Using the self-developed large-scale horizontal electrochemical machining equipment, under the conditions of voltage 7.5 V, current 1850 A, composite electrolyte 10%NaCl + 9%NaNO3, electrolyte temperature 30 °C, inlet pressure 1.2 MPa, and cathode feed rate 100 mm/min, the surface roughness of Ra0.741 μm and the forming accuracy of 0.035 mm aluminum alloy thin-walled inner spiral deep hole stable machining was completed. The research shows that the cathode structure optimization simulation can effectively shorten the cathode development cycle and reduce the test cost. [ABSTRACT FROM AUTHOR]

Functionality-oriented micro-structures, such as micro-dimples and grooves, are widely used in tribology and heat transfer. Jet electrochemical machining (JEM) is effective to fabricate micro-structures on metallic surfaces. However, in traditional JEM, the unrestricted electrolyte flowing can induce stray corrosion on workpiece, and thus, both surface quality and machining localization are reduced. In this paper, a novel electrolyte-confinement technique is proposed for JEM, a high-density liquid (perfluorotripropylamine, FTPA) is used to confine the electrolyte flowing region on workpiece when electrolyte exits nozzle, facilitating reduction in stray corrosion on workpiece and overcut of micro-structures. A multi-physics model including two-phase flow field and electric field is developed to analyze the electrolyte confined by FTPA, and both simulation and observation results show that the area of electrolyte flowing on the workpiece is confined well by FTPA, and the current density distribution becomes concentrated, which enhances the machining localization. Compared to traditional JEM, the etch factor of micro-dimple is improved by 2.5 times and there is no stray corrosion. The material removal rate is increased due to the concentration of current distribution on the workpiece surface. Furthermore, profile evolution of micro-dimples revealed that with feed depth increased, FTPA could flow into the micro-dimple to protect the sidewall from continuous dissolution, thus forming vertical sidewall. Additionally, electrolyte flowing region is still confined during the scanning motion of nozzle, and the etch factor increases from 0.41 to 8.8 compared to traditional JEM. Moreover, increasing inter-electrode gap could reduce electrolyte flowing region on workpiece, further enhancing machining localization. [ABSTRACT FROM AUTHOR]

Drilling precise micro-holes in glass material has brought a new challenge, primarily due to its application in microfluidic devices. It is required to reduce machining time and simultaneously achieve repeatability of the process. The machined hole should have minimum overcut to get desired hole diameter. Maximum hole circularity and minimum heat-affected zone are the essential hole characteristics to achieve controlled machining. The multi-criteria decision-making (MCDM) method is quite effective in selection of best possible combination of outputs from several alternative solutions. The experimental data from the previously published paper is used in the current study. As input parameters, the experiment data include voltage, tool feed rate, and machining time. The radial overcut (ROC), circularity of the machined hole and heat-affected zone (HAZ) were calculated as output responses. The experiments were conducted using copper and nickel-coated copper tools in previous study and response data were used in current work. The present study uses the methods which include hybrid grey relational analysis (GRA), technique for order performance by similarity to ideal solution (TOPSIS), and VIšekriterijumsko KOmpromisno Rangiranje (VIKOR) methods for the selection of the best combination of process parameters in drilling to obtain the optimal geometric characteristic of a hole, i.e. optimal values of ROC, circularity and HAZ, in glass using electrochemical discharge machining (ECDM). In this study, weight calculation for MCDM was proposed using entropy and analytic hierarchy process (AHP) methods and combined to get final weights using the fuzzy logic tool, which determines the importance of AHP and entropy weights using the expert opinion. The final weights were used to calculate the ranks from each MCDM method and determine optimal process parameter selection in ECDM hole drilling with copper and nickel-coated copper tools. The fuzzy logic method determined that the weight contribution from AHP is 0.586 in the present study. Genetic algorithm-based multi-objective optimization was conducted, and a non-dominated Pareto front was generated. The Spearman correlation method was used to determine the relationship between different MCDM methods. The current study will be helpful in selecting the best combination of process parameters in drilling holes during ECDM machining using MCDM methods. [ABSTRACT FROM AUTHOR]

The passivation characteristics of titanium alloys in electrolytes are often the main reason that impede the electrochemical reaction process. Hence, maintaining uniform electrochemical dissolution is a prerequisite for stable electrochemical machining (ECM) of titanium alloys. In this study, a novel cathode structure with built-in insulator is proposed, whichimproves machining stability of titanium alloys in ECM. Flow dynamics simulation results show that the cathodes with built-in insulator 1 or insulator 3 demonstrate more uniform flow effect. ECM experiments reveal that the optimized cathode can reduce the time of current from transition section to balance section, presenting a optimal transition time of 180 s. Compared with the original cathode, the sample surface machined using the optimized cathode is smooth without defects. Additionally, the optimal width of the non-processing stray corrosion area decreases from 603.47 μm to 214.54 μm, and 1010.47 μm to 349.25 μm. The optimal machining taper angle is 9.85°. [ABSTRACT FROM AUTHOR]

The current study explores the effectiveness of the ECM process when machining newly developed high entropy alloy (HEA)-reinforced magnesium composites. To evaluate the machinability, the study focuses on two key output constraints: surface roughness (Ra) and material removal rate (MRR). Experimental trials involve adjusting variables such as feed rate (FR), current, Electrolyte concentration (EC), & voltage in which experiment design is done through Taguchi method. Results highlights voltage as the most important input parameter governing Ra, followed by current. Similarly, voltage emerges as the primary influencer for MRR, with current being the second most influential. Furthermore, artificial neural networks (ANN) yielded predictions closely aligns with the experimental data. The optimal parameter set identified through CRITIC-WASPAS method included 5 Wt.% HEA, 15 V Voltage, 2 Amps current, 0.3 mm/min feed, and 25 g/lit electrolyte concentrations, resulting in a surface finish of 3.47 µm and a production rate of 0.039 mg/min. [ABSTRACT FROM AUTHOR]

This study investigated the impact of varying atomization amounts on composite machining involving both atomized electrical discharge ablation machining and electrochemical machining (EDAM-ECM). Additionally, this study examined the effects of different atomization amounts on the material removal rate, relative electrode wear rate, processing waveforms, surface roughness, surface morphology and elements, and the EDAM-to-ECM ratio. Moreover, a theoretical model for describing the material removal process in composite processing was developed. Furthermore, the effect of the ECM ratio on the processing results was quantitatively analyzed through the integration of statistical circuits with a formula for calculating recast layer thickness. The model was used to predict and select the optimal atomization amounts required to achieve recast layer removal during processing. The results revealed that at an atomization amount of 200 mL/min, 16.7% of the total material removal was attributable to ECM, indicating the successful removal of the recast layer. At this atomization amount, the fabricated sample maintained a machining precision of 0.02 mm. [ABSTRACT FROM AUTHOR]

A multistage inner cone hole (MICH) consists of numerous inner cone holes of varying degrees of conicality and length and is frequently employed in diverse machinery. Due to the use of difficult-to-machine materials and the demand for high machining quality, precision machining has become an urgent challenge. To improve the surface finish quality of MICH, a novel electrochemical machining (ECM) process assisted by a hydraulic self-driven rotating magnetic field is proposed in this paper. A hydraulic self-driven rotating shaft with magnets attached to the cathode is designed, which can be driven by the electrolyte to rotate and generate a rotating magnetic field during the ECM process. The rotating characteristics of the hydraulic self-driven rotating shaft and the rotating magnetic field characteristics are studied via simulations. According to the simulation analysis results, the parameters related to the rotating shaft and the rotating magnetic field are optimized. Finally, the ECM cathode of MICH was machined, and a machining experiment was conducted. The experimental results indicate that the surface finish quality of MICH machined by the proposed ECM is better than that of conventional ECM, the maximum dimensional error is 0.1 mm, and the surface roughness is Ra 0.695 μm. [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]

Electrochemical machining has shown advantages over conventional processing for difficult-to-process materials. In this study, electrochemical machining methods were applied to the surface treatment of 2Cr13 stainless steel. Magnetic field assistance was employed for the experiments and the variations in magnetic induction intensity were taken into consideration. The surface roughness of machined samples was detected and the surface morphology was observed. The results showed that electrochemical machining was an effective treatment for surface roughness reduction. After the introduction of a magnetic field of 200 mT, lower surface roughness was realized for the same machining time, which indicated that the magnetic field helped to promote the improvement of processing efficiency. Moreover, the processing efficiency was further enhanced with the increase of the magnetic induction intensity to 300 mT. In the regime of magnetic field-assisted electrochemical machining for 20 min, a high-precision surface with a roughness of 0.28 μm was achieved for 2Cr13 stainless steel. The simulation results demonstrated that the magnetic field increased the current density at the anode surface and accelerated electrochemical anodic dissolution. With the increase of the magnetic induction intensity, the current density reinforcement became significant. The enhancement mechanism of magnetic field-assisted electrochemical machining was revealed by employing the theory of magnetohydrodynamics. [ABSTRACT FROM AUTHOR]

Screw drill is one of the most widely used power drilling tools in the field of deep sea drilling because of its excellent performance such as low drilling speed, high torque, and strong overload capacity. However, it has the problems of complex internal structure and long processing stroke of screw drill stator. In this paper, the electrochemical machining (ECM) technology is used to solve the problem of internal spiral curved surface special-shaped deep hole machining. Firstly, the initial cathode structure with spirally increasing tooth surface of six machining teeth is designed, and the gas-liquid two-phase flow field model of the gap is established to simulate and analyze it. The simulation results show that the flow field distribution of the electrolyte in the machining gap is not uniform and the bubble concentration is high. Secondly, the initial cathode structure is optimized by adding different numbers of liquid-increasing grooves on the tooth surface of the machined tooth, and the gas-liquid two-phase flow field is simulated. The simulation results show that the cathode structure with four additional baths on each tooth surface results in a better overall flow of electrolyte in the machining gap, a flow rate of more than 3 m/s in the machining area, and a significant reduction in the concentration of electrolyte bubbles, with a reduced rate of 18.7% and a smaller distribution area for the highest bubble concentration, ensure the machining accuracy. Finally, the orthogonal experiment of 4 factors and 4 levels was designed, and the optimized processing parameters were obtained by gray correlation analysis method, that is, inlet pressure of 0.4 MPa, machining voltage of 11 V, duty cycle of 40%, and cathode feed rate of 0.9 mm/min, under which the deviation of the large end diameter of the deep special-shaped hole was 0.15 mm, the surface roughness of the inner wall of the hole was 0.487 μm. The data shows that this combination of processing parameters meets the production requirements of the product. The data shows that this combination of machining parameters meets the production requirements of the product. The COMSOL simulation method significantly shortens the research cycle and saves research costs. [ABSTRACT FROM AUTHOR]

Wire electrical discharge machining (WEDM) is a non-conventional machining process renowned for precision in machining complex profiles, especially in high-strength and hard materials. This process also found other functions in machining cylindrical workpieces, known as wire electrical discharge turning (WEDT). The material removal mechanism of this process is based on electrical discharges, and evaluating the productivity of the continuous process to a great extent depends on the material removal of individual single discharges. In order to study the influence of rotational speed in material removal of erosion in cylindrical workpieces, theoretical and experimental studies of each single spark are necessary. This comprehensive study delves into the influence of rotational speed in WEDM processes applied to cylindrical workpieces. The research includes a series of single discharge experiments, and introduces a computational fluid dynamics (CFD) thermal model. The developed thermal model demonstrates the capability to predict the material removal rate of a single discharge with an error of 8.6% relative to experimental data. Furthermore, the investigation extends to continuous erosion studies, analyzing the material removal rate under varying rotational speeds. The overall material removal rate decreases 13% due to the declining material removal rate of each single discharge. Additionally, a removal efficiency parameter of erosion of cylindrical workpieces is introduced to provide an evaluation of the process and the influence of crater overlaps. The removal efficiency for various rotational speeds ranges between 22 and 24%, influenced by the proportion of normal discharges and the efficiency of crater overlaps. [ABSTRACT FROM AUTHOR]

Traditional blade electrochemical machining (ECM) adopts electrolyte unidirectional flow (EUF), resulting in serious accumulation of insoluble byproducts, gas, and Joule heat along the flow path. Here, an electrolyte intermittent commutation flow (EICF) was reported. Blade formed with EICF model was simulated, by comparison with EUF. Exploratory experiments were carried out, and how the time ratio of forward electrolyte flow time (tF) and reverse electrolyte flow time (tR) affects the blade ECM performance was investigated. The manufacturing accuracy and surface roughness depend on tF:tR, and they first improve and then deteriorate, reaching its optimal value at tF:tR = 1:3. Finally, the surface morphology is less affected by the tF:tR, the dissolution morphology exhibits that grain boundary is preferentially susceptible to electrochemical attack, compared with grain. The reason for this corrosion mechanism is that Ti and Nb are more easily enriched at the grain boundaries, while Cr, Fe and Ni are depleted. [ABSTRACT FROM AUTHOR]

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]