Electrochemical Micromachining Process Research Articles

Optimization of the Parameters of the Electrochemical Micromachining Process Using Artificial Neural Network (ANN) Models to established a Simple Relationship Between Machining Rate (MR), Overcut (OC) and Input Data

Optimization of the Parameters of the Electrochemical Micromachining Process Using Artificial Neural Network (ANN) Models to established a Simple Relationship Between Machining Rate (MR), Overcut (OC) and Input Data

Real-time monitoring of process current and its correlation with micro-feature accuracy and surface topography in electrochemical micromachining of nitinol

The nickel-titanium alloy known as Nitinol classified as a shape memory alloy is distinguished by its exceptional attributes, including shape memory effect, biocompatibility, and superelasticity. However, its thermo-mechanical dependent transformation behavior makes it difficult to process using traditional methods. Electrochemical micromachining (ECMM), a non-traditional fabrication method, uses anodic dissolution process to produce microfeatures on Nitinol. The current work emphasizes the impact of process current on the machining accuracy and surface topography of microchannels produced during ECMM of Nitinol utilizing ethylene glycol-based sodium nitrate electrolyte. The ECMM process parameters that were studied are pulsed potential, molar concentration, and micro-tool scan rate, and the development of the process current resulting in variation of these parameters during microchannel fabrication was closely observed. The statistical parameters, namely, the average process current and the process current fluctuation, were derived from the process current data that were further analyzed with respect to input parameters. The machining accuracy and the surface topography of the microchannel are analyzed by measuring the width overcut, channel depth, stray region, width standard deviation, and average surface roughness of the fabricated microchannel. The results showed that monitoring the process current in real-time is an effective way of controlling the process, particularly when it comes to fabricating micro-features that must adhere to strict predetermined criteria.

Parametric investigation of pulse frequency and microtool rotational speed for precise fabrication of microchannels on nitinol shape memory alloy through ECMM

Nitinol, a material with a unique combination of properties like shape memory effect, superelasticity, and biocompatibility, has become popular in the biomedical and micro-electro-mechanical systems (MEMS) industries. Electrochemical micromachining (ECMM) has emerged as an excellent method for micromachining Nitinol shape memory alloy (SMA) due to its ability to provide superior surface integrity and absence of any thermal effect. This study aimed at improving the surface integrity and the accuracy of the microfeatures on Nitinol fabricated through the ECMM process. The effects of process parameters like pulse frequency and microtool’s rotational speed on the diametral overcut of the microfeature were investigated at different inter-electrode gaps. The findings revealed that at 1 MHz pulse frequency and 500 rpm microtool rotating speed, the diametral overcut ranged from 0.163 µm at interelectrode gap (IEG) of 5 µm to 1.626 µm at IEG of 1 µm, indicating a precise microfeature fabrication. At the same parametric combination, the machined depth varied from 2.89 µm at IEG of 5 µm to 5.56 µm at IEG of 1 µm, suggesting a proportionate change in depth of the microfeature. Moreover, precise microchannels with average surface roughness values of 17.5 nm, 9.5 nm, and 12.4 nm were fabricated on the Nitinol surface at pulse frequencies of 1 MHz, 2 MHz, and 3 MHz, respectively.

Prediction of material removal rate of SS304 alloy in electrochemical micromachining using machine learning

Electrochemical micromachining (ECMM) is a non-traditional machining process used in machining microfeatures that are being used in the fabrication of MEMS, finishing surgical tools, implants, and cooling channels. Machine learning (ML) algorithms can be used to predict the output of a machining process based on the given input parameters. In this Work, ML is interpreted into ECMM where, different ML models were built based on Decision tree regression, Random Forest regression, and Support vector regression algorithms to find the relationship between the interactive effects of the type of electrolyte, voltage, feed rate, and duty cycle on Material Removal Rate (MRR). The work also aims to find the best-fit algorithm and approach toward the prediction of MRR of AISI SS304 alloy when machined in ECMM using Regression Analysis. The results showed that higher efficiency was attained in the Decision tree regression model with a training accuracy of 99.87% and testing accuracy of 99.75% and decision tree was found to be the best fit algorithm for the ECMM process for the single response parameter.

Polarization studies- A method to select and optimize electrolyte for electrochemical micromachining process

This paper aims to identify the most suitable electrolyte for electrochemical micromachining of AISI 304 stainless steel by polarization studies. Corrosion behavior of the material will be analyzed using specialized potentiostat equipment. The electrochemical studies were conducted to examine the impact of different electrolytes on the corrosion behavior of SS304 alloy. These corrosion studies, performed with various electrolytes, help determine the optimal electrolyte for AISI 304 stainless steel. Based on the optimized results obtained from the electrochemical studies, a preferred mixed electrolyte for AISI 304 stainless steel was identified. To micro-drill AISI 304 stainless steel alloy, electrochemical micromachining experiments were conducted using suitable input parameters and the preferred electrolyte. The micro-drilling was performed with an electrically conductive 300 µm diameter copper tool on AISI 304 stainless steel (SS304), achieving a drilling depth of 300 µm. Voltage, duty ratio and feed rate are the input parameters considered for machining AISI 304 stainless steel. The output responses are corrosion behavior and 3D surface roughness (Sa). The corrosion behavior was analyzed through Scanning Electron Microscopy (SEM) studies to examine the surface obtained. The results clearly demonstrated that the mixed electrolytes utilized for machining SS304 alloy yielded favorable outcomes in terms of both geometric aspects and surface characteristics. Furthermore, the experimental findings confirmed that polarization studies improve machining characteristics and reduce the number of trials required to identify the suitable electrolyte. By applying polarization techniques to ECMM, energy consumption and costs associated with the process can be reduced.

Influence of Silver-Coated Tool Electrode on Electrochemical Micromachining of Incoloy 825

Incoloy 825 alloy is often used in calorifiers, propeller shafts, and tank vehicles owing to the improved resistance to aqueous corrosion. The electrochemical micromachining process can be utilized to machine such an engineering material owing to higher precision and lower tool wear. In the present study, an investigation was performed to enhance the process of creating micro-holes using silver-coated copper tool electrodes. The sodium nitrate electrolyte was used under different levels of input parameters such as voltage, electrolyte concentration, frequency, and duty cycle with a view to improving material removal rate, conicity, overcut, and circularity. It was found that silver-coated copper tool electrode had a high material removal rate (MRR), better overcut, conicity, and circularity compared to uncoated copper tools in most cases, due to its high corrosive resistance and electrical conductivity. From SEM and EDS analysis, it was observed that better surface topography of the micro-holes is obtained with silver-coated copper tool electrode while machining Incoloy 825 alloy in the micromachining process.

Optimization of Process Parameters in Electrochemical Micromachining of AMCs by Using Different Techniques of Weight Evaluation

The application of electrode heating is proposed in electrochemical micromachining (EMM). In the EMM process, the temperature of the electrode, voltage, duty cycle, and electrolyte concentration are considered process parameters. Taguchi L18 mixed-level orthogonal array (OA) design was adopted for designing the experiments and this study highlights the effect of temperature on responses such as radial overcut (ROC), material removal rate (MRR), and conicity factor (CF). In addition, multicriterion design making (MCDM) with VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje, i.e., multi-criteria optimization and compromise solution) technique is used for finding the best alternatives based on the distinct weight assessing methods such as equal weights method (EWM), analytic hierarchy process (AHP), and entropy-based weights method (EBWM). Furthermore, a confirmation test is also conducted to find the best optimal parameters and their levels among the EWM-VIKOR, AHP-VIKOR, and EBWM-VIKOR. The results revealed that AHP-VIKOR provides a maximum improvement of 0.945 among the three methods.

Evolutionary algorithms based optimization of electrochemical discharge micromachining process during micro-channel fabrication on glass

Evolutionary algorithms based optimization of electrochemical discharge micromachining process during micro-channel fabrication on glass

Multiobjective Optimization of Heat-Treated Copper Tool Electrode on EMM Process Using Artificial Bee Colony (ABC) Algorithm.

Electrochemical micromachining (EMM) is a plausible method for manufacturing high accuracy and precision microscale components in a broad range of materials. EMM is commonly utilized to manufacture turbine blades for automobiles and aircrafts. In this present study, the EMM process was performed with a heat-treated copper tool electrode on aluminum 8011 alloy. The process parameters such as voltage, concentration of electrolyte, frequency, and duty factor were varied to analyze the effect of a heat-treated electrode on material removal rate (MRR), overcut, conicity, and circularity. It was observed that high MRR was obtained with lower overcut with an annealed electrode. The better conicity and circularity were obtained with a quenched electrode compared to other heat-treated and untreated tool electrodes. The artificial bee’s colony (ABC) algorithm was used to identify the optimum parameters and, finally, the confirmation test was carried out to evaluate the error difference on the machining process. The optimum combination of input process parameters found using TOPSIS and ABC algorithm for the EMM process are voltage (14 V), electrolyte concentration (30 g/L), frequency (60 Hz), and duty cycle (33%) for the annealed tool electrode and voltage (14 V), electrolyte concentration (20 g/L), frequency (70 Hz), and duty cycle (33%) for the quenched tool electrode. It was confirmed that 95% of accurate response values were proven under the optimum parameter combination.

Neural Network (NN)-Based RSM-PSO Multiresponse Parametric Optimization of the Electro Chemical Discharge Micromachining Process During Microchannel Cutting on Silica Glass

The production of miniature parts by the electrochemical discharge micromachining process ([Formula: see text]-ECDM) draws the most of attractions into the industrial field. Parametric influences on machining depth (MD), material removal rate (MRR), and overcut (OC) have been propounded using a mixed electrolyte (NaOH:KOH- 1:1) varying concentrations (wt.%), applied voltage ([Formula: see text]), pulse on time ([Formula: see text]s), and stand-off distance (SOD) during microchannel cutting on silica glass (SiO[Formula: see text]). Analysis of variances has been analyzed to test the adequacy of the developed mathematical model and multiresponse optimization has been performed to find out maximum MD with higher material removal at lower OC using desirability function analysis as well as neural network (NN)-based Particle Swarm Optimization (PSO). The SEM analysis has been done to find unexpected debris. MD has been improved with better surface quality using a mixed electrolyte at straight polarity using a tungsten carbide (WC) cylindrical tool along with [Formula: see text], [Formula: see text], and [Formula: see text] axis movement by computer-aided subsystem and combining with the automated spring feed mechanism. PSO-ANN provides better parametric optimization results for micromachining by the ECDM process.

Electrochemical Micromachining of Linear Micropattern on Stainless Steel Surface

Maskless electrochemical micromachining process with SU-8 2150 masked tool has been introduced containing microstructures with higherprofile accuracy that are generated on SS-304. In this research work, to make maskless EMM method with more cost-effective, substantial adaptations are provided to this technique and an advanced version of EMM process is applied for microtexturing. In this modified technique, a special microtextured cell unit including (micromachining cell, electrical connection, and electrolyte flow scheme) is assembled by the mechanical force and perpendicular cross flow system has been developed inside the cell. Experimentation is conducted to explore the machining influence of the advanced maskless EMM process for fabricating linear micropattern. The machining outcomes of voltage, frequency, and duty ratio on MRR, dimensional accuracy, textured depth, and surface roughness are investigated during microtexturing. The investigational research reveals that this advanced maskless EMM technique can generate highly identical micropatterns having MRR of 2.2 mg/min, width overcut of 19.76μm, textured depth of 14.4μm and surface roughness of 0.0307μm.

A performance study of electrochemical micro-machining on SS 316L using suspended copper metal powder along with stirring effect

ABSTRACT Electrochemical micro-machining (ECMM) is widely used for machining small-sized components, intricate shapes, and hard materials. Fabrication of micro-holes in stainless steel 316L (SS 316L) can be effortlessly achieved by the ECMM process rather than other machining methods, owing to its favorable machining characteristics and advantages. This paper tries to elucidate the performance of ECMM on the machining of SS 316L using an eco-friendly citric acid as an electrolyte medium, and the results are compared with copper metal powder suspended in a citric acid electrolyte (suspended electrolyte) and copper metal powder suspended in a citric acid electrolyte with the assistance of a mechanical overhead stirrer (suspended electrolyte with stirrer effect). The output performance parameters such as MRR and overcut are calculated by varying the input response parameters such as machining voltage, duty cycle, and electrolyte concentration. From the experimental results at higher parameter levels, the highest MRR and moderate overcut are obtained for suspended electrolyte with stirrer effect. For suspended electrolyte, moderate MRR and the highest overcut are detected. The least MRR and reduced overcut are found for citric acid electrolyte. SEM and EDAX analysis have been carried out to see the machined micro-hole and the composition present in the specimen.

Analysis of circuit current in electrochemical micromachining process under the application of different waveforms of pulsed voltage

Selection of optimal pulsed voltage parameters such as waveform, pulse rise and fall time, frequency, and duty ratio is very important to achieve the desired machining efficiency and accuracy in electrochemical machining (ECM). At present, this selection is done by conducting time-consuming and costly trial experiments. It is well understood that the volume and rate of material dissolution in ECM is dependent on the current flowing between the two electrodes. However, only a part of this current, called as Faradaic current, is responsible for the anodic dissolution and the rest of it, called as capacitive current, is consumed in charging the electrical double layer (EDL) capacitance which forms at the interface. Therefore, it is vital to understand the variation of Faradaic current in the system to arrive at optimal pulse parameters. An increase in the current flowing between the two electrodes does not ensures an increase in the Faradaic component of that current. To the best of authors' knowledge, there does not exists any method or device, to date, which can break the system current into its components and provide their variation explicitly. This research attempts to fill in this gap by provide a method of breaking the overall system current into its constituents by investigating the system under consideration using electrochemical impedance spectroscopy (EIS). The results of EIS are used to virtually construct an equivalent electrical circuit in MATLAB® Simscape and the current is simulated for different waveforms of pulsed voltage input. To access the correctness of the trends of Faradaic current obtained through simulations, an experimental study is conducted. Both simulation and experimental study is conducted for three waveforms of pulsed voltage namely: half wave rectified rectangular (RVW), sinusoidal (SVW), and triangular (TVW). For experimentation, these waveforms are obtained with the help of a rectification-cum-amplification circuit which is designed and developed in lab. Further optimization of triangular waveform is performed by varying its rise and fall time in five different cases. It is finally concluded that the trends of Faradaic current obtained from simulation study are in good agreement with the experimental results.

Effect of different electrolytes on electrochemical micro-machining of SS 316L

The use of stainless steel 316L (SS 316L) in the medical, marine, aerospace, bio-medical, and automobile sectors increases rapidly. Electrochemical micro-machining (ECMM) is the appropriate method for machining SS 316L due to its burr-free machining surface, no residual stress, and high precision. However, some limitations are found in using strong electrolytes, such as HCl, H2SO4, KOH, NaNO3, and NaCl, which reportedly face difficulties in disposing to the environment and handling issues. Hence, this paper addresses overcoming the disadvantages encountered in the ECMM process when using strong electrolytes to machine SS 316L. Therefore, different organic electrolytes such as tartaric acid (C4H6O6), citric acid (C6H8O7), and a combination of tartaric and citric acid (mixed electrolyte) are considered to select the best electrolyte. Process parameters like machining voltage, duty cycle, and electrolyte concentration are included in determining machining performance. The performance of ECMM is evaluated using material removal rate (MRR) and overcut. The overcut of tartaric acid electrolyte is 179% less than mixed electrolyte for the parameter combination of 12 g/l, 11 V, and 85%. On the other hand, the mixed electrolyte shows 114.2% higher MRR than the tartaric acid electrolyte for the parameter solutions of 25%, 11 V, and 20 g/l. Furthermore, the citric acid electrolyte shows the second-lowest overcut and higher MRR in all aspects of machining performance. Field emission scanning electron microscope (FESEM) studies are carried out to realize the effect of electrolytes on the machining surface.

Performance study of electrochemical micromachining using square composite electrode for copper

The use of micro components is increasing day by day in the industries such as aviation, power circuit boards, inkjet nozzle, and biomedical. Among various non-traditional micromachining methods, electrochemical micromachining (EMM) shows unique characteristics, such as no tool wear, no residual stress, and high accuracy. In this research, EMM is considered to study the effect of square-shaped stainless steel (SS) and aluminum metal matrix composite (AMC) tools on square hole generation. The significant process parameters, such as machining voltage, duty cycle, and aqueous sodium nitrate (NaNO3) electrolyte of varying concentrations, are considered for the study. The performances of the EMM process are evaluated in terms of machining rate (MR) and Overcut (OC). The AMC tool shows 43.22% lesser OC than the SS tool at the parameter combinations of 8 V, 85%, and 23 g/L. Also, the same parameter combination MR for the SS tool is 71.6% higher than the AMC tool. Field emission scanning electron microscope image (FESEM) analysis shows that the micro square hole generated using composite electrode shows micro-pits on the circumference of the square hole. The energy-dispersive X-ray spectroscopy (EDAX) analysis is conducted to verify the presence and distributions of reinforcement in the AMC tool.

Suitability of electrolytes and anodic dissolution behavior of 17-4 PH stainless steel

17-4 PH SS alloy finds widespread applications in turbine blades, power plants, marine and chemical industries. However, some of its mechanical properties such as high tensile and fatigue strength, good toughness, high hardness and formability make its machinability poor. Thus, non-conventional machining processes such as electrochemical micromachining (ECMM), which removes the material by chemical dissolution, has better potential to fabricate micro features of high surface quality. However, the ECMM behavior of 17-4 PH SS alloy has not been exhaustively explored yet. It is very important to understand the regular dissolution patterns to improve machining stability and machined surface quality. Therefore, the present work aims at studying the suitability of different electrolytes in ECMM process for the fabrication of micro features with better dimensional accuracy and surface quality on 17-4 PH SS alloy. The electrolytes used in the experimentation are an aqueous solution of NaBr, NaCl, NaNO3and a compound aqueous solution of NaCl + NaNO3. The performance characteristics such as radial overcut, dimple depth and some aspects of surface integrity have been investigated. Experimental results showed that better dimensional accuracy and surface quality have been achieved with NaCl + NaNO3electrolyte owing to the combined properties of passive and non-passive electrolytes.

Selected Aspects of Electrochemical Micromachining Technology Development.

The paper focuses on the fundamentals of electrochemical machining technology de-elopement with special attention to applications for micromachining. In this method, a material is removed during an anodic electrochemical dissolution. The method has a number of features which make it attractive technology for shaping parts with geometrical features in range of micrometres. The paper is divided into two parts. The first one covers discussion on: general characteristics of electrochemical machining, phenomena in the gap, problems resulting from scaling down the process and electrochemical micromachining processes and variants. The second part consists of synthetic overview of the authors’ research on localization of pulse electrochemical micromachining process and case studies connected with application of this method with use of universal cylindrical electrode-tool for shaping cavities in 1.4301 stainless steel. The latter application was conducted in two following variants: electrochemical contour milling and shaping carried out with sidewall surface of rotating tool. In both cases, the obtained shape is a function of electrode tool trajectory. Selection of adequate machining strategy allows to obtain desired shape and quality.

Fabrication of high aspect-ratio tungsten microtools through controlled electrochemical etching

ABSTRACT High-aspect-ratio cylindrical tungsten microtools were fabricated through the electrochemical micro-machining (µECM) process. The effects of eight different electrolytes in combination with the different major machining parameters were investigated and reported in this article. KOH(aq) electrolyte was found to be the most suitable electrolyte for the fabrication of tungsten microelectrodes. The Taguchi technique was utilized for optimizing the major process control parameters to minimize the taper angle of the fabricated micro-tools. During the tool fabrication process, the deposited electrochemical reaction on the tool surface played an important role to achieve controlled dissolution of the tool materials and helped in producing a uniform surface. The microtools of diameter 40 µm with aspect-ratio of about 175 were fabricated with the optimal settings of dominant machining parameters. The fabricated microtools were used to drill through drill-holes on a nickel plate of thickness 1050 µm using the same µECM setup. The detailed experimental investigations are carried out and conclusive remarks are drawn based on the experimental results.

Experimental investigation of the electrochemical micromachining process of Ti-6Al-4V titanium alloy under the influence of magnetic field

Abstract An attempt has been made to study the influence of magnetic field on the micro hole machining of Ti-6Al-4V titanium alloy using electrochemical micromachining (ECMM) process. The presence of magneto hydro dynamics (MHD) is accomplished with the aid of external magnetic field (neodymium magnets) in order to improve the machining accuracy and the performance characteristics of ECMM. Close to ideal solution for magnetic and nonmagnetic field ECMM process, the parameters used are as follows: concentration electrolyte of 15 g/l; peak current of 1.35 A; pulse on time of 400 s; and duty factor of 0.5. An improvement of 11.91–52.43% and 23.51–129.68% in material removal rate (MRR) and 6.03–21.47% and 18.32–33.09% in overcut (OC) is observed in ECMM of titanium alloy under the influence of attraction and repulsion magnetic field, respectively, in correlation with nonmagnetic field ECMM process. A 55.34% surface roughness factor reduction is ascertained in the hole profile in magnetic field-ECMM in correlation with electrochemical machined titanium alloy under nonmagnetic field environment. No machining related stress is induced in the titanium alloy, even though environment of electrochemical machining process has been enhanced with the presence of magnetic field. A slight surge in the compressive residual factor, aids in surge of passivation potential of titanium alloy, resulting in higher resistance to outside environment.

Influence of Variant Electrolyte in Electrochemical Micromachining of Micro Holes in SMA Using Taguchi Optimization

Electrochemical micromachining (ECMM) is one of the commercially successful modern machining processes used in various manufacturing industries. Nitinol, a shape memory alloy (SMA) material used as micro and nano component in bio medical fields is difficult to machine using traditional methods due to its super elasticity and shape memory effect. This problem induced in studying the machining characteristics of NiTi alloy using ECMM Process. In this work, an effort is taken to produce micro holes in SMA—NiTi alloy of 0.25 mm thickness using variant electrolytes such as the passivating electrolyte (PE) and the non-passivating electrolyte (NPE) to study the machining characteristics. The variable input parameters considered are voltage, duty cycle and feed rate to study their effect on performance characteristics such as MRR, overcut, circularity and conicity. This study resulted in finding the suitable and optimized parameters for machining Nitinol with PE and NPE with better precision and good surface integrity. Optimization studies are also carried out by Taguchi method using minitab statistical software.