Electrochemical Discharge Machining Process Research Articles

Experimental investigation of micro-machining of borosilicate glass using an ultrasonic assisted rotary electrochemical discharge machining (UA-RECDM) process

Electrochemical discharge machining is an advanced micro-machining process for machining of conductive as well as non-conductive hard and brittle materials, e.g. glass, ceramics, silicon wafer, etc. The present work explores the machining of glass using an in-house developed novel ultrasonic assisted rotary electrochemical discharge machining setup. The setup has specialized features, such as using ultrasonic vibrations to tool the electrode and incorporating rotary motion for manipulating the workpiece. Experiments were conducted using a one factor at a time approach by varying the tool feed rate, the amplitude of the vibrations and the rotation of the workpiece as process parameters. The quality of the machining output was evaluated by observing two key parameters: the overcut and the circularity of the hole. It was observed that as the workpiece rotation speed increased from 40 rpm to 60 rpm, the overcut in the machined samples decreased from 181.378 μm to 163.564 μm. The rotary motion of the workpiece caused a seeping action of the electrolyte in the hydrodynamic regime, leading to the formation of a thin gas film and the stabilization of the discharging process. The morphology of the machined hole exhibits better circularity, low heat-affected zones, minimum micro-cracks and smooth edges at its periphery due to stable discharge formation.

Computational modelling and experimental investigation of micro-electrochemical discharge machining by controlling the electrolyte temperature

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

Characteristics and improvement of the double-pass electro-chemical discharge machining

Glass and ceramics have broad applications in modern industries; however, unique properties such as brittleness, and low machinability limit their fabrication processes. This way, electro-chemical discharge machining (ECDM) is a new method that can shape hard, brittle, and non-conductive materials. ECDM improvement is the subject of recent investigations through the application of chemical and physical phenomena. Current research studies the accuracy and surface integrity (cracks and HAZ) aspects of the double-pass ECDM process (DP) which is a new and straightforward method. During the double-pass process, two sequential passes are employed to shape the final geometry. In addition, the variable voltage technique is studied to achieve higher machining efficiency in DP. Results showed that in the diameter difference of 100 µm, the double-pass process reduced overcut by up to 21% compared to the typical ECDM process. Also, the size and number of cracks and the extent of HAZ were significantly decreased. Finally, in the diameter difference larger than 300 μm (the constant voltage of 32 V), the enhancement modification (variable voltage) reduced the overcut by more than 80%. At the same time, depth results remained close (less than 5% difference) to the simple ECDM process.

Micro ECDM process comparison using different tool feed methods of constant gravity and spring-force

Quartz glass has been widely used in multiple frontier fields of science and technology owing to its excellent chemical and mechanical properties, such as optical communication, semiconductor, photovoltaic power, and aerospace. ECDM (electrochemical discharge machining) is a non-traditional material removal process suitable for machining non-conductive materials of high hardness and brittleness. The tool electrode feed method is a key factor affecting the ECDM process. Experimental research was carried out for comparing the conventional gravity feed method and a newly-developed spring-force feed method. Micro tool electrodes of Φ150 µm were fabricated by combining the method of TF-WEDG (tangential feed-wire electrical discharge grinding) and reverse micro EDM (electrical discharge machining). Machined microstructures of blind holes, channels, squares, and patterns were compared by the gravity feed method and the spring-force feed method respectively. The experimental results show that the spring-force feed method can improve the micro ECDM process considering the aspects of dimensional accuracy, overcuts, deteriorated edges, surface topography, and tool wear.

Micro-ECDM Performances Analysis Using Fuzzy Logic and ANFIS During Micro-Channel Fabrication on Silica Glass

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

Process capability of electrochemical discharge machining: A review

Electrochemical discharge machining (ECDM) is a hybrid machining formed by combining the principles of electrochemical machining and electrical discharge machining. The ECDM is unconventional micromachining that can fabricate holes, blind holes, micro-cavities and grooves on brittle insulating materials such as quartz, glass, silicon wafers and different composites that are difficult to machine. These non-conducting materials have sundry applications such as Micro Electric-Mechanical Systems, biomedical and electronics items. The ECDM provides maximum material removal rate and good surface quality with minor tool wear. The study describes how different process parameters affect machining. The assessment mainly focuses on various tool electrode geometries and materials that are used in ECDM. The present article investigates the ramifications of different types of electrolytes and additives mixed in electrolytes used during the ECDM process on the machined zone. This paper comprehensively reviews the effect of change in applied voltage, machining gap and an inter-electrode gap in the ECDM and it also analyses the fabrication of different materials including glass, quartz, ceramics and composites.

Dimensional accuracy enhancement of machined-hole through UAECDM-process under the magnetic-field-assistance

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

Surface Quality of Al2O3 Ceramic and Tool Wear in Diamond Wire Sawing Combined with Oil Film-Assisted Electrochemical Discharge Machining

Diamond wire sawing is one of the most widely used methods of cutting Al2O3 ceramic because it has good machining accuracy and causes less surface damage. However, its material removal rate (MRR) needs to be improved with the increasing demand for Al2O3 ceramic parts. In this paper, spark discharges are generated around the diamond wire based on the electrochemical discharge machining (ECDM) process. An oil film-assisted ECDM process is applied to solve the difficulty of generating spark discharges when the thickness of the workpiece exceeds 5.0 mm due to the difficulty of forming a hydrogen gas film. Experimental results show that the combination of oil film-assisted ECDM and diamond wire sawing improved the MRR of Al2O3 ceramic. Oil film-assisted ECDM may improve the surface quality of machined parts and reduce the wear on diamond wire. Therefore, this research focuses on the surface quality of Al2O3 ceramic and tool wear in diamond wire sawing combined with oil film-assisted ECDM. Surface roughness and topography, recast layer, and elements of the machined surface are analyzed. The tool wear is studied using SEM images of diamond wire. The results provide a valuable basis for application of diamond wire sawing combined with oil film-assisted ECDM.

Experimental investigation of micro-machining on borosilicate glass using mist flow aided WECDM

Wire electro-chemical discharge machining (WECDM) process is a variant of electro-chemical discharge machining process and is a novel method to machine electrically non-conductive materials. In the present research investigation, an in-house developed WECDM setup with mist flow was used to generate micro channels on borosilicate glass. The electrolyte was provided in the form of mist, formed with the combination of electrolyte and compressed air. The mist flow system was used to control the machining process that improved the stability of the spark, and flushing in the machining zone resulted in a smooth surface of machined channels. Electrolyte concentration, duty factor, wire feed rate, and mist flow rate were chosen as input process parameters, and their effect on output quality characteristics such as material removal rate and width of cut was evaluated. the performance of were during. The addition of the mist flow technique in the process resulted in an improvement in surface finish, heat affected zone (HAZ) and discharge characteristics. ANOVA analyses were carried out to obtain the significant process parameters that affected the output characteristics. Scanning electron micrograph images were captured in order to analyze the surface morphology of the machined channel and revealed thermal cracks, HAZ, irregular surface and recast layer in the samples machined with low mist flow rate as compared to samples machined using high Mist flow rates.

On innovative approach in ECDM process by controlling the temperature and stirring rate of the electrolyte

ABSTRACT In the wake of drawbacks of existing processes, electro chemical discharge machining (ECDM) is an evolutionary method for the micromachining of glass. However, poor flushing coupled with insufficient electrolyte replenishment and unstable temperature deteriorates the ECDM performance. Therefore, the present study is an attempt to enhance the performance by controlling the temperature and stirring rate of the electrolyte in ECDM using a magnetic stirrer that is an innovative approach, termed as S-ECDM. The voltage, electrolyte temperature, pulse-on time and electrolyte stirring rate have been considered as the process parameters. The aspect ratio (AR) and heat-affected zone (HAZ) of micro-hole have been considered as the response characteristics. The interaction of electrolyte stirring with other process parameters synergizes the energy generation and channelization behavior at optimal conditions. At optimal conditions, the AR and HAZ were found to be 0.692 and 0.404 mm2, respectively.

Enhancement of Electrochemical Discharge Machining Process with Pressurized Tool Feeding Mechanism

In the present era, Microfluidic devices play a vital role in the field of pharmaceutical and bio-medical industry. The Electrochemical Discharge Machining (ECDM) process is a promising micromachining process for fabricating microfluidic devices using a micro subtractive material removal process on highly transparent material such as glass. A microfluidic device consists of microchannels, which are interconnected with the help of microholes. The feeding mechanism in the ECDM process plays a vital role in the fabrication of micro features with desired geometry. Therefore in the present research, authors have introduced a novel method for feeding mechanism, i.e. Pressurized Tool Feeding Mechanism (PTFM). The authors have discussed the design and development of PTFM with designed details and compared the machining features with the Pressurized Work Feeding Method (PWFM). In PTFM, a zero working gap is maintained throughout the machining process with the help of spring back pressure. Using present PTFM, the major limitation of PWFM was minimized significantly and fabricated straight holes without undesired hole deviations. A provision has also been made in the PTFM attachment to drill an inclined hole with a desired angle in any direction. This technique will be helpful in the fabrication of microfluidic devices in a one-go for microfluid mixing and separation in a single chip.

Multi‐Objective Optimization During Magnetic Field Assisted ECDM of Alumina‐Zirconium Dioxide Ceramic Composite using Battle Royale Optimization

Alumina‐Zirconium dioxide (Al2O3‐ZrO2) Ceramic Composite Material (CCM) is specifically known for its enhanced mechanical and corrosion resistance properties and is widely used as raw material for mechanical parts like, pump components, die inserts, bearings, etc. As a result, industrialists are searching for an efficient method for machining this Al2O3‐ZrO2 material. In this regard, a hybrid unconventional machining process called Electrochemical Discharge Machining (ECDM) is adapted to analyze the machinability of Al2O3‐ZrO2 CCM. Besides, to ensure the efficiency of the ECDM process, a magnetic field is also given to the tool electrode during this study to improve the Material Removal Rate (MRR) of the ECDM machine. The experiment is designed using Response Surface Methodology (RSM) by changing the magnitudes of input controls, namely Electrolytic Concentration (EC), Inter‐electrode Gap (IEG) and Applied Voltage (AV). Moreover, a novel hybrid machine learning optimization strategy called Deep Belief Network based Battle Royal Optimization (DBN‐BRO) algorithm is developed to predict and optimize the ECDM process. Finally, the optimum results are perceived from 55 V AV, 22.727% EC and 40.909 mm IEG input levels. The proposed method shows less than 0.6207 Root Mean Square Error (RMSE) and tools nearly 80 iterations for optimizing the results.

Optimization of process parameters in ECDM machining using Taguchi based grey relation analysis

Electrochemical discharge machining (ECDM) is a hybrid machining process capable of micromachining conductive and nonconductive materials. The recent development and application of nonconductive materials, such as glass, composites, and ceramics in MEMS and microfluidic devices, have emphasized studying the ECDM process for micro holes and channel formation. The current study uses Taguchi's L27 orthogonal array to design the experiments, evaluate responses by the signal-to-noise ratio, analyze the variance of process parameters (ANOVA), and predict optimal settings for a multi-objective response using grey relation analysis (GRA). The experiments were conducted using two tools, a bare copper tool and Nickel coated copper tool, over a glass substrate. The machining process's output characteristics (radial overcut, heat-affected zone, and hole circularity) were studied by varying input parameters such as applied voltage, tool feed rate, and machining time. The experimental results revealed that Nickel coated Cu tool reduces the average hole overcut and heat-affected zone width and increases the overall circularity of the hole as compared to the bare Cu tool. Based on grey relational grade analysis, the optimal parameters were identified: the applied voltage of 36 V, tool feed rate of 110 µm/min, and one-minute machining time with Nickel coated copper tool. In contrast, a bare copper tool electrode provides optimal process parameters as an applied voltage of 36 V, 110 µm/min tool feed, and a machining time of two minutes for drilling holes in borosilicate glass.

Non-contact micromachining by a dynamic feed rate controlled electrochemical discharge machining process

Electrochemical discharge machining (ECDM) is an emerging micromachining method to drill advanced non-conductive materials such as Hexagonal boron nitride (hBN). Physical contact of micro tools with work material could cause machining inaccuracies, excessive tool wear, and even tool breakage. In this study, a control system based on monitoring the force generated by the ECDM gas film has been developed to achieve non-contact machining of ECDM by dynamically adjusting the tool feed rate. The accuracy of the control system was verified by accelerometer and Fast Fourier Transformation (FFT) data. In the modules, it was found that a non-contact machining process requires the FFT amplitude to be lower than 42 V for a 1200 rpm tool rotation. The experimental results show consistent micro-holes with an average diameter of 650 µm and less than 20 µm error in the overcut achieved using this control system.

Micro-machining and process optimization of ultrasonic assisted rotary µ-electrochemical discharge machining using TOPSIS method

Glass is a substance that is gaining numerous applications in many industries, such as biomedical, nuclear, etc., due to its hard, transparent, and inert nature. The main challenge is to machine glass due to its brittle nature. Electrochemical Discharge Machining (ECDM) is a novel process that is being used to machine such hard and electrically non-conductive materials. Over the years, researchers tried to incorporate many other processes into the ECDM process in order to increase the process capabilities. In this research, Ultrasonic assisted Rotary µ- ECDM process was used to drill holes in glass workpiece. In this process, the rotary motion was provided to the workpiece rather than to the tool to observe the results of this process. Experiments were performed using Taguchi’s L9 orthogonal array taking amplitude of vibrations, rotational speed, and tool feed rate as the input parameters and overcut and circularity as the response characteristics. In addition to this, multi-response process optimization was carried out using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method to optimize the process.

Hybridization of μ-electrochemical discharge machining (μ-ECDM) process: A review

The Electrochemical Discharge Machining process is a non-conventional and a novel micro machining technique, which combines the advantage of ECM (chemical etching) and EDM (melting and vaporization) to machine hard, brittle and electrically non-conductive materials like glass, ceramics and composites with improved surface finish and machining rate. It is extensively used for making surface channels, microgrooves and micro-holes in glass. The necessity for hybridization of the ECDM process was triggered in order to improve the efficiency and machining performance of the process. The purpose of this article is to provide information in form of a review to readers on the existing triplex hybrid techniques of the ECDM process that is based on primary and secondary methods and its advantages have been discussed.

Study on the double-pass electrochemical discharge machining process

ABSTRACT Electrochemical discharge machining (ECDM) is a nontraditional machining process applied to nonconductive and brittle materials such as glass and ceramic. In recent years, investigations have focused on improving machining efficiency, especially the material removal rate (MRR). In this regard, different techniques, including chemical and physical phenomena, have been employed on different components of the ECDM system. Current research applies a new and straightforward method to improve the MRR without the consequent complexity of other techniques (improved machining efficiency). In this way, the machining process applies in two sequential passes (double-pass machining) to shape the final geometry. In the typical ECDM process, the whole geometry is machined by one pass process. Results showed that by employing the double-pass technique, the maximum depth reached 660 µm, which was 35% higher than the single-pass (SP) process (the total machining time of SP was the same as double-pass). In addition, a significant average improvement percentage of 45% was achieved. The optimum diameter difference of the tools in the double-pass process was 300 µm, which led to the highest depth values. Depending on the tool changing time, the double-pass process is economically efficient in machining depths of more than 250 µm.

Chain discharging behavior induced by gas film expansion and its influence on the electrochemical discharge machining (ECDM) process

Chain discharging behavior induced by gas film expansion and its influence on the electrochemical discharge machining (ECDM) process

Multi Response Optimization of ECDM Process for Generating Micro Holes in CFRP Composite Using TOPSIS Methodology

The applications of carbon fiber reinforced polymer composites (CFRPCs) in aerospace, automotive, electronics and lab-on-chip devices require precise machining processes. Over the past decade, there have been numerous attempts to machine CFRPCs using both traditional and unconventional machining techniques. However, because of their limitations, these methods have not gained widespread acceptance. In the present research investigation, Electrochemical Discharge Machining (ECDM) process has been employed to produce micro-holes on CFRPC. The experimental strategy was scheduled using L9 orthogonal array keeping applied voltage, electrolyte concentration and inter-electrode gap as input parameters. The material removal rate (MRR) and overcut were selected as output parameters. The technique for order preference by similarity to the ideal solution (TOPSIS) methodology was executed for multi-response optimization. The overcut and MRR of machined samples improved from 150 µm to 48 µm and 2.232 mg/min to 2.1267 mg/min correspondingly while using the optimum parametric settings of the TOPSIS approach. The shape of drilled micro-holes produced by the TOPSIS process is indicative of a machined surface of superior quality, with a reduction in the number of micro-cracks and a diameter that is uniform.

Powder mixed electrochemical discharge process for micro machining of C103 niobium alloy

This work demonstrates the viability of the powder-mixed micro-electrochemical discharge machining (PMECDM) process to fabricate micro-holes on C103 niobium-based alloy for high temperature applications. Three processes are involved simultaneously i.e. spark erosion, chemical etching, and abrasive grinding for removal of material while the classical electrochemical discharge machining process involves double actions i.e. spark erosion, and chemical etching. The powder-mixed electrolyte process resulted in rapid material removal along with a better surface finish as compared to the classical micro-electrochemical discharge machining (MECDM). Further, the results are optimized through a multi-objective optimization approach and study of the surface topography of the hole wall surface obtained at optimized parameters. In the selected range of experimental parameters, PMECDM shows a higher material removal rate (MRR) and lower surface roughness (Ra) (MRR: 2.8 mg/min and Ra of 0.61 μm) as compared to the MECDM process (MRR: 2.01 mg/min and corresponding Ra of 1.11 μm). A detailed analysis of the results is presented in this paper.