Electrochemical Discharge Machining Research Articles

Grey Relational Analysis Optimization of Input Parameters for Electrochemical Discharge Drilling of Silicon Carbide by Gunmetal Tool Electrode

The electrochemical discharge machining process (ECDM) is a hybrid advanced technology integrated with electrochemical and electro-discharge processes has used for the manufacturing of non-conducting along with conducting materials. The silicon carbide is non-conducting material which has widely used in various fields such as automobile, aviation, medical, nuclear reactor, and missile. The machining of silicon carbide is a challenging task by using non-conventional along with conventional machining processes due to its physical properties. The current research work shows the machining of Silicon carbide material by using fabricated ECDM machine setup with gunmetal tool material. The Taguchi L27 orthogonal array technique is applied for experimental work. The grey relational analysis optimization is applied for the investigation of optimum input factors for better output responses. The input process factors like electrolyte concentration, applied voltage, and rotation of tool and outcome results such as machined depth and the diameter of hole were checked after drilling of silicon carbide material. The experimental results indicate the electrolyte concentration is the leading factor for diameter of hole and depth of machined hole subsequent to voltage and tool rotation.

A Study of Response Parameters during ECDM on Quartz Material

Electrochemical discharge machining (ECDM) is a hybrid machining process that combines the possible characteristics of Electro Discharge Machining (EDM) and Electrochemical Machining (ECM) machining. In the present work, Quartz is used as work piece material and potassium hydroxide (KOH) as an electrolytic medium. Experiments were carried out by considering the three factors at three different levels. The input variables are Voltage, Electrolyte Concentration (EC) and Inter-Electrode Gap (IEG). The experimental response variable is Material Removal Rate (MRR). The process variables were analyzed and optimized using ANOVA from the Minitab 14 statistical tool. The response parameters are predicted by using Artificial Neural Network (ANN) and linear regression equation was generated to predict the experimental values. The results reveal that, voltage and electrolyte concentration have approximately equal percentage of contribution in achieving maximum MRR.

On near-dry wire ECDM of Al6063/SiC/10p MMC

ABSTRACT Metal matrix composites (MMC’s) with their exceptional properties are gaining importance in many industries (i.e., automobile, structural, aerospace, etc.). The secondary processing of MMC’s, like machining, is challenging and sometimes infeasible by conventional machining processes. The present study reports development and investigation on a new non-conventional hybrid machining process named near-dry wire electrochemical discharge machining (ND-WECDM). The investigation involved understanding the material removal mechanism of developed ND-WECDM for machining of Al6063/SiC/10p MMC. A detailed experimental investigation was planned and conducted using Taguchi’s L18 mixed-level design. The influences of input parameters (i.e., pulse on-time, applied voltage, mist flow rate, wire feed rate, and pulse off-time) were analyzed on the slit width (SW) and slit depth (SD) as the performance characteristics. The significant parameters affecting the ND-WECDM process were identified by applying the ANOVA. The SW and SD were most affected by the applied voltage and pulse on-time, respectively. In the ND-WECDM process, material removal is due to electric discharge (ED), electrochemical dissolution (ECD), and thermal spalling (TS). ND-WECDM process is found competent to develop micro features on Al6063/SiC/10p MMC.

Pulse Classification for an Electrochemical Discharge Machining Process Based on Fuzzy Logic Approach

A pulse classification technique for monitoring the type of discharges in an electrochemical discharge machining (ECDM) process is presented in this research paper. The performance of an ECDM process is affected by many factors which make it hard for control strategies to be formulated for this process. The pulse classifier plays an important role to develop control strategies and later to improve the process. The proposed system uses the current and voltage waveforms measured through the gap as input signals for the classification system. A fuzzy inference system (FIS) is used to categorize both input signals into one of the four proposed pulse types, according to their specific behavior. For the experimental validation, data samples taken during the machining process were recorded to evaluate the performance of the pulse classifier with raw data. Raw data of the gap signals is properly classified based on the proposed FIS.

Study of electrochemical discharge machining of glass

Brittle and difficult to cut materials are difficult to machine with accessible conventional machining techniques keeping in view ECDM was pioneered to design micro features as micro channels, micro holes etc. Researchers developed variety of techniques of m/c through Electrochemical Discharge Machining as Electrochemical discharge grinding, turning, milling, trepanning etc. Various materials like ceramics, quartz, pyrex glass, glass fibre reinforced composite, Metal Matrix Composite, Kevlar/epoxy composite. And also the effect of various process parameters like voltage, feed rate, current, electrolyte concentration etc need to analysed during Electrochemical. Discharge Machining. This review is to explore the result of variety of process parameters involved in ECDM. It epitomized with the view to provide further research in ECDM.

Experimental Study of Tool Wear in Electrochemical Discharge Machining

Electrochemical discharge machining (ECDM) is an emerging special processing technology for non-conductive hard and brittle materials, but it may encounter the problem of tool wear due to its process characteristics, which affects the processing accuracy. In this study, in the non-machining state, the tungsten carbide spiral cathode with a diameter of 400 μm was selected to analyze the influencing mechanism of the process parameters on tool wear, and a suitable voltage range for the processing was obtained. The influence of the cathode’s loss behavior on the film formation time and the average current of spark discharge was discussed based on the current signal. The results show that the tool wear mainly appears from the bottom to the end and edge tip of the protrusion. Loss is mainly in the form of local material melting or gasification at high temperature. In addition, the loss may shorten the film formation time, but the effect on the average current of spark discharge is small.

Improvement of machining accuracy in EDCM by enhanced electrochemical reaming based on a non-metallic backing layer

Electrochemical Discharge Machining (ECDM) is potentially applicable for the fabrication of film-cooling holes. However, It is extremely difficult for the holes to achieve higher precision and machining quality owing to the working liquid diminish in the lateral machining gap. In this study, a non-metallic backing layer was proposed to overcome the diminish of working liquid, and the electrochemical reaming, as a post-processing method for ECDM, was used to further improve the machining accuracy and quality of the holes. First, the three-dimensional morphology of the melted pit of a paraffin backing layer was scanned to obtain the geometric parameters. Then, simulation analysis and experimental verification of auxiliary flushing by using the non-metallic backing layer were performed. The machining performance of the holes machined with electrochemical reaming based on non-metallic backing layer was confirmed by the observations of the surface topography of the hole wall and orifice, measurement of the orifice precision, and analysis of the element composition on the surface of the orifice wall. Finally, an optimum combination of machining parameters for electrochemical reaming is obtained through a process parameter optimization experiment.

Environmental aspects of various electrolytes used in electrochemical discharge machining process

Electrochemical discharge machining (ECDM) is a hybrid process comprising of features of both electrochemical machining and electrical discharge machining. The combined features enable ECDM process to expand its applications to conductive and non-conductive materials. In recent years, several attempts have been made to utilize ECDM process for micro-machining of glass, composites, ceramics, steel, super-alloys, etc. The machining behaviour of ECDM process is significantly affected by several process parameters including electrolytic properties, tool electrode, etc. The present research article focuses on environmental aspects of different electrolytes used in ECDM by analysis of fume mass concentration and characterization of fume particles generated during machining. The average size, morphologies and chemical composition of fume particles were studied by field emission scanning electron microscopy and energy-dispersive spectroscopy, respectively. The fume mass concentration increased from 30.35 to 220.76 mg/m3, 15.10 to 98.34 mg/m3 and 40.56 to 290.0 mg/m3 with increases in electrolyte concentrations from 20 to 50% of NaOH, NaCl and HCl, respectively. The average size of fume particles generated in ECDM process was less than 100 nm. Additionally, the Fourier transform infrared spectroscopy of breathing air revealed the presence of amines, CH4, NO2, SO2, CO2, thio compound disulphides and halogenated hydrocarbons in the breathing zone of operator.

Multi-Response Optimization of ECDM Parameters for Silica (Quartz) Using Grey Relational Analysis

Electrochemical discharge machining (ECDM) has successfully demonstrated the micro-machining of pioneering engineering materials, regardless of their properties such as glass, quartz, silicon nitride ceramics, composites, etc. Yet numerous intrinsic challenges are there that should be addressed during the micro-hole drilling process with ECDM such as low material removal rate (MRR), high area of the heat-affected zone (HAZ), high hole tapering (HT), high radial overcut (ROC) and circularity error (CE). However, the determination of the input parameters’ optimum level for multi-response parameters is still a strenuous work. This present study investigates the machining performance of the ECDM process during the machining of silica (Quartz) through establishing the optimum combination of the level of the parameters for multi-response parameters. MRR, HAZ, HT, ROC, and CE were picked as response parameters. Experiments were performed in consonance with Taguchi’s L9 orthogonal array and response measurements were analyzed through Grey Relational Analysis (GRA) to identify the optimum levels of input process parameters for their combined fusion i.e. maximum MRR, minimum HAZ, minimum HT, minimum ROC, and minimum CE. Results exhibited that electrolyte concentration (wt.%) is the utmost governing input parameter followed by applied voltage (V) and inter-electrode gap ((IEG), mm) for controlling the multi-response parameters simultaneously. GRA optimized parameters were determined as 35 V, 15 wt.%, and 25 mm with 68.34% contribution only from the electrolyte concentration. Based on experimental investigation, micro-holes were successfully drilled on Silica (quartz) material with the success of the utilized method to assess the machining performance of the electrochemical discharge machining process.

Wire-Electrochemical Discharge Machining of SiC Reinforced Z-Pinned Polymer Matrix Composite Using Grey Relational Analysis

The SiC reinforced z-pinned composites are becoming advantageous in the field of aerospace and defense sector due to their superior mechanical properties. The reinforcement of SiC particles makes them difficult to machine with conventional machining processes. In the present research investigation, the micro-slicing of SiC reinforced z-pinned composites has been attempted using wire electrochemical discharge machining (WECDM). WECDM is newly emerging technique which combines the process features of electrochemical machining (ECM) and wire electrical discharge machining (WEDM) processes. The experiments were planned using Taguchi’s methodology using L9 Orthogonal array to study the effect of various process parameters i.e. applied voltage, wire feed rate (WFR) and duty cycle on the output quality characteristics such as diametric overcut (DOC) and material removal rate (MRR). The grey relational analysis (GRA) methodology was implemented for multi-response optimization. The diametric overcut and material removal rate of machined samples at optimum parametric conditions of GRA method improves from 71.87 μm to 60.20 μm and 34.20 mg/min to 32.30 mg/min respectively. The morphology of micro-sliced sample using GRA method signifies better quality machined surface with minimization of micro-cracks and uniform cutting.

Sustainable electrochemical discharge machining process: Characterization of emission products and occupational risks to operator

Electrochemical discharge machining (ECDM) process is prominent machining process for processing of composites, glass, ceramics, and super-alloys. In the recent years, the ECDM process has attained popularity due to its applicability to generate micro-holes, micro-channels on different materials irrespective to their properties. This study presents the various environmental aspects of ECDM process for its transformation to sustainable and green manufacturing. The exhaustive analysis of fume particles generated in ECDM process with their characterization and health impacts has been attempted in the present work. A detailed procedure has been reported to explore the effect of applied voltage and electrolyte concentration on fume mass concentration, fume particles size, particle morphologies, and chemical composition. The morphology of fume particles revealed presence of spherical, irregular, rectangular, and agglomerations shapes. The chemical composition of fume particles indicates presence of metallic toxic and carcinogen elements such as Al, Fe, Cr, Cu, Ti, Ni, etc. The presence of hazardous compounds in the breathing zone was studied using Fourier transform infrared spectroscopy analysis of breathing air. Additionally, occupational risks associated with fumes emission and their control measure has been addressed in this research work.

Micro-Drilling of Sapphire using Electro Chemical Discharge Machining.

Electrochemical discharge machining (ECDM) refers to a non-traditional machining method for performing effective material removal on non-conductive hard and brittle materials. To increase the ECDM machining efficiency, traditionally, the method of increasing the machining voltage or increasing the electrolyte concentration is used. These methods can also cause overcut reaming of the drilled holes and a rough surface on the heat affected area. In this study, an innovative combinational machining assisted method was proposed and a self-developed coaxial-jet nozzle was used in order to combine two assisted machining methods, tool electrode rotation and coaxial-jet, simultaneously. Accordingly, the electrolyte of the machining area was maintained at the low liquid level and the electrolyte was renewed at the same time, thereby allowing the spark discharge to be concentrated at the contact surface between the front end of the tool electrode and the machined material. In addition, prior to the machining and micro-drilling, the output of the machining energy assisted mechanism was further controlled and reduced. For the study disclosed in this paper, experiments were conducted to use different voltage parameters to machine sapphire specimens of a 640 μm thickness in KOH electrolyte at a concentration of 5 M.

Application of nano electrolyte in the electrochemical discharge machining process

As a nontraditional machining process, electrochemical discharge machining (ECDM) can apply to hard and brittle materials such as glass and ceramic. Improvement of process efficiency is an important topic that has been addressed in many investigations using various techniques such as magnetic field and ultrasonic vibrations.Nano particles are new and advanced materials that can be dispersed in a fluid to obtain a nano fluid with desirable specifications. This method can be implemented in the ECDM process by the application of the nano electrolyte. Nano electrolyte can present enhanced properties, in particular enhanced electrical and thermal conductivities which lead to more powerful discharges and greater material removal.In order to study the variation of discharge physics, consequent captures from discharges were taken. Besides using current signal diagrams, larger numbers of discharges were found using nano electrolytes. Results of hole depth showed that both Cu and Al2O3 nano electrolytes improved the hole depth as 21.1% and 18.7%, respectively. An undesirable effect of nano electrolyte was observed on the entrance overcut, which raised 8.3% and 10.7% using Cu and Al2O3 nano electrolytes, respectively, in comparison to the simple electrolyte. This drawback is negligible compared to the significant improvement of hole depth. SEM images of tool wear showed larger molten materials on the tool main edges by the application of nano electrolyte.

On prolongation of discharge regime during ECDM by titrated flow of electrolyte

In electrochemical discharge machining (ECDM), the drilling of micro holes has been established through two regimes (i.e., discharge and hydrodynamic regimes). In discharge regime, the material removal mechanism is directly controlled by the number of spark discharges and it allows fast penetration of tool electrode inside the work material, whereas in hydrodynamic regime, the accumulation of bubbles at hole entrance and inadequate supply of electrolyte toward tool tip limit the penetration rate during deep hole drilling. In order to achieve consistent machining conditions, particularly during deep hole drilling, the prolongation of discharge regime is essential. Thus, in the present research endeavor, a ECDM with titrated flow of electrolyte was attempted. The application of titrated flow of electrolyte in ECDM process drilled micro through holes in 1350-μm-thick work material in approximately 30 s. In comparison to the conventional ECDM process, the presented method reduces the machining time by 7 times and also improves the machining accuracy by reducing the hole entrance diameter by 1.25 times. The consistency obtained in discharge characteristics as well as in penetration rate is evident in the prolongation of discharge regime during ECDM with titrated flow of electrolyte. The underlying material removal mechanism has also been presented. Multicriteria optimization (MCO) was also performed to predict the suitable parametric combination for higher penetration rate and low hole entrance diameter of the machined micro holes. The results obtained from the current investigation presents titrated flow of electrolyte as a one of the fastest machining strategy (that provides a penetration rate of 45 μm/s) to drill the micro holes by ECDM process.

Preface

SVKM's NMIMS, Mukesh Patel School of Technology Management and Engineering, Shirpur Campus proudly hosted the second "International Conference on Emerging trends in Manufacturing, Engines and Modelling" from 23rd -24th December, 2019. It was jointly organized by the Department of Mechanical Engineering, MPSTME Shirpur Campus and Mumbai. The inaugural function of the conference was enlightened by the august presence of Mr. Ashutosh Pandey - MD and CEO, Mahindra First Choice Wheels as the Chief Guest, Dr. K.B. Patil - Director of SVKM's NMIMS, Dhule Campus as the Guest of Honour, Dr. R S Gaud- Director MPTP Shirpur Campus, Dr. Nikhlesh Kumar Sharma- Director (Engineering) & Chairman ICEMEM 2019, Dr. K. K. Gupta Co-Chairman ICEMEM 2019, Dr. Gowri Sankara Rao- Dean(SAST), Dr Narayan Chandak- Associate Dean, Dr Basant Kumar Mohanty Associate Dean (Research), Dr Ashwini Deshpande - Associate Dean (SPTM), Shri Rahul Dande- Chief Accountant and Administration, Dr Rakesh Choudhari- Head (Mechanical), Shri Rajeev Dalal- Deputy Registrar, All HOD's, Faculty members and more than 100 participants. The inaugural function commenced with the customary felicitation of the guests followed by the Saraswati Vandana. Dr. Nikhlesh Kumar Sharma, Director (Engineering Programs), MPSTME presented the welcome note to the guests, invited speakers, delegates and the participants. Dr. K.K. Gupta - Co-Chairman of the Conference briefed about the theme of the conference and presented the salient features of the event and expectations from them. Dr. R.S Gaud, Director, MPTP, Shirpur Campus introduced the audience about the legacy of SVKM's NMIMS and the laurels brought by the campus at various levels. His speech was followed by the address of Dr. K.B. Patil. He had been the Vice-Chancellor of North Maharashtra University, Jalgaon. The audience were fortunate to gain his insights on engineering education and employability in general which represented his vast experience in the field of education and academic administration. The last but the most awaited address was delivered by Mr. Ashutosh Pandey who had graciously accepted the invitation of the organizing committee to be the Chief Guest of the inaugural function. A civil engineering graduate with an MBA from FMS, Delhi, Mr. Pandey pointed out the need for developing multiple skills. He highlighted the current trends in the job market and discussed about the capabilities sought after by the employers. An important take-away from his address is the fact that technology environment is constantly getting disrupted and therefore everyone has to be on their toes to withstand the corresponding challenges. The address was truly captivating and thought provoking. The ceremony culminated with the vote of thanks proposed by Prof. M. Ramachandran, Convenor ICEMEM 2019 followed by the tea break. The keynote sessions on the first day were divided into two segments.

An experimental study of process parameters on material removal rate in ECDM process

This article highlights on Electro Chemical Discharge Machining (ECDM) process which is an unconventional machining process used to cut several conductive and non-conductive materials. Electro-chemical machining (ECM) and electro-discharge machining (EDM) processes are already developed and are available in market. Presently the emphasis is on developing hybrid machining process to utilize the benefits of both processes. ECDM is a process that combines the features of ECM and EDM processes to machine non-conductive materials like borosilicate glass, soda lime glass, silicon wafers etc. Present work addresses the machining of non-conductive material by drilling hole in Borosilicate glass through the use of stainless steel as tool material and sodium hydroxide (NaOH) as electrolyte. Experiments were conducted as per Taguchi method by selecting different parameters like electrolyte concentration, applied voltage and machining time with three different levels. Material removal rate (MRR) was calculated for all the experiments. In this paper the effect of total machining time on MRR had been studied. From the results it is observed that MRR directly depends on machining parameters; further, the significance of input parameters were analyzed by analysis of variance.

Investigations into surface topography of glass microfeatures formed by pulsed electrochemical discharge milling for microsystem applications

Experimental investigations into the effect of duty cycle and electrolyte concentration on the surface topography in the microchannel formation in the soda-lime glass substrate by a pulsed electrochemical discharge machining are reported. These microstructures are required in various microsystems applications such as microfluidics, integrated-passive-devices for radio-frequency MEMS, 3-D glass interposer. No significant machining happened at lower duty cycles ( 500 µm) having complex shapes were demonstrated by using a multi-pass milling technique. The capability of the presented method in making buried redistribution lines in 3D MEMS inductor is also shown.

Sonication of tool electrode for utilizing high discharge energy during ECDM

ABSTRACTThe use of high applied voltage during the electrochemical discharge machining (ECDM) process forms a thick gas film and generates high discharge energy on film breakdown. This results in polarization and evaporation of electrolyte at the tooltip. Consequently, the ECDM process results in a low depth of penetration (DOP) with a large hole overcut (HOC). The present investigation is an attempt for utilizing high discharge energy during the ECDM process using sonication of tool electrode. The experimental results reveal that sonication regulates the gas bubble departure radius and thereby controls the gas film thickness. Besides, an increase in the electrolyte concentration reduces the gas film thickness and results in the generation of high-intensity and high-frequency electric discharges. Sonication results in improved electrolyte replenishment and sludge removal. A mathematical model is developed to understand the effect of process parameters on the gas bubble departure radius. Also, the present investigation compares ultrasonic-assisted electrochemical discharge machining (UAECDM) and the general ECDM process. Sonication of tool electrode during UAECDM process exhibit improvement in material removal rate (MRR) by 11.13%, DOP by 27.17% and reduction in HOC by 23.10% over the ECDM process.

Electrochemical discharge machining modeling through different soft computing approaches

The processes’ modeling is an important aspect in the industry since it allows to obtain high productivity with energy and material savings. The hybrid process electrochemical discharge machining (ECDM) is subject to uncertainty and inaccuracy levels in the parameters, so a viable option to model this process is through soft computing techniques such as fuzzy logic and artificial neural networks. In this work, we present three models using fuzzy logic, backpropagation network, and radial basis function network for the prediction of the material removal rate (MRR). The gap voltage (Vg), peak current (Ip), and frequency (f) were taken as input parameters. A 3-factor full factorial design was developed with 2 levels (23), two replicas, and four central points. The model with the higher accuracy according to experimental result was radial basis function artificial neural network with 97.25% of accuracy.

Effect of Tool Electrode-Workpiece Gap in the Microchannel Formation by Electrochemical Discharge Machining

Microchannels in a glass-based substrate are widely used in biomedical, and microfluidic devices, buried redistribution lines (RDLs), etc. Tool electrode-workpiece gap and tool feed rate are very important process parameters for the fabrication of microchannels using electrochemical discharge machining (ECDM) process. This paper reports the effect of these parameters on the material removal and geometric characteristics of the microchannels formed in soda-lime glass substrates. Microchannels were fabricated with alkaline electrolytes i.e. NaOH and KOH with varying concentrations at different tool electrode-workpiece gaps. Experiments were performed using a DC power supply with high carbon steel needles as tool electrode. Finite element based thermal model showed a similar trend between the predicted microchannel depth and width with the experimental values. Compared to KOH electrolyte, higher channel depth and width were obtained with NaOH electrolyte for a given parametric setting. At higher tool electrode-workpiece gap and tool feed rate, lower channel depths were obtained. Higher microchannel widths were obtained at a gap of 20 μm and 10 μm with NaOH and KOH electrolyte, respectively. Tool wear was found to be decreasing as the tool electrode-workpiece gap and the tool feed rate was increased. KOH electrolyte resulted in lower tool wear compared to NaOH electrolyte.