Wire Electrochemical Discharge Machining Research Articles

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.

Helical wire electrochemical discharge machining on large-thickness Inconel 718 alloy in low-conductivity salt-glycol solution

Wire electrochemical machining (WECM) is a flexible and effective method for machining complex-shaped metal components, but the ability to machine large-thickness workpieces is hampered by the difficulty of transporting electrolytic products in the narrow machining gap. This paper proposes a novel hybrid machining technique that combines the characteristics of WECM and wire electric discharge machining（WEDM）, namely, helical wire electrochemical discharge machining. The formation mechanism of electrical discharge in salt-glycol solution was elucidated. Experiments and simulation were conducted to verify the machining mechanism and investigate the performance of the proposed technique. The results show that as the recast layer can be removed by electrochemical action during the proposed process, the surface quality is effectively improved. Minimum surface roughness of the slit sidewall after machining reaches Ra = 0.12 μm. Minimum standard deviation of the slit after machining reaches 5 μm. Moreover, the existence of the discharges significantly improves the transport of the electrolytic products, thus ensuring high machining efficiency. In the experiments, the maximum feed rate of the helical wire electrochemical discharge machining reaches 7 μm/s (12.6 mm2/min). Finally, mortise structures of Inconel 718 with good machining accuracy and surface quality are fabricated with a feed rate of 5 μm/s (9 mm2/min), demonstrating that electrical discharge assisted helical wire ECM is a promising technique for machining large-thickness hard metal materials.

Parametric optimization of traveling wire electrochemical discharge machining (TW-ECDM) process for aspect ratio during machining of borosilicate glass

Glass owing to its transparency, chemical resistance, and high strength to weight ratio has gained importance in various advanced applications including MEMS, lab-on-chip devices, microfilters, micropumps, microvalves, microfluidics, and so on. The borosilicate glass serves as the substrate of microdevices due to its good surface integrity, corrosion, and thermal shock resistance but the micromachining of glass due to its brittleness and non-conductivity had been posing serious challenges with accuracy and precision. A recently developed hybrid non-conventional machining technique called electrochemical discharge machining (ECDM) has emerged as a successful tool for cutting these materials. The present paper discusses the effect of voltage, electrolyte concentration, and inter-electrode gap on the aspect ratio of machined micro slots on borosilicate glass with the help of TW-ECDM set up using Taguchi L9 array design of experiments. The results show the voltage has emerged as the main effecting factor followed by electrolyte concentration and inter-electrode gap. Using this novel process micro slots having an aspect ratio of up to 28 have been machined successfully.

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.

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.

Improving quartz micro-machining performance by magnetohydrodynamic and zinc-coated assisted traveling wire-electrochemical discharge machining process

In this industrial revolution era, machining of advanced non-conducting material like quartz is difficult and costly with existing conventional machining processes. Further its high hardness, brittleness and non-conducting nature add-up to machining difficulties. Traveling Wire-electrochemical discharge machining (TW-ECDM) process has a good potential of machining of quartz material. TW-ECDM process is a hybrid and complex combination of electrochemical machining (ECM) and wire-electrical discharge (W-EDM) machining process. However, due to poor electrolysis process, sparking phenomenon is not steady and uniform at higher machining depth. In the present work, the authors have tried to investigate the feasibility of Magnetohydrodynamic (MHD) assisted TW-ECDM process for machining of quartz. This MHD approach produces the magnetic field which helps to improve the electrolysis process, accuracy, and efficiency. Also, first-time zinc-coated brass wire of diameter 0.15 mm has been used to improve the machining performance. A hybrid approach of Taguchi robust design and ANOVA was used to analyze the process performance. Experimental results reveal that the MHD approach enhances the material removal rate (MRR) and reduces the surface rousghness (Ra) as compared to without MHD approach. The improvement in MRR was found from 25.35% to 83.72% and Ra reduced from 9.06% to 28.79%/ Additionally, an experimental result shows that quartz machined by TW-ECDM with MHD approach yielded longer and straight machined cut with less kerf width. Henceforth, the proposed hybrid MHD and zinc-coated brass wire approach is simple, easy, economically viable, environmental friendly and does not require any major changes in the existing machining setup. Moreover, the length of cut, kerf width and machine profile were also analyzed by scanning electron microscope.

Experimental Investigation of Wire-Electrochemical Discharge Machining (WECDM) Performance Characteristics for Quartz Material

The machining of quartz due to hard, non-conducting and brittle behavior with desired accuracy and precision is always a challenge. Quartz is widely used in MEMS/MOEMS applications. However, wire electrochemical discharge machining (WECDM) has great potential to machine hard and brittle materials like quartz, glass FRP, etc. The WECDM process is a hybrid non-conventional manufacturing process which combines characteristics of electrochemical machining (ECM) and wire-electrical discharge machining (W-EDM). The present study discusses the investigation of the effect of the governing process parameters such as voltage, electrolyte concentration, and wire speed (feed) on material removal rate (MRR) and surface roughness (Ra) during the micro-machining of quartz using self-developed tabletop desktop WECDM setup. The hybrid methodology of Taguchi orthogonal arrays and Analysis of variance (ANOVA) is used to find the optimum parameters and their significant contribution to response parameters respectively. Experimental results reveal that a better surface finish and high material removal rate was obtained by zinc layered brass wire (150 μm diameter). The machining of quartz under the zinc layered brass wire can indeed enhance the surface quality characteristics and material removal rate. Also, the mathematical models were established in order to derive the relationship between input and response parameters which was successfully validated by the confirmation experiment. Furthermore, the machining quality observed by a Scanning electron microscope (SEM), reveals the presence shallow cracks at higher-end input parameters.

Fabrication of micro-slits using W-ECDM process with textured wire surface: An experimental investigation on kerf overcut reduction and straightness improvement

In this work, a vertical configuration of wire electrochemical discharge machining (W-ECDM) process with textured wire surface was used to machine the micro-slits on glass. The effects of process parameters like applied voltage, pulse on time, electrolyte concentration and feed rate were experimentally investigated on the size and geometry of micro-slits in terms of kerf overcut and straightness. The discharging mechanism for textured and smooth wire surfaces have been evidenced by the simulation results and high speed imaging. The simulation results revealed that the textured surface of wire electrode resulted in intensification of localized electric fields over the entire machining face of wire electrode. Thus, the breakdown of gas film from the textured surface of wire electrode generates spark discharges from the entire face of wire electrode. The underlying material removal mechanism of W-ECDM process during micro-slitting operation has been proposed and illustrated with appropriate schematics. Additionally, second-order regression models were developed to determine the relationships between input process parameters and responses. Features plots were used to correlate the response characteristics with respect to input process parameters. Desirability approach was used to optimize the parametric ranges for minimum kerf overcut and maximum straightness. The parametric combination of applied voltage of 48 V, pulse on time of 3 ms, feed rate of 3 mm/min and electrolyte concentration of 15% wt./vol. is recommended to machine the micro-slits with minimum kerf overcut of 105 μm and maximum straightness of 94.42%.

Experimental Study of Micro Electrochemical Discharge Machining of Ultra-Clear Glass with a Rotating Helical Tool

Electrochemical discharge machining (ECDM) is one effective way to fabricate non-conductive materials, such as quartz glass and ceramics. In this paper, the mathematical model for the machining process of ECDM was established. Then, sets of experiments were carried out to investigate the machining localization of ECDM with a rotating helical tool on ultra-clear glass. This paper discusses the effects of machining parameters including pulse voltage, duty factor, pulse frequency and feed rate on the side gap under different machining methods including electrochemical discharge drilling, electrochemical discharge milling and wire ECDM with a rotary helical tool. Finally, using the optimized parameters, ECDM with a rotary helical tool was a prospective method for machining micro holes, micro channels, micro slits, three-dimensional structures and complex closed structures with above ten micrometers side gaps on ultra-clear glass.

Traveling Wire Electrochemical Discharge Machining (TW-ECDM) of Quartz Using Zinc Coated Brass Wire: Investigations on Material Removal Rate and Kerf Width Characteristics

In this era, advanced non-conducting materials are gaining importance due to their superior properties. However, it is difficult to micro-machine these materials inefficiency and also economically still persists with currently used advanced non-traditional machining processes. Non-traditional machining processes are typically unfeasible for quartz material owing to its properties such as high strength, high melting point, high temperature-resistance, chemical stability and brittleness. Traveling wire electrochemical discharge machining (TW-ECDM) process is newly developed non-traditional machining process and has great potential for machining of quartz ceramics. Coated wire has been used to reduce the wire breakage and improves the efficiency. The input important input parameters have been selected for this process as applied voltage, electrolyte concentration and wire speed. Taguchi robust design was perform to identify the optimal parametric conditions using L9 orthogonal array. Signal to noise (S/N) ratio and ANOVA were used to find the optimal parametric conditions and relative contribution of the input parameters respectively. Also, the surface finish was analyzed by scanning electron microscope (SEM). First time, coated wire with diameter of 0.15 mm has been used during TW-ECDM process. These obtained results present in this article will provide new guidelines to the micro-manufacturers, engineers and researchers.

Shape-cutting of quartz glass by spark discharge-assisted diamond wire sawing

Shape-cutting of quartz glass is difficult due to its high hardness, brittleness, and electrically insulting properties. This paper explores shape-cutting of quartz glass by spark discharge-assisted diamond wire sawing. The spark discharges were generated around diamond wire based on wire electrochemical discharge machining (WECDM). In the NaOH electrolyte, chemical etching of quartz glass took place with the occurrence of spark discharges. The chemical etching products were immediately removed by the quickly moving diamond wire. The diamond wire could keep straight with appropriate process parameters, which is essential to ensure machining accuracy. Experiments were conducted to analyze the effects of applied voltage, wire speed, and workpiece feed rate on machining performance. The diamond wire bending was measured to study the cause of poor machining accuracy. In addition, the overcut by spark discharges was presented close to the workpiece surface. To solve this problem, two thin soda-lime glass plates were put on the top and bottom surfaces of the quartz glass. As a result, the overcut only existed on the soda-lime glass, and good machining accuracy was achieved on quartz glass.

Research on oil film-assisted wire electrochemical discharge machining

Wire electrochemical discharge machining (WECDM) has the potential for cutting insulating materials. In order to achieve electrochemical discharges, WECDM is usually conducted on horizontal wire setup. It makes the design of machine tool difficult, especially in machining parts which require multi-axis control. The control of electrolyte level that has a significant influence on machining stability is also a complicated problem. In addition, the electrolyte cannot be sprayed to the machining zone with a relative high velocity to ensure a good electrolyte circulation, else the vulnerable hydrogen gas film that is used to electrically insulate the tool wire from the electrolyte can be destroyed. This paper proposes an oil film-assisted WECDM method. The oil film is online covered on the tool wire, and so the electrolysis only occurs at the positions where the oil film is absent. As a result, a stable insulating film, which consists of oil and hydrogen gas, is formed on the tool wire. Experimental results showed that electrochemical discharges were obtained during machining a 10.0-mm thick quartz glass on a vertical wire setup with spraying electrolyte condition. Finally, the effects of process parameters (applied voltage, electrolyte spraying velocity, wire speed, and workpiece feed rate) on machining performance were analyzed based on cutting experiments.

Experimental investigation of micro wire electrochemical discharge machining by using a rotating helical tool

The wire electrochemical discharge machining (WECDM) process is an effective way to machine high aspect ratio of micro-structures on non-conductive, hard, and brittle materials like quartz glass and ceramics. In this paper, the newly developed micro WECDM by using a rotary helical tool is proposed. Many experiments are conducted to investigate the machining localization of the WECDM with a rotating helical tool. The present study discusses the effects of machining parameters like applied voltage, frequency, duty factor, spindle speed, and feed rate on the side gap during the slicing of glass workpiece by using the developed WECDM setup. Experimental results demonstrates that the side gap rises with the increase in applied voltage and duty factor and reduces with the rise in frequency, spindle speed, and feed rate. Series of kerfs with 138μm width are fabricated successfully by the optimized parameters. The complex closed structure, the high aspect ratio kerf, and the pattern structure with high aspect ratio are obtained by this method.

Predictive analysis of criterial yield during travelling wire electrochemical discharge machining of Hylam based composites

Predictive analysis of criterial yield during travelling wire electrochemical discharge machining of Hylam based composites

Effect of adding SiC powder on surface quality of quartz glass microslit machined by WECDM

Quartz, being hard and brittle, is difficult to machine. Although good machining effects of quartz have been achieved by wire electrochemical discharge machining (WECDM), the surface quality of microslits obtained needs to be enhanced and higher machining precision is desired. To attain improvement in quartz machining, this study performs WECDM under titrated electrolyte flow with the addition of silicon carbide (SiC) powder. On the one hand, titrated electrolyte can facilitate rapid replenishment of the electrolyte, which contributes to maintain the stability of the insulating gas film, thus ensuring frequent and steady electrical discharge for better machining precision. On the other hand, the SiC powder added can help polish the finished workpiece for surface quality enhancement. Experiments are conducted to determine the appropriate machining parameters and to explore the processing mechanisms involved. Comparison in terms of machining precision and surface quality is made for WECDM conducted with and without additives. Experimental results show that better surface roughness and precision of microslits can be obtained with brass wire electrodes of 150 μm diameter and SiC powder of 11 μm at 5 wt%. The addition of abrasive SiC powder helped decrease surface roughness from 1.13 to 0.22 μm, an improvement in surface quality by 80 %. Moreover, the mean slit width was also reduced from 200 to 185 μm. Hence, WECDM of quartz glass under titrated electrolyte with SiC powder added to the electrolyte can indeed enhance surface quality and precision of the microslit. Moreover, not only does such approach use less electrolyte, but also it incurs lower cost and less pollution, making it cost effective and environmental friendly.

Parametric Analysis of Travelling Wire Electrochemical Discharge Machining Process

Travelling Wire Electrochemical Discharge Machining (TW-ECDM) process is a special type of Electrochemical Spark Machining (ECSM) process which has a greater effectiveness for machining of electrically non-conducting material like hylam based fiber reinforced plastics (FRP). The recent research paper focuses the parametric analysis on machining criteria such as material removal rate (MRR) and Overcut (OC) for slot cutting operation considering applied voltage, electrolyte concentration, feed rate of wire and pulse on time etc as process parameters. This paper shows the single and multi-objective optimization for determining the optimal parametric combination of TWECDM for maximum MRR and minimum OC based on response surface methodology (RSM). From the parametric analyses it is concluded that applied voltage has more significant effects on MRR and OC during TW-ECDM slot cutting operation.

Wire electrochemical discharge machining (WECDM) of quartz glass with titrated electrolyte flow

Electrochemical discharge machining (ECDM) is a promising technique with great potential for application to machining non-conductive brittle materials. In this study, wire electrochemical discharge machining (WECDM) was applied to processing quartz glass with electrolyte supplied in titrated flow. During WECDM, under surface tension and gravity, the electrolyte flows down in droplets, over the graphite auxiliary electrode and brass wire, producing oxygen and hydrogen bubbles, respectively. The fluid inside the droplet forms eddies on the two sides of the quartz, removing chips and electrolysis resultants. Rapid replenishment of electrolyte to constant concentration can ensure even distribution of current density and a stable insulation gas film can thus be formed. Experimental results show that quartz glass processed by WECDM with titrated electrolyte flow yielded long straight slits of small mean width. In addition, with the electrolyte supplied in droplets, less electrolyte is consumed in the process. The proposed droplet titration approach to WECDM of quartz glass incurs less cost and pollution, making it both cost effective and environmental friendly.

Micro-electrochemical discharge cutting of glass using a surface-textured tool

Wire electrochemical discharge machining (WECDM) has been suggested as a micro-cutting method for non-conductive materials such as glass and ceramics. However, the WECDM process using traveling wire suffers from low surface integrity because of the high working voltage and long reactive tool length compared to those of the micro-ECDM process. In this research, a cylindrical tool with micro-textures on the surface is proposed as a cutting electrode. Partial electrical shielding of the tool electrode was also employed to stabilize the discharge characteristics by minimizing the reactive tool area. Two-dimensional contour cutting of soda-lime glass using the proposed method is demonstrated.

Wire Electrochemical Discharge Machining of Al2O3 Particle Reinforced Aluminum Alloy 6061

The behavior of wire electrochemical discharge machining of Al2O3 particle-reinforced aluminum alloy 6061 was studied. The effects of machining voltage, current, pulse duration, and electrolyte concentration, on material removal rate (MRR) were evaluated in the light of the contribution of the electrical discharge machining (EDM) and electrochemical machining (ECM) actions. The relative strength of the EDM and ECM activities in the machining process under different conditions was studied with the aid of the voltage waveforms. It was found that the conditions of high current or high concentrations of electrolyte would promote the ECM activity and result in a high MRR. The relative importance of the various cutting parameters on MRR was established using orthogonal analysis. The results suggest that to achieve the highest MRR, the applied current is the most influential factor among current, pulse duration and electrolyte concentration. This outcome is supported by experimental results and is explained in terms of the surface area of the matrix phase and the spark gap size.

Improving machining performance of wire electrochemical discharge machining by adding SiC abrasive to electrolyte

The use of wire electrochemical discharge machining (WECDM) to slice hard brittle materials has recently been studied because its effectiveness is independent of the mechanical characteristics of the machined materials. Therefore, materials with high hardness, brittleness, strength and electrical insulation, which are difficult-to-cut, can be machined. In ECDM, the electrochemical reaction produces hydrogen bubbles, which accumulate around the cathode. A thin gas layer forms on the surface of the electrode and isolates the electrode from the electrolyte. When a voltage that exceeds the critical voltage is applied, continuous discharge occurs. The material near the electrode is removed by the discharge erosion and chemical etching. The use of WECDM to cut electrically insulating materials has only recently been investigated. However, the breakdown of the gas in the bubbles and the vibration of the wire in WECDM strongly affect the shape accuracy. This work aims to improve the over cut quality by adding SiC abrasive to the electrolyte. A mechanism that combines discharge, chemical etching and abrasive cutting is studied. The effects on expansion, roughness and material removal rate (MRR) are discussed. The experimental results reveal that adding abrasive reduces the slit expansion because it increases the critical voltage. The particles disrupt the bubble accumulation to form an isolating layer around the wire, increasing the critical voltage and reducing the discharge energy. The surface roughness is improved because the abrasive helps to refine the micro-cracks and melted zone that is formed by discharge heat erosion. Meanwhile, smaller grit produces lower roughness. The quality of the slit can be controlled; its expansion and roughness of the slit are 0.024 mm and 0.84 um Ra, respectively.