Wire Cut Electro Discharge Machining Research Articles

Study of Wire-Cut Electro-Discharge Machining of Heat-Resistant Nickel Alloys.

This paper presents an analysis and theoretical model for assessing the quality and accuracy of wire-cut electro-discharge machining (WEDM) of products made from novel heat-resistant nickel alloys such as CrNi56KVMTYB. It is observed that WEDM processing of Ni alloy led to high surface roughness for the thick specimens, and electrical parameters such as pulse duration for the selected range depict an insignificant role in the value of surface roughness. On the other hand, the cut width of the machined surface decreases as the pulse duration increases, while the cut width is elevated for thick workpieces. Secondary discharges developed in WEDM have negative effects that cause sludge adhering and deterioration in the quality and productivity of processing. The regression model is developed to predict the surface roughness and cut width of machined surfaces, which holds significant importance in modern engineering. The workpiece is examined for surface integrity and material deposition. It is observed that an increase in the height of the specimen leads to the occurrence of secondary discharges, which in turn results in the formation of cracks on the surfaces of high-temperature nickel alloys. These cracks have a detrimental effect on the performance of critical products made from next-generation heat-resistant nickel alloys.

Analysis of Wire-Cut Electro Discharge Machining of Polymer Composite Materials.

This study presents the analysis of wire-cut electro-discharge machining (WIRE-EDM) of polymer composite material (PCM). The conductivity of the workpiece is improved by using 1 mm thick titanium plates (layers) sandwiched on the PCM. Input process parameters selected are variable voltage (50–100 V), pulse duration (5–15 μs), and pause time (10–50 μs), while the cut-width (kerf) is recognized as an output parameter. Experimentation was carried out by following the central composition design (CCD) design matrix. Analysis of variance was applied to investigate the effect of process parameters on the cut-width of the PCM parts and develop the theoretical model. The results demonstrated that voltage and pulse duration significantly affect the cut-width accuracy of PCM. Furthermore, the theoretical model of machining is developed and illustrates the efficacy within the acceptable range. Finally, it is concluded that the model is an excellent way to successfully estimate the correction factors to machine complex-shaped PCM parts.

A study on the machinability behaviour of Al6061-ZnO<SUB align="right">(p) metal matrix composite through wire-cut electro discharge machining using multi objective optimisation on the basis of ratio analysis

Aluminium matrix composites are effective and qualified materials in the industrial domain. The presence of abrasive reinforcing particles and the conventional machining of these materials induces ...

A study on the machinability behaviour of Al6061-ZnO<SUB align="right">(p) metal matrix composite through wire-cut electro discharge machining using multi objective optimisation on the basis of ratio analysis

A study on the machinability behaviour of Al6061-ZnO<SUB align="right">(p) metal matrix composite through wire-cut electro discharge machining using multi objective optimisation on the basis of ratio analysis

Parametric Optimization of EN-31 Steel in Wire Cut Electro Discharge Machining by Taguchi Technique

Amongst the various methods of machining, Electro Discharge Machining is the convenient alternatives for the industries due to non-contact of work piece and tool. In the study of various EDM processes the main target is to achieve the better finish of surface, high material removal rate and good dimensional accuracy by regulating the different input parameters. There are various applications of EDM such as aerospace parts, medical equipments, dies and moulds, nuclear and automobile industry. In this experimental study, a trial has made to look the impact of input factors like pulse-on, pulse-off, peak current, tension of wire on rate of material removal, gap current and time for machining. Taguchi (L9 OA) and Analysis of Variance technique were used to optimize the outcomes for wire cut EDM of EN-31 tool steel. The outcomes revealed that Ton and Toff are the leading cogent factor for material removal rate and gap current respectively.

A Role of cryogenic in Wire cut EDM process

Novel techniques are being focused on the enrichment of the performance characteristics under different machining processes. Cryogenic is one of such novel practices that tunes the surface integrity with vast variations with the traditional machining processes. Dimensional accuracy, surface roughness, material removal rate with less reduction in scrap of material is one of the prior targets of production process. Wire cut Electro Discharge Machining (WEDM) is one method that satisfy with upgrading performance characteristics. In order to step-up these performance characteristics in attaining superior quality, cryogenics practices have collaborated with the WEDM process. Present paper deals with the reviews of the researchers that have been performed over cryogenic treated WEDM process. Effect of performance characteristics like pulse on, pulse off, current, voltage, wire tension, wire feed is discussed with relation to material removal rate, tool wear rate and surface roughness evolved. Key concept of paper is to include the research ideology with best feasible techniques that can prevail in production practice in order of contribute to the forthcoming researches in industrial and production departments.

Application of Machine Learning Techniques for Multi Objective Optimization of Response Variables in Wire Cut Electro Discharge Machining Operation

Wire Cut Electrical Discharge Machining (WEDM) is a non-conventional thermal machining process which is capable of accurately machine alloys having high hardness or part having complex shapes that are very difficult to be machined by the conventional machining processes. The WEDM finds applications in automobiles, aero–space, medical instruments, tool and die industries, etc. The input parameters considered for WEDM are pulse on time, pulse off time, flushing pressure, servo voltage, wire feed rate and wire tension. Performance of WEDM is mainly assessed by output variables such as, material removal rate (MRR), kerf width (Kw) and surface roughness (Ra) of the work piece being machined. Looking at the need of a suitable optimization model, the present work explores the feasibility of machine learning concepts to predict optimum surface roughness and kerf width simultaneously by making use of experimental data available in the literature for machining of Hastelloy C– 276 using WEDM. In most of the literatures, single objective optimization has been carried out for predicting optimum cutting parameters for WEDM. Hence, the present work presents a methodology that makes use of a machine learning algorithm namely, gradient descent method as an optimization technique to optimize both surface roughness and kerf width simultaneously (multi objective optimization) and compare the results with the existing literatures. It was observed that the input parameters such as pulse on time, pulse off time, and peak current have significant effect on both surface roughness and kerf width. The gradient descent method was successfully used for predicting the optimum values of response variables.

Ultrasonic Vibration Assisted Electro-Discharge Machining (EDM)-An Overview.

Many of the industrial processes, including material removal operation for shape generation on the surface of material, exploit the assistance of ultrasonic vibrations. This trend of using ultrasonic vibration in order to improve the process performance is becoming more and more prominent recently. One of the significant applications of this ultrasonic vibration is in the industrial processes such as Electro-discharge machining (EDM), where ultrasonic vibration (UV) is inserted as a medium for enhancing the process performance. Mostly ultrasonic vibration is applied along with the EDM process to increase the efficiency of the process through debris cleansing from the sparking gap. There have been significant changes in ultrasonic assisted technology during the past years. Due to its inherent advantages, ultrasonic assistance infiltrated in different areas of EDM, such as wire cut EDM, micro EDM and die sinking EDM. This article presents an overview of ultrasonic vibration applications in electric discharge machining. This review provides information about modes of UV application, impacts on parameters of performance, optimization and process designing on difficult-to-cut materials. On the bases of available research works on ultrasonic vibration assisted EDM, current challenges and future research direction to improve the process capabilities are identified. Literature suggested improved material removal rate (MRR), increased surface roughness (SR) and tool wear ratio (TWR) due to the application of ultrasonic vibration assisted EDM. However, tool wear and surface roughness can be lessened with the addition of carbon nanofiber along with ultrasonic vibration. Moreover, the application of ultrasonic vibration to both tool and workpiece results in higher MRR compared to its application to single electrode.

Fabrication of serpentine micro-channels on glass by ultrasonic machining using developed micro-tool by wire-cut electric discharge machining

A rapid method for fabrication of micro-channel on glass substrates is introduced and investigated in this paper. Wire-cut electro discharge machining (WEDM) and ultrasonic machining (USM) were used as manufacturing processes for machining the micro-tools and micro-channels, respectively. The copper micro-tool was machined using WEDM and the optimal design of the tool was achieved using Taguchi design of experiment. After overall evaluation criteria (OEC) analysis, the optimum conditions were achieved as Ton as 25 μs, Toff as 6 μs, Ip as 1 A, and Wf as 75 mm/s. Further, it was used for fabrication of micro-tools with different profiles such as square, circular, and zigzag. The fabricated micro-tools were used to machine serpentine micro-channels on glass using USM at various power ratings such as 40, 50, and 60%. After machining, net overcut of the micro-channels were found as 74.65, 75.86, and 81.75 μm for square, circular, and zigzag profiles, respectively.

Multi-performance optimisation of micro electro-discharge machining during deep micro-slots fabrication using foil tool electrode

This study attempts to investigate and optimise the effects of process parameters like voltage, sensitivity, duty factor and capacitance on performance characteristics such as material removal rate (MRR), tool wear rate (TWR), width expansion, length expansion and depth of slot during fabrication of deep and long micro-slots on brass work material by micro electro-discharge machining (micro-EDM). Copper foil is used as tool electrode of thickness 240 μm and width of 8 mm shaped by wire-cut electro-discharge machining. The randomised experiments were performed twice and mean response is considered for analysis to achieve accuracy in the results. Single-optimal parametric setting conditions obtained from the grey relational analysis (GRA) and confirmatory test results showed an improved machining performance of the process. Capacitance is observed to be the most influencing parameter followed by duty factor, sensitivity and voltage. Also, the feasibility of copper foil as a tool electrode is analysed and found high machining rate with more accurate micro-feature geometry.

Multi response optimization in wire electrical discharge machining of Inconel X-750 using Taguchi’s technique and grey relational analysis

AbstractThe effective optimization of machining process parameters affects dramatically the cost and production time of machined components as well as the quality of the final products. This study presents an investigation on cutting speed and surface roughness of Inconel X-750 using Wire-cut electric discharge machining process. Six input process parameters of Wire-cut Electro Discharge Machining—spark gap voltage, pulse-on time, pulse-off time, wire feed rate, peak current and wire tension—were chosen to study their effects on the selected responses. Taguchi’s design of experiments methodology has been used for planning, designing and conducting the experiments. The grey relational analysis has been applied in conjunction with the Taguchi’s parameter design approach for the optimization of multiple responses. The analysis of variance has been applied to identify the significance of different parameters. Finally the confirmation experiments were performed to validate the predicted optimized results.

Effect of different machining processes on the tool surface integrity and fatigue life

Ultra-precision grinding, wire-cut electro discharge machining and lapping are often used to machine the tools in fine blanking industry. And the surface integrity from these machining processes causes great concerns in the research field. To study the effect of processing surface integrity on the fine blanking tool life, the surface integrity of different tool materials under different processing conditions and its influence on fatigue life were thoroughly analyzed in the present study. The result shows that the surface integrity of different materials was quite different on the same processing condition. For the same tool material, the surface integrity on varying processing conditions was quite different too and deeply influenced the fatigue life.

Identification of a Crack in Clamped-Clamped Beam using Frequency-based Method and Genetic Algorithm

The natural frequencies of cracked and uncracked clamped-clamped beam are measured using single-input multi-output (SIMO) based experimental modal analysis (EMA). The crack present at various locations on the beam is generated using wire cut electro discharge machining process (WEDM). The crack is assumed to be transverse and one dimensional partial cut of a beam and is modeled as equivalent elastic rotational spring. Using Euler-Bernoulli beam theory, a closed form solution of the structural/mechanical member is presented. The measured frequencies of the beam with crack are utilized to identify crack location and its severity by the frequency-based approach as well as genetic algorithm (GA) based intelligent search for the same test points. GA is executed to find global minima of a fitness function that is a function of measured and theoretical frequencies of the cracked beam. The results of predicted crack location and its severity by both the approaches are compared and found to be good agreement with the actual crack parameters.

Experimental investigation of flow boiling heat transfer in novel oblique-finned microchannels

Oblique fins are modified from its conventional straight fins counterpart via the introduction of oblique cuts at specific locations, leaving obliquely-shaped fins with secondary microchannels. The benefits of having these secondary microchannels have been conclusively demonstrated in single-phase mode, however, they have yet to be tested in two-phase mode, which forms the motivation behind this study. Flow boiling experiments are conducted in the oblique-finned microchannel heat sink, made from a copper block with a footprint area of 25×25mm2. 40 parallel microchannels, each with a nominal width of 0.3mm are machined with wire-cut electro-discharge machining process. The nominal width of the oblique cuts, on the other hand, is half of that of the parallel microchannels. Tests are performed with FC-72 dielectric fluid with an inlet temperature of 29.5°C, with a range of mass fluxes from 175kg/m2s to 350kg/m2s and heat fluxes from 6W/cm2 to 120W/cm2. Flow boiling results and discussion on its heat transfer performance and pressure drop characteristics are presented in this paper. It is found that nucleate boiling is the dominant heat transfer mechanism at low heat fluxes, with a transition to convective boiling-dominant via thin-film evaporation occurring at medium heat fluxes. A full convective boiling mechanism is observed thereafter prior to CHF. These observations agreed well with high-speed flow visualisation images. Inlet pressure fluctuations within the oblique-finned microchannels are extremely small, indicating that the oblique fins are able to considerably stabilise the flow boiling process.

Surface integrity and material transfer investigation of pure titanium for rough cut surface after wire electro discharge machining

This article presents an experimental investigation of wire cut electro discharge machining of pure titanium. The marvelous characteristics of pure titanium such as its compatibility and noticeable physical, mechanical and biological performances have led to their increased application in various industries especially in seawater pipings, heat exchangers, implants, prosthesis, airframe and aircraft engine parts over the last 50 years. However, due to low thermal conductivity of titanium and their reactivity with cobalt in most tool materials, there are some difficulties in machining titanium and its alloys by conventional machining. On the other hand, unconventional machining processes especially wire cut electro discharge machining are more appropriate techniques for machining difficult-to-machine materials like pure titanium. This research work is mainly focused on microstructure analysis in terms of machining parameters such as pulse on time, pulse off time, peak current, spark gap using energy-dispersive X-ray, scanning electron microscope and X-ray diffraction techniques. The present results reveal that pulse on time and peak current significantly deteriorate the microstructure of machined samples, which produces the deeper, wider overlapping craters, pockmarks, globules of debris and micro-cracks. The microstructure analysis of rough cut surface was based upon the theory of electrical discharge phase and metallurgical physics.

Flow boiling heat transfer and pressure drop in stepped fin microchannels

Experiments on flow boiling were conducted in stepped fin microchannels. The test vehicles were made from copper with two different footprint areas, designated as SFMC1 and SFMC2. The microchannels were formed by wire cut Electro Discharge Machining process and have surface roughness (Ra) of about 2.0μm. Tests were performed, with deionized water, on channels having nominal width of 300μm and a nominal aspect ratio of four over different mass velocity and heat flux range and inlet temperature of 90°C. The experimental results of flow boiling in stepped fin microchannels and discussion on its heat transfer characteristics, instabilities and two-phase pressure drop are presented. The experimental data was plotted on Taitel–Dukler flow regime map to predict the flow boiling regimes existing within the channel under different operating conditions. The heat transfer mechanism and the flow boiling instabilities are explained based on the existent flow boiling regime. High speed visualizations are shown to validate the explanation.

“Optimization Of Parameters For Wedm Machine For Productivity Improvement”

Optimization of operating parameters is an important step in machining, particularly for operating unconventional machining procedure like Wirecut Electro Discharge Machining. Since wire-cut EDM has experienced explosive growth in application users demand and need maximum productivity and through-put, increased accuracy, and predictable performance. Also machines and job requirements vary greatly, which can make selection of the correct operation parameters a daunting task. As a result, experimentation is necessary if optimum results are to be achieved. Although this reference is not intended to be all-encompassing, it should be a useful guide for selection of parameters. A suitable selection of machining parameters for the process relies heavily on the operator's technologies and experience and they do not provide the optimal machining conditions. In every manufacturing process, material removal rate needs to be maximized while controlling quality by controlling electrode wear rate. In this work, an attempt has been made to optimize the machining parameters for minimum electrode wear rate and maximum material removal rate in WEDM process. Experiments were performed under different cutting conditions of Wire feed (WF), wire tension (WT), discharge current of the machine and discharge voltage (V). Experiments were executed as per Taguchi's L-9 orthogonal array. The output responses were optimized using signal-to-noise (S/N) ratio in addition to Desirability function approach to convert a multi objective optimization problem to a single objective optimization problem.

Simulations and experiments in punching spring-steel devices with sub-millimeter features

This work demonstrates the feasibility of meso-scale (100μm to mm) punching of multiple holes of intricate shapes in metals. Analytical modeling, finite element (FE) simulation, and experimentation are used in this work. Two-dimensional FE simulations in ABAQUS were done with an assumed material modeling and plane-strain condition. A known analytical model was used and compared with the ABAQUS simulation results to understand the effects of clearance between the punch and the die. FE simulation in ABAQUS was done for different clearances and corner radii of the punch, die, and holder. To complement modeling with real experiments and for the purpose of comparison, a set of punches and dies were made to punch out a miniature spring-steel gripper. Comparison of compliant grippers made by wire-cut electro discharge machining (EDM) and punching shows that realizing sharp interior and re-entrant corners by punching is not easy to achieve. However, the promise of realizing meso-scale parts with complicated shapes through punching is demonstrated in this work; and further work is identified and some strategies are suggested for improvement. The main contribution of this paper is in adapting the well-established punching and blanking operations to the meso-scale as a viable alternative to making miniature devices currently dominated by lithography-based techniques.

Experimental investigations of flow boiling heat transfer and pressure drop in straight and expanding microchannels – A comparative study

Flow boiling experiments were conducted in straight and expanding microchannels with similar dimensions and operating conditions. Deionized water was used as the coolant. The test vehicles were made from copper with a footprint area of 25 mm × 25 mm. Microchannels having nominal width of 300 μm and a nominal aspect ratio of 4 were formed by wire cut Electro Discharge Machining process. The measured surface roughness (Ra) was about 2.0 μm. To facilitate easier comparison with the straight microchannels and also to simplify the method of fabrication, the expanding channels were formed with the removal of fins at selected location from the straight microchannel design, instead of using a diverging channel. Tests were performed on both the microchannels over a range of mass fluxes, heat fluxes and an inlet temperature of 90 °C. It was observed that the two-phase pressure drop across the expanding microchannel heat sink was significantly lower as compared to its straight counterpart. The pressure drop and wall temperature fluctuations were seen reduced in the expanding microchannel heat sink. It was also noted that the expanding microchannel heat sink had a better heat transfer performance than the straight microchannel heat sink, under similar operating conditions. This phenomenon in expanding microchannel heat sink, which was observed in spite of it having a lower convective heat transfer area, is explained based on its improved flow boiling stability that reduces the pressure drop oscillations, temperature oscillations and hence partial dry out.

PARAMETRIC INFLUENCE AND OPTIMIZATION OF WIRE EDM OF HOT DIE STEEL

Wire-cut Electro Discharge Machining (WEDM) is a special form of conventional EDM process in which the electrode is a continuously moving conductive wire. The present study aims at determining parametric influence and optimum process parameters of Wire-EDM using Taguchi's technique and a Genetic algorithm. The variation of the performance parameters with machining parameters was mathematically modeled by Regression analysis method. The objective functions are defined as Dimensional Error (DE), Surface Roughness (SR) and Volumetric Material Removal Rate (VMRR). Experiments were designed as per Taguchi's L16 Orthogonal Array (OA) wherein Pulse-on duration, Current, Pulse-off duration, Bed-speed and Flushing rate have been considered as the important input parameters. The matrix experiments were conducted for the material Hot Die Steel (HDS) having the thickness of 40 mm. The Heat Affected Zone (HAZ) characteristics of the eroded materials were assessed by Scanning Electron Microscope (SEM) and the microhardness of the material was tested using Vickers microhardness tester. The results of the study reveal that among the machining parameters, it is preferable to go for smaller pulse-off duration for achieving overall good performance. Regarding pulse-on duration, higher values are recommended for error constrained machining with higher MRR and constrained/limited values for attaining good surface texture. Smaller current is suggested for better surface finish/texture control, medium range for error control and high value for MRR. Finally, the validation exercise was performed with the optimum levels of the process parameters. The results confirm the efficiency of the approach employed for optimization of process parameters in this study.