Study on the movement of wire electrode during fine wire electrical discharge machining process

The effect of heterogeneous second phase on the machinability evaluation of spheroidal graphite cast irons in the WEDM process

ABSTRACTDuring the wire electrical discharge machining (WEDM) process, the vibrations of the wire generated by the gap force is the main cause of imprecision. To achieve more precise results with better accuracy, understanding of the vibration management of the wire is essential. In this article, the wire’s vibration behavior is introduced briefly, followed by an exploration of an equation, derived from Hamilton’s principle, which expresses the vibration of a wire moving axially. This equation is presented under some simplified assumptions. In addition, the relationship between the maximum amplitude of the vibration and the main relative variables is presented. The solution demonstrates that a thicker workpiece results in a larger amplitude of vibration, yet the axial speed of the wire has no impact on the maximum amplitude.

Deep-cryogenic treatment brings some remarkable improvements in mechanical properties by refining the microstructure of the materials. In recent times, cryo-processing has been successfully applied to toughened and high strength to weight ratio work piece materials and tools in electrical discharge machining (EDM) and wire electrical discharge machining (WEDM) for improving machining efficiency. In the present investigation, coated Bronco cut-W wire electrode and Inconel 718 work piece are subjected to deep cryogenic treatment (-196°C). The microstructure of deep cryo-treated and untreated wire electrode and work piece is observed by scanning electron microscope (SEM). The effect of deep cryogenically treated wire electrode and work piece on various performance characteristics are studied during taper cutting operation in WEDM process. Taguchi's experimental design has been applied to determine the optimal parameter setting considering six input parameters such as part thickness, taper angle, pulse duration, discharge current, wire speed and wire tension on various performance measures such as angular error, surface roughness and cutting speed. The study reveals that deep cryogenic treatment of both wire electrode and work piece can improve the machining performance in WEDM.

An on-line pulse trains analysis system of the wire-EDM process

The selection of optimum machining conditions, during wire electric discharge machining process, is of great concern in manufacturing industries these days. The increasing quality demands, at higher productivity levels, require the wire electric discharge machining process to be executed more efficiently. Specifically, the material removal rate needs to be maximized while controlling the surface quality. Despite extensive research on wire electric discharge machining process, determining the desirable operating conditions in industrial setting still relies on the skill of the operators and trial-and-error methods. In the present work, an attempt has been made to optimize the machining conditions for maximum material removal rate and maximum surface finish based on multi-objective genetic algorithm. Experiments, based on Taguchi’s parameter design, were carried out to study the effect of various parameters, viz. pulse peak current, pulse-on time, pulse-off time, wire feed, wire tension and flushing pressure, on the material removal rate and surface finish. It has been observed that a combination of factors for optimization of each performance measure is different. So, mathematical models were developed between machining parameters and responses like metal removal rate and surface finish by using nonlinear regression analysis. These mathematical models were then optimized by using multi-objective optimisation technique based on Non-dominated Sorting Genetic Algorithm-II to obtain a Pareto-optimal solution set.

Non-traditional machining methods like wire electric discharge machining (WEDM) appear to be an ideal choice for machining high strength super alloys like Inconel 706, because of their capability to generate intricate profiles with high accuracy. However, wire breakages are a common problem in the WEDM process and adversely affect the productivity, accuracy, and surface quality. Therefore, the aim of this work is to investigate and comprehend the phenomenon of wire breakage using Inconel 706 as work material and brass wire, diffused brass wire, and zinc-coated brass wire as electrode materials. Six process parameters—pulse-on time, pulse-off time, peak current, spark gap voltage, wire feed rate, and wire tension—have been varied experimentally to determine their effect on the frequency of wire failure. According to the findings, the zinc-coated brass wire breaks with the lowest frequency when compared to the other two. Additionally, an ideal range of input variables has been proposed for efficient WEDM of Inconel 706 without unexpected wire breakages. This range can also be utilized for further research work related to modeling and optimization in WEDM of Inconel 706.

The surface of two types of powder metallurgical (PM) tool steels (i.e., with and without nitrogen) was prepared using wire electrical discharge machining (WEDM). From each grade of tool steel, seven surfaces corresponding to one to seven passes of WEDM were prepared. The WEDM process was carried out using a brass wire as electrode and deionized water as dielectric. After each WEDM pass the surface of the tool steels was thoroughly examined. Surface residual stresses were measured by the X-ray diffraction (XRD) technique. The measured stresses were found to be of tensile nature. The surface roughness of the WEDM specimens was measured using interference microscopy. The surface roughness as well as the residual stress measurements indicated an insignificant improvement of these parameters after four passes of WEDM. In addition, the formed recast layer was characterized by means of scanning electron microscopy (SEM), XRD, and X-ray photoelectron spectroscopy (XPS). The characterization investigation clearly shows diffusion of copper and zinc from the wire electrode into the work material, even after the final WEDM step. Finally, the importance of eliminating excessive WEDM steps is thoroughly discussed.

A high-precision constant wire tension control system for improving workpiece surface quality and geometric accuracy in WEDM

Wire electrical discharge machining (WEDM) is one of the most important non-traditional machining methods that is widely used in various industries. The present research work is concerned with the influences of process variables on quality of machined specimen obtained from WEDM process. The process parameters to manufacture mold structure included wire feed speed, wire tension and generator power, and in the current research, the effects of these variables on the aim factors, namely dimensional accuracy, hardness and roughness of product surface have been investigated, simultaneously. In order to obtain the optimal experiment, the multi-objective optimization with discrete solution area has been employed. Method based on the removal effects of criteria (MEREC) and weighted aggregates sum product assessment (WASPAS) techniques have been used with the aim of weighting the objective functions and discovering the best practical experiment. In the following, the regression analysis has been employed to study the effects of variables on response factors. A good correlation between the results gained from two analysis methods was observed. Based on MEREC-WASPAS hybrid technique, the weights of roughness, hardness and dimensional accuracy of machined part were calculated to about 89%, 9% and 2%, respectively. In the selected optimal experiment, the amount of wire feed speed, wire tension and generator power variables were considered to, in turn, 2 cm/s, 2.5 kg, and 10%.

It is vital to study the impact of heat since it has an unwanted phenomenon on the operating life of parts produced, which is in turn effect the cost of production.when dimension accuracy is the primary function Wire cut machining comprehensively used specially when machining hard metal by using precisely controlled sparks that occur between a very thin wire and a workpiece in the presence of a dielectric fluid.The aim of this research is to study the effects of some Wire Electrical Discharge Machining (WEDM) variables on heat affected zone, white layer and Surface Roughness (SR) of high speed steel using ANOVA method to analyze the behavior of control parameters such as pulse on time (µs), current and wire tension.Experimental investigations separates into two main parts in the first one the wire electrical discharge machining process was accomplished on smart EDM (Electra wire cut machine), and in the second part the roughness of the machined samples surface was tested and the samples were prepared to be measured.The results shows that the heat affected zone and the white layer are affected with the risen of the current and pulse on time values more than the risen in wire tension values, as well as the wire tension affects the surface roughness more than the current and pulse on time.

The wire electrical discharge machining (WEDM) allowed success in the manufacture of the hard, fragile, and materials difficult to cut, especially for electroconductive ceramic materials. In this study, the mathematical models of material removal rate (MRR) and surface roughness (SR) used for the machinability evaluation in the WEDM process of aluminum oxide-based ceramic material (Al2O3 + TiC) have been carried out. The experimental plan adopts the face centered central composite design (CCD). The mathematical models using the response surface methodology (RSM) are developed so as to investigate the influences of four machining parameters, including the peak current, pulse on time, duty factor, and wire speed, on the performance characteristics of MRR and SR. It has been proved that the proposed mathematical models in this study would fit and predict values of the performance characteristics, which would be close to the readings recorded in experiment with a 95% confidence level. The significant parameters that critically affect the performance characteristics are examined.

Experimental investigation of angular error during taper cutting of titanium (ASTM Grade 2) using WEDM process

An investigation of material removal rate and surface roughness of squeeze casted A413 alloy on WEDM by multi response optimization using RSM

The present work emphasis on behavior of zinc-aluminium alloy reinforced with silicon carbide particles when machined with wire electric discharge machining process (WEDM). The difficulty faced by conventional machining is severe tool damage while machining metal matrix composites. Electrical discharge machining can be successfully employed for machining MMC in the place of conventional machining to reduce the tool damage and to produce complicated contours with superior finish. In the present study ZA43 reinforced with SiCp is machined by wire EDM process. Machining is carried-out by varying applied current of (2, 4 and 6amp.), pulse on time (4, 8 and 16μs) and pulse off time (5, 7 and 9μs) while other parameters such as voltage, dielectric flushing pressure, wire tension etc. are maintained constant. It is observed that reduction in the material removal rate and increase in surface roughness for increasing reinforcement percentage in the composite. It is also observed that applied current and pulse on time increases the material removal rate where as pulse off time has less effect on it.

Characterization of Surface Integrity of Ti6Al4V Alloy Machined by Using Wire Electrical Discharge Machining Process