Vibration modeling and analysis of wire during the WEDM process

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

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.

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.

In machining of engineering materials, a wire electrical discharge machining process is having capability to cut the materials which are tough in characteristics. In findings the best machining parameters combination, a Taguchi coupled grey relational analysis (TGRA) method is a proven method. In this study, three Wire electrical discharge machining process parameters and output performance characteristics such as surface roughness and material removal rate are taken into consideration. The experimental procedure was followed as per orthogonal array design concept. The optimum parameters were found as pulse on time of 110 msec, pulse off time of 60 msec and input current of 10 amps obtained the machining process performance characteristics. The result indicates with increase in pulse on time increases the in the energy, therefore increases cutting rate led to improve in the materials removal rate. From the statistical analysis, pulse on time was recognized as predominating process parameter contributing 93.87% followed by input current as 3.96% and pulse off time as 0.18%.

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

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

The machining of Nitinol shape memory alloys (SMA) through conventional machining techniques imposes several challenges due to the alloys’ comprehensive mechanical qualities. Wire electrical discharge machining (WEDM) process is a non-conventional machining technique that is suitable mainly for producing complex shape geometries with excellent surface features for difficult-to-cut materials. The current study attempted the use of a near-dry WEDM process for Nitinol SMA with the consideration of multiple response variables. The studied literature and machine capabilities have identified input factors of pulse-on-time (Ton), pulse-off-time (Toff), and current and output factors of MRR, SR, and RLT. Through the Taguchi approach, a total of nine experimental trials were designed to analyze the performance of the process. The statistical significance of input factors on the performance measures was studied with the help of ANOVA techniques. Statistical analysis for all the output measures has shown that the generated regression terms had a significant influence. For single output measures, the current was found to have a substantial effect on both MRR and SR, while Toff was the most significant contributor in the case of RLT. The obtained results of residual plots for all performance measures implied good ANOVA results. The effect of near-dry WEDM variables was studied on output measures through main effect plots. Grey relational analysis (GRA) has been employed to attain optimal parametric settings of multiple performance measures. GRA technique for the optimal parametric settings of simultaneous performance measures of MRR, SR, and RLT was found to have a Ton of 30 µs, Toff of 24 µs, and current of 4 A. Validation trials were conducted to check the adequacy of the GRA technique. The minor acceptable deviation was recorded among the anticipated and recorded values. This clearly reveals the acceptability of the integrated approach of the Taguchi–Grey method. The surface morphology for the near-dry and wet-WEDM has also been investigated through scanning electron microscopy (SEM). The author considers that the present study will be beneficial for users working in WEDM and near-dry WEDM processes for hard machining materials.

Studies are made on the wire electrical discharge machining (WEDM) process performance parameters such as material removal rate, kerf and surface roughness of Incoloy®Alloy800 following the Taguchi’s design of experiments. ANOVA is performed to trace the statistically significance of input parameter (viz. gap voltage, pulse-on-time, pulse-off-time and wire feed) on the WEDM process parameters. A simple multi-objective optimization approach is suggested for specifying a set of optimum input parameters to achieve maximum material removal rate, and minimum surface finish and kerf width.

Attempt has been made to optimise surface roughness (Ra) of cold worked high carbon and high chromium hard die steel (AISI: D2) by wire electrical discharge machining (WEDM) process. In present study fractional factorial design of experiment has been used at two levels to conducted five different sets of experiment. Tan-sigmoid and pure line transfer function-based four layered back propagation artificial neural network (BPANN) approach have been applied to develop a suitable model with six WEDM process input parameters and two output parameters, i.e., Ra and material removal rate (MRR). The effect of input parameters has been analysed by training data for the best model using analysis of variance (ANOVA). The model S2 has been found satisfactory as training correlation coefficient (R2) is 99.2% and adjusted correlation coefficient (Radj)2 is 99.1%. The minimum surface roughness has been found using root mean square error (RMSE) approach.

This article reports about analysis and optimization of surface roughness parameters (i.e. average roughness Ra and maximum roughness Rt) of wire electrical discharge machined fine-pitch miniature spur gears made of brass. Effects of four wire electrical discharge machining process parameters (i.e. voltage, pulse-on time, pulse-off time and wire feed rate) on the surface roughness parameters of the miniature gears were studied by conducting 29 experiments with two replicates each and designed based on Box–Behnken approach of response surface methodology. Analysis of variance study found all four input parameters to be significant. Experimentally, the surface roughness has been found to increase with higher voltage and longer pulse-on time and decrease with longer pulse-off time and higher wire feed rate. Desirability analysis was used to optimize the wire electrical discharge machining parameters, so as to minimize the Ra and Rt simultaneously. Optimum values of Ra and Rt obtained from the confirmation experiments conducted at the optimized wire electrical discharge machining parameters are superior than the values reported in the literature. Artificial neural network model has been developed for prediction of the surface roughness of the wire electrical discharge machined miniature gears. Very close agreement was found among the surface roughness values predicted by response surface methodology and artificial neural network with the corresponding experimental values.

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.

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.

Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of an underwater rotary spindle is first introduced. The spindle is added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometry. Mathematical models for material removal rate and surface finish in cylindrical wire EDM of the free-form cylindrical workpiece are derived. Experiments are conducted for cylindrical and 2D wire EDM of brass and carbide work-materials. Comparing to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates could be achieved in the cylindrical wire EDM. The surface finish and roundness of parts generated by cylindrical wire EDM at different part rotational speeds and wire traverse speeds are measured and analyzed.