EDM Process Research Articles

Experimental investigation for the effects of wire EDM process parameters over the tapered cross-sectional workpieces of titanium alloys (Ti6Al-4V)

Abstract. The main purpose of this research is to examine the outcomes of process parameters of Wire Electro-discharge Machining over the tapered workpieces of Titanium Alloy (Ti6Al-4V). Taper angle, current and pulse-off time are considered as the controllable factors effecting the response variables. Each sample has been cut with varying sets of machine controllable parameters to assess their effect on response variables; kerf width, wire wear, Material Removal Rate and surface roughness. Analysis of variances is applied, and mean Reponses are determined to recognize and compare the most influencing parameters over the response variables for the WEDM Process. Regression model for the response variables are also developed using which optimized WEDM process parameters are determined for the optimal response variables. It can be concluded that varying thickness of materials due to tapered cross section affects all the four-response variable, while, current and pulse-off time along with their interactions have high impact over the response variables.

Finite element simulation and experimental investigation of Ti-5Al-2.5Sn titanium alloy during EDM process

In this paper, a finite element method (FEM) has been developed for 2D axisymmetric thermal model for the prediction of temperature distribution profile on workpiece during electro discharge machining and for the calculation of material removal rate (MRR) from the temperature isotherm. For MRR prediction, model uses a number of essential features viz. thermal properties of workpiece, shape and size of heat source (Gaussian heat distribution), material flushing efficiency, pulse off/on time, amount of heat division among the tool, dielectric fluid and workpiece etc. For developing the thermal model ANSYS software was used for the single spark simulation. In this investigation, Ti-5Al-2.5Sn titanium alloy and cylindrical copper was chosen as workpiece and electrode respectively. A comparative investigation has been performed considering the influence of process parameters viz. pulse on time, gap voltage, and peak current for experimental and theoretical MRR. Temperature distribution after material killing has been analyzed on the workpiece surface alongside the depth and radial direction. The model validation has been done by comparing the experimental MRR with the theoretical MRR and a good relationship has been found between them.

Formation of thick electrical discharge coatings

Abstract Thick electrical discharge coatings, also known by the commercial name “MSCoating”, can be applied on complex shapes and cavities to repair components or act as protective coatings. A variant of the EDM process, it can be used to make coatings up to several mm thickness on electrically conductive substrates. In this paper, an insight into the microstructure and formation mechanism is made through the production of experimental coatings using sacrificial Stellite 31 electrodes on stainless steel substrates. The coatings comprised mostly of ‘splats’ of CoCr. In addition, a significant amount of directly deposited un-melted electrode material was present, along with regions of oxide splats and substantial porosity. Using single discharge analysis, individual deposits contained both melted and un-melted electrode material. Through analysis of the debris, it was found that electrode material either formed spherical particles through melting and resolidification within the discharge gap, or in the form of original unmelted electrode material. It is thought that the low peak pulse section of the current waveform results in increased melting and solidification of material within the discharge gap and on the workpiece. The high peak pulse section of the waveform results in increased mechanical pull-out from the electrode, a proportion of which attaches to the workpiece. The ratio between the peak pulses was found to affect the amount of energy per unit volume of coating material for re-melting. The process is then followed by several discharges preferentially located in the spark region resulting in coating consolidation and build-up through further deposition and re-melting of material. Clustering of discharges was found to be critical in coating formation, where such areas exhibited increased deposition of electrode material. Under the conditions used in the study, the threshold for electrode particle size was found to be between 45 and 70 μm, suggesting that powder diameter is fundamental to thick coating formation. The density of debris within the discharge gap, dependant on the Duty Factor, is thought to correlate with the rate of material deposition from electrode to substrate, where an ideal density of debris produces a large amount of uncontrolled and preferential sparking/arcing, enhancing depositon and attachment.

Machining Characteristics of IN718 by EDM with Cooled Electrode and Vibration of the Workpiece

Inconel718 has been widely used in various fields for its good performance, but it is difficult to machine with traditional machining methods. Electrical discharge machining is an alternative competitive process to machine Nickel-based alloys by electrical erosion. In order to improve reduce the electrode loss and improve the machining efficiency, the horizontal ultrasonic vibration of the workpiece and the cryogenic cooling of the tool electrode were applied into the EDM process. Material removal efficiency, surface roughness, surface topography, and microhardness have been characterized.

Application of Grey-Taguchi Method in Performance Evaluation of EDM Process by Varying Tool Material

Application of Grey-Taguchi Method in Performance Evaluation of EDM Process by Varying Tool Material

Wire EDM process optimization for machining AISI 1045 steel by use of Taguchi method, artificial neural network and analysis of variances

Wire electrical discharge machining (WEDM) process used in a wide spectrum of industrial applications. AISI 1045 is medium carbon steel, because of its excellent physical and chemical properties, it is used in many applications. However, the review of the state of the art literature reveals that literature is lacking research to optimize WEDM process for machining AISI 1045 steel. The objectives of this research are building ANN model to predict metal removal rate (MRR) and surface roughness (Ra) values for machining AISI 1045 steel, identifying the significance of the pulse on-time (TON), pulse off time (TOFF) and servo feed (SF) for the MRR and Ra, and selecting optimal machining parameters that give maximum MRR value and that give the minimum Ra value. Taguchi method (Design of Experiments), artificial neural network (ANN), and analysis of variances (ANOVA) used in this research as a methodology to fulfill research objectives. This research reveals that the architecture (3-5-1) of ANN models is the best architecture to predict the Ra and MRR with about 98.136% and 97.3% accuracy respectively. It can be realized that TON is the most significant cutting parameter affecting Ra by P % value 42.922% followed by TOFF with a P % value of 24.860%. SF was not a significant parameter for Ra because of Fα > F. For MRR, the most significant parameter is TON with a P % value of (71.733%), i.e. about three times the TOFF P % value (21.796%) and the SF parameter has a small influence with P % value 3.02%. The analysis confirmed that the optimal cutting parameters for maximum MRR were: TON at the third level (25 µs), TOFF at the first level (20 µs), and SF at the third level (700 mm/min). On the other hand, the optimal cutting parameters for minimum Ra were: TON at the first level (10 µs), TOFF at the third level (40 µs), and SF at the first level (500 mm/min). Future work may focus on optimizing the WEDM process for machining other types of materials or other sets of parameters and performance measures.

Numerical simulation of the effect of crater morphology for the prediction of surface roughness on electrical discharge textured Ti6Al4V

Extensive efforts (mathematical, numerical, and analytical) have been earlier tried to replicate the EDM process in its true nature. In the present work, the surface roughness (Ra) of the electrical discharge textured Ti6Al4V has got mathematically modeled. The parametric influence on the morphology of the developed craters got elucidated at distinct process conditions. The influential factors, viz. current (I, 2–10 A) and pulse on time (Ton, 100–300 μs), were varied to conduct a full factorial set of simulations and experimentations, keeping voltage (V, 30 V) as a constant. The I and V possessed dominant influence for material removal along the radial and axial directions (respectively), whereas the impact of Ton remained uniform in both the directions. Besides, two distinct considerations (based on the positioning of multi-overlapping craters) for prediction of Ra got proposed; the secondary craters superimposing with the primary along its circumference were found to fetch convincing results [with a maximum possible error (average) of 16%]. Simulation and experimentation results were compared using Ra data, crater morphological images, and radius to depth ratio (Rrd) plots. The outcomes were in close concordance with acceptable tolerances. The variation got attributed to the uncontrollable/disregarded factors (formation of recast layer and short circuit ensuing debris interference), prevalent in the case of in situ work environments.

Multi-response optimization of magnetic field assisted EDM through desirability function using response surface methodology

Abstract Magnetic field assisted electrical discharge machining (MFAEDM) is the modification of in conventional EDM process by use of magnetic field on EN-31. This article explain the application of response surface methodology to analyzes the effect of various process parameters such as Ton, Toff and Ip on performance measures such as material removal rate (MRR), electrode wear rate (EWR) and overcut (OC). Analysis of variance was used to check the adequacy of response surface model and significance of process parameters on performance measures. Multi-objective desirability function has been applied to obtain the optimal process parameter settings. Thereafter, machined surface of EN-31 characterized through SEM and EDX. The novelty of this paper is to improve the strategies for flushing the debris which remain clogged in standard EDM in-between machining gap that will interrupts the regular discharge conditions and reduces cutting rate as well as deteriorate the surface characteristics.

Optimization of Wire EDM Process Parameters for Medical Grade Nickel Titanium Shape Memory Alloy

Abstract Nickel Titanium (NiTi) alloys are the class of smart materials classified under shape memory alloys. The traditional machining of these alloys is hard because of various inherent mechanical characteristics of these alloys. Therefore, non-traditional machining process such as wire electro discharge machining (WEDM) has been employed for machining of such alloys. The present study is focused on multi-performance characteristic simultaneous optimization of WEDM process parameters, in which three system control factors, namely, pulse on time (TON), pulse off time (TOFF) and wire feed (WF) are considered for simultaneously maximizing material removal rate (MRR), while minimizing surface roughness (SR) and tool wear rate (TWR). The simultaneous optimization is performed using Taguchi’s Quality Loss Function. Analysis of means and analysis of variance have been carried out to identify the significance level of each system control factor. The different levels of settings and the optimized setting have been analysed using scanning electron microscope images for surface morphological studies. The multi-response optimization investigations revealed that TON is the major contributing factor and optimal performance values were obtained at TON of 125μs, TOFF of 25μs and at WF of 4 m/min.

Process Parameter Optimization in EDM using Heat Treated Al Tool and without Heat Treated Al Tool

In this experimental work , we investigated optimization of process parameters in EDM using Taguchi method by taking Low carbon steel as work piece. Process parameters chosen were Pulse on-time (Ton), Flushing pressure(P) and Pulse Current(IP) . Here we have chosen L9 orthogonal array to study the effect of main factors and interaction between factors on the response variable i.e. Surface Roughness (SR), Material removal Rate (MRR) and Tool Wear Rate (TWR). The contribution of the main factors and interaction were determine here. The MR), TWR and surface integrity are some of the important performance attributes of EDM process. The objective of EDM is to get high MRR along with achieving reasonably good surface quality of machined component with reduced tool wear rate for Low carbon steel material.

Evaluation of die-sinking Electric Discharge Machine with Smart Machine Controller

A programmable logical control based Smart Machine Controller (SMC) has been developed to control the EDM process. SMC extracts the EDM process variables for rough, semi-finish and finish machining operations from the developed database. The experimental database was created by conducting pilot experimentations after conducting the validation experiments, the SMC was tested on six different dies and mold steel materials with original machine controller and the results show that the MRR and surface finish improved significantly when used with SMC machining parameters. The developed SMC is very effective and highly interactive when compared to the original die-sinking EDM machine controller.

Effects of process parameter on performance measures in electrical discharge machining using copper and brass electrodes

In the study of modern-day technology, it’s performance and parameters are evaluated using the EDM process in the drilling of stainless steel 316 material. SS316 material is widely used in many industrial applications such as heat transfer process and chemical tank. This test involves testing more material removal rate, improving the material hardness, reducing the electrode wear rate and machining time. The experiment is based on Taguchi L18 orthogonal array with 6 levels and 6 parameters like current, dielectric pressure, electrode shape, spark gap, polarity, pulse on and off time. Comparison of copper and brass electrodes in this experiment research is being conducted on how copper electrodes behave differently and exhibit better mechanical performance than brass electrodes. Brass electrode, with its high electrical resistance, low melting point and low thermal conductivity, copper has better performance than brass electrode and the different experimental levels and conditions are investigated.

Parametric Optimization of Wire Cut EDM Process on ‘AISID3 Steel’ using Genetic Algorithm and Grey Relation Analysis

Parametric Optimization of Wire Cut EDM Process on ‘AISID3 Steel’ using Genetic Algorithm and Grey Relation Analysis - written by D. Vishnuvardhan Reddy , P V Sanjeeva Kumar published on 2020/02/17 download full article with reference data and citations

Experimental Investigation on Surface Roughness, Hardness and MRR of Stainless Steel 316L in EDM with Distilled water as electrolyte using Taguchi Method

Stainless steel 316 L is combination of chromium-nickel-molybdenum austenitic stainless steel developed to improve the corrosion resistance better than alloy 304.It also provides higher creep, stress-to-rupture ratio and good tensile strength at elevated temperatures. Machining in Distilled water has given better result at higher MRR and low tool wear rate than in kerosene. The machining accuracy was not very good but the surface finish was slight better. This paper deals with the optimization and analysis of the EDM process of SS 316L. The Taguchi method was used to determine the combination of EDM process parameters like current, pulse ON, pulse OFF, Voltage which minimize surface roughness and maximize hardness of the material. The experiments were planned & performed as per L9 orthogonal array (OA) and signal-to-noise (S/N) ratio was applied to determine the proposed performance characteristics.

Comparison of geometrical accuracy and surface finish of cam profile generated by wire-EDM and CNC milling machine

CAM is a machining element that has a curved groove or curved outline used for converting rotary motion into the form of linear motion or vice versa. The radial cam is a type of cam which having rotating plate or disc with an outer circumference shaped for producing a linear movement to a follower which is held against it. The quality of the final machined component surface depends on the accuracy and surface finish, position, orientation and run-out. The main aim of this paper is to machine a CAM profiles with CNC milling and wire cut EDM process and comparing the surface finish and accuracy of the machined surface with surface roughness tester and coordinate measuring machine (CMM).

Active gap capacitance electrical discharge machining of polycrystalline diamond

This paper introduced a novel active gap capacitance electrical discharge machining (AGC-EDM) method for high efficiency machining of polycrystalline diamond. Graphene was used for the first time in an EDM process to increase the gap capacitance, which would result in enlarged inter-electrode discharge explosive force and higher processing stability. The new principle and machining mechanisms were introduced; an equivalent circuit model was established; and factors that affect the machining performance were analyzed. In order to valid the theory and assumptions and investigate the effectiveness of the new approach, EDM experiments and comparative study were conducted. Test results showed that discharge explosive force in the new AGC-EDM was increased dramatically and the machining process became more stable. The material removal rate in AGC-EDM was found to be more than 10 times higher than that of the normal EDM while the relative electrode wear was reduced by 70 %.

FEM model development for the simulation of a micro-drilling EDM process

The present paper aims to describe the development of a FEM model for the simulation of a die-sinking micro-EDM process. A commercial FEM code specific for the simulation of thermo-mechanical forming processes was used. The developed model was based on the capacity of the code to simulate the removal process or the separation of the material through the mesh element deletion. The electrical discharges were simulated through a proper heat flux and the material melting temperature was set as a trigger for the element deletion. The heat flux was related to the EDM process parameters by means of mathematical models selected from the literature. In the first part of the present work, a model based on a single discharge analysis was developed; then, the model was extended to a sink EDM process characterised by repeated discharges. The model was validated in terms of machining time, top diameter and MRR by the execution of experimental tests.

Machining performance of Inconel 718 using graphene nanofluid in EDM

ABSTRACTInconel 718 in a nickel-based superalloy has excellent mechanical properties such as high tensile and impact strength, excellent oxidation, and corrosion resistance. Unlike most superalloys, it is suitable for the application of high strength in cryogenic as well as at elevated temperature. In this present work, the machinability of Inconel 718 through the EDM process and the performance of graphene nano as a dielectric medium are investigated. Therefore, the concentration of the graphene nanofluid in deionized water is investigated. The influence of the three major process parameters is studied the EDM. The technological characteristics chosen for the study of the performance of graphene nanofluid are MRR, surface roughness, and TWR. The response data confirm the significant influence of those selected process parameters on the yield. The graphene nanofluid shows improvement in machining performance. The waveform identifies stable spark phenomena in the NPMEDM process. The machined surface morphology is examined through field emission scanning electron microscopy (FE-SEM) images.

Electro discharge machining of Inconel 718 alloy and process optimization

ABSTRACTElectro-discharge machining (EDM) is a well-known nontraditional machining operation frequently employed by engineers especially in mold and automobile industries. As a hard material, Inconel 718 superalloy is highly utilized in various industries due to its excellent mechanical properties. Therefore, the EDM process of this alloy provides some technical benefits. Rough surface quality and long process time are two important challenges with respect to the EDM operation. There are several adjustable parameters in EDM that affect process conditions significantly, and unlike the previous studies, only experimental evaluation of process parameters cannot lead to optimal and comprehensive results. In this regard, new strategies such as evolutionary optimization algorithms can be efficiently used to optimize the process conditions. Therefore, the purpose of the present study is to perform experimental investigation and to use efficient intelligent methods based on artificial neural networks and nondominated sorting genetic algorithm for simultaneously optimizing the EDM process of Inconel 718 alloy. Based on this, the influence of process parameters including gap voltage, pulse-on time, peak current, and pulse-off time was studied on material removal rate and surface quality. In addition, the optimal process conditions were successfully obtained using the hybrid strategy.

Fundamental research of applying tungsten carbide-cobalt as tool electrode material for sinking EDM

The manufacturing process milling is limited in machining specific geometries like inner contours with sharp edges, high aspect ratios or defined radii. Sinking EDM (S-EDM) is an appropriate process to machine complex features if the negative geometry is machinable. The tool electrode wear is a critical factor, because it affects machining accuracy and process efficiency. The tool electrode wear depends on S-EDM processing parameters, the geometry and material of the tool electrode. The material tungsten carbide-cobalt owns suitable thermophysical properties for the application as tool electrode material in EDM. Most applications of tungsten carbide-cobalt in EDM are limited to EDM drilling processes, where tungsten carbide tube electrodes are widely used. The advancements in milling of hard materials enable an economic manufacturing of tungsten carbide-cobalt form electrodes for sinking EDM applications. However, it is not investigated which composition of the material tungsten carbide-cobalt is the most appropriate for the application as tool electrode material in S-EDM. Additionally, there are no suitable EDM process parameters in order to benefit from the material characteristics of the respective tungsten carbide-cobalt. Focus of this work is the analysis of different tungsten carbide grades regarding the average grain size and the cobalt content in order to identify correlations between the material characteristics and the EDM process results. Therefore, eight different tungsten carbide grades with four different grain sizes and five different cobalt contents were applied in S-EDM experimental analysis. The experimental studies showed a general suitability of tungsten carbide-cobalt tool electrodes for EDM-processing, where the material removal rate is comparable to commonly used tool electrode materials. Nevertheless, the relative tool wear shows inferior results. It could be observed that higher cobalt content and coarser grain size of the applied tungsten carbide tool electrodes are advantageous for S-EDM.