micro-EDM Process Research Articles

On-machine evaluation of micro-EDM process signature in radio frequency (RF) domain: A step towards cost-effective data collection in a multiphysical process

On-machine evaluation of micro-EDM process signature in radio frequency (RF) domain: A step towards cost-effective data collection in a multiphysical process

Improving Micro-EDM Machining Efficiency for Titanium Alloy Fabrication with Advanced Coated Electrodes.

Enhancing the operational efficacy of electrical discharge machining (EDM) is crucial for achieving optimal results in various engineering materials. This study introduces an innovative solution-the use of coated electrodes-representing a significant advancement over current limitations. The choice of coating material is critical for micro-EDM performance, necessitating a thorough investigation of its impact. This research explores the application of different coating materials (AlCrN, TiN, and Carbon) on WC electrodes in micro-EDM processes specifically designed for Ti-6Al-4V. A comprehensive assessment was conducted, focusing on key quality indicators such as depth of cut (Z), tool wear rate (TWR), overcut (OVC), and post-machining surface quality. Through rigorous experimental methods, the study demonstrates substantial improvements in these quality parameters with coated electrodes. The results show significant enhancements, including increased Z, reduced TWR and OVC, and improved surface quality. This evidence underscores the effectiveness of coated electrodes in enhancing micro-EDM performance, marking a notable advancement in the precision and quality of Ti-6Al-4V machining processes. Among the evaluated coatings, AlCrN-coated electrodes exhibited the greatest increase in Z, the most significant reduction in TWR, and the best OVC performance compared to other coatings and the uncoated counterpart.

MICRO-EDD OF INCONEL 800 USING ELECTROMAGNETIC FIELD

Micro-electro-discharge drilling ([Formula: see text]EDD) is a type of non-traditional machining process used for drilling micro-holes of desired dimensions with a high aspect ratio. But, there are no such research works that could have explained the desired accurate circular shape of micro-holes. The need for a more advanced hybrid machining process to improve the overall efficiency in terms of mainly desired circular shape and radial overcut is evolved. In this research work, an electromagnetic field force-assisted micro-EDM process has been carried out on Inconel 800 with a copper tool of 450[Formula: see text][Formula: see text]m. Experimental results showed that measured metal removal rate and tool wear rate decreased for ascending values of magnetic flux density, peak current and gap voltage, whereas circularity increases linearly with an increase in magnetic flux density and also the effects of magnetic field on circularity of micro-holes on Inconel 800 are more predominant than other parameters.

Investigation of micro-electro-discharge machining process parameters during machining of M2 hardened die-steel

Micro-electro-discharge machining (micro-EDM) is a well-known micromachining method to create microstructures on hard-to-cut materials. To further exploit the capability of micro-EDM, the present research work investigates the effect of various important micro-EDM process parameters on the material removal rate (MRR), tool wear rate (TWR), and overcut (OC) during micro-cavity machining of M2-hardened die-steel. A Taguchi experimental design was used to study the effects of three process parameters namely pulse-on-time (Ton), peak current (Ip), and gap voltage (Vg). The experimental results showed that the most influencing process parameter in the present experimental investigation is peak current, Ip followed by pulse-on-time, Ton and gap voltage, Vg. Furthermore, a recent and effective method i.e. Measurement of Alternatives and Ranking according to COmpromise Solution (MARCOS) has been successfully employed to determine optimal process parametric combination for micro-EDM process to achieve maximum MRR and minimum TWR and OC during machining of micro-cavity on M2-hardened die-steel. From the present research investigation, the optimal micro-EDM process parametric combinations obtained for higher MRR, lower TWR and OC are found as 1 A of peak current, 30 μs pulse-on time and gap voltage of 60 V. Furthermore, through various scanning electron microscope micrographs of micro-cavities and micro-machined surfaces, analysis has been done to find out the micro-cavity with best geometrical accuracy and surface feature to validate the best and most ideal combinations of micro-EDM input parameters for micromachining operations. The results of this study show that micro-EDM is a promising process for machining M2-hardened die-steel. The optimization of process parameters using the MARCOS methodology can further improve the machining efficiency and accuracy of micro-EDM.

Micro-electro discharge machining characteristics of tungsten-copper for electronic devices

ABSTRACT Micro-machining involves the removal of small amounts of material by action other than that of a sharp-edged tool. The most common technique being electrical discharge machining (EDM). The material removal rate and edge definition of the finished product are based on different process parameters. This study is aimed to characterise micro-EDM process parameters for tungsten–copper and to achieve maximum material removal rate without affecting the edge definition and surface roughness while using smaller electrodes. Eight process parameters were studied for their influence on the material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). Taguchi design of experiments was carried for 36 experimental runs. The ANOVA analysis showed that the MRR depends largely on voltage, energy and current, while the TWR depends on the energy and voltage. The surface roughness value (Ra) was influenced more by energy, incremental depth and the pulse width, thus differing from MRR and TWR. The optimum parameter set for higher MRR (10e-3 mm3/min) and lower Ra (0.13 µm) was deduced from regression analysis, and the confirmation tests showed less than 8 % deviation from the predicted values. The SEM studies showed greater depths of craters in the surface machined for higher MRR.

Simultaneous electrochemical and electrodischarge machining process: An approach to sustainable manufacturing

Manufacturing of Net Finished Shape (NFS) microholes in Inconel 718 materials with faster machining rate can offer significant benefits in terms of reduced waste, improved efficiency, and lower production costs, which are essential for sustainable manufacturing. However, the existing manufacturing method, namely electrochemical machining (ECM), results in slow machining with uncontrolled dissolution, leading to increase production time, energy consumption, and carbon emission associated with the manufacturing process. The current manuscript investigates the reason attributes for these problems through potentiodynamic polarization test. Subsequently, a new machining process known as Simultaneous electrochemical and electrodischarge machining (SECEDM) has been proposed. This frugal manufacturing-based machining process offers high machining rate (MR) and better overall hole circularity (OHC) through the synergistic effect of anodic dissolution and electrochemical discharges. The obtained results reveal that the SECEDM process offers nearly 261 % and 141 % higher MR and 1.23 % and 3.78 % better OHC than electrochemical machining (ECM) and electrodischarge machining (EDM), respectively. Moreover, SECEDM outperforms the simultaneous micro-EDM and micro-ECM process (SEDCM) process by seven times in machining rate and promotes localized dissolution than ECM. Overall, SECEDM's benefits, including its high machining rate, superior surface quality, sustainability, eco-friendliness, and elimination of the need for secondary finishing processes, make it an ideal candidate for the next-generation manufacturing process.

A physics-informed CNN-TSE hybrid network for micro-EDM process monitoring and control

Despite being a widespread non-conventional processing technique, electrical discharge machining (EDM) has been complicated due to its removal mechanisms and weak process stability for decades. Process monitoring is an enabling technology to offer an indirect insight into the discharge phenomena, understanding the probabilistic anomaly events such as arcs and short circuits. However, the transient high-frequency pulse train poses a great challenge for statistical monitoring and control. Traditional approaches are limited to single pulse analysis, which hinders a deep understanding of the process. To address the challenge, this paper proposes a novel physics-informed deep learning architecture for real-time micro-EDM process monitoring. To prepare condition labels, a series of signal-processing techniques including sensory fusion, pulse-shape filtering and pulse segmentation are employed, followed by observation diagrams on two critical indicators, i.e. discharge energy and discharge time interval. A decision logic that allows embedding of domain knowledge is formulated, yielding physics-informed labels on each pulse train. For online monitoring applications, a hybrid hierarchical structure that combines a 1D convolutional neural network (1D-CNN) and a Transformer encoder (TSE) is designed to simultaneously extract local pulse features and temporal dependencies between pulse sequences. This deep learning model achieves a classification accuracy of 96% on the validation dataset and reaches precision and recall scores of more than 92% on the test dataset with varying processing parameters. Two model interpretation approaches, i.e. gradient-weighted class activation mapping (Grad-CAM) and attention visualization, are adopted. Consequently, it is found that the CNN module assigns high feature importance to the breakdown and maintaining stages of one pulse and the TSE module improves the feature salience and reliance on the condition of distinct events. This monitoring network is further demonstrated on a control application for adaptive regulation of the micro-EDM drilling process. The results of deep-hole drilling suggest that the CNN-TSE model can highly improve the process stability and hence the machining quality.

Comparative study of micro-die sink and micro-EDM drilled holes for electrode wear and surface roughness

Electrical Discharge Machining (EDM) is one of the most widely used non-traditional machining processes due to its numerous advantages. Since there is a continuous demand for miniaturized components, micro-EDM became a very popular process. The high temperature of melting and vaporization in the machining zone causes uncontrollable electrode wear to occur in the micro-Electrical discharge machining (micro-EDM) process. In the micro-EDM process, it will make a great impact on dimensional accuracy. In this study, a comparison of micro die sinking and micro Electric Discharge drilling processes has been conducted for the three varying levels of parameters for Voltage, Capacitance, and their effect on the Electrode Wear Rate (EWR) and Surface Roughness (Sa) were studied. Then the parameter that is more strongly influencing the unwanted EWR and Surface Roughness was identified and discussed. The maximum percentage change in surface roughness while micro-EDM die sinking and micro-EDM drilling was found to be 66% and 50%. for the given capacitance also 68% and 49% for the given voltage. Similarly, the highest percentage of EWR occurred while micro-EDM die sinking and micro-EDM drilling has been found at 67% and 65% for the given capacitance also 78% and 52% for the given voltage. The erosion of electrode at the bottom surface has been observed before and after the micro-EDM die-sinking and drilling processes.

Surface integrity of tungsten carbide microelectrodes fabricated using reverse micro-EDM by varying electrode materials

Recently, there has been a notable trend towards miniaturizing components across diverse industries. The reverse micro electrical discharge machining (reverse micro-EDM) process has gained prominence for microelectrodes array fabrication. However, this process often induces undesirable surface attributes on microelectrodes, including rough topography, elevated residual tensile stresses, increased surface roughness, microcracks, recast layers, and heat-affected zones (HAZ). Consequently, assessing the influence of tool materials on microelectrode surface integrity becomes crucial. This study systematically investigates the effect of distinct tool materials on the surface roughness of microelectrodes fabricated using reverse micro-EDM. Three tool materials were considered: copper, brass C38500, and aluminum 3003. The results robustly establish copper as the most efficient tool material for reverse micro-EDM applications, showcasing superior productivity and performance. Employing copper as the tool material under specific conditions yielded a remarkable achievement, a minimal surface roughness of 0.38 µm on tungsten carbide microelectrodes at 90 V, 10nF, and 5 µm/sec. These findings underscore the potential of copper as a promising tool material for fabricating microelectrodes via reverse micro-EDM.

Characterization of process parameters in micro EDM on stainless steel

A versatile operational technique called Micro-Electrical Discharge Machining (Micro-EDM) is employed to initiate miniature holes in hard materials to enable efficient conduction in the applications of micro machining. Short-term discharge of electric pulses of a high discharge current between the tool used and the work piece eliminate material on the surface. A study was performed to evaluate the impact of Micro-EDM process characteristics on Stainless Steel 304 with the help of a brass electrode the high utility levels of the metal in several industries. The current study undertakes to experiment with pulse durations of 3 μs, 4 μs, and 5 μs at a current intensity range of 20A with an emphasis on performance measurements including Metal Removal Rate (MRR) and Tool Wear Rate (TWR).This is achieved by drilling 1.0 mm and 1.5 mm micro holes on SS 304. The Taguchi approach uses a mixed 2–3 design to assess the findings. Subsequently, the outcomes of the study of tiny holes related to both diameters are contrasted to determine the significance of factor variables.

A novel servo-stabilized electromagnetic levitation formicro-EDM processing and its feasibility analysis

The purpose of this paper is to evaluate the feasibility of a novel gap-controlled strategy for micro-EDM process using magnetic levitation. The tool is levitated and positioned accurately using a unique actuator arm. The actuator arm attained the required positioning accuracy in the thrust (Z) direction to ensure a uniform and smooth discharge free of arcing and short circuits. Experiments were carried out using a copper tool and EDM oil on Nimonic superalloy (Grade C-263). Material removal rate (79.26 µg/min), tool wear rate (19.75 µg/min), and average surface roughness (Ra = 1.196 µm) all proved the efficacy of the developed technology. Furthermore, the machining stability and average specific energy (1.7350 J/μg) were examined and compared to the experimental results of traditional EDM, as well as literature data. Maglev μ-EDM is substantially more stable than traditional EDM, according to a comparison of the current-voltage (V-I) curve. Microholes, micropores, recast layer, and other surface topographical features are detected in a low amount using FESEM. The bidirectional material movement and elemental diffusion are shown by elemental characterization using EDX analysis.

Development of a Hybrid Intelligent Process Model for Micro-Electro Discharge Machining Using the TTM-MDS and Gaussian Process Regression.

This paper proposed a hybrid intelligent process model, based on a hybrid model combining the two-temperature model (TTM) and molecular dynamics simulation (MDS) (TTM-MDS). Combined atomistic-continuum modeling of short-pulse laser melting and disintegration of metal films [Physical Review B, 68, (064114):1–22.], and Gaussian process regression (GPR), for micro-electrical discharge machining (micro-EDM) were also used. A model of single-spark micro-EDM process has been constructed based on TTM-MDS model to predict the removed depth (RD) and material removal rate (MRR). Then, a GPR model was proposed to establish the relationship between input process parameters (energy area density and pulse-on duration) and the process responses (RD and MRR) for micro-EDM machining. The GPR model was trained, tested, and tuned using the data generated from the numerical simulations. Through the GPR model, it was found that micro-EDM process responses can be accurately predicted for the chosen process conditions. Therefore, the hybrid intelligent model proposed in this paper can be used for a micro-EDM process to predict the performance.

Achieving nano-patterned features by micro-EDM process using vertically aligned ZnO nanorods grown on microprobe tip: A scaling approach

Fabricating the nanopatterned features through a cost-effective nanomachining technique is one of the great challenges in NEMS industries. The micro-electrical-discharge machining process is one of the promising machining technologies which is capable to write the micro-scale features on any electrically conductive materials. However, its potential has not been tested yet for replicating the nanoscale features through the scaling approach. Hence, this article addresses a scaling approach for fabricating the nanopatterned features on super finished titanium alloy (Ti-6Al-4 V) using vertically aligned ZnO nanorods grown on the apex of the microtip. For achieving this, first of all, cylindrical micro-tools of diameter (ø) 90–95 μm (tungsten) were fabricated through a micro-electrochemical turning process under KOH (2.5 M) electrolyte medium. On the apex of the micro tools, the ZnO nanorods were grown by the low-temperature hydrothermal process by dipping the apex of the tip in seed and growth solution followed by essential heat treatment at 90 °C. It was found that the grown nanorods were well defined in shape and size and further utilized as nanotools during short-duration discharge (5 ms) μ-EDM experiments. It was expected that by downsizing the tooltip, the discharge energy per unit pulse may be reduced due to the localization effect. Moreover, it is well-known fact that the discharge happens only in the nearest established gap in the μ-EDM process. The experimental results of this study confirmed the same. The FESEM micrographs were utilized for the morphological characterization of formed nanopatterned cavities, microtools, and nanorods while the chemical characterization of the same is carried out by EDX spectroscopy. Additionally, the stability of the machining process was tested first for multiple discharge energy pulses then after a short duration discharge energy pulse has been characterized by voltage-current (V-I) waveforms during nanocavity fabrication. Finally, the supporting results of this experimental investigation show the feasibility of the approach towards nano-EDM with extensive potentials/applications in micro/nanofabrication devices.

Research on micro-EDM discharge state detection technology based on inter-electrode impedance variation characteristics

To address the difficulty in detecting the discharge state of a narrow pulse width and small duty cycle pulse, in this study, we investigate the variation characteristics of the inter-electrode impedance in the micro-EDM process and propose a detection method to distinguish different discharge states in micro-EDM based on the change in electrical signal caused by the change characteristics. The influence of the pulse width and duty cycle on the quality of micro-EDM is summarised. The results show that the workpiece surface machining quality can be considerably improved by compressing the pulse width of the pulse power supply. A micro-EDM discharge state detection system based on the variation characteristics of the inter-electrode impedance is designed, and experiments verify the detection method. The control strategy of the discharge state detection system is analysed, and a control strategy based on the forward direction and discharge state is proposed. The machining effect of the control strategy is tested through a trial-machining experiment. According to the machining control strategy, the control signal is outputted, which can realise a stable and efficient micro-EDM process.

A hybrid MCDM approach for parametric optimization of a micro-EDM process

A hybrid MCDM approach for parametric optimization of a micro-EDM process

Pulsed Power Supply Superposed With Radio Frequency Oscillating Wave for the Improvement of Micro-Electrical Discharge Machining Process

Abstract During the micro-electrical discharge machining (micro-EDM) process, the dielectric property of narrow interelectrode gap is transiently changing. With the hysteretic servomotion of spindle, the effective discharge ratio (EDR) between electrodes is low. In this research, a pulsed power supply superposed with the radio frequency (RF) oscillating wave of controllable frequency and amplitude is proposed in order to induce interelectrode continuous discharge, so that, the machining efficiency and accuracy are improved simultaneously. The experimental results of microhole machining show that under the oscillating frequency of 160 MHz and amplitude of ±10 V, the machining efficiency is increased by 35%, the tool electrode wear rate (TWR) remains almost unchanged, and the taper error of microhole is reduced by 43%. Furthermore, the process of relatively enlarging discharge gap range and increasing number of discharges after superposition is discussed, and the proper superposed oscillating amplitude is identified.

Experimental investigations on the wear behaviour of micro-EDM-fabricated textured tools during dry turning of Ti6Al4V

PurposeThis paper aims to focus on analysing the wear characteristics of tungsten carbide tools on which various micro patterns are fabricated to study its effect on the machinability of Ti-6Al-4V at dry turning conditions.Design/methodology/approachMicro-patterns such as dimples, linear grooves and a novel combination of dimples and linear grooves were fabricated on rake faces of uncoated tools by micro-EDM process. Impact of these patterns on tool wear and chip morphology characteristics under dry machining conditions were analysed, and their performances were compared with the non-textured tool (NTT).FindingsEncouraging results in terms of minimal tool wear and favourable chip morphology characteristics were observed in case of all the textured tools, which demonstrated better tribological characteristics in contrast to NTT. The average flank wear was reduced by 43.5, 32 and 24.7% in dimple textured tool (DTT), linear textured tool (LTT) and hybrid textured tool (HTT), respectively, as compared to NTT. The average chip curl diameters measured for NTT, DTT, LTT, and HTT were observed to be 6.60, 3.51, 4.0 and 4.31 mm, respectively.Originality/valueThe contribution of this work lies in fabricating innovative patterns using cost-effective micro-EDM process and analysing how the patterns, depending upon their dimensional area and wear debris accumulation characteristics, influence the machinability of Ti-6Al-4V in the absence of any lubrication mediums.

Prediction of tool wear length in micro-EDM process using an artificial neural network

Consideration of tool wear (TR) is the most significant parameter for machining in the micro-EDM process. Frequent tool wear is a major problem in the electric discharge machining process. This has a negative impact on the geometrical correctness of the workpiece's machined features. An accurate prediction can provide crucial information for a manufacturer to develop accurate strategies for machining parts. In this paper, an artificial neural network model has been developed using a backpropagation algorithm. The developed model has been used to predict the tool wear of the electrode used in the Micro-EDM process, which is one of the relevant and challenging areas which can be addressed by the application of advanced management and computation theory. Further, alternative predicting models have been developed using time series and regression techniques. A comparative study has been performed for these three methods. It was observed that the artificial neural network-based method provides better results in comparison with time series and regression-based models with the highest coefficient of determination (R2) value.

Experimental study of micro-EDM on EN24 steel with normal brass, tin coated brass, cryogenic treated brass tool by varying the machining parameters

The main aim of the present study is to determine the optimal parameters on machining the material EN24 Steel with three different brass tools by using Micro Electrical Discharge (Micro EDM). EN24 Steel is widely used in many applications because of its hardness, easy to heat treat and tempering with minimum surface scaling. This paper investigates on EN24 steel with normal brass tool, Tin coated brass tool and cryogenic treated brass tool using Micro-EDM process. The experiment was conducted based on the Taguchi technique and studied the influence of the electrodes on the geometric parameters like overcut, taper angle and circularity. The result shows that the coated tool is the most significant effect on the geometric parameters.

Micro-EDM of micro-stepped hole based on the wear of micro-bit

ABSTRACT Applying different micro-bits with different sizes to carry out step-by-step drilling is a common technique to obtain micro-stepped holes. However, the possibility of repeated misalignments in the clamping of micro-bits will affect the machining accuracy of the micro-stepped holes. Furthermore, for difficult processing materials such as die steel and cemented carbide, it is difficult to obtain ideal machining results through drilling. Under this background, micro-stepped hole was processed on die steel based on the electrical discharge machining (EDM) wear of micro-bits. Firstly, a high-speed rotating micro-bit was used to perform micro-EDM on die steel to obtain a basic micro-hole. During the micro-EDM process, the micro-bit was worn and thus its length was reduced. Secondly, the worn micro-bit shook along a defined axis to carry out micro-EDM on the die steel workpiece, thus machining micro-stepped hole on the basic micro-hole. This method avoided the clamping error of micro-bit found in other techniques and improved machining accuracy of micro-stepped hole. Through the analysis of variance (ANOVA) of processing parameters and the establishment of surface response model, the appropriate processing parameters were selected. Finally, under the action of appropriate processing parameters, micro-stepped hole was obtained by the proposed method.