Micro-electrical Discharge Machining Research Articles

Numerical simulation and experimental validation on the mechanism of crater evolution in electrical discharge micromachining

The plasma-material interaction and evolution mechanism of a solitary crater governs the nature of the surface, either plain or textured, created through the electrical discharge micromachining (EDMM) process. Therefore, it is indispensable to understand the fundamentals of a single crater evolution, which involves melt pool hydrodynamics and material vaporization under intense plasma pressure. The plasma pressure during the workpiece heating phase alters the vaporization phenomenon and melt ejection, warranting an in-depth understanding. In light of this, the current work proposes a two-dimensional (2-D) multiphysics numerical model of the melt pool hydrodynamics during EDMM. The model incorporates thermal evolution along with the effects of active plasma pressure during the heating phase of the substrate with the help of a coupled thermo-fluidic model. The simulation results reveal the predominant role of plasma pressure on the crater morphology evolution, plasma flushing efficiency (PFE) and recast layer thickness (RLT). The predicted single crater profile is validated using single-spark experiments with reasonable agreement. Thereafter, the formation mechanism of a single crater has been extended to multi-crater creation for textured surface generation.

Micro-electrical discharge machining of nitinol alloy using coated electrode and multi-energy field

ABSTRACT Nitinol alloys are widely utilized across various fields owing to their exceptional elasticity and shape memory characteristics. Their low thermal conductivity, high strength, and high toughness pose significant challenges to conventional machining technologies. To address these challenges, several non-conventional machining processes such as electrical discharge machining have been developed. This study introduces an innovative approach that combines the use of insulated coated electrodes with multi-energy field-assisted electrical discharge machining to improve the application of electrical discharge machining in machining deep microporous. We investigated the effects of the insulated electrode and multi-energy field on surface morphology, taper accuracy, diameter cutting, and the thickness of the recast layer in detail. The findings suggest that the insulated coated electrode combined with multi-energy field-assisted electrical discharge machining achieves better taper accuracy and lower diameter cutting, resulting in a smoother surface and a more uniform, thinner recast layer compared to traditional electrical discharge machining.

Comparative Study of Ultrasonic Vibration-Assisted Die-Sinking Micro-Electrical Discharge Machining on Polycrystalline Diamond and Titanium.

Die-sinking micro-electrical discharge machining (micro-EDM) is a potential method used to fabricate intricate structures without complex electrode motion planning and compensation. However, machining efficiency and poor discharge states are still bottlenecks. This study conducted a comparative investigation into the impact of ultrasonic vibration on die-sinking micro-EDM of polycrystalline diamond (PCD) and pure titanium (TA2). By adjusting discharge parameters, this study systematically evaluated the influence of ultrasonic vibration on these two materials based on discharge waveforms, motion trajectories, effective discharge counts and groove profiles. At an open-circuit voltage of 100 V, ultrasonic vibration promotes die-sinking micro-EDM of PCD. However, when the open-circuit voltage increases to 200 V, ultrasonic vibration exhibits inhibitory effects in general. Conversely, for TA2, ultrasonic vibration shows a promoting effect at both voltages, indicating the differences of ultrasonic vibration-assisted die-sinking micro-EDM on PCD and TA2. For PCD, ultrasonic cavitation improves the discharge gap environment, accelerating the removal of discharge debris. For TA2, due to its poor thermal conductivity, ultrasonic cavitation acts to break the arc, accelerating heat transfer. These research findings provide guidance for ultrasonic vibration-assisted die-sinking micro-EDM in industrial applications.

Controlling recast layer and material removal in reverse µEDM for sustainable fabrication of microelectrode arrays

Microelectrode arrays (MEAs) are essential for researching neurons and heart tissue because they record and stimulate neuronal activity. For manufacturing MEAs on conductive materials, reverse microelectrical discharge machining, or reverse µEDM, presents a viable method. However, achieving precise MEAs requires control over recast layers generated during micromachining. This study focuses on recast layer thickness (RLT) and material removal rate (MRR) as key performance indicators for sustainable reverse µEDM fabrication of MEAs. RLT affects surface stability, while MRR influences energy consumption and cost. Optimising these responses depends on three input factors: feed rate, capacitance, and voltage. ANOVA analysis reveals that capacitance is crucial in both MRR and recast layer thickness (RLT) in reverse µEDM, contributing to 88.71% and 94.04% simultaneously. A hybrid artificial neural network-genetic algorithm for global optimisation was employed. The optimised parameters 46.5nF capacitance, 110 V voltage, and 5 µm/sec feed yielded a minimum RLT of 1.58 µm and a maximum MRR of 0.3 mm³/min. These advancements signify significant improvements in the precision and efficiency of MEAs fabrication through reverse µEDM, contributing to its sustainable implementation.

Effect of tool feed rate and tool rotation speed on the microchannel geometry of AA6063-SiC composites machined by micro ED milling

ABSTRACT Miniaturisation of products is an emerging trend in the current scenario. Conventional micromachining of metal matrix composites poses difficulties due to the heterogeneous nature of the material and the presence of hard reinforcement particles. Micro-electric discharge machining has emerged as a proficient method for the precision machining of challenging materials. In this work, micro-ED milling of AA6063–4 wt. % SiC composite was carried out using a graphite electrode. Being the primitive unit of 3D machining, microchannels were machined on the workpiece at different discharge energies, tool feed rates, and tool rotation speeds. The geometrical features of the channel such as channel width, kerf width, taper of the microchannels, and process indicators like tool wear rate and material removal rate were studied. The 6 µm/s tool feed rate, 500 rpm tool rotation speed, and 500 µJ discharge energy provided the desired results for the studied responses.

MICRO-EDM OF TI–6AL–4V USING VARIOUS TOOL MATERIALS: MULTI-RESPONSE OPTIMIZATION AND SURFACE CHARACTERIZATION

In this paper, experimental analysis was performed during micro-electrical discharge machining (micro-EDM) of titanium alloy Ti–6Al–4V (grade 5) using three types of tools viz. copper (Cu) tool, tungsten carbide (WC) tool, and synthetic graphite (Gr) grade three tool. The main process parameters were taken as (a) pulse on time ([Formula: see text]), (b) pulse off time ([Formula: see text]), (c) voltage (V), and (d) capacitance (C). The output responses were taken as the material removal rate (MRR) and tool wear rate (TWR). Taguchi method coupled with grey relational analysis (GRA) (L[Formula: see text] orthogonal array) technique was applied to optimize the input process parameters for both the responses. Scanning electron microscopy (SEM) analysis of the workpiece and tool was also performed to investigate the morphology of the machined surface and tool surface. Energy-dispersive spectroscopy (EDS) analysis was performed to investigate the elemental composition of the machined surface. The experimental finding reveals that tungsten carbide is the most suitable tool material for machining the chosen workpiece for obtaining optimal MRR and TWR. The optimum condition for the copper tool was found as 180[Formula: see text]V, 1000[Formula: see text]pf, 10[Formula: see text][Formula: see text]s ([Formula: see text]), and 10[Formula: see text][Formula: see text]s ([Formula: see text]). Meanwhile, the optimum parametric condition for tungsten carbide and graphite tools was found to be the same as 240[Formula: see text]V, 100[Formula: see text]pf, 20[Formula: see text][Formula: see text]s ([Formula: see text]), and 5[Formula: see text][Formula: see text]s ([Formula: see text]).

Optimization of Machining Parameters and Analysis of the Surface Characteristics in Micro-electrical Discharge Machining of 310 and 316 Stainless Steel

Optimization of Machining Parameters and Analysis of the Surface Characteristics in Micro-electrical Discharge Machining of 310 and 316 Stainless Steel

Optimizing micro-EDM with carbon-coated electrodes: A multi-criteria approach

The pursuit of precision machining in engineering materials has ignited an imperative to advance electrical discharge machining (EDM) techniques. This study is a deep dive into the domain of micro-electrical discharge machining ([Formula: see text]EDM) with a specific focus on the utilization of carbon-coated tool electrodes. The primary objective is to elucidate the influence of carbon-coated electrodes on vital machining parameters, including machining depth (Z coordinate), tool wear rate (TWR) and overcut (OC) in [Formula: see text]EDM operations. Moreover, the investigation extends to scrutinizing surface characteristics generated by [Formula: see text]EDM with carbon-coated tool electrodes. To enhance performance, carbon-coated tungsten carbide tool electrodes are employed for machining titanium alloy (Ti–6Al–4V) workpieces. The optimization process seeks to identify the optimal combination of process parameters using a Taguchi-DEAR-based multi-response approach. Experimental findings reveal that integrating carbon-coated electrodes significantly improves the [Formula: see text]EDM process, leading to enhanced surface performance metrics. Notably, this study identifies specific parameter settings that effectively optimize machining quality indicators. By achieving a voltage of 160[Formula: see text]V, a capacitance of 10,000[Formula: see text]pF and a tool rotation of 600[Formula: see text]RPM, the research contributes valuable insights into the intricate realm of [Formula: see text]EDM, highlighting the potential for enhanced surface performance through strategic parameter manipulation.

Research on feed-pulse collaborative control method in micro-electrical discharge machining

Research on feed-pulse collaborative control method in micro-electrical discharge machining

Editors' Choice—Improving Quality of EDMed Micro-Holes on Titanium via In Situ Electrochemical Post-processing: A Transient Simulation and Experimental Study

Electrical discharge micromachining (EDM) poses challenges to the fatigue-life performance of machined surfaces due to thermal damage, including recast layers, heat-affected zones, residual stress, micro-cracks, and pores. Existing literature proposes various ex situ post-processing techniques to mitigate these effects, albeit requiring separate facilities, leading to increased time and costs. This research involves an in situ sequential electrochemical post-processing (ECPP) technique to enhance the quality of EDMed micro-holes on titanium. The study develops an understanding of the evolution of overcutting during ECPP, conducting unique experiments that involve adjusting the initial radial interelectrode gap (utilizing in situ wire-electrical discharge grinding) and applied voltage. Additionally, an experimentally validated transient finite element method (FEM) model is developed, incorporating the passive film formation phenomenon for improved accuracy. Compared to EDM alone, the sequential EDM-ECPP approach produced micro-holes with superior surface integrity and form accuracy, completely eliminating thermal damage. Notably, surface roughness (Sa) was reduced by 80% after the ECPP. Increasing the voltage from 8 to 16 V or decreasing the gap from 60 to 20 μm rendered a larger overcut. This research’s novelty lies in using a two-phase dielectric (water-air), effectively addressing dielectric and electrolyte cross-contamination issues, rendering it suitable for commercial applications.

Post-processing of powder bed fused stainless steel: micro-machining and micro-electrical discharge machining

Post-processing of powder bed fused stainless steel: micro-machining and micro-electrical discharge machining

A review of experimental investigations to attain productive and sustainable micro-electrical discharge machining process on metals and superalloys

Purpose This study aims to understand the current production scenario emphasizing the significance of green manufacturing in achieving economic and environmental sustainability goals to fulfil future needs; to determine the viability of particular strategies and actions performed to increase the process efficiency of electrical discharge machining; and to uphold the values of sustainability in the nonconventional manufacturing sector and to identify future works in this regard. Design/methodology/approach A thorough analysis of numerous experimental studies and findings is conducted. This prominent nontraditional machining process’s potential machinability and sustainability challenges are discussed, along with the current research to alleviate them. The focus is placed on modifications to the dielectric fluid, choosing affordable substitutes and treating consumable tool electrodes. Findings Trans-esterified vegetable oils, which are biodegradable and can be used as a substitute for conventional dielectric fluids, provide pollution-free machining with enhanced surface finish and material removal rates. Modifying the dielectric fluid with specific nanomaterials could increase the machining rate and demonstrate a decrease in machining flaws such as micropores, globules and microcracks. Tool electrodes subjected to cryogenic treatment have shown reduced tool metal consumption and downtime for the setup. Practical implications The findings suggested eco-friendly machining techniques and optimized control settings that reduce energy consumption, lowering operating expenses and carbon footprints. Using eco-friendly dielectrics, including vegetable oils or biodegradable dielectric fluids, might lessen the adverse effects of the electrical discharge machine operations on the environment. Adopting sustainable practices might enhance a business’s reputation with the public, shareholders and clients because sustainability is becoming increasingly significant across various industries. Originality/value A detailed general review of green nontraditional electrical discharge machining process is provided, from high-quality indexed journals. The findings and results contemplated in this review paper can lead the research community to collectively apply it in sustainable techniques to enhance machinability and reduce environmental effects.

Process Chains for Micro-Manufacturing: Modeling and Case Studies

As the complexity of micro-products increases, the micro-manufacturing processes, tool setups, and measurement processes have to be more precise and efficient. Combining them in a multi-stage process chain can effectively improve production accuracy and performance and reduce limitations and production costs. This paper focuses on the process chains for the manufacturing of micro-products and presents the state of the art, highlighting the specific characteristics of the existing models of process chains for micro-manufacturing. Based on the critical review of these characteristics, an evolution of the process chain model for micro-manufacturing is proposed, considering machining, measurement/characterization, referencing processes, and their combination into a suitable sequence. The proposed model accounts for relevant aspects of micro-manufacturing, such as size effects and technological fingerprints at the microscale. This paper also discusses the hierarchical properties of multiple micro-manufacturing process chains and some specific techniques to address the critical issue of referencing processes. Furthermore, some relevant case studies involving micro-electrical discharge machining, micro-injection molding, additive manufacturing, and micro-milling are presented to demonstrate how the micro-manufacturing potentiality can be increased using process chains.

Salient aspects on micro-electrical discharge machining of nitinol for cardiovascular applications

Micro-electrical discharge machining (micro-EDM) is a widely used technique for producing complex geometries with high precision in metals, including nitinol (NiTi) alloys. This review provides insights into the process parameters, electrode material, and surface integrity for the micro-EDM of NiTi. The pulse duration, pulse frequency, and discharge current are critical parameters that affect the machining performance of NiTi. Copper-tungsten and tungsten carbide are commonly used electrode materials for micro-EDM of NiTi. The surface integrity of the machined surface is an essential consideration for biomedical applications. There is a pressing need for the investigation of the microstructure and phase transformation of NiTi after micro-EDM to understand the influence of machining on the material properties. This review provides valuable information for researchers and engineers to optimize the machining performance and improve the material properties of NiTi for biomedical applications.

Mechanism Analysis of Discharge Energy in the Electrostatic-Field-Induced Electrolyte Jet Micro-EDM.

The discharge energy determines the machining resolution, minimum processable feature size, and surface roughness, which makes it a hot research topic in the microelectrical discharge machining (EDM) field. In this paper, a kind of novel discharge-energy-generation method in micro-EDM is investigated. In this method, the opposite induced charges on the electrolyte jet and workpiece serve as the source of the discharge energy. The operating mechanism of this discharge energy is revealed by analyzing the equivalent discharge circuit. The unique discharge current and voltage between the electrolyte jet and the workpiece are sampled and investigated. In contrast with the pulsating energy in conventional EDM, this study shows that the direct current (DC) voltage source can automatically generate a continuously periodical pulsating discharge in the electrostatic-field-induced electrolyte jet (E-Jet) EDM process. After further analyzing the electric signals in a single discharge process, it can be found that the interelectrode voltage experienced a continuous sharp electric breakdown, a nearly unchanging process, and a fast exponential recharging process. The discharge frequency increases as the electrolyte concentration and interelectrode voltage increase but decreases as the interelectrode distance increases. The discharge energy per pulse increases with the increasing interelectrode distance and electrolyte concentration but with the decreasing interelectrode voltage. Finally, the electrostatic-field-induced discharge-energy generation and change mechanisms are revealed, which provides a feasible method for micro-EDM with continuous tiny pulsed energy only using the DC power supply.

Study on the Electrical and Geometrical Parameters of Micro Electrical Discharge Machining

Introduction: Micro-Electrical Discharge Machining (μEDM) is a technique for noncontact machining of conductive or semiconductor materials. It is mainly adapted to machining hard materials. Its principle is based on the creation of electrical discharges between the micro tool and the workpiece, which are immersed in a dielectric. Methods: Methods: It is a complementary process to mechanical or laser micromachining techniques or microelectronics (RIE, DRIE, LIGA). These methods can reach a resolution of 50 nm, but their main drawback is that they are mainly dedicated to silicon. The µEDM process depends on several physical, geometrical, and/or electrical parameters that need to be optimized in order to achieve a resolution lower than 5 µm in a reproducible way. The objective of this paper is to study the effect of the applied voltage VEE and the micro-tool diameter on the machining performances (removed volume, lateral gap, machining depth, and crater shape). Result: Result: The optimal parameters were used during drilling holes. An applied voltage of VEE = 50V was used as an optimal parameter. Conclusion: Concerning the diameter of the micro tool, we propose to use large diameter wires (Φ=250μm; Φ=125μm) during the roughing phase for machining complex structures and small diameter micro tools (Φ=80μm; Φ=40μm; Φ=20μm) during the finishing phase.

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.

Investigation on Wire Electrochemical Discharge Micro-Machining.

With the development of MEMS, the machining demand and requirements for difficult-to-machine metal micro parts are getting higher. Microelectric discharge machining is an effective method to process difficult-to-machine metals. However, the recast layer caused by high temperatures in microelectric discharge machining affects the properties of machined materials. Here, we propose the wire electrochemical discharge micro-machining (WECDMM) and develop a new electrolyte system, which removes the recast layer. In this study, the mechanism of WECDMM was elucidated. The electrolyte was optimized through a comparison experiment, and NaNO3-glycol solution was determined as the best electrolyte. The influences of key process parameters including the conductivity of the electrolyte, pulse voltage, pulse-on time and wire feed rate were analyzed on the slit width, standard deviation, the radius of fillet at the entrance of the slit and roughness. Typical microstructures were machined, which verified the machining ability of WECDMM.

Mathematical modeling for radial overcut on powder mixed micro-electrical discharge machining (μ-EDM) of TZM-molybdenum superalloy by response surface methodology

Mathematical modeling for radial overcut on powder mixed micro-electrical discharge machining (μ-EDM) of TZM-molybdenum superalloy by response surface methodology

Sensors-based discharge data acquisition and response measurement in ultrasonic assisted micro-EDM drilling

Micro-electrical discharge machining (μEDM) suffers from the problem of low material removal rate (MRR) and poor surface finish, especially when there are recurring abnormal sparks. Such sparks are mainly due to the accumulation of unflushed debris in the discharge zone resulting in a frequent arcing phenomenon. Vibration assistance to μEDM has proven contributions to the MRR and surface finish enhancement, but the intrinsic information on discharge pulse modification due to the vibration is unclear. The present work proposes a pulse categorization strategy to understand the nature of discharge pulses during the conventional and ultrasonic vibration assisted μEDM. The discharge pulses were acquired at a sufficiently high sampling rate using NI LABVIEW-based data acquisition through an in-house developed pulse discrimination system (PDS). The developed PDS is simultaneously used to estimate the real-time discharge energies of individual pulses and their histograms with the machining progress. The acquired information from the developed PDS is used to justify the variations in discharge energy, discharge frequency, surface roughness and accuracy with increasing machining depth. Vibration assistance to the μEDM process was found beneficial, with an 18% increase in the discharge energy, and a 7.14% reduction in the percentage error in depth. The surface roughness at high-energy settings reduces from 3.2 μm to 0.45 μm because of ultrasonic vibration assistance.