Developments in non-conventional machining for sustainable production - a state of art review

Abstract

Fabrication and Characterization of Surrogate Fuel Particles Using the Spark Erosion Method

In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy\u27s Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile content of dispersion. This issue can be remedied through the development of higher density fuel phases or through an optimization of fuel particle size and volume loading. The latter requirement necessitates the development of fabrication methods to produce small, micron-order fuel particles. This research examines the capabilities of the spark erosion process to fabricate particles on the order of 10 μm. A custom-built spark erosion device by CT Electromechanica was used to produce stainless steel surrogate fuel particles in a deionized water dielectric. Three arc intensities were evaluated to determine the effect on particle size. Particles were filtered from the dielectric using a polycarbonate membrane filter and vacuum filtration system. Fabricated particles were characterized via field emission scanning electron microscopy (FESEM), laser light particle size analysis, energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and gas pycnometry. FESEM images reveal that the spark erosion process produces highly spherical particles on the order of 10 microns. These findings are substantiated by the results of particle size analysis. Additionally, EDS and XRD results indicate the presence of oxide phases, which suggests the dielectric reacted with the molten debris during particle formation

Development of Arrayed Structures Using Reverse EDM (R-EDM)

In recent years, reverse electric discharge machining (R-EDM) has been developed as a method for the fabrication of arrayed structures which find applications in the fabrication of fins and component assembly. In this study, the feasibility of R-EDM process in the fabrication of arrayed features of Ø 3 mm and height 2 mm on mild steel has been studied through response surface methodology (RSM) based experimentation. The influence of machining parameters i.e., peak current (Ip), pulse-on time (Ton) and flushing pressure (Fp) on some of the vital response characteristics like material removal rate (MRR), surface roughness (SR), taper, cylindricity error and micro hardness and surface morphology of the pillared structures has been investigated. Further, a hybrid optimization method i.e., principal component analysis (PCA) based grey relational analysis (GRA) technique, is utilized to obtain optimal parameter combination with an aim to improve machining conditions for fabrication of arrayed features during R-EDM process. Analysis of variance (ANOVA) results shows that Ip has significant effect followed by Ton on MRR and Ip has major contribution towards SR, taper and cylindricity error. Micro hardness has maximum value in heat affected zone (HAZ). The optimal parameter combination based on PCA based GRA is found to be Ip = 10 A, Ton = 100 µs and Fp = 0.3 kg/cm2 which was further ascertained using confirmatory tes

Investigation of process parameters for stable micro dry wire electrical discharge machining

Micro dry wire electrical discharge machining (μDWEDM) is a process where gas is used as the dielectric fluid instead of a liquid. In this process, certain modifications of wire electrical discharge machining (WEDM) are needed during the machining operation to achieve stable machining. Smooth and stable machining operation in μDWEDM process remains as a critical issue. Thus, this paper presents the investigation of process parameters for a stable μDWEDM process. The investigation was performed on a stainless steel (SS304) with a tungsten wire as the electrode using integrated multi-process machine tool, DT 110 (Mikrotools Inc., Singapore). The experimentation method used in this phase was a conventional experimental method, one-factor-at-a-time (OFAT). Types of dielectric fluid, dielectric fluid pressure, polarity, threshold, wire tension, wire feed rate, wire speed, gap voltage, and capacitance were the controlled parameters. The machined microchannels were observed using scanning electron microscope (SEM). Stable and smooth machining operation of μDWEDM was found to be with compressed air as the dielectric fluid, workpiece positive polarity, 24% threshold, 0.0809 N wire tension, 0.2 μm/s wire feed rate, and 0.6 rpm wire speed

Investigations on Machining Aspects of Inconel 718 During Wire Electro-Discharge Machining (WEDM): Experimental and Numerical Analysis

Wire electro- discharge machining (WEDM) is known as unique cutting in manufacturing industries, especially in the good tolerance with intricate shape geometry in die industry. In this study the workpiece has been chosen as Inconel 718. Inconel 718 super alloy is widely used in aerospace industries. This nickel based super alloy has excellent resistance to high temperature, mechanical and chemical degradations with toughness and work hardening characteristics materials. Due to these properties, the machinability studies of this material have been carried-out in this study. The machining of Inconel 718 using variation of wire electrode material (brass wire electrode and zinc coated brass wire) with diameter equal to 0.20mm has been carried out. The objective of this study is mainly to investigate the various WEDM process parameters and performance of wire electrodes materials on Inconel 718 with various types of cutting. The optimal process parameter setting for each of wire electrode material has been obtained for multi-objective response. The kerf width, Material Removal Rate (MRR) and surface finish, corner error, corner deviation and angular error are the responses which are function of process variables viz. pulse-on time, discharge current, wire speed, flushing pressure and taper angle. The non-linear regression analysis has been developed for relationship between the process parameter and process characteristics. The optimal parameters setting have been carried out using multi-objective nature-inspired meta-heuristic optimization algorithm such as Whale Optimization Algorithm (WOA) and Gray Wolf Optimizer (GWO). Lastly numerical model analysis has been carried out to determine MRR and residual stress using ANSYS software and MRR model validated with the experimental results. The overlapping approach has been adopted for solving the multi-spark problem and validate with the experimental results

Investigation of Dry and Near-Dry Electrical Discharge Milling Processes.

The dry and near-dry electrical discharge machining (EDM) processes are investigated in this research. Dry EDM uses gas to replace the liquid dielectric fluid in conventional EDM. Near-dry EDM applies liquid-gas mixture as the dielectric fluid. The EDM milling configuration is used to supply the dielectric fluid through a rotary tubular tool electrode. The process is capable to achieve both high material removal rate (MRR) and fine surface finish. Experimental investigation is conducted to achieve high MRR for rough machining. Effect of process parameters, including electrode material, dielectric fluid and discharge parameters are investigated. The oxygen-assisted dry EDM is proved capable to provide high MRR (39 mm3/min) and low tool wear. The mechanism of the enhanced MRR is attributed to the rapid exothermic oxidation stimulated by the oxygen environment and high discharge energy density. The dry and near-dry EDM milling is exploited for the finishing process. The effects of different dielectric fluids, electrode materials and discharge parameters are investigated. Efforts are made to realize a mirror-like surface finish (0.09 µm Ra). Key factors and observations during the ultra fine finishing EDM are discussed. Process planning is conducted to integrate the oxygen-assisted dry EDM roughing and near-dry EDM finishing processes. A model is built for the EDM finishing process to simulate the discharge crater formation on the anode workpiece. A computational fluid dynamics (CFD) package, FLUENT, is used to model the crater formation process. Realistic crater and debris geometry is simulated by the model. Experiments are conducted to validate the simulation. The model supports the experimental findings that the near-dry EDM and low discharge energy is beneficial for better surface finish.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/60725/1/tjstorm_1.pd

Investigation of mechanisms affecting tool surface during electrochemical machining

Electrochemical machining (ECM) is a very important technology in the machining of difficult-to-cut materials. Pulsed electrochemical machining (PECM) is a variant of ECM that employs a pulsed voltage at high current density. PECM improves the control of the machining process when compared with direct current ECM. The contactless nature of ECM and PECM by the anodic dissolution of the workpiece propound no tool ablation. Nevertheless, in a few studies, tool damages, namely the formation of pits and geometrical changes, have been observed. The reason for these damages was not fully and properly investigated until now, which turns out to be the objective of investigation in this work. This study considers three hypotheses to research the tool changes during PECM and ECM: Hydrogen embrittlement, cavitation erosion, and cathodic corrosion. A systematic study of monitoring possible changes at martensitic stainless steel 1.4112 tool during ECM and PECM in aqueous NaNO3 electrolyte is performed. Experimental results of this study show that hydrogen embrittlement and cavitation erosion are not the reason for causing changes on the tool. It is identified for the first time that cathodic corrosion is the possible mechanism of causing the changes on the tool in this study. The approach is investigating microstructure before and after the process, as microstructure can store information regarding phenomena happening during the process.Die elektrochemische Bearbeitung (ECM) ist eine sehr wichtige Technologie für die Bearbeitung von schwer zerspanbaren Materialien. Die gepulste elektrochemische Bearbeitung (PECM) ist eine Variante der ECM, bei der eine gepulste Spannung mit hoher Stromdichte verwendet wird. PECM verbessert die Steuerung des Bearbeitungsprozesses im Vergleich zur Gleichstrom-ECM. Die berührungslose Natur von ECM und PECM durch die anodische Auflösung des Werkstücks bedingt keinen Werkzeugabtrag. Dennoch wurden in einigen Studien Werkzeugschäden, nämlich die Bildung von Pits und geometrische Veränderungen, beobachtet. Der Grund für diese Schäden ist bisher noch nicht vollständig und angemessen untersucht worden, was sich als Ziel der Untersuchung in dieser Arbeit herausstellt. In dieser Studie werden drei Hypothesen zur Erforschung der Werkzeugveränderungen während der PECM und ECM aufgestellt, welche wie folgt lauten: Wasserstoffversprödung, Kavitationserosion und kathodische Korrosion. Es wird eine systematische Studie zur Überwachung möglicher Werkzeugveränderungen bei martensitischem rostfreiem Stahl 1.4112 während der ECM- und PECM-Bearbeitung in wässrigem NaNO3-Elektrolyten durchgeführt. Die experimentellen Ergebnisse dieser Studie zeigen, dass Wasserstoffversprödung und Kavitationserosion nicht die Ursache für Veränderungen am Werkzeug sind. In dieser Studie wird zum ersten Mal festgestellt, dass kathodische Korrosion der mögliche Mechanismus ist, der die Veränderungen am Werkzeug verursacht. Der Ansatz in dieser Studie ist die Untersuchung der Mikrostruktur hinsichtlich verschiedener Aspekte vor und nach dem Prozess, da die Mikrostruktur Informationen, über die während des Prozesses auftretenden Phänomene speichern kann

Electrical Discharge Coating a Potential Surface Engineering Technique: A State of the Art

Electrical discharge coating (EDC) process is used to deposit material on workpiece surface from sacrificial or green compact tool electrode in an electrical discharge machine. The paper presents the mechanism of EDC using green compact electrode and powder mixed dielectric methods. The tool electrode material, electrode size, process parameters, and type of dielectrics can directly affect the surface integrity of workpiece. Here, a process map of EDC as a function of process parameters, its classification, advantages, and applications for a wide range of engineering materials offers a proper template for the evaluation of coating phenomena. This study shows that EDC is an economic process as compared to other costlier techniques. Additionally, the effect of various EDM and EDC parameters on surface integrity and tribological behavior of deposited coatings is studied with their pros and cons. Finally, the current research trends of EDC and its challenges are elaborated.info:eu-repo/semantics/publishedVersio

An investigation and analysis of Process Parameters for EDM Drilling machine using Taguchi method

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Experimental investigation of EDM parameters on machining AIMg10 15%SiC composite based on Taguchi method

Mestrado em Engenharia MecânicaO objetivo do estudo é investigar os efeitos da corrente de pico, servo voltagem, pulso on-time e pulso off-time na perfuração por electroerosão da liga de Alumínio Magnésio reforçado com carbonetos de silício e determinar a sua influência num grupo de parâmetros de saída, que incluem a taxa de remoção de material, desgaste do elétrodo, sobre corte radial e conicidade. Para melhor entender o problema experimental e todas as questões que este inclui, em primeiro lugar, foi feita uma revisão da literatura que abrange todos os princípios, tecnologias e aplicações do processo de electroerosão. Os dados para esta pesquisa foram recolhidos no laboratório de tecnologias não convencionais na "Gheorghe Asachi" Universidade Técnica de Iasi. O design de experiencias foi escolhido através do metodo Taguchi, nomeadamente o array L9. O primeiro objetivo desta pesquisa é encontrar a combinação ideal dos níveis de parâmetros através do método de Taguchi. O segundo objetivo é encontrar a contribuição da cada parâmetro de entrada para cada parâmetro de saída usando o método de análise estatística Análise da Variância. Objetivo final é desenvolver um modelo matemático para prever os valores de saída experimentais, através do software GW-Basic. Os resultados mostraram que os parâmetros com uma maior influência sobre a taxa de remoção de material e desgaste dos elétrodos foram a servo voltagem e corrente de pico, com 49% e 24% em relação ao primeiro parâmetro e 84% e 10% em relação ao segundo. O sobre corte radial foi mais influenciado pela corrente de pico e pelo pulso on-time, com 29% e 35%. Relativamente a conicidade, os parâmetros com mais influência foram corrente de pico e o pulso on-time, com 47% e 33% em termos de contribuição. Além disso, os níveis de combinação ótima de parâmetros associadas com a taxa de remoção de material, desgaste dos elétrodos, sobre corte radial e conicidade foram também obtidos. As respostas em estudo podem ser previstas usando os modelos matemáticos com um erro médio de 2% para a taxa de remoção de material, 16% para o desgaste do elétrodo, de 2% para sobre corte radial e 2% para a conicidade.The purpose of this study is to investigate the effects of peak current, servo voltage, pulse on− time and pulse off − time on electrical discharge drilling of an aluminum magnesium reinforced with particles of silicone carbide and determine their influence on a range of output parameters such as material removal ratio, electrodewear,radial over cut and taper. To better understand the experimental problem and all issues that it includes, firstly, was done a literature review that covers all the electrical discharge machining principals, technologies and applications.The data for this research was collected on the “non conventional“ machining technologies laboratory at “Gheorghe Asachi” Technical University of Iasi. The design of experiments was chosen by Taguchi method, namely, orthogonal array L9.The first goal of this research is to find the optimum parameter level combination through the Taguchi method. The second goal is to find the contribution of the each parameter for each output using the statistic method Analysis of variance. Final goal was to find a mathematical model to predict the experimental output values, through a software GW-Basic. The results shows that the parameters with more influence on material removal ratio and electrode wear responses were servo voltage and peak current, with 49% and 24% regarding the first output and 84% and 10% the second. Radial over cut was more influenced by peak current and pulse on-time, with 29% and 35%, concerning the taper, the parameters with more influence were also peak current and pulse on-time but with 47% and 33% of contribution. In addition, the optimal combination levels of machining parameters associated with material removal rate, electrode wear, radial over cut and taper were also drawn. Responses in study can be predicted using the Mathematical models with a average error of 2% for material removal rate, 16% for electrode wear, 2% for radial over cut and 2% for taper