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Parametric optimization of process parameters for Electric discharge Machining of Tungsten carbide (93% WC and 7%Co)

Sharma Rajiv Kumar

Production Engineering Archives

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2020

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Vol. 26, Iss. 4

154--161

EN

Nowadays there is a huge demand of High Strength Temperature Resistance (HSTR) alloys such as titanium, carbide, nimonics and ceramics in aerospace, defence and electronics. Among these alloys machining of tungsten carbide alloy is of interest, because of its numerous applications. Complex shapes of tungsten carbide are not generally made by traditional manufacturing process. To machine tungsten carbide with high accuracy, non-traditional machining process like Laser beam machining, Electron beam machining and Electrical discharge machining are a proper choice. In the present paper, the authors have machined Tungsten carbide (93% WC and 7%Co) with copper electrode. The machining is performed on EDM MODEL 500 X 300 ENC with VELVEX EDMVEL-2 as dielectric oil. The 17 experiments are carried out based on RSM (Box-Behnken) method. Further, in order to find the optimum combination grey relational approach is used. The results showed that pulse-on-time of 40µs, pulse-off-time of 2µs and current of 8A are optimum combination for machining of Tungsten carbide (93% WC and 7%Co). Lastly, the confirmation experiment has been conducted.

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Effect of Distilled Water and Kerosene as Dielectrics on Machining Rate and Surface Morphology of Al-6061 During Electricdischarge Machining

Arshad Rubab, Mehmood Shahid, Shah Masood, Imran Muhammad, Qayyum Faisal

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 3

162--169

EN

Electric Discharge Machining (EDM) is widely used for manufacturing complex metal parts. The machining parameters like dielectric fluid, electrode material, current, voltage and pulse rate during EDM are controlled to obtain desired Material Removal Rate (MRR) and it also affects the surface morphology of manufactured components. In this research, effect of changing machining parameters, dielectric fluid (distilled water and kerosene) and electrode materials (copper and graphite) on surface morphology of Al 6061 T6 alloy during EDM is investigated. It is observed that the distilled water reacts with the molten aluminum and produces deep pits / voids on the surface due to liberation of hydrogen gas. A micro crack network is seen radiating from the edge of these pits. It is believed that the very high thermal conductivity of distilled water is responsible for the micro crack network and reduced material removal rate when compared with non-reactive kerosene oil.

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Machining parameter optimization for EDM machining of Mg–RE–Zn–Zr alloy using multi-objective Passing Vehicle Search algorithm

Parsana S., Radadia N., Sheth M., Sheth N., Savsani V., Prasad N. E., Ramprabhu T.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

799--817

EN

Mg alloys are known for their specific strength, stiffness, damping capacity, EMI shielding. Particularly, Rare earths added Mg alloys find applications in the gear box casing, transmission housing, engine mount, ribs, frames, instrument panels due to their improved corrosion resistance, pressure tightness, specific strength and creep strength. Reemergence of Mg alloys in the aircraft structural applications demands for advanced machining processes such as EDM to fabricate complex geometry parts. In this study, parametric multi-objective optimization of EDM on Mg–RE–Zn–Zr alloy is carried out using the novel meta-heuristic algorithm – Passing Vehicle Search (PVS). The input parameters considered are pulse-on (Ton), pulse-off (Toff) and peak current (A). Response surface method (RSM) is implemented through the Box–Behnken design to formulate a mathematical model for Material Removal Rate (MRR), Tool Wear Rate (TWR) and Roundness of holes. The accuracy of theoretical model has been established using the confirmation runs. Using the weighted sum method, the multi-objective PVS calculated optimal solutions for different weights to generate 2-D and surface pareto fronts. These pareto fronts were evaluated for performance determination of PVS using novel and established metrics such as spacing, spreading, hypervolume and pure diversity. The values of performance metrics indicate acceptable nature of the graphs and such analysis would facilitate better comparisons of solutions to select algorithms for optimization. Finally, decision making is illustrated with the help of level diagrams to draw up practical inferences for designing production plans and providing the best choice of machining parameters according to their preferences.

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Determination of residual stress distribution in high strength aluminum alloy after EDM

Mehmood S., Sultan A., Anjum N. A., Anwar W., Butt Z.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 1

29--35

EN

Thermal energy produced by discrete and random electric sparks in electric discharge machining (EDM) melts surface material. A portion of this molten material is removed and the remaining material resolidified by rapid cooling in a hydrocarbon oil. The effect of repeated heating and cooling of the surface and sub surface material with complex temperature gradients results in residual stresses in machined parts. The aim of this investigation is to determine the distribution of residual stresses in the depth of machined material with respect to discharge current, most important electric parameter during EDM. It is well known that surface finish is dependent on discharge current. Therefore, investigations were carried out for smaller discharge current levels i.e. 3, 6, 9, 12 ampere. Hole-drill strain gauge method is used for the determination of residual stresses in the depth of material. For comparison purposes, residual stresses are also determined for conventionally turned specimens. This study provided quantitative analysis of the residual stresses for various discharge current in EDM which is a key parameter in deciding the service life of material.