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Open accessJournal ArticleDOI: 10.3390/MET11030419

Experimental analysis and optimization of EDM parameters on HcHcr steel in context with different electrodes and dielectric fluids using hybrid Taguchi-based PCA-Utility and CRITIC-Utility approaches

04 Mar 2021-Vol. 11, Iss: 3, pp 1-22
Abstract: Industries demand stringent requirements towards economical machining without hindering the surface quality while cutting high carbon high chromium (HcHcr) steel. Electrical discharge machining (EDM) of HcHcr steel aims at reducing machining cost (i.e., maximize material removal rate (MRR) and minimize tool wear rate (TWR)) with good surface quality (i.e., minimize surface roughness (SR)). A comparative study was carried out on EDM of HcHcr D2 steel (DIN EN ISO 4957) by applying Taguchi L18 experimental design considering different electrode materials (copper, graphite, and brass), dielectric fluids (distilled water and kerosene), peak current, and pulse-on-time. The process performances were analyzed with respect to material removal rate, surface roughness, and tool wear rate. Pareto analysis of variance was employed to estimate the significance of the process variables and their optimal levels for achieving lower SR and TWR and higher MRR. Hybrid Taguchi-CRITIC-Utility and Taguchi-PCA-Utility methods were implemented to determine the optimal EDM parameters. Higher MRR of 0.0632 g/min and lower SR of 1.68 µm and TWR of 0.012 g/min was attained by graphite electrode in presence of distilled water as dielectric fluid compared to the brass and copper. Additionally, a metallographic analysis was carried out to study the surface integrity on the machined surfaces. Micrographic analysis of the optimal conditions showed lower surface roughness and fewer imperfections (lesser impression, waviness surface, and micro-cracks) compared to worst conditions.

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Topics: Surface integrity (55%), Electrical discharge machining (55%), Surface roughness (54%) ... read more
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19 results found


Open accessJournal ArticleDOI: 10.1016/J.JMRT.2021.09.038
Rakesh Chaudhari, Sakshum Khanna, Jay J. Vora, Vivek Patel  +4 moreInstitutions (3)
Abstract: Excellent characteristics of multi-walled carbon nanotubes (MWCNTs), such as higher toughness and stiffness, enlarged strength, and high thermal conductivity, make them an attractive choice to improve surface characteristics and machining performance. In the current study, MWCNTs mixed with dielectric fluid in the wire electrical discharge machining (WEDM) process was used to enhance the machining performance of Nitinol shape memory alloy (SMA). Significance of WEDM machining variables such as current, pulse-on time (Ton), pulse-off time (Toff), and variation in powder concentration of MWCNTs are studied on material removal rate (MRR) and surface roughness (SR). The addition of MWCNTs substantially improves the machining performance by increasing MRR and simultaneously reducing the SR. Improvement in the MRR of 75.42% and SR of 19.15% is achieved with the use of MWCNTs at 1 g/L in comparison to the conventional WEDM process. An advanced parameterless TLBO algorithm is used for simultaneous optimization of multiple responses. An advanced parameterless TLBO algorithm is used to find the optimal solution of multiple responses. Single objective optimization result has yielded maximum MRR of 0.5262 g/min at a current of 5 A, Ton 110 μs, Toff 1 μs and MWCNTs amount of 1 g/L while minimum SR of 1.27 μm at a current of 1 A, Ton 1 μs, Toff 24 μs and MWCNTs amount of 1 g/L. MOTLBO algorithm is used for simultaneous optimization of MRR and SR. Lastly, the surface integrity of machined surfaces using a field emission scanning electron microscope (FESEM) is also studied to evaluate the effect of MWCNTs on recast layer thickness (RLT) and other surface defects. The incorporation of MWCNTs has shown a substantial reduction in RLT and other surface defects such as reduction in globules of debris, melted material deposition, micro-crack-free, and micro-pores-free surfaces.

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2 Citations


Open accessJournal ArticleDOI: 10.1016/J.JMRT.2021.07.144
Abstract: In the current study, near net-shaped selective laser melting (SLM) technology was employed to build nickel-based superalloy Inconel 625 (IN625) parts with good quality. Taguchi method was employed to formulate a systematical study, analyze, and optimize the influencing factors, i.e., laser power (LP), scan speed (SS) and hatch distance (HD) on the resulting micro-hardness (MH) and surface roughness (SR) of the build samples. Scanning electron microscope (SEM) and X-ray diffraction analysis were carried out to characterize the powder morphology (spherical shaped particle possessing the size of 35 ± 6 I¼m) and the surface of the build samples. Laser power was the most contributing factor on the analyzed parameters (MH and SR), followed by the scanning speed and hatch distance. Taguchi determined optimal condition (MH: LP = 270 W, SS = 800 mm/s, HD = 0.08 mm; SR: LP = 270 W, SS = 800 mm/s, HD = 0.08 mm) which resulted in higher microhardness of 416 HV and lower surface roughness of 2.82 I¼m. Higher MH was attributed to the minimal porosity, while the uniform smooth surface of the build samples resulted in low SR as evident from the SEM images and surface texture analysis. Super ranking concept (SRC) was used to optimize the MH and SR simultaneously, by determining a single optimal condition (LP = 300 W, SS = 600 mm/s, HD = 0.10 mm). The obtained optimal condition resulted in a MH of 382 HV, and a SR of 3.92 I¼m. The results of optimal conditions are validated subjected to SEM morphologies. © 2021 The Authors

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Topics: Surface roughness (51%), Taguchi methods (50%)

2 Citations


Open accessJournal ArticleDOI: 10.3390/MET11071105
11 Jul 2021-
Abstract: In this work, wire electrical discharge machining (WEDM) of aluminum (LM25) reinforced with fly ash and boron carbide (B4C) hybrid composites was performed to investigate the influence of reinforcement wt% and machining parameters on the performance characteristics. The hybrid composite specimens were fabricated through the stir casting process by varying the wt% of reinforcements from 3 to 9. In the machinability studies, the WEDM process control parameters such as gap voltage, pulse-on time, pulse-off time, and wire feed were varied to analyze their effects on machining performance including volume removal rate and surface roughness. The WEDM experiments were planned and conducted through the L27 orthogonal array approach of the Taguchi methodology, and the corresponding volume removal rate and surface roughness were measured. In addition, the multi-parametric ANOVA was performed to examine the statistical significance of the process control parameters on the volume removal rate and surface roughness. Furthermore, the spatial distribution of the parameter values for both the responses were statistically analyzed to confirm the selection of the range of the process control parameters. Finally, the quadratic multiple linear regression models (MLRMs) were formulated based on the correlation between the process control parameters and output responses. The Grass–Hooper Optimization (GHO) algorithm was proposed in this work to identify the optimal process control parameters through the MLRMs, in light of simultaneously maximizing the volume removal rate and minimizing the surface roughness. The effectiveness of the proposed GHO algorithm was tested against the results of the particle swarm optimization and moth-flame optimization algorithms. From the results, it was identified that the GHO algorithm outperformed the others in terms of maximizing volume removal rate and minimizing the surface roughness values. Furthermore, the confirmation experiment was also carried out to validate the optimal combination of process control parameters obtained through the GHO algorithm.

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Topics: Surface roughness (53%), Process control (52%), Machining (51%) ... read more

1 Citations


Open accessJournal ArticleDOI: 10.3390/MI12060711
Qi Jing1, Yongbin Zhang2, Lingbao Kong1, Min Xu1  +1 moreInstitutions (2)
17 Jun 2021-Micromachines
Abstract: In micro-electrical discharge machining (micro-EDM) milling, the cross-section of the microgroove machine is frequently not an ideal rectangle. For instance, there are arc shapes on the bottom and corners, and the sidewall is not steep. The theoretical explanation for this phenomenon is still lacking. In addition to the tip discharge effect, the essential reason is that there is an accumulative difference in time and space during the shape change process of a tool electrode and the microstructure formation on a workpiece. The process parameters are critical influencing factors that determine this accumulative difference. Therefore, the accumulative difference mechanism in time and space is investigated in this paper, and then a theoretical model is developed to simulate the micro-EDM milling process with a straight-line single path. The simulation results for a cylindrical electrode at the two rotational speeds of 0 (nonrotating) and 300 rpm are compared, while the results for a cylindrical electrode and a square electrode at a rotation speed of 0 are also compared to verify that different process parameters generate accumulative differences in the time and space of material removal. Finally, micro-EDM milling experiments are carried out to verify the simulation model. The maximum mean relative deviation between the microgroove profiles of simulation results and those of experiments is 11.09%, and the profile shapes of simulations and experiments have a good consistency. A comparative experiment between a cylindrical electrode and a hollow electrode is also performed, which further verifies the mechanism revealed in the study. Furthermore, the cross-section profile of a microgroove can be effectively controlled by adjusting the process parameters when utilising these accumulative differences through fabricating a microgroove with a V-shaped cross-section by a square electrode and a microgroove with a semi-circular cross-section by a cylindrical electrode. This research provides theoretical guidance for solving the problems of the machining accuracy of detail features in micro-EDM milling, for instance, to machine a microgroove with an ideal rectangular cross-section.

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Topics: Machining (55%)

1 Citations


Journal ArticleDOI: 10.1016/J.HYDROMET.2021.105732
01 Nov 2021-Hydrometallurgy
Abstract: This paper describes an efficient process of recovering valuable metals from a copper anode slime sample using green chemicals such as choline chloride (ChCl) based deep eutectic solvents (DESs). The leaching agents include ChCl-urea, ChCl-ethylene glycol, ChCl-urea-ethylene glycol and ChCl/urea-deionized water in a 1:2, 1:2, 1:0.5:1.5, and 1:1 ratio, respectively. Prior to leaching experiments, chemical and mineralogical characterization of copper anode slime was performed. Considerable amount of precious metals was detected in the copper anode slime by chemical analysis. The main phases of copper anode slime detected by XRD and SEM/EDX analysis were namely Cu2O, SnO2, and, PbSO4. After leaching experiments, 97% of copper was recovered from the copper anode slime using ChCl-urea under an optimum condition at 95 °C of reaction temperature, 4 h reaction duration and, 1/25 g/mL solid/liquid ratio. The results showed that 91% of silver was extracted from the anode slime under the optimum condition with ChCl-urea DES composition, 95 °C reaction temperature, 48 h reaction duration, and 1/10 solid/liquid ratio. Gold was not leachable in the experiment using ChCl based DES with hydrogen bonding reagents such as urea and ethylene glycol. Moreover, the results revealed that PbSO4 was very soluble in DES prepared by ChCl and urea.

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Topics: Leaching (metallurgy) (55%), Anode (54%), Copper (53%) ... read more

1 Citations


References
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65 results found


Open accessJournal ArticleDOI: 10.1080/14786440109462720
Karl Pearson F.R.S.1Institutions (1)
Abstract: (1901). LIII. On lines and planes of closest fit to systems of points in space. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 2, No. 11, pp. 559-572.

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8,942 Citations



Journal ArticleDOI: 10.1016/0305-0548(94)00059-H
Abstract: The association of weights in multiple criteria problems is a critical stage of the whole decision making process. In some decision situations the extraction of subjective preferences is either difficult or undesirable. This paper proposes a method for the determination of objective weights which is based on the quantification of two fundamental notions of MCDM: the contrast intensity and the conflicting character of the evaluation criteria. The latter notion is of great importance in interfirm comparisons because the financial indices used are often highly correlated. The method developed is applied to a sample of industrial firms. The results are compared to those obtained by other sets of objective weights and show this method ensures a better compromise of the criteria examined.

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687 Citations


Journal ArticleDOI: 10.1016/J.IJMACHTOOLS.2006.08.026
Abstract: Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporising. The electrode and the work piece must have electrical conductivity in order to generate the spark. There are various types of products which can be produced using EDM such as dies and moulds. Parts of aerospace, automotive industry and surgical components can be finished by EDM. This paper reviews the research trends in EDM on ultrasonic vibration, dry EDM machining, EDM with powder additives, EDM in water and modeling technique in predicting EDM performances.

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668 Citations


Journal ArticleDOI: 10.1016/J.IJMACHTOOLS.2007.10.017
Avanish Kumar Dubey1, Vinod Yadava1Institutions (1)
Abstract: Laser beam machining (LBM) is one of the most widely used thermal energy based non-contact type advance machining process which can be applied for almost whole range of materials. Laser beam is focussed for melting and vaporizing the unwanted material from the parent material. It is suitable for geometrically complex profile cutting and making miniature holes in sheetmetal. Among various type of lasers used for machining in industries, CO2 and Nd:YAG lasers are most established. In recent years, researchers have explored a number of ways to improve the LBM process performance by analysing the different factors that affect the quality characteristics. The experimental and theoretical studies show that process performance can be improved considerably by proper selection of laser parameters, material parameters and operating parameters. This paper reviews the research work carried out so far in the area of LBM of different materials and shapes. It reports about the experimental and theoretical studies of LBM to improve the process performance. Several modelling and optimization techniques for the determination of optimum laser beam cutting condition have been critically examined. The last part of this paper discusses the LBM developments and outlines the trend for future research.

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Topics: Laser beam machining (67%), Laser cutting (60%), Machining (58%)

638 Citations