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Wire arc additive manufacturing (WAAM) has emerged as an important type of metal additive manufacturing technique in recent years. The most critical challenge in WAAM is to achieve the desired surface roughness of deposited layers. The improvement of surface roughness can play an important role in improving the quality of parts made using WAAM. In this study, three machine learning (ML) algorithms, such as artificial neural network (ANN), random forest (RF) and XGboost algorithm, have been used to predict the surface roughness of deposited beads. A dataset for training and testing the ML models has been obtained using a 3D optical profilometer by measuring the surface roughness of a single-layer deposited bead of aluminium alloy. The performance of ML algorithms was evaluated using statistical metrics such as mean square error (MSE), mean absolute error (MAE) and coefficient of determination (R2). Tuning of hyperparameters helped in improving the performance of ML models. Among the three ML algorithms, the XGBoost and ANN algorithms outperformed RF in predicting the roughness of WAAM deposited parts. This novel approach can help industries in the modelling of process parameters and easy implementation of WAAM with minimal resources, just with the use of real-time data. [ABSTRACT FROM AUTHOR]

This article investigates the feasibility of producing an in-situ micro tool rod using micro-electrochemical spark machining (µ-ECSM) technology. The study included the examination of both electrical factors (such as voltage and duty factor) and non-electrical factors (such as electrolyte concentration and spindle speed) as the input parameters for the machining process. The responses measured in the study were the reduction in tool diameter and the surface roughness of the micro tool produced. The potassium hydroxide solution is used as a working fluid. The results indicate that voltage is the most crucial factor that influences micro tool fabrication. The utmost reduction in tool diameter, measuring 279.5 µm, occurred when utilizing machining parameters of 35V, 30%, 4 wt.%, and 600 rpm. Meanwhile, the lowest surface roughness for the micro tool was 3.42 µm, achieved with machining parameters of 35V, 10%, 4 wt.%, and 600 rpm. Additionally, the impact of machining settings on the micro tool electrode is covered. [ABSTRACT FROM AUTHOR]

This work demonstrates the viability of the powder-mixed micro-electrochemical discharge machining (PMECDM) process to fabricate micro-holes on C103 niobium-based alloy for high temperature applications. Three processes are involved simultaneously i.e. spark erosion, chemical etching, and abrasive grinding for removal of material while the classical electrochemical discharge machining process involves double actions i.e. spark erosion, and chemical etching. The powder-mixed electrolyte process resulted in rapid material removal along with a better surface finish as compared to the classical microelectrochemical discharge machining (MECDM). Further, the results are optimized through a multiobjective optimization approach and study of the surface topography of the hole wall surface obtained at optimized parameters. In the selected range of experimental parameters, PMECDM shows a higher material removal rate (MRR) and lower surface roughness (Ra) (MRR: 2.8 mg/min and Ra of 0.61 mm) as compared to the MECDM process (MRR: 2.01 mg/min and corresponding Ra of 1.11 µm). A detailed analysis of the results is presented in this paper. [ABSTRACT FROM AUTHOR]

Maraging steel is one of the exotic materials showing the potential for application in the field of the aerospace industry. However, machining these materials with high surface quality and material removal rate is problematic. The micro-electro chemical discharge (MECDM) process is capable of resolving this problem to some extent, however, due to the spark action, it fails to attain a high surface finish. In the current investigation, micro-hole drilling is performed on maraging steel with powder-mixed alumina (1% wt. of Al2O3) using the micro-electro chemical discharge machining (PMECDM) process. The effect of different input process factors, for example, voltage (V), duty cycle (D), the electrolyte concentration (C), are considered for investigating the machining performance, i.e., rate of material removal (MRR) and roughness of surface (SR) of the machined substrate. Further, a comparative analysis is established between micro-ECDM (MECDM) and mixed powder ECDM (PMECDM). The Box–Behnken design is used to conduct all the experiments and analysis of variance (ANOVA) is used to optimize the results. The outcomes reveal that MRR in PMECDM is enhanced by 34%, and the average surface roughness is reduced by 21% over the MECDM process. The maximum MRR was observed to be 2.44 mg/min and the hole machined by the PMECDM results in a cleaner hole wall surface than the MECDM process due to the grinding action by the powder particles. The residual stress measurement indicates that the PMECDM (−128.3 ± 3.85 MPa) has the lowest equivalent stress as compared to the parent material (−341.04 ± 10.24 MPa) and MECDM (−200.7 ± 6.02 MPa) surfaces. The applied voltage is the most significant parameter, followed by the duty factor and electrolyte concentration for enhancing the MRR and surface finish. The addition of powder improves the surface integrity of the machined surface as compared to the surfaces produced by the MECDM processes. [ABSTRACT FROM AUTHOR]

The work aims to assess the influence of tool electrode material while surface modification of Ti-alloy through the micro-electrical discharge coating (μEDC) process. Brass and tungsten micro-tool (800 μm)are chosen based on their mechanical, thermal, and electrical properties to conduct the experiments at different coating criteria such as duty cycle, voltage, and powder (tungsten disulphide) concentration. Various performance indexes i.e., micro-hardness, surface roughness, and recast surface height, are evaluated. Energy-dispersive X-ray spectroscopy (EDX) recognizes the elemental presence on the recast zone formed over Ti-alloy. A comparative analysis of the surfaces generated using both thetools is carried out for their performance measurement. The modified samples' hardness improved by twice the base material due to the formation of hard phases of tungsten and titanium, as affirmed by the EDX study. The results indicate that both the micro-tool electrodes' mechanical, electrical, and thermal properties significantly affect the process parameters for surface alteration of Ti-alloy. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to explore the possibilities of modifying the dielectric by adding alumina (Al2O3) nanopowder for improving the machining performances. The performance of newly developed nano powder-mixed electrical discharge machining (NPMEDM) process is compared with conventional EDM. Peak current, gap voltage and pulse-on time are taken as considerable process parameters to investigate material removal rate (MRR), surface roughness (SR), recast layer thickness, surface morphology, surface topography and induced residual stress. It is observed that the nanopowder-mixed dielectric medium gives better surface finish and higher metal removal rate as compared to conventional dielectric. The value of MRR increases from 32.75 to 47 mg/min and surface roughness improves from 2.245 to 1.487 μm. Thereafter, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) investigation of the machined surface reveals that presence of micro-crack, micro-hole and uneven deposition decrease substantially during NPMEDM process. Also, induced tensile residual stress on the machined surface significantly reduces in this modified process. Further, the basic mechanism of these processes are investigated by analysing pulse train discharge waveforms and reveals the better sparking stability of NPMEDM process, which results in the higher MRR and better surface quality. [ABSTRACT FROM AUTHOR]

In recent years, wire-electrical discharge machining (WEDM) has gained popularity in the industry due to its capability to generate complicated shapes in exotic materials, irrespective of their hardness. Conventional machining of Nimonic C-263 superalloy is an extremely difficult and costly process due to its high hardness and tool wear rate. The present research work investigates the influence of the WEDM process parameters on different performance measures during machining of Nimonic C-263 superalloy. A mathematical model for all four important performance measures, namely, cutting rate, surface roughness, spark gap, and wire wear ratio, was developed and the responses were used for studying the interrelationship between performance measures and process parameters. The optimal settings of operating conditions were predicted using desirability function. The effectiveness of multicut strategy was also investigated in the article. [ABSTRACT FROM AUTHOR]

The present work explores the potential applications of sustainable micro-electrical discharge coating (μ-EDC) process for surface modification of micro-components using solid lubricating powder mixed in bio-oil (Jatropha and Neem oil) as a dielectric medium. The surface modification was carried out on Ti-alloy work piece by setting the voltage and duty factor at different levels. Different characterization technique was followed to evaluate the micro-hardness, surface roughness, and coating layer thickness of the modified surfaces. The analysis of results are presented for the individual oil and powder mixed oil. For Jatropha, the maximum micro-hardness obtained is 642.43 HV 0.1 (128%, 274.02 HV 0.1 for base material), average surface roughness (R a) ranges from 0.54 μm to 1.83 μm; whereas for neem oil, the maximum obtained micro-hardness 592.90 HV 0.1 , R a range: 0.78 μm–1.64 μm. When the above oils were mixed with MoS 2 powder, the obtained results were further enhanced. The maximum micro-hardness obtained were 543.75 HV 0.1 and 712.43 HV 0.1 , and R a ranges from 0.47 μm to 1.39 μm, and 0.43 μm–1.35 μm, for Jatropha+MoS 2 and neem+MoS 2 , respectively. The transfer of tool and dielectric materials is affirmed through EDX plots. [Display omitted] • Novel environment friendly and sustainable coating method for solid lubrication in miniature components. • Conversion of bio-oils (Neem and Jatropha) to bio-dielectrics which can be used for micro-electrical discharge coating. • Among all bio-dielectrics, Neem + MoS 2 produces the best hardness (712.43 HV) and minimum roughness profiles (0.43 μm). • Replacement of conventional synthetic dielectric by proposed bio-dielectrics without disturbing the ecological balance. [ABSTRACT FROM AUTHOR]