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Surface integrity is one of the key elements used to judge the quality of machined surfaces, and surface roughness is one such quality parameter that determines the pass level of the machined product. In the present study, AISI D2 steel was machined with electric discharge at different process parameters using Jatropha and EDM oil. Titanium dioxide (TiO2) nanopowder was added to the dielectric to improve surface integrity. Experiments were performed using the one variable at a time (OVAT) approach for EDM oil and Jatropha oil as dielectric media. From the experimental results, it was observed that response trends of surface roughness (SR) using Jatropha oil are similar to those of commercially available EDM oil, which proves that Jatropha oil is a technically and operationally feasible dielectric and can be efficiently replaced as dielectric fluid in the EDM process. The lowest value of S.R. (i.e., 4.5 microns) for EDM and Jatropha oil was achieved at current = 9 A, Ton = 30 μs, Toff = 12 μs, and Gap voltage = 50 V. As the values of current and pulse on time increase, the S.R. also increases. Current and pulse-on-time were the most significant parameters affecting S.R. Machine learning methods like linear regression, decision trees, and random forests were used to predict the surface roughness. Random forest modeling is highly accurate, with an R2 value of 0.89 and an MSE of 1.36% among all methods. Random forest models have better predictive capabilities and may be one of the best options for modeling complex EDM processes. [ABSTRACT FROM AUTHOR]

The present study attempts to analyze the impact of abrasive water jet machining (AWJM) process parameters on surface roughness and kerf taper properties of hardened AISI 440C stainless steel. Considering process parameters such as jet-water pressure, nozzle traverse rate, and stand-off height, the experiments are planned using the central composite design (CCD) of response surface methodology (RSM). Analysis of variance (ANOVA) is applied to the experimental data to determine which process parameters significantly affecting the surface roughness (Ra) and kerf taper properties. It is observed that surface roughness and kerf taper are significantly affected by all the three mentioned process parameters. Surface roughness decreases by increasing jet-water pressure. Ra decreases with a decrease in stand-off height and nozzle traverse rate. Kerf taper decreases by increasing jet-water pressure. After that, it decreases as the nozzle traverse rate and stand-off height decrease. Both coded and uncoded responses are incorporated into the developed predictive model. The study finds that the model's predicted values agree with the observed data. The next step involves optimization, i.e., adjusting the process's variables until the surface roughness and kerf taper are minimized. Furthermore, the machined surface of the work material was carefully analyzed under the optical microscope to give preliminary insight into the surface profile and waviness. The erosion made by abrasive particles is visible. To gain further insight into the machined surface characteristics, it was further observed using microscopic at 100× magnification. The machined samples were then scanned using scanning electron microscopy (SEM) for microstructural study and analysis. [ABSTRACT FROM AUTHOR]

The design of flapping wing micro aerial vehicle (FWMAV) imposes several challenges with reference to dimensional stability for micro mechanism assembly and ability to withstand cyclic loading conditions. Earlier manufacturing methods such as injection moulding and wire cut electrical discharge (EDM) machining necessitate more human efforts, time-consuming and increase cost of preparation of mould. The 3D printing (3DP) process seems to be well suited to manufacture small and intricate parts with good accuracy and reduces the labour cost. In this article, three 3DP technologies with various polymer materials such as Polyjet (Polymethyl methacrylate), Multijet (Polypropylene–light) and Stereolithography (Polypropylene Fumarate) are exploited to fabricate micromechanical linkages of FWMAV mechanism. The structural characteristics of these 3DP materials are evaluated using Finite Element Analysis. The aerodynamic performance of 3D printed mechanism assemblies is evaluated for various angle of attack at diverse wind speed conditions using the developed test rig. Wind tunnel experimental results revealed that low elastic modulus materials produced more amount of lift and high elastic modulus materials experienced less drag. These experimental results suggested that 3DP can be utilized to manufacture small batch of micro mechanism components as an alternative to injection moulding and wire cut EDM. [ABSTRACT FROM AUTHOR]