Search

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]

Process planning of sheet metal part is an important activity in the design of compound die. Traditional methods of carrying out this task are manual, tedious, time-consuming, error-prone and experience-based. This paper describes the research work involved in the development of an expert system for process planning of sheet metal parts produced on compound die. The proposed system is organized in six modules. For development of system modules, domain knowledge acquired from various sources of knowledge acquisition is refined and then framed in form of 'IF-Then' variety of production rules. System modules are coded in AutoLISP language and user interface is created using visual basic (VB). The system is capable to automate various activities of process planning including blank modeling, blank nesting, determining punch force required, selection of clearance between punch and die, identifying sheet metal operations, and determining proper sequence of operations for manufacturing the part. The proposed system can be implemented on a PC having VB and AutoCAD software, therefore its low cost of implementation makes it affordable even for small scale sheet metal industries. [ABSTRACT FROM AUTHOR]

Purpose: Type 2 diabetes mellitus (T2DM) is a silent killer disorder which is a public health challenge all over the world. The higher morbidity and mortality rate of T2DM hobble health care systems and the economy worldwide. Insulin resistance and relatively reduced insulin secretion are the main characteristics of T2DM. The present study was aimed to design and develop a bimodal release formulation of repaglinide and metformin hydrochloride to control the changes in blood sugar level according to daily routine and to maintaining it in an appropriate range using experimental design techniques. Methods: The bilayer press-coated tablet showing time-controlled release was formulated using direct compression method by forming repaglinide immediate release layer and another of metformin hydrochloride as a time-controlled release layer. The 3 factorial design was applied for the press-coated layer of metformin hydrochloride by varying the concentration of polymers. Results: Optimized composition was found to be shown the drug release of 62.44 % of repaglinide and above 98 % of that of metformin hydrochloride with a predesigned lag time. The patient-friendly formulation was found to be beneficial which mainly decreases dosing frequency, increases the therapeutic effect of both insulin-sensitizing drugs, and releases the drugs with a predetermined time pattern. Conclusions: The work accomplished successfully developed a time-controlled, bilayer, bimodal release formulation for T2DM having immediate release of repaglinide and time-controlled release of metformin hydrochloride using press-coating technique. The formulation will increase patient compliance as compared to formulation containing individual drug available in the market. [ABSTRACT FROM AUTHOR]