The objective of the present experimental study is to find competency of magnetorheological fluid finishing process in improving the finishing and dimensional accuracy of miniature holes drilled by the electro-discharge drilling process. For this, holes of 2.0 mm diameter, drilled in aluminium 6063 alloy-based metal matrix composite, is finished using indigenously developed magnetorheological fluid finishing setup. The input parameters of the process, viz. supply current, MR fluid flow rate, finishing time and pole geometry, are optimized for machining characteristics, viz. average surface roughness height (R a , µm) and Taper (TAP, degree). Experiments are carried out which are based on the Taguchi experimental design L 16 orthogonal array. Grey relational analysis (GRA) is further carried out to obtain the combination of the input machining parameters for optimizing both the response characteristics simultaneously. From GRA, it is found that higher values of supply current, fluid flow rate and finishing time with flat pole geometry have generated optimal machining performance characteristics and the most influential controllable factor is the finishing time. Microscopic analysis is performed using field emission scanning electron microscope and atomic force microscope on the surfaces of holes before and after MR fluid finishing operation. The results have shown that the developed MR fluid-based finishing process significantly enhances the characteristics of holes. The surface roughness from a region of unfinished hole is found to be 5.4 µm, whereas it is in nm range for the finished surface.

Magnetorheological (MR) fluid finishing process is an application of MR technology in which controllability of the MR fluid is used advantageously to finish the workpiece surface. MR finishing fluid changes its stiffness in accordance with the applied magnetic field and hence it behaves like a flexible finishing tool. A relative motion between this tool and workpiece removes the material from the machining surface. The quality of the final finished surface depends on the constituents of the finishing fluid and the applied magnetic field strength as these parameters affect the rheological properties of the fluid. A study on the rheological properties of the fluid at high shear rates is carried out through Taguchi Design of Experiments to characterize its flow behaviour to be used in continuous flow finishing process. Constitutive modeling of the fluid sample is done using Bingham Plastic, Casson Fluid and Herschel Bulkley fluid models to characterize their rheological behavior. The Hershel-Bulkley model is found to be the best suited model for the finishing fluid. Analysis of Variance has revealed that volume percentage of iron particles is the most significant parameter with a contribution of 91.68% on the yield stress and viscosity on the finishing fluid. The highest yield stress of the fluid is observed between magnetic flux density ranges from 0.3 to 0.5 Tesla. An optimised combination is then synthesized to confirm the theoretical results. The effect of temperature is also studied on the optimised fluid which has shown that temperature shares an inverse relation with the yield stress of the finishing fluid.

In the present work, a newly developed gas injection bottom pouring vacuum stir casting technique has been envisaged for the fabrication of Aluminium MMCs which is a fully automated and one of its kind. Aluminium 6063-T6 alloy is used as the matrix, and the aluminium oxide (Al2O3) particles are taken as reinforcement. Different experiments have been performed on the fabricated MMCs to ascertain its mechanical and morphological properties. The presence of various elements and grain morphology of the fabricated MMCs are confirmed by Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscope (SEM) and mapping. The experimental results revealed that the hardness of Al/Al2O3MMC had increased by 1.71 times and maximum tensile strength had increased by 1.27 times in comparison to the monolithic aluminium alloy. The results establish that the proposed methodology of MMC fabrication can be effectively utilized for fabrication of homogeneously reinforced MMCs for various engineering and industrial applications.

Purpose The purpose of the study is to fabricate a joint between two aluminium metal matrix composites using microwave hybrid heating (MHH). Design/methodology/approach Taguchi design of experiments was applied to conduct the experimental study. The mechanical properties such as ultimate tensile strength, micro-hardness and porosity were studied. Grey Relational Analysis was applied to understand the significance of fabrication parameters of best performing sample. The dominant factor of fabrication was analysed using ANOVA. The best performance sample was further characterised using X-ray diffraction and field emission scanning electron microscopy. Energy dispersive X-ray was used to analyse the elemental composition of the sample. Findings The Aluminium Metal Matrix Composite (AMMC) joint was successfully fabricated using MHH. The mechanical properties were mainly influenced by the fabrication factor of exposure time. Originality/value The formation of AMMC joint using MHH might explore the way for the industries in the field of joining.

No abstract