Surface composite fabrication through Friction Stir Processing (FSP) is evolving as a useful clean process to enhance surface properties of substrate. Better particle distribution is key to the success of surface composite fabrication which is achieved through multiple passes. Multiple passes significantly increase net energy input and undermine the essence of this clean process. This study proposes a novel approach and indices to relate the particle distribution with the FSP parameters. It also proposes methodology for predicting responses and relate the response with the input parameter. Unit stirring as derived parameter consisting of tool rotation speed in revolutions per minute (rpm), traverse speed and shoulder diameter was proposed. The particle distribution was identified to be achieved in three stages and all three stages bear close relationship with unit stirring. Three discrete stages of particle distribution were identified: degree of spreading, mixing and dispersion. Surface composite on an aerospace grade aluminum alloy AA7050 was fabricated successfully using TiB₂ as reinforcement particles. FSP was performed with varied shoulder diameter, rotational speed and traversing speed and constant tool tilt and plunge depth using single pass processing technique to understand the stages of distribution. Significant relationships between processing parameters and stages of particle distribution were identified and discussed.

In this study, a solid-state fabrication route via friction stir processing (FSP) was used to fabricate Nitinol particulate (NiTi_p)-reinforced magnesium-based composites to avoid the diffusion reaction and the formation of brittle interfacial compounds. The effect of four tool profiles on the homogeneity in the dispersion of NiTi_p particles in the magnesium matrix and microhardness was examined and analyzed. A counter-clockwise scrolled shoulder with a plain cylindrical pin and three tools with a flat shoulder having plain cylindrical pin, left-hand, and right-hand threaded pins were used and compared. The tool profiles were observed to exhibit a significant influence on the microstructure of the fabricated Mg/NiTi_p composites. A wider and more uniform distribution of NiTi_p particles along with superior bonding with magnesium matrix was achieved with a left-hand threaded cylindrical pin tool. The incorporation of NiTi_p gave rise to a significant increase in the microhardness of the fabricated composites due to a variety of strengthening mechanisms.

Parametric optimization of Electric Discharge Machining (EDM) assumes more challenge while machining newer materials for the best yield particularly used in the field of medical, marines and aerospace. In most cases, one methodology/approach does not provide satisfactory results as EDM is a very difficult process. Combination of two or more techniques has been quite successful to solve multi-objective optimization problems. This paper employs a combination of grey relational analysis (GRA) and principal component analysis (PCA) as a multi-objective optimization technique to optimize the process input parameters during EDM of Inconel 825. Experiments were designed by Taguchi’s L₃₆ orthogonal array (OA) for seven input parameters and three performance measures. The optimal combination of EDM parameters is determined using GRA. Then, PCA is adopted to find out the weighting values corresponding to various performance measures. Consideration of two different dielectric fluids, work piece material i.e. Inconel 825 and three different electrode materials is the novelty of this work. Finally, the results are validated by running confirmatory tests. A significant enhancement in performance characteristics has been obtained and reported.

Generative manufacturing is an innovative technology which is almost 30 years old. It has the ability of quickly transforming concept into physical models. The design cycle is contracted manifolds by utilising these techniques. One of a versatile generative manufacturing technique is fused deposition modelling (FDM) which is used for production of robust and economical prototypes. In the present research, effect of percentage contribution of critical process parameters on the build time requirements of the FDM process is examined for the given build volume in Fortus 250MC modeller. ABS P430 cubical and spherical primitives of constructive solid geometry, which display spatial symmetry in a given build volume, are chosen as work piece. Response surface methodology is utilised as the statistical tool for experimental design and modelling. This work is an attempt towards explicitly defining the process parameters which affect the build time and their percentage contribution. It has been established by this research that the percentage contribution of slice height outweighs the effect of air gap and orientation towards the estimation of build time. Other FDM build parameters like width and inclination of rasters as also width of contours contributes relatively less towards the build time and material volume quantities.