Papers by Author: Jose Mathew

Abstract: By considering several applications of aluminum based particle reinforced composites especially in automobile, aerospace and electronic industries, in this work, prediction of machinability responses of A356 alloy-SiC particles (5, 10, 15 and 20 vol%) reinforced metal matrix composites is described. Composites were synthesized by vacuum hot pressing (VHP) assisted powder metallurgy (P/M) process. Effect of cutting speed (Vc), feed (f), depth of cut (d) and quantity of SiC (vol %) on machinability of composites in terms of material removal rate (MRR) and resultant cutting forces (F_R) during end milling were investigated. Milling experiments were carried in dry condition based on central composite design and KISTLER dynamometer was used to measure cutting forces. Resultant cutting force values were increased from 21 to 105 N with an increase in ‘f’ and ‘d’, but decreased with increase in ‘Vc’. Increase in machining parameters increased the MRR from 2.3 to 8.6 × 10³ mm³/min and increase in SiC reduced the MRR. Statistical modeling with cubic response equations were used to predict the results and predicted results were closely matching with experimental values.

Abstract: This work is on the preparation of microelectrodes for μ-EDM operation using μ-WEDG process. Electrodes of Ø500 μm are fabricated with various discharge energy machining conditions. Effects of gap voltage, capacitance & feed rate on the surface finish of the electrodes and overcut of the thus produced micro holes are investigated. The profile of microelectrodes is measured using surface roughness tester with 2μm stylus interfaced with SURFPAK software. The study demonstrated that for brass electrodes an arithmetic average roughness value as low as 1.7μm and an overcut of 3 µm could be achieved. The significant machining parameters are found using ANOVA. Surface of the produced microelectrodes are examined using Scanning Electron Microscope. μ-WEDG process parameters could be adjusted to achieve good surface integrity on microelectrodes. Experimental results showed that the surface roughness of microelectrodes depended primarily on feed rate of the electrode. The observations showed the clear and quantitative correlation existing between the micrometer level surface quality and process parameters. The resulting microelectrodes are found to be of exceptionally high quality and could be used for μ- EDM operation on different types of work materials.

Abstract: The present work is aimed at optimizing the parameters of micro Wire Electric Discharge Machining (µ-WEDM) process by considering the simultaneous effects of input parameters viz: gap voltage, capacitance and feed rate. Experiments were planned and conducted using DoE techniques. ANOVA was performed to find out the significance of each factor. Regression models were developed for the experimental results of surface roughness and overcut of the micro slots produced on aluminium. Then Genetic Algorithm (GA) was employed to determine the values of optimal process parameters for the desired output value of micro wire electric discharge machining characteristics.