NOPR Collection:

Experimental and numerical evaluation of geometric variation of critical SZW in 20MnMoNi55 steel

2019-02-26T09:52:23Z

Title: Experimental and numerical evaluation of geometric variation of critical SZW in 20MnMoNi55 steel Authors: Saxena, Sanjeev; Dutta, B K Abstract: In the present investigation variation of SZWc due to thickness, relative crack size and geometry has been explored in 20MnMoNi55 material using both experimental and numerical techniques. The results showed dependency of critical SZW on thickness and its independency on relative crack size. The critical SZW determined using SE(B) fracture specimen is 17-18% lower than C(T) and A(T) specimens. The numerical critical SZW methodology predicted the experimental results well. Importance of integral average stress measure parameter while defining minimum thickness criteria is also shown in the results. Page(s): 357-365

Application of advanced algorithms for enhancement in machining performance of Inconel 718

2019-02-26T09:50:10Z

Title: Application of advanced algorithms for enhancement in machining performance of Inconel 718 Authors: Deshpande, Yogesh V; Andhare, Atul B; Padole, P M; Sahu, N K Abstract: Inconel 718 is the most promising nickel-based alloy finding wide usage in engineering applications because of its good mechanical properties. However, this alloy is difficult to machine and results in poor surface quality after machining. Optimization of parameters is essential for improving machining performance of this costly and hard to cut material. The research discusses estimation of optimum parameters using teaching-learning based optimization (TLBO) and compares them to those obtained by genetic algorithm (GA) in turning of Inconel 718. The parameters cutting speed, feed rate and depth of cut are selected as independent variables. The experiments are designed using central composite design of response surface methodology for the modelling of turning process. Surface roughness, tool flank wear and cutting temperature are selected as response parameters for minimization. The adequacy of modified models developed by response surface methodology are tested and then utilized for formulation of multi-objective optimization function. The function is solved by GA and TLBO. After comparing optimization results, the best algorithm is used for confirmation test. Convergence of TLBO algorithm is much faster as compared to GA even though there is very little difference in the optimum values of parameters. Page(s): 366-376

An experimental investigation into the role of sintering temperature on the metal removal rate of titanium powder metallurgy products through Taguchi method

2019-02-26T09:47:38Z

Title: An experimental investigation into the role of sintering temperature on the metal removal rate of titanium powder metallurgy products through Taguchi method Authors: Das, Arunangsu; Sarkar, Susenjit; Karanjai, Malobika; Sutradhar, Goutam Abstract: The present work is undertaken to investigate and characterize the machining characteristics (such as metal removal rate, etc) of uni-axially pressed titanium sintered powder metallurgy components. Powder is uni-axially pressed at designated pressure of 840 MPa to form cylindrical samples and the green compacts are sintered at 0.001 mbar for about 4 h with sintering temperature varying from 1350°C to 1450°C. Machining experiments are conducted at different parameters in a CNC operated wire-cut EDM. The metal removal rate (MRR) of the machined surface was measured critically. The influence of pulse-on time, pulse-off time and sintering temperature on the MRR of the sintered preforms has been investigated thoroughly. The maximum MRR was achieved at 10 μs of pulse-on time, 11 μs of pulse-off time and sintering temperature of 1450°C. Page(s): 377-382

Multi-performance optimization of micro-drilling using Taguchi technique based on membership function

2019-02-26T09:44:27Z

Title: Multi-performance optimization of micro-drilling using Taguchi technique based on membership function Authors: Shunmugesh, K; Panneerselvam, K Abstract: Carbon fibre reinforced polymers (CFRP) tends to be employed in the manufacture of aerospace industry, construction and costly sports cars, wherever robust and lightweight materials are needed. The present aims to evaluate and optimize the micro-drilling machining process on carbon fibre reinforced polymer composite material in terms of multiple performance characteristics of circularity and cylindricity errors. Micro-drilling tests based on Taguchi L₂₇ orthogonal array are carried out on CFRP laminates under varying cutting conditions of spindle speed, feed rate and drill diameters. The process outcomes are assessed in-terms of circularity and cylindricity errors. The influence and percentage contribution of process parameters are examined by analysis of variance (ANOVA). Taguchi methodology supported by membership function is used for the optimization of the multiple responses transformed to the output of signal-to-noise (S/N) ratio. The scope of the experimental design is to minimize circularity and cylindricity errors simultaneously. Confirmation tests are performed to verify the effectiveness of the proposed hybrid approach. Page(s): 383-390