Faculty Publications
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Item Experimental investigations on performance characteristics in wire electro discharge machining of Ti50Ni42.4Cu7.6 shape memory alloy(2013) Narendranath, S.; Manjaiah, M.; Basavarajappa, S.; Gaitonde, V.N.This article investigates the effect of pulse on time, peak current and pulse off time on wire electro discharge machining characteristics of Ti 50Ni42.4Cu7.6 shape memory alloy. A Ti 50Ni42.4Cu7.6 alloy was prepared by conventional tungsten arc melting. The machining experiments were performed as per Box-Behnken design on computer control wire electro discharge machining machine using molybdenum wire electrode. The relationships between the process parameters (pulse on time, peak current and pulse off time) and wire electro discharge machining responses (surface roughness and material removal rate) have been established using response surface methodology-based quadratic models. The analysis of variance has been employed to test the significance of the developed second-order mathematical models. The parametric analysis-based results reveal that low peak current with prolonged pulse on duration leads to reduced surface roughness. However, combination of low peak current with low pulse on time is beneficial for achieving better material removal rate for machining of shape memory alloy. © IMechE 2013.Item Wire electric discharge machining characteristics of titanium nickel shape memory alloy(Nonferrous Metals Society of China B12 Fuxing Road Beijing 100814, 2014) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.TiNi shape memory alloys (SMAs) have been normally used as the competent elements in large part of the industries due to outstanding properties, such as super elasticity and shape memory effects. However, traditional machining of SMAs is quite complex due to these properties. Hence, the wire electric discharge machining (WEDM) characteristics of TiNi SMA was studied. The experiments were planned as per L27 orthogonal array to minimize the experiments, each experiment was performed under different conditions of pulse duration, pulse off time, servo voltage, flushing pressure and wire speed. A multi-response optimization method using Taguchi design with utility concept has been proposed for simultaneous optimization. The analysis of means (ANOM) and analysis of variance (ANOVA) on signal to noise (S/N) ratio were performed for determining the optimal parameter levels. Taguchi analysis reveals that a combination of 1 ?s pulse duration, 3.8 ?s pulse off time, 40 V servo voltage, 1.8×105 Pa flushing pressure and 8 m/min wire speed is beneficial for simultaneously maximizing the material removal rate (MRR) and minimizing the surface roughness. The optimization results of WEDM of TiNi SMA also indicate that pulse duration significantly affects the material removal rate and surface roughness. The discharged craters, micro cracks and recast layer were observed on the machined surface at large pulse duration.Item Analysis of surface roughness and hardness in titanium alloy machining with polycrystalline diamond tool under different lubricating modes(Universidade Federal de Sao Carlos, 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.The present work deals with the investigation on machining of difficult-to-machine material titanium alloy (Ti-6Al-4V) using poly crystalline diamond (PCD) tool under different coolant strategies, namely dry, flooded and MQL. Taguchi technique has been employed and the optimization results indicated that MQL lubricating mode with cutting speed of 150 m/min, feed rate of 0.15 mm/rev, nose radius of 0.6 mm and 0.25 mm depth of cut is necessary to minimize surface roughness and dry mode with cutting speed of 150 m/min, feed rate of 0.15 mm/rev, nose radius of 0.6 mm and 0.75 mm depth of cut is necessary to maximize surface hardness. The results indicate the substantial benefit of the minimum quantity of lubrication (MQL) and justify PCD inserts to be the most functionally satisfactory commercially available cutting tool material for machining titanium alloys for better surface finish and hardness.Item Selection of optimal process parameters in ball burnishing of titanium alloy(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.The current study deals with the analysis and optimization of the ball burnishing process of titanium alloy (Ti-6Al-4V). The Taguchi method was employed to determine the best combination of ball burnishing process parameters - such as burnishing speed, burnishing feed, burnishing force and number of passes - to minimize surface roughness and maximize hardness. The dry burnishing experiments were planned as per L9 orthogonal array (OA,) and signal-to-noise (S/N) ratio was applied to measure the proposed performance characteristics. Analysis of means (ANOM) and analysis of variance (ANOVA) were carried out to evaluate the optimal levels and to obtain the level of importance of the burnishing parameters, respectively. Validation tests with optimal levels of parameters were performed to illustrate the effectiveness of Taguchi optimization. The optimization results revealed that burnishing feed and burnishing force are the significant parameters for minimizing the surface roughness, whereas number of passes and burnishing force play important roles in maximizing the hardness. © 2014 Taylor & Francis Group, LLC.Item Analysis of surface roughness and hardness in ball burnishing of titanium alloy(Elsevier B.V., 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.Ball burnishing is a popular post-machining metal finishing operation. An attempt has been made in this paper to optimize the process parameters during burnishing of titanium alloy (Ti-6Al-4V). Ball burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and number of passes were considered to minimize the surface roughness and maximize the hardness. The lubricated ball burnishing experiments were planned as per L25 orthogonal array and signal to noise (S/N) ratio was applied to measure the proposed performance characteristics. The validation tests with the optimal levels of parameters were performed to illustrate the effectiveness of Taguchi optimization. The optimization results revealed that burnishing feed and burnishing speed are the significant parameters for minimizing the surface roughness, whereas burnishing force and number of passes play important roles in maximizing the hardness. The optimization results showed greater improvements in surface finish (77%) and hardness (17%) when compared to pre-machined surfaces. © 2014 Elsevier Ltd. All rights reserved.Item Effect of electrode material in wire electro discharge machining characteristics of Ti50Ni50-xCux shape memory alloy(Elsevier Inc. usjcs@elsevier.com, 2015) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.Abstract TiNiCu alloy belongs to new class of shape memory alloy (SMA), which exhibits superior properties like shape memory effect, super elasticity and reversible martensitic transformation phase and thus find broad applications in actuators, micro tools and stents in biomedical components. Even though, SMA demonstrates outstanding property profile, traditional machining of SMAs is fairly complex and hence non-traditional machining like wire electric discharge machining (WEDM) has been performed. Hence, there is a need to investigate the WEDM performance characteristics of shape memory alloys due to excellent property profile and potential applications. In the present investigation, various machining characteristics like material removal rate (MRR), surface roughness, surface topography and metallographic changes have been studied and the influence of wire material on TiNiCu alloy machining characteristics has also been evaluated through ANOVA. Ti50Ni50-xCux=10, 20 was prepared by vacuum arc melting process. The proposed alloy as-cast material exhibits austenite property (B2 phase) and having higher hardness when compared to TiNi alloy. The investigation on WEDM of Ti50Ni50-xCux alloy reveals that the machining parameters such as servo voltage, pulse on time and pulse off time are the most significant parameters affecting MRR as well as surface roughness using both brass and zinc coated brass wires. However, machining with zinc coated brass wire yields reduced surface roughness and better MRR and also produces less surface defects on the machined surface of Ti50Ni50-xCux alloys. © 2015 Elsevier Inc. All rights reserved.Item Influence of process parameters on material removal rate and surface roughness in WED-machining of Ti50Ni40Cu10 shape memory alloy(Inderscience Publishers, 2016) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.Among the shape memory alloys (SMAs), TiNi SMAs have been typically used as the functional elements in the larger part of the industries due to exceptional properties like super elasticity and shape memory effect. However, traditional machining of these alloys is fairly complex due to these properties. The non-traditional machining process like electric discharge machining (EDM) exhibits outstanding capability in machining of these alloys. The poor selection of machining parameters may cause increased roughness of workpiece and lesser material removal rate. Hence, an effort has been made in the present work to explore the effects of three process parameters, such as pulse on time, pulse off time and servo voltage in wire electric discharge machining (WEDM) of Ti50Ni40Cu10 shape memory alloy (SMA) using zinc coated brass wire electrode on material removal rate and surface roughness using response surface methodology (RSM)-based mathematical models. The experiments were planned as per central composite design (CCD). The investigations revealed that pulse on time and servo voltage have predominant effects in maximising material removal rate and minimising surface roughness. The best combination of the process parameters for multi-response optimisation was obtained through desirability function. ©2016 Inderscience Enterprises Ltd.Item Evaluation of wire electro discharge machining characteristics of Ti50Ni50-xCux shape memory alloys(Cambridge University Press, 2016) Manjaiah, M.; Laubscher, R.F.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.The machining of shape memory alloys (SMAs) is fairly essential and integral part in the manufacture of components for utilizing in engineering applications. An effort has been made in the present work to study the effect of wire electro discharge machining process parameters such as pulse on time (T on), pulse off time (T off) and servo voltage (SV) have been analyzed on material removal rate and surface roughness. The investigation clearly reveals that an increased pulse on time with decrease in pulse off time as well as SV increases the amount of material removed in machining of SMAs. On the other hand, the surface roughness increases with increased pulse on time and decreases with increased pulse off time as well as SV. The surface topography of the machined surface was analyzed using scanning electron microscope (SEM) and confocal micrographs. Phase changes on the machined surface with respect to pulse on time and SV were evaluated from X-ray diffractometer (XRD) analysis. © Materials Research Society 2016.Item Wear resistance enhancement of titanium alloy (Ti-6Al-4V) by ball burnishing process(Elsevier Editora Ltda, 2017) Revankar, G.D.; Shetty, R.; Rao, S.; Gaitonde, V.N.The objective of the research was to improve the wear resistance of titanium alloys by ball burnishing process. Burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and number of pass were considered to minimize the specific wear rate and coefficient of friction. Taguchi optimization results revealed that burnishing force and number of pass were the significant parameters for minimizing the specific wear rate, whereas the burnishing feed and speed play important roles in minimizing the coefficient of friction. After burnishing surface microhardness increased from 340 to 405 Hv, surface roughness decreased from 0.45 to 0.12 ?m and compressive residual stress were generated immediately below the burnished surface. The optimization results showed that specific wear rate decreased by 52%, whereas coefficient of friction was reduced by 64% as compared to the turned surface. The results confirm that, an improvement in the wear resistance of Ti-6Al-4V alloy has been achieved by the process of ball burnishing. © 2016 Brazilian Metallurgical, Materials and Mining Association.Item Influence of materials and machining parameters on drilling performance of syntactic foams(ASTM International, 2018) Ashrith, H.S.; Doddamani, M.; Gaitonde, V.N.; Gupta, N.The effects of drilling parameters and material properties are investigated on epoxy matrix syntactic foams reinforced with 20, 40, and 60 volume percent glass microballoon. The influences of cutting speed, feed, drill diameter, and filler content on drilling performance are studied based on the full factorial design of experiments using tungsten carbide twist drills. Based on experimental results, machinability aspects within the range of the chosen input parameters are predicted using response surface methodology-based models, which can guide industrial practitioners for choosing the appropriate process parameters. Microscopy is conducted on the drilled specimens to understand crack initiation and propagation mechanisms. The thrust force and specific cutting coefficient of syntactic foam are 40 % lower as compared to those of neat epoxy. The surface roughness of syntactic foams is higher than that of neat epoxy. The micrographs of drill bits show negligible tool wear. These results show the possibility of using syntactic foams in industrial applications in which the drilling of material is required for reasons such as joining using bolts. © © 2018 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959