Journal Articles
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Item Experimental studies of flow patterns of different fluids in a partially filled rotating cylinder(Isfahan University of Technology, 2009) Mukunda, P.G.; Rao, S.; Kiran Aithal, A.S.; Shrikantha, S.R.An attempt has been made to investigate the various parameters affecting the fluid behaviour, partially filled in a rotating cylinder. When the cylinder is rotating at 'high' speed, a liquid forms a hollow cylinder. Different patterns are observed in the fluids for the rotatioal speeds below a critical speed. This study should give us some insight into molten metal behaviour during centrifugal casting. An extensive experimental investigation is required to obtain an appropriate functional relationship by knowing and understanding some dimensionless parameters. Here the effect of dimensionless parameters ? (which is 2 g/?2d, where g, ? and d denotes gravitational acceleration, container rotation rate and inner diameter of liquid cylinder) and G (number of times the gravity) was studied as variation of rotation speed, viscosity and aspect ratio of the mould.Item Inference of optimal speed for sound centrifugal casting of tin(Metallurgical Society of CIM, 2009) Mukunda, P.G.; Rao, S.; Rao, S.S.During centrifugal casting when a mould is rotated at low and very high speeds, defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guessing but based on experience. The defects in the casting are mainly due to the behaviour of the molten metal during the teeming and solidification process. The motion of molten metal at various speeds and its effect during casting are addressed in this paper. Tin is taken as an experiment fluid and its performance during various rotational speeds is discussed. The microstructures and hardness of all the castings are also investigated. © Canadian Institute of Mining, Metallurgy and Petroleum.Item Influence of rotational speed during centrifugal casting on sliding wear behaviour of the Al-2Si alloy(2009) Mukunda, P.G.; Rao, S.; Rao, S.S.The microstructures and dry sliding wear behaviour of an Al-2Si alloy cast centrifugally are studied. Results indicate that at optimum speed the cast has a microstructure consisting of uniformly distributed ?-Al grains and fine eutectic silicon grains. The cast exhibited better wear resistance compared to the same cast prepared at different rpms. This paper attempts to investigate the influence of the microstructural changes in the Al-2Si alloy by varying the rotational speed of the mould and its combined action on the dry sliding wear behaviour. © Higher Education Press and Springer-Verlag 2009.Item Wear and machinability study of SiCp reinforced and Al2O3p reinforced Al-Si alloy composites(Praise Worthy Prize, 2010) Sudheer Reddy, S.; Mukunda, P.G.; Suresh Hebbar, H.Keeping in mind a range of industrial applications, the performance of Al-Si alloy reinforced with ceramics as a metal matrix composites manufactured using Stir casting technique have been investigated. Aluminum-Silicon alloys of near eutectic composition (12% Silicon by weight) and Hypereutectic (17% Silicon by weight) were the matrix materials used. The two matrix materials were processed under identical conditions using two different reinforcements Silicon Carbide (SiCP) and Aluminium Oxide (Al2O3p) in particulate form with 0, 5, 7.5 & 10 Vol%. Wear and friction coefficients were determined from dry sliding wear tests of cast Particle Reinforced Metal Matrix Composites(PMMC's) at 20, 40, 60 N test loads and at 1.42 & 2.22m/s sliding velocities. Cutting forces exerted and Surface Roughness (Ra) produced during machining of cast PMMC's with Polycrystalline Diamond (PCD) and K10 cutting inserts at 75 m/min & 118 m/min cutting speed were studied. Wear of Al2O3P reinforced alloys was around 20% higher than SiCP reinforced alloys. PCD cutting insert seems appropriate in machining Al-Si alloy composites needing lesser cutting force and producing better surface finish. © 2010 Praise Worthy Prize S.r.l.- All right reserved.Item Influence of rotational speed of centrifugal casting process on appearance, microstructure, and sliding wear behaviour of Al-2Si cast alloy(Korean Institute of Metals and Materials, 2010) Mukunda, P.G.; Rao, S.; Rao, S.S.Although the manner in which the molten metal flows plays a major role in the formation of the uniform cylinder in centrifugal casting, not much information is available on this topic. The flow in the molten metal differs at various rotational speeds, which in turn affects the final casting. In this paper, the influence of the flow of molten metal of hyper eutectic Al-2Si alloys at various rotational speeds is discussed. At an optimum speed of 800 rpm, a uniform cylinder was formed. For the rotational speeds below and above these speeds, an irregular shaped casting was formed, which is mainly due to the influence of melt. Primary á-Al particles were formed in the tube periphery at low rotational speed, and their sizes and shapes were altered with changes in rotational speeds. The wear test for the inner surface of the casting showed better wear properties for the casting prepared at the optimum speed of rotation. © KIM and Springer.Item Influence of teeming temperature of molten tin in centrifugal casting(2010) Mukunda, P.G.; Shrikantha, S.R.; Rao, S.; Kiran Aithal, A.S.During centrifugal casting, when a mould is rotated at very low and very high speeds, defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behaviour of the molten metal during teeming and solidification process. The studies of melt flow in partially filled rotating cylinders have indicated many features, which were not mentioned in the literatures of centrifugal casting. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Molten tin has been taken for the experiments, and its behaviour during various rotational speeds is explained. © 2010 W. S. Maney & Son Ltd.Item Experimental study on rate of solidification of centrifugal casting(2010) Madhusudhan; Narendranath, S.; Mohan Kumar, G.C.M.; Mukunda, P.G.Centrifugal casting is a process of producing casting by causing molten metal to solidify in rotating moulds. The quality of the final casting is mainly depending upon the flow pattern of the molten metal and rate of solidification, which in term depends upon the rotational speeds of the mould. Experiments have been conducted by rotating a partially filled horizontal axis cylinder at different rotational speeds and also at different fluid temperatures. Cooling rates of the liquids were observed at different rotational speeds, which depend upon the relative movement between the inner surface of the rotating mould and the fluid. This study gives us some insight into the effect of rotational speed on solidification rate of centrifugal casting. Micro structures of centrifugally cast Al-12 Si castings are also exhibit the same behavior for different rotational speeds.Item Evolution of microstructure and hardness of AL-SI functionally graded material cast through centrifuge technique using hypereutectic and eutectic Al-SI(2011) Kiran Aithal, A.S.; Desai, V.; Narendranath; Mukunda, P.G.Functionally Graded Materials (FGMs) are a new class of inhomogeneous materials wherein the composition and the microstructure is varied to alter the material property within a component. The present study is to fabricate a Functionally Graded Al-Si in-situ material and to characterize. Al-Si alloys with 17wt%Si (hyper eutectic) and 11.7wt%Si (eutectic) have been used to fabricate Al- Si FGMsby centrifuge casting process. The microstructural characteristics and hardness profiles of these FGMs have been evaluated. The study shows the structure of Al-Si samples produced by this method show Hyper eutectic through Eutectic to Hypo eutectic structure along their depth. It also reveals that hardness of the sample and the silicon content decrease steeply along the depth of the sample.Item Experimental investigation on thermally enhanced machining of high-chrome white cast iron and to study its machinability characteristics using Taguchi method and artificial neural network(Springer-Verlag London Ltd, 2014) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.Machining of hard-to-wear materials such as high-chrome white cast iron (HCWCI) and high-manganese steels is an uphill task when conventional route followed. Alternatively, thermally enhanced machining (TEM) can be used to minimize the tooling cost very effectively. This paper presents the detailed study of TEM of HCWCI in which the effect of cutting parameters and surface temperature of the stock material on machinability characteristics (cutting forces and surface roughness) are analyzed using ANOVA and artificial neural network (ANN). The experimental work was conducted to follow Taguchi techniques. HCWCI is finding newer applications in mining; mineral processing industries were the workpiece in the machining studies using cobalt-based cubic boron nitride insert tool. Localized heat was added at the tool-work interface which softens the metal and eases the machining operation. The influences of the control factors on the process responses have been analyzed using analysis of variance (ANOVA), and the results are correlated using ANN. Linear regression was used to establish the relation between the control parameters and the process responses. The results show that TEM causes easy shearing of the material, leading to the reduction in cutting forces with expected improvement in tool life and surprisingly good surface finish. The confirmation tests suggest both second-order regression and ANN which are better predictive models for quantitative prediction of TEM of HCWCI, and ANN is more accurate of the two. Also, it was proved that oxy-LPG flame heating is an economical option compared to laser-heated machining in hard turning process. © 2014 Springer-Verlag London.Item Machinability investigations on high chrome white cast iron using multi coated hard carbide tools(Springer India sanjiv.goswami@springer.co.in, 2014) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.This study investigated the performance of multilayer hard coated carbide tool and multi-response optimization of the turning process for an optimal parametric combination to yield the minimum cutting forces and machining power with a maximum material removal rate (MRR) using Taguchi and artificial neural network (ANN) methods. In recent times, high chrome white cast iron finds increasing applications in aerospace, mining, mineral process industries. Its machinability using carbide insert (TiC/TiCN/Al2O3) cutting tool has been studied. The influences of cutting parameters on the cutting forces, MRR and machining power of the process have been analyzed using analysis of variance and the results are correlated using ANN. Linear regression method was used to establish the relation between the cutting parameters and the process responses. The confirmation test reveals that, the accuracy of prediction of ANN is better than that of the regression analysis. In view of the good performance of the carbide tools (at optimum conditions), it can replace the cosly CBN, with improved economic benefits. © 2014 Indian Institute of Metals.