MACHINABILITY STUDIES OF Ti - ALLOY USING NANO FLUID

Abstract

Although there have been great advances in the development of cutting tool materials which have significantly improved the machinability of a large number of metallic materials, titanium alloys are still considered as difficult to cut material. The study is aimed to investigate application of nanofluid as cutting fluid during turning of Ti-6A1-4V for improving its machinability. Nanofluids are fluids engineered by dispersing nanometer-size structure in base fluid in colloidal state. Nanometer size structure may be in the form of particles, fibers, droplets or tubes. It was pointed out by several researchers that substitution of conventional coolants by nanofluid appears promising in grinding operation because nanoparticles provide better cooling and superior lubrication between surfaces under extreme loading condition. Then why not explore nanofluid as cutting fluid during turning process. With this reasoning, CuO based nanofluid has been used in the present work to explore the possibility of improving the machinability of Ti alloy. Nanofluids have a much higher and strongly temperature dependent thermal conductivity at very low particle concentrations than conventional fluids. Also nanofluids have excellent tribological properties. Both of these properties of nanofluid are desirable for applying it as cutting fluid during the machining operations. Therefore, in order to investigate effect of nanofluid during turning operation, a setup has been developed and fabricated. It consists of four systems - machine tool system, data acquisition system, nanofluid collection and supply system, nanofluid synthesis system. Preliminary studies were carried out with 1%, 2% and 3% concentrated CuO nanofluid with and without emulsion of water miscible vegetable oil based metal cutting fluid. It was observed that very high concentration of nano particles increase the density of fluid and adversely affects the cutting force. But in contrast, surface finish improves with very high concentration of nano particle. 2% CuO nanofluid with emulsion of metal cutting fluid showed good iii results with reduction in thrust force, cutting force and surface roughness by 17%, 10% and 3% respectively. Detailed parametric study was carried out with 1.5% concentrated CuO nanofluid with emulsion of metal cutting fluid and Taguchi methodology was followed to carry out optimization of the process parameters. The results have been compared among CuO nanofluid and emulsion of metal cutting fluid condition. The analysis of the Taguchi method reveals that, in general feed rate significantly affects the surface finish, while depth of cut mainly affects the cutting force. But the entire range of optimum parameters and their contribution is not changed considerably by the use of CuO nanofluid as cutting fluid. Tool wear study was also carried out in order to investigate the influence of CuO nanofluid over the tool life. Turning of Ti-6A1-4V for 210 seconds with 1.5% CuO nanofluid in emulsion of metal cutting fluid improved the tool life by 12% compared to turning with only metal cutting fluid. Keywords: Titanium alloys, Nanofluid, Cutting fluid, Flood cooling, Turning, Optimization, Tool life.