Investigation of Machinability of Titanium Alloy (Grade 5): Experimental and Numerical Analysis

Abstract

Now a days to survive in the competitive market in the field of manufacturing sector, the industries are much more concerned about the qualitative, efficient and quantitative production as well as with a cleaner and eco-friendly manufacturing processes. In the manufacturing sector to achieve the desired shape and size of the product machining is one of the most widely used manufacturing technique. However, machining of difficultto-cut materials through conventional methods is the most challenging task. Titanium alloy falls in the category of difficult-to-machine materials due to its peculiar properties such as low thermal conductivity, high chemical reactivity, generation of high cutting temperature and cutting forces during machining due to low volume specific heat and work hardening. It is mostly used in the aerospace, biomedical, automotive, petrochemical and marine sectors due to its impressive properties like high strength to weight ratio, good corrosion resistance, high fatigue strength and sustainance at elevated cutting temperature.

In this research work, the machining of titanium alloy with different types of cutting tools at different ranges of process parameter such as cutting speed, feed and depth of cut have been carried out to provide a better understanding of the machinability criteria of the various responses such as cutting force, cutting temperature, surface roughness, flank wear of the cutting tool, material removal rate and chip reduction coefficient. Orthogonal array techniques and response surface methodology approach were included to perform the experiments. The comparisons between the quadratic model and experimental data are done and the optimum parameteric condition is obtained through various multiobjective optimization techniques. The characteristic of the different types of chip during machining such as shape, size and morphology of the serrated tooth have been analyzed. The effects of process variables on the tool wear have been analyzed. The 3D model of the cutting insert according to the SNMG120408 specification was modeled using Solidwork 2012 software. The FEM simulation of turning operations of cutting insert and workpiece according to the variation of the process variables have been carried out using DEFORM-3D software. The cutting forces, cutting temperature are predicted and validated with experimental data. The effective stress, effective strain, cutting tool interface temperature tool wear-worn geometry those are difficult to obtain through experiments have been analyzed through the FEM simulations. New type of microgroove cutting tool has been modeled and compared with non-microgroove and other different types of microgroove cutting tool. During FEM simulation of microgroove cutting insert, the effects of process parameters on the responses such as, cutting force, cutting temperature, effective stress, effective strain, tool wear rate and cutting tool interface temperature has been analyzed.

The optimal cutting conditions of various types of inserts are obtained. It is observed that, the tool wear increases by increasing the cutting speed, feed and depth of cut. Most of the chips formed are of snarled cork screw type, long tubular and long helical type. The formation of serrated chips was observed at the higher range of the process variables. With the increase in the cutting speed, free surface lamella of the chips increases, thereby the shape of the sawtooth becomes more clear and prominent. The predicted results of the quadratic model for the output responses has a close agreement with the experimental results. The results of the FEM simulation are very close to the experimental data. It is observed that during FEM simulation, the thrust force and the main cutting force are reduced with the microgroove cutting tool as compared to non-microgroove cutting tool. The cutting temperature, effective stress, tool wear rate and cutting tool interface temperature reduces. It may be due to the improvement of the cutting performance of the microgroove cutting inserts. This may be due to the reduction in the tool-chip contact area and frictional surfaces. The 45° inclined microgroove patterned cutting tool shows an overall better cutting performance as compared to other microgroove cutting tools. Modeling results are validated with available experimental results.