Comparative investigations into high speed machining of A-B titanium alloy (Ti-6al-4v) under dry and compressed Co_2 gas cooling environment

摘要

Productivity is adversely affected by frequent tool failure/wear in the turning of titanium and its alloys, because temperature exponently rises during machining in cutting zone. Conventional cutting fluids are not that much effective in maintaining/controlling the machining heat generated in the tool-workpiece interface. In the present work, comparative investigations into turning of Ti-6Al-4V alloy under compressed CO_2 gas snow cooling impinged on the rake surface of the cutting tool insert is undertaken. The influence of compressed CO_2 gas cooling on the process forces, surface integrity (microhardness beneath the machined surface and surface roughness) have been investigated and compared with dry machining. Under compressed CO_2 gas snow cooling machining, surface roughness was found to reduce by 1.10-28.10 %. However the cutting forces, radial forces and feed forces have been increased by 2.59 - 10.19 %; 1.69 - 22.92 % and 89.80 - 955.29 % respectively. Investigations on microhardness revealed harder subsurface upto 200 μm in all the cases. However, beyond 200 μm and upto 450 μm from the subsurface was found to be softened. In addition to experimentation response surface model for cutting force, surface roughness and microhardness variation have also been developed. The model predictions had found to agree with the experimental results.