Influence of Coolant Flow Rate on Tool Life and Wear Development in Cryogenic and Wet Milling of Ti-6Al-4V

The use of cryogenic coolants has emerged as a way to improve productivity in machining Ti-alloys. In this study, liquid carbon dioxide is used as coolant in face milling of Ti-6Al-4 V with PVD coated inserts. The influence of coolant flow rate on tool life is studied by means of controlled experiments. Tool life is shown to improve with higher flow rates of coolant, the effect being stronger in cryogenic compared to wet milling due to the fact that the cryogenic coolant delays the wear development. The tool life is determined by notch wear irrespective of coolant nature in titanium milling. Different analyses were used to understand the mechanism behind the delay of notch wear development when using carbon dioxide coolant.