Tool life and cutting forces on semi-finish milling of titanium alloy

Abstract

Titanium alloys present excellent strength-to-weight ratio, high corrosion resistance and good hot mechanical properties, and so are key materials for aerospace applications. On the other hand, they present poor machinability because of their high chemical affinity to tool materials, low thermal conductivity, ability to keep good mechanical properties at high temperatures, and low Young's modulus. This last characteristic generates variation of chip thickness, which means high vibration levels, especially in machining processes involving interrupted cutting, like milling. This work aims to study how tool life and cutting forces are influenced by the tool entering angle and the tool-workpiece contact angle when semi-finish face milling Ti-6Al-4V alloy. Results show that using low entering angle extends tool life due to both, low radial load and very low frequencies associated to radial force. On the other hand, using low radial immersion angle impairs tool life, as tool insert enters the workpiece on adverse conditions.