A new cutting tool design for cryogenic machining of Ti-6Al-4V titanium alloy

Titanium alloys are extensively used in aerospace and medical industries. About 15% of modern civil aircrafts are made from titanium alloys. Ti⁻6Al⁻4V, the most used titanium alloy, is widely considered a difficult-to-machine material due to short tool life, poor surface integrity, and low productivity during machining. Cryogenic machining using liquid nitrogen (LN₂) has shown promising advantages in increasing tool life and material removal rate whilst improving surface integrity. However, to date, there is no study on cutting tool geometry and its performance relationship in cryogenic machining. This paper presents the first investigation on various cutting tool geometries for cryogenic end milling of Ti⁻6Al⁻4V alloy. The investigations revealed that a 14° rake angle and a 10° primary clearance angle are the most suitable geometries for cryogenic machining. The effect of cutting speed on tool life was also studied. The analysis indicated that 110 m/min cutting speed yields the longest tool life of 91 min whilst allowing for up to 83% increased productivity when machining Ti⁻6Al⁻4V. Overall the research shows significant impact in machining performance of Ti⁻6Al⁻4V with much higher material removal rate.