Study on vibration reduction mechanism of variable pitch end mill and cutting performance in milling titanium alloy

The vibration reduction mechanism of variable pitch end mills was analyzed by the theory of energy balance of the frequency spectrum line. The variable pitch mill can reduce the forced vibration in the cutting process due to the uniform distribution of frequency spectrum line energy and lower peak energy of the cutting force. Aimed at the vibration phenomenon which restricted the efficiency in cutting aero material titanium alloy, high-speed cutting experiments of titanium alloy Ti6Al4V were set with variable and equal pitch mills under dry and down-milling environment. The influences of cutting speeds on cutting forces and tool vibration were analyzed at time domain and frequency domain, respectively, by which the vibration reduction mechanism of variable pitch mill was verified. Due to the misalignment of end mill no. 3, high-level cutting forces and tool vibration were caused by the unequal cutting load on each edge. It is found that severe tool vibration was produced under the cutting speed of 150 m/min because of low-frequency resonance in the cutting process.