Mechanics and dynamics study of helical milling process for nickel-based superalloy

Helical milling is a new high-quality hole-making process which offers many advantages such as better chip transportation and lower cutting forces and cutting temperature than conventional drilling. This paper presents the mechanics and dynamics of helical milling process for nickel-based superalloy. Firstly, according to the kinematics and undeformed chip geometry of helical milling, a cutting force model which considers the variation of the axial depth of cut, the rounded corner effect, and the helix angle of the cutter is established. Next, on the basis of proposed cutting force model, the dynamic cutting forces of helical milling are calculated, and the stability of the operation is simulated with full-discretization method. Finally the cutting force and chatter stability models are validated by verification tests on a nickel-based superalloy GH4169 workpiece. The results show that the simulated cutting forces and chatter stability lobes agree with the measured data well and it is feasible to replace the conventional drilling with helical milling when machining the nickel-based superalloy.