Chatter in milling is still a main obstacle in surface finish,machining accuracy and tool life.Its prediction and avoidance are challenging subjects in the machining field.In this paper,an improved semi-discretization method is proposed to predict variable spindle speed milling with helix angle.Based on tool geometry and machining theory,the cutting region is divided into five different cases to calculate the cutting force.The influences of radial immersion rate and modulation parameters relative to variable spindle speed milling are explored.By comparison with constant spindle speed,the simulation results show that the variable spindle speed scheme can obtain a larger range of stability.In short,the helix angle and variable spindle speed play an important role in the stability of milling process.
