Modified full-discretization method of bull-nosed end milling process stability analysis

The article deals with the stability analysis of bull-nosed end milling of the titanium alloy workpiece. The full-discretization method for three-degree-of-freedom system is used as a basis for stability investigation. The mathematical model of this method is proposed to be modified by adding the process damping forces occurring due to regenerative chatter. The damping forces are expressed in the equations of the tool motion through the equivalent process damping coefficient which is evaluated differently depending on the part of the bull-nosed end mill geometry. Frequency response function of the end mill and tool clamp system are estimated in COMSOL Multiphysics. The modified full-discretization method stability analysis and stability lobe diagram plotting are carried out in Matlab software. Experimental investigation of vibration during the process of bull-nosed end milling on S500L 5-axis milling center is performed. The experimental and computational results are shown to be partially divergent which may be caused by several possible inaccuracies in evaluation of the cutting force coefficients and the frequency response function.