Authors : Babak Fadaei and Hossein Pourbashash
Abstract: This study describes a theoretical model for prediction of chatter vibration in ball end milling of flat surfaces using discrete time domain approach. A model is developed for dynamic cutting process which takes into consideration the variation of helix angle of the ball end mill along the cutting edge. The vibration of the tool is calculated by using a lumped-parameter model with two degrees of freedom. Expressions are based on the dynamics of ball end milling with regeneration in the uncut chip thickness. The dynamic cutting force coefficients are derived from orthogonal cutting data base using oblique transformation method and the dynamic parameters of cutting process such as shear stress, friction angle and shear angle due to variation in spindle speed and feed rate are considered. An update semi-discretization method is used to produce stability lobes. When the process is highly intermittent which occurs at high speeds and low radial depth of cuts, the stability lobes are more accurately solved by semi-discretization method. The chatter stability limit is indicated by the critical nominal depth of cut. The stability lobes agree well with the analytical method, the computationally expensive and complex numerical time domain simulations.
Babak Fadaei and Hossein Pourbashash, 2018. Chatter Instability Prediction of Ball-End Milling in Discrete Time Domain. Agricultural Journal, 13: 98-106.