5-axis milling is an important machining process for several industries such as aero-space, automotive and die/mold. It is mainly used in machining of sculptured surfaces where surface quality is of extreme importance. Being one of the most important prob-lems in machining, chatter vibrations must be avoided in manufacturing of these com-ponents as they result in high cutting forces, poor surface finish and unacceptable part quality. Chatter free cutting conditions for required quality with higher productivity can be determined by using stability models. Up to now, dynamic milling and stability models have been developed for 3-axis milling operations; however the stability of 5-axis proc-esses has never been modeled. In this paper, a stability model for 5-axis milling opera-tions is proposed. The model can consider the 3D dynamics of the 5-axis milling proc-ess including effects of all important process parameters including lead and tilt angles. Due to the complex geometry and mechanics of the process, the resulting analytical equations are solved numerically in order to generate the stability diagrams
