Machine Tool Chatter and Surface Quality in Milling Processes

Abstract

Two degree of freedom model of milling process is investigated. The governing equation of motion is decomposed into two parts: an ordinary differential equation describing the stable periodic motion of the tool and a delay-differential equation describing chatter. Stability chart is derived by using semi-discretization method for the delay-differential equation corresponding to the chatter motion. The stable periodic motion of the tool and the associated surface location error are obtained by a conventional solution technique of ordinary differential equations. Stability chart and surface location error are determined for milling process. It is shown that at spindle speeds, where high depths of cut are available through stable machining, the surface location error is large. The phase portrait of the tool is also analyzed for different spindle speeds. Theoretical predictions are qualitatively confirmed by experiments.