Approaches for chatter reduction in deep cavity and intricate surface milling

Abstract

The goal of the project was to increase the metal removal rate or improve the surface quality of an intricate surface cut by a long overhang tool. The results of the metal cutting tests show that the surface quality of a finish cut at conventional milling speeds can be improved by approximately 50% by using a stepped or tapered tool. In applications with straight walls or intricate surfaces where the larger diameter base of the tool interferes with the workpiece, a high stiffness 5 axis machine can achieve the desired geometry. Damping treatments such as the squeeze film damped tool and the viscoelastic ring were developed that could significantly increase the dynamic stiffness of a long overhang tool. These damping treatments did not improve the workpiece surface finish at conventional milling speeds. However, metal cutting theory indicates that more damping could be beneficial in high speed milling applications in which the vibration amplitude of the tool's resonant cantilever mode limits the stable depth of cut. This study has also produced an analytic model and damping methods that will enable designers to tailor the dynamic response of a tool to attenuate the vibrations that cause chatter at higher spindle speeds.