Control of milling process dynamics through a mechatronic tool holder with purposely designed Joint Interface

Machine tool joints have significant influence on the dynamic characteristics of the machine tool and therefore on the response of the machining system to excitations from the cutting process. In cases of unstable response, generally described as chatter, surface quality of a machined work-piece and tool life deteriorate significantly. This paper presents a novel way of exploiting joints in order to control the dynamic response of the system, by integrating a mechatronic tool holder (Joint Interface Module - JIM) in the machine tool. This system has a purposely designed joint interface with controllable natural characteristics (stiffness and damping). These characteristics are controlled by altering the applied preload on the internal joint interface of the tool holder. The preload on the joint interface is controlled by pneumatic means. In doing so, a milling process during which the stability limit was exceeded became stable during the machining process, without alteration of the process parameters.