Investigation of Boring Bar Dynamics for Chatter Suppression

Chatter is a concern in boring process, due to the low dynamic stiffness of long cantilever boring bars. Chatter suppression in machining permits higher productivity and better surface finishes. In order to improve the performance of boring operations, several researchers have investigated electro- and magneto-rheological fluids and piezoelectric and electromagnetic actuators as vibration absorbers. In this study, we investigated the feasibility of shifting the natural frequency of boring bar based on semi-active fluid control. Mass at the end of a boring bar was modulated to tune its natural frequency by adjusting the level of fluid in a reservoir. At the same time, different damping materials were used to improve dynamics of the boring bar. Experimental modal analysis was used to obtain frequency response functions for different system configurations. A finite element model was proposed and validated with experimental results. A chatter stability analysis examined chatter suppression characteristics of the proposed method.