Chatter Reduction in Turning by Using Piezoelectric Shunt Circuits

In this paper, the effect of piezoelectric shunt damping (PSD) on chatter vibrations in turning process is studied. Chatter is a self-excited type of vibration that develops during machining due to process-structure dynamic interactions resulting in modulated chip thickness. Chatter is an important problem, since it results in poor surface quality, reduced productivity and reduced tool life. The regenerative chatter results from phase differences between two subsequent passes of the cutting tool and occurs earlier than mode coupling chatter in most cases. In regenerative chatter theory, stability limit in the cutting process is inversely proportional to the negative real part of frequency response function (FRF) of the cutting tool-workpiece assembly. If the negative real part of the FRF at the cutting point can be decreased, depth of cut, in other words productivity rates, will increase. In piezoelectric shunt damping method, an electrical impedance is connected to a piezoelectric transducer which is bonded to the main structure. In this study, resistive – inductive – capacitive shunt circuit is used, whose elements are optimized with genetic algorithm to minimize the real part of the FRF for certain target frequencies. Afterwards, the effect of the optimized piezoelectric shunt damping on the absolute stability limit of the cutting process is investigated.