Regenerative chatter control in turning process using constrained viscoelastic vibration absorber

This paper focuses on utilization of viscoelastic material to control regenerative chatter in turning process. Self-induced vibrations can lead to the condition called regenerative chatter which produces violent relative vibrations between cutting tool and workpiece and reduces tool life and productivity. The regenerative chatter in turning processes can be controlled by maximizing negative real part of the frequency response function of cutting tool structure. In order to achieve this, a constrained viscoelastic vibration absorber (CVVA) is used. A CVVA consists of a viscoelastic material, such as natural rubber, which is sandwiched between two similar or dissimilar metallic layers. The CVVA is used as a cantilever beam whose fundamental natural frequency is tuned to the natural frequency of the dominant mode of cutting tool/tool holder. The optimum stiffness and damping coefficient of the CVVA are found using a numerical optimization technique and these optimal values are used to find the dimensions of CVVA. The resulting natural frequency of CVVA is verified using finite element simulation software ANSYS. The effectiveness of CVVA in controlling regenerative chatter in a compact CNC lathe is also analysed by constructing stability lobes which are plots of depth of cut vs spindle speed.