Development of constrained layer damping toolholder to improve chatter stability in end milling

Abstract

The chatter occurs during milling operation when the axial depth of cut is too large and/or the spindle speed approaches one of natural frequencies of the machining system. The critical axial depth of cut and stable spindle speed ranges for chatter occurrence are influenced by dynamic stiffness and natural frequency of the milling toolholder. In this work, a novel constrained layer damping toolholder was developed to increase chatter stability of end milling operation. Firstly, optimum design geometrical parameters were analytically solved with respect to optimum damping and constraining layer materials. Then the developed damping toolholder was manufactured. Lastly, modal tests and cutting experiments were carried out to verify the effectiveness of chatter suppression with the developed damping toolholder. The frequency response, cutting forces and machined surface quality were measured and compared. It is found that the dynamic stiffness and critical axial depth of cut for the developed damping toolholder are 600% higher than those of the conventional mono-solid toolholder with steel alloys. The natural frequency of the developed damping toolholder has increased by 19%, which can allow wider spindle speed ranges for stable end milling operations.