Enhanced Damping in Long Slender End Mills

The limiting chatter-free depth of cut in milling is dependent on the dynamic stiffness of the tool/holder/spindle system. A method for increasing the dynamic stiffness by providing additional damping is demonstrated. The proposed damper is a multi-fingered cylindrical insert placed in an interior bore located inside conventional milling cutters. Spindle rotation forces these flexible fingers against the inner surface of the tool, and bending of the tool during cutting dissipates energy through friction, leading to improved damping and dynamic stiffness. This paper presents an analytical model of the damper, experimental measurements of tool response, and comparison between stable cutting depths using both a conventional tool and one with the damping insert.