Rotary cutting tool with tunable vibration absorber

A rotary cutting tool, comprising:

• a shank portion;
• a cutting portion adjoining the shank portion and having a cutting end, the cutting portion having a plurality of blades separated by helically twisted flutes, each blade including a leading face, a trailing face, and a land surface extending between the leading face and the trailing face;
• and
• a tunable vibration absorber disposed within an internal cavity formed in the cutting portion, the internal cavity having a helical shape that corresponds with the shape of the helically twisted flutes, the tunable vibration absorber has a corresponding helical shape to the internal cavity helical shape, the tunable vibration absorber comprising an absorber mass and a resilient material disposed between the absorber mass and a wall of the internal cavity,
• wherein the internal cavity has a first diameter section disposed within the shank portion and having a length, L1, and a second diameter section adjoining the first diameter section for receiving the tunable vibration absorber, the first diameter section having a first diameter and the second diameter section having a second diameter smaller in magnitude than the first diameter, the second diameter section having a total length equal to L2+L3+G, where L3 is a length of the tunable vibration absorber, L2 is a length of the internal cavity without the tunable vibration absorber located between the first diameter section and the tunable vibration absorber, and G is a length of a gap between the tunable vibration absorber and an end wall of the internal cavity,
• wherein L2 is greater than L3,
• wherein the lengths L1, L2, L3 and G are measured in a direction parallel to a central, longitudinal axis, CL, of the rotary cutting tool,
• wherein the helical shape of the internal cavity extends over a length, measured in the direction parallel to the central, longitudinal axis, CL, of the rotary cutting tool, greater than the length L3,
• wherein the tunable vibration absorber is tuned to a desired frequency by selecting mechanical properties of the absorber mass and the resilient material, and
• wherein the desired frequency of the tunable vibration absorber causes destructive interference between the tunable vibration absorber and the rotary cutting tool, thereby suppressing vibration of the rotary cutting tool during a cutting operation.