When an endmill is used in high-speed machining, chatter vibration of the tool canrncause undesirable results. This vibration increases tool wear and leaves chatter marksrnon the cutting surface. To reduce the chatter vibration, a layered-beam damper isrninserted into the hole at the center of the tool. The friction work done by the relativernmotion between the tool and damper reduces chatter vibration. The purpose of thisrnresearch is to design and optimize the configuration of the damper to obtain thernmaximum damping effect.rnThe analytical method has been reviewed, which is based on the assumption ofrnconstant contact pressure and uniform deflection. For the numerical approach,rnnonlinear finite element analysis is employed to calculate the distribution of therncontact pressure under the centrifugal and cutting forces. The analytical andrnnumerical results are compared and discussed.rnIn order to identify the effect of the damperâ€™s configuration, two design variablesrnare chosen: the inner radius of the damper and the number of slotted dampers. Duringrnthe parameter study and optimization, the inner radius is varied from 1.5mm torn3.5mm and the number of slotted dampers is varied from 2 to 10.rnResults show that the damping effect is maximum when the inner radius is 1.5mmrnand the number of slotted dampers is 5. However, this result depends on the operatingrncondition. Thus, it is suggested to prepare a set of dampers and to apply thernappropriate one for the optimum damping effect for a given operating condition.