Abstract: A rotary cutting tool such as an endmill includes a coating on its radial relief surfaces for enhancing damping of vibratory motion of the tool at speeds which permit the relief surfaces to rub on the workpiece being machined. The coating has a hardness substantially less than that of the remainder of the tool. In a preferred embodiment, the tool is made of tungsten carbide, steel, or ceremet, and the coating is aluminum or an alloy thereof, having a thickness of about 0.0015 inch for tools with cutting diameters of about 1/4 inch to about 1 inch.

Abstract: The present invention provides a friction stir welding device for optimizing the depth of a friction stir welding tool in a workpiece. The welding device includes a spindle and a welding tool in rotatable communication with the spindle. The welding device also includes an inner housing defining an aperture through which the welding tool at least partially extends. Preferably, the inner housing has a plurality of cam followers. The device also includes an outer housing defining an aperture for at least partially receiving the inner housing. The outer housing has a base member and a riser that is rotatably mounted to the base member and that defines a plurality of inclined surfaces upon which the plurality of cam followers ride. The welding device includes a sensor in electrical communication with a controller for measuring the magnitude of force exerted by the welding tool upon the workpiece.