Abstract: A rotary blade has a rotary substrate with chips disposed about the outer edge of the substrate. The substrate further has two sets of semicircular slits. The first set of semicircular slits is disposed annularly about the rotary substrate on a circle coaxial with the center of rotation of the rotary blade. The semicircular slits open toward the center of rotation. The second set of semicircular slits are disposed on a circle inside of the circle of first slits. These slits open outwardly, thus blocking, at least partially, the first semicircular slits from the center of rotation. A filler material is filled into the semicircular slits, the slits thus providing a vibration damping effect. The chips may be attached to the outer edge of the rotary substrate by concave profiled cassette stands.

Abstract: Method for welding cutter-segments characterized by focusing an electron beam or a laser beam on the boundary between a carbon-steel core body (7) and segments (1). Each segment is formed by a Co (cobalt) powder compact, containing diamond or CBN grit, which has been sintered to nearly 100% apparent density. The boundary may or may not have Ni (nickel)-filler. In cases of bond materials other than Co, the segment (1) has a structure of double layers (4, 5), one layer of which is composed of a powder compact, containing diamond or CBN grit, which has been sintered to nearly 100% apparent density, and the other layer (5) of which is composed of a sintered Co powder compact without any grit. The carbon-steel core body (7) welded by the above-mentioned method is thereafter tempered at 350.degree.-450.degree. C. if necessary. A steel core having no slot at its periphery may be used as the core body.