US Patent 7494302 Throw-away tip

A throw-away tip of which two principal surfaces each comprises a land surface 5 provided along the periphery thereof, a central surface 7 provided on the inside of the land surface 5, a recess (a chip breaker groove) interposed therebetween, and at least one protrusion 8 that extends from the central surface 7 toward the land surface 5, wherein height of the land surface is made equal to the height of at least the top surface of the protrusion 8 so that at least the top surface of the protrusion of the central surface and the land surface both serve as contact surface.