Abstract: A grader blade includes a grader blade body that has a recess in a bottom edge, and a tri-grade insert assembly is received within the recess. The tri-grade insert assembly includes a leading insert, a mediate insert and a trailing insert. The leading insert has an impact wear resistance and fracture wear resistance greater than the mediate insert and the trailing insert. The trailing insert has an abrasion wear resistance and down-pressure wear resistance greater than the leading insert and the mediate insert. The mediate insert has an impact wear resistance and fracture wear resistance greater than the trailing insert and an abrasion wear resistance and down-pressure wear resistance greater than the leading insert.

Abstract: A cutting bit for impinging earth strata wherein the cutting bit includes a highly wear-resistant elongate cutting bit body, which has an axial forward end and an axial rearward end, an enlarged dimension head portion at the axial forward end and a reduced dimension shank portion at the axial rearward end. The highly wear-resistant elongate cutting bit body has a maximum transverse dimension and a longitudinal axial length. The cutting bit includes a superhard insert, which is affixed to the head portion at the axial forward end of the cutting bit body. The cutting bit has a slimness ratio, which comprises the ratio of the maximum transverse dimension to the longitudinal axial length wherein the cutting bit exhibits a slimness ratio ranging between about 0.15 and about 0.60.

Abstract: A grader blade includes a grader blade body that has a recess in a bottom edge, and a tri-grade insert assembly is received within the recess. The tri-grade insert assembly includes a leading insert, a mediate insert and a trailing insert. The leading insert has an impact wear resistance and fracture wear resistance greater than the mediate insert and the trailing insert. The trailing insert has an abrasion wear resistance and down-pressure wear resistance greater than the leading insert and the mediate insert. The mediate insert has an impact wear resistance and fracture wear resistance greater than the trailing insert and an abrasion wear resistance and down-pressure wear resistance greater than the leading insert.

Abstract: A rotatable cutting tool carried in a bore of a holder wherein the holder has a forward surface surrounding a forward end of the bore. The rotatable cutting tool includes an elongate cutting tool body that has a central longitudinal axis, an axial forward end and an axial rearward end. The cutting tool body contains a socket in the axial forward end thereof whereby the socket receives a hard insert therein. The cutting tool body has an enlarged diameter collar mediate of the axial forward end and the axial rearward end. The mediate collar presents an axial forward facing surface and an axial rearward facing surface. The cutting tool body has an axial forward hardness region beginning at and extending a first pre-selected distance in an axial rearward direction from the axial forward end to encompass the axial forward facing surface of the collar. The axial forward hardness region has a hardness equal to or greater than a first hardness, as well as a first average hardness.