US Patent 9694432 Drill reamer

A drill reamer (20) comprises an elongate body (21) disposed about a longitudinal axis. The elongate body comprises flutes (22a-22d) having separate hard cutting sections (27a, 28′a, 28″a, 28′b, 28″b) and a soft cutting section (24a, 24b). The soft cutting section is formed of a material such as carbide having a hardness that is less than that of the hard cutting sections, which may be formed of polycrystalline diamond. At least one first hard cutting section (27a) is axially displaced relative to at least one second hard cutting section (28′a, 28″a). The reamer has a tip cutting edge (23a, 23c) and tapered cutting edge portions (24a-24d) disposed at an acute angle relative to the longitudinal axis.