Diamond coated cutting member and method of making the same

DETAILED DESCRIPTION Referring to the drawings, FIG.
1 illustrates a generally cylindrical sintered substrate blank, generally designated as 10, for a twist drill, i.
e.
, an elongate rotary cutting member.
It should be appreciated that while the specific embodiment is a twist drill, the invention may encompass other rotary cutting members.
For example, each one of a tap, a burr, a countersink, a reamer, or an endmill is a cutting member that is within the scope of the invention.
As will become apparent from the description hereinafter, the embodiment of the invention that includes the removal of materials as the last processing step has particularly good application to the manufacture of bodies with complex geometries.
More specifically, because the last step comprises the removal of material through machining or the like, this process maintains the dimensional integrity and dimensional tolerances necessary in the production of a body with a complex geometry or shape.
Referring back to FIG.
1, substrate 10 has opposite axially forward and rearward ends 12 and 14, respectively.
Substrate 10 presents a generally cylindrical surface 16 along the entire length thereof so that the overall geometry of substrate 10 is cylindrical.
A typical material for the substrate 10 is tungsten carbide cemented with cobalt.
Other typical materials include tungsten carbide-based material with other carbides (e.
g.
TaC, NbC, TiC, VC) present as simple carbides or in solid solution.
The amount of cobalt can range between about 0.
2 weight percent and about 20 weight percent, although the more typical range is between about 5 weight percent and about 16 weight percent.
Typical tungsten carbide-cobalt (or tungsten carbide-based/cobalt) compositions used for a twist drill or other elongate cutter member (e.
g.
, an endmill or a reamer) include the following compositions and their properties.
Composition No.
1 comprises between about 11.
0 and about 12.
0 weight percent cobalt, between about 1.
2 and about 2.
6 weight percent tantalum and between about 0