Cutting tools with two-slope profile

1. A tool insert, which comprises:

a substrate having an inner face which has a center, the inner face sloping outwardly and downwardly from the center;

an annular face which slopes downwardly and outwardly from the inner face;

a ledge surrounding an outer periphery of the annular face; and

an abrasive layer having a center and a periphery a cutting edge, the abrasive layer integrally formed on the substrate and having a thickness of at least about 0.1 mm.

2. The tool insert of claim 1 , wherein the substrate comprises cemented metal carbide.

3. The tool insert of claim 1 , wherein the abrasive layer comprises diamond, cubic boron nitride, wurtzite boron nitride, or a combination thereof.

4. An abrasive tool insert, comprising:

a substrate having an inner face which has a center, the inner face sloping outwardly and downwardly from said center at an angle from about 5° to about 15°;

an annular face which slopes downwardly and outwardly from the inner face at an angle of from about 20° to about 75°;

a ledge surrounding an outer periphery of the annular face; and

an abrasive layer having a cutting edge, the abrasive layer being integrally formed on the substrate,

wherein the abrasive layer has a thickness of at least about 0.1 mm.

5. The tool insert of claim 4 , wherein an interface between the substrate and the abrasive layer is non-planar.

6. The tool insert of claim 4 , wherein the substrate comprises cemented metal carbide.

7. The tool insert of claim 6 , wherein the cemented metal carbide comprises a Group IVB, Group VB, or Group VIB metal carbide or a combination thereof.

8. The tool insert of claim 4 , wherein the abrasive layer comprises diamond, cubic boron nitride, wurtzite boron nitride, or a combination thereof.

9. The tool insert of claim 4 , wherein the non-planar interface comprises a sawtooth pattern of concentric rings.