Method of producing holes and countersinks in polycrystalline bodies

1. A method of producing at least one through-hole and countersink in at least one ultrahard insert comprising:

providing a body having a first major surface and an opposite second major surface;

forming at least one pilot hole in said body using a laser, wherein said at least one pilot hole extends from said first major surface to the opposite second major surface of said body;

cutting said pilot hole using a wire electrical discharge machine to produce a straight cylindrical portion and top conical portion;

forming a countersink on at least one side of said body using an electrical discharge grinding machine; and

severing said at least one ultrahard insert from said body forming a finished insert, wherein said finished insert includes a through-hole and a countersink.

2. The method of claim 1 , further comprising machining a profiled curved countersink out of the body confined to a carbide substrate of the body.

3. The method of claim 1 , wherein multiple pilot-holes are formed in said body.

4. The method of claim 1 , wherein said method is independent of thickness and composition of a polycrystalline cubic boron nitride or a polycrystalline diamond layer.

5. The method of claim 1 , where the concentricity of the through-hole and inscribed circle of the insert is about 0.02 mm.

6. The method of claim 1 , wherein the said finished insert comprises integral relief angles cut during the severing process.

7. The method of claim 1 , wherein said finished insert comprises grind-stock of about 0.08 mm due to the presence of the through-hole, countersink and integral relief angles.

8. The method of claim 1 , further comprising creating a top taper thereby creating an entrapped conical part.

9. The method of claim 8 , wherein the entrapped conical part is ejected upwards by the wire electrical discharge machine by turning a top nozzle of the wire electrical discharge machine off and a bottom nozzle of the wire electrical discharge machine on.

10. The method of claim 1 , wherein the body comprises a layer of polycrystalline ultra-hard material bonded to a substrate.

11. The method of claim 10 , wherein the substrate comprises cemented carbide.

12. The method of claim 10 , further comprising machining the countersink into the substrate, wherein the countersink is spaced apart from the layer of polycrystalline ultra-hard material.

13. A method of producing at least one through-hole and countersink in at least one ultrahard insert comprising the steps of:

providing a body having a first major surface and an opposite second major surface;

forming at least one pilot-hole in said body using a laser, wherein said at least one pilot-hole extends from said first major surface to the opposite second major surface of said body;

cutting said pilot-hole using a wire electrical discharge machine to produce a straight cylindrical portion and top conical portion;

forming a countersink on at least one side of said body using an electrical discharge grinding machine;

creating a top taper thereby creating an entrapped conical part; and

severing said at least one ultrahard insert from said body wherein said insert includes a through-hole and countersink.

14. A method of producing at least one through-hole and countersink in at least one ultrahard insert comprising:

providing a body having a first major surface and an opposite second major surface;

forming at least one-pilot hole in said body using a laser, wherein said at least one pilot-hole extends from said first major surface to the opposite second major surface of said body;

cutting said pilot hole using a wire electrical discharge machine to produce a straight cylindrical portion and top conical portion;

forming a countersink on at least one side of said body using an electrical discharge grinding machine;

machining a profiled curved countersink out of the body confined to a carbide substrate of the body; and

severing said at least one ultrahard insert from said body wherein said insert includes a through-hole and countersink.