Ceramic cutting insert and method of making same

Patent metadata

Field	Value
Publication number	US-9238285-B2
Application number	US-7385308-A
Country	US
Kind code	B2
Filing date	Mar 11, 2008
Priority date	Mar 12, 2007
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

The present invention relates to a method of manufacturing a ceramic cutting insert, based on an oxide ceramic or a nitride ceramic or a mixed ceramic material, possibly containing whiskers, in a process comprising the powder metallurgical steps of providing a ready-to-press ceramic powder, pressing the ready-to-press powder into a compact of desired shape, sintering the compact to dense a ceramic blank followed by tumbling the ceramic blank, to remove sinter skin and provide an edge rounding.

First claim

The invention claimed is:

1. A method of manufacturing a ceramic cutting insert, based on an oxide ceramic, a nitride ceramic or a mixed ceramic material in a process comprising the powder metallurgical steps of
providing a ready-to-press ceramic powder,
pressing the ready-to-press powder into a compact of desired shape,
sintering the compact to a dense ceramic blank and
tumbling the ceramic blank to remove sinter skin and provide an edge rounding.

2. A method of claim 1 comprising tumbling said blank until it has an edge rounding with a W value of from about 30 to about 70 μm, an H value of from about 30 to about 70 μm and a W/H ratio of from about 0.8 to about 1.6, and a mean surface roughness value, MR a value, of equal to or less than about 0.30 μm.

3. A method of claim 1 wherein the compact has a rounded shape.

4. A method of claim 1 wherein the ceramic material is a sialon grade.

5. A method of claim 1 wherein tumbling is conducted for a time being equal to or more than about 300 minutes.

6. A method of claim 1 wherein tumbling is performed in a vibratory tumbler.

7. A method of claim 1 wherein the ceramic material includes whiskers.

8. A method of claim 2 wherein the MR a value is equal to or less than about 0.25 μm.

9. A method of claim 1 wherein the compact has a rounded shape and the tumbling is conducted for a time being equal to or more than about 300 minutes.

10. A method of claim 1 wherein a tumbling media includes ceramic chips.

11. A method of claim 10 wherein the ceramic chips are aluminum oxide chips.

12. A method of claim 10 wherein a weight ratio of chips:blanks is from about 3:1 to about 7:1 and a total blank weight being from about 5 to about 13 kg.

13. A method of claim 1 further comprising subjecting a tumbled insert to a grinding operation on selected surfaces followed by a second tumbling step to provide a smooth surface and/or an edge rounding.

14. A method of claim 13 , wherein selected surfaces are a top surface and a bottom surface of an insert having a rounded shape.

15. A method of claim 1 , wherein a surface zone is removed to a depth of about 8 μm to about 10 μm.

16. A method of claim 1 , wherein a surface zone is removed to a depth of about 8 μm.

17. A method of claim 1 , wherein a surface zone is removed to a depth of about 10 μm.

Assignees

• Endtbacka Thomas
• Sandvik Intellectual Property

Inventors

• Endtbacka Thomas

Classifications

• B23B2200/245

  rounded · CPC title

• C04B35/597

  based on silicon oxynitride, {e.g. SIALONS} · CPC title

• B23B2226/18

  Ceramic · CPC title

• B23B2200/3609

  Chamfers · CPC title

• C04B41/91

  involving the removal of part of the materials of the treated articles, e.g. etching · CPC title