Tool wear in finish hard turning 03:01

Tool wear can be divided in 4 different groups, each containing a number of specific tool wear types.

• Abrasive wear – A change in tool geometry through continuous loss of tool material 
• Flank wear
• Crater wear
• Notch wear
• Deformation – A change in tool geometry without loss of tool material
• Plastic deformation
• Chemical Wear
• Diffusion
• Breakage – A sudden change in tool geometry with loss of tool material
• Edge breakage
• Chipping
• Flaking

In finish hard turning, the “desired” tool wear is abrasive wear; flank wear, crater wear and notch wear, all wear types that are continuous and predictable.

Deformation and chemical wear is not often seen in finish hard turning (unless the material hardness is below 50 HRC).

Breakages can happen, either as a result of too much abrasive wear, or due to a problem in the machine, like a component being clamped the wrong way.

Having only abrasive wear allows the user to run a test insert, establish a maximum tool life, and then set the tool life limit in the machine tool at a safe limit, let’s say 80% of maximum tool life. The user can then be sure that no sudden stops will occur due to breakages.

The desired tool wear should be a combination of flank wear and crater wear. Depending on material composition, notch wear can also be present.

A balanced tool wear like this tells the user that cutting data he is using is right. If the crater wear is too large, the cutting speed should be reduced, and if the flank wear is too large, the cutting speed should be increased.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com