Edge Selection for CBN Inserts

21 July 2022

The cutting edge shape of the CBN insert mainly includes the edge land (edge ​​length, edge width), the edge angle, the edge R, the wiper edge, etc.


By analyzing these main elements and understanding the relationship between them and cutting performance, the optimal cutting edge shape can be determined for different machining materials and cutting conditions, so that the performance of CBN inserts can be best reflected.


The cutting edges of CBN inserts are divided into four forms:F ,E ,T and S.


Selection, definition, and characteristics of the Cutting edge

F shape cutting edge:
F shape cutting edge
The sharp cutting edge helps to improve the roughness of the processed surface, and it is not easy to lead to chatter marks. But because it is too sharp, the durability is slightly poor, so it is only used when processing general cast iron and requires higher.
roughness: the roughness could reach to Ra0.8-Ra1.6, Mostly cutting for fine finishing of car brake discs.
E shape cutting edge:
E shape cutting edge
Honing for edge could reduce microchipping, and help to improve the edge integrity, but it has a greater cutting force than a sharp edge. The heavier for the honing, the better for the cutting edge shape, and the better for the strength. but cutting resistance and cutting heat will also increase. When the system rigidity and machine power are sufficient or do interrupt cutting it could choose heavy honing. The E-cutting edge is often used for precision milling inserts.
T shape cutting edge:
T shape cutting edge
Chamfering(Do a cutting edge with edge width and angle) is beneficial to improve the impact resistance of the cutting edge, and it is mostly used for fine-turning hardened steel with a small margin(ap<0.1). Compared with the S-edge, it is beneficial to improve the quality of the processed surface and help to ensure dimensional stability. When the phenomenon of"chewing" occurs after using the S-edge, it can be considered to change S-edge to the T-edge.
S shape cutting edge:
S shape cutting edge
The cutting edge has the best strength and comprehensive cutting performance, and it's the most widely used cutting edge for CBN inserts.
S02020 is mostly used for cast iron, and S01020 is mostly used for hardened steel parts.
Edge angle:
The larger the chamfer, the better the impact resistance of the cutting edge, but the cutting resistance will increase, which requires higher system rigidity and machine power. Ordinary cast iron 15°-25°, hard cast iron 20°-30° or interrupted cutting, hardened steel 20°-35°.
Edge width:
The chamfer width is generally less than the feed rate per revolution. 020 is used for cutting cast iron, and 010 is usually used for cutting hardened steel.For large margin and high feed rough turning of hard iron, it is recommended to use a combination of larger chamfer width and heavy honing, such as commonly used 050 and 100, for better impact resistance and longer turning roll life.
Double edges:
When turning hard cast iron with a large machining allowance, it is recommended to use a double chamfer, eg: S20015/01030, for better impact resistance and excellent cutting performance.
T and S cutting edges
Application of different cutting edge types
Application of different cutting edge types

Major factor

Cutting edge selection principles and recommendations


feed rate 0.5

Cast Iron

Suggest S02020

Hard Cast Iron

Suggest S02020 S010020




cutting edges


Hardened steel

When the ap<0.1mm

f<0.1mm/r suggest T01025


suggest S01020

System rigidity

The S-type is recommended when the rigidity is good, and the T and F types are available when the rigidity is poor

Workpiece rigidity

The S-type is recommended when the rigidity is good, and the T and F types are available when the rigidity is poor.

Machine power

When the power is good, the heavy honing edge type can be considered to increase the durability of the CBN inserts.

Intermittent cutting

On intermittent cutting we could consider increase the chamfering angle and heavy honing edge type, ordinary cast iron recommends S02030, Hardened steel recommends S01030, hard cast iron recommends double chamfer S20015/01030


S-type and heavy-honing cutting edges could help improve durability


When the roughness requirements are high, it is recommended to use the F-type or the smoothing edge type.

Feed rate per revolution

We can customize the blade for you according to the workpiece you are processing, please contact us if you need it. More SuperHard Products Co., Ltd. will always be by your side to help you meet and overcome any metal cutting challenge you encounter! Contact Us!
---EDITOR: Miya Ma
---POST: Cynthia Lee
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