Why CBN tools can machine the workpiece above HRC60?

25 December 2020

pcd and pcbn cutting tools


At present, CBN tools are the best wear-resisting tool materials in the field of black metal processing. After demonstration, cubic boron nitride tool life is generally several times to dozens of times of carbide and ceramic blade. As a brittle superhard cutting tool material, high hardness is its most obvious characteristic, and toughness is its most basic guarantee.


pcd and pcbn cutting tools


Cubic boron nitride (CBN) is a kind of high hardness synthetic material, its hardness (HV7300 ~ 9000) is second only to diamond, but its heat resistance and chemical stability are much higher than diamond, it can withstand 1300 ~ 1500℃ high temperature, and iron group metal straight 1200 ~ 1300℃ is not easy to have chemical action. Therefore, CBN tool is not only suitable for the processing of non-ferrous refractory materials, but also suitable for the cutting of quenched steel, cold hard cast iron and high temperature alloy and other ferrous refractory metal materials. Semi-finishing and finishing with CBN tool can reach IT5, and the surface roughness can be reduced to Ra1.25 ~ 0.2 m. CBN tool cutting can completely replace grinding in terms of tool life and surface roughness.

In addition, since CBN is chemically inert to iron group metals and has the characteristics of high hardness, wear resistance, high temperature resistance and good strength, etc., its processing objects are mostly hardened steel with high hardness and difficult to process materials, and there are few data about using CBN tool to cut soft materials. In order to clarify the applicable scope of CBN tool, the durability of CBN tool was measured by turning hardened steel with different hardness, and some notable phenomena were found.

pcd and pcbn cutting tools



Then Why CBN tools can machine the workpiece above HRC60?


1. CBN tools have high hardness and wear resistance, the hardness of itself is HRC95-100, thus it has good wear resistance and can easy to machine the workpiece above HRC60


2. CBN tools have higher thermal stability and high-temperature red-hardness, can stand 1400--1500℃ high temperature. When machine workpiece above HRC60, therefor the temperature generated won’t lead to the phenomenon of rapid wear or collapse of the tool edge.


3. CBN tools have lower friction coefficient and excellent bonding resistance. When machine workpiece above HRC60, it is hard to form retention layer or chip tumor, thus can obtain higher surface quality.


4. CBN tools is hard to have chemical reaction with iron material at 1200℃ in high-speed machining. In addition, CBN tools will hydrolyze with water at 1000℃ or so. Therefore, dry cutting is often used for machining with CBN tools. In green processing of black metal materials, the choice of CBN tools, has become a rising trend.

Moresuperhard can provide you various CBN tools for  hard to be machined materials with high hardness such as dardened steels,etc.




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