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What materials are CBN Inserts suitable for machining?

Updated: Jul 2, 2022

Since entering the 21st century, the biggest change for the manufacturing industry technology is the change of cutting tool materials. The former alloy tools and ceramic tools cannot meet the needs of various difficult-to-machine materials any more. At this time, CBN (cubic boron nitride) tools are developed and improved, begin to become the mainstream tools for cutting difficult materials.

CBN (cubic boron nitride) is a super-hard material manufactured by artificial synthesis. Because of its excellent hardness, good high temperature resistance and wear resistance, it has been widely used in the tool industry. In this article, we will talk about the main performance characteristics of ToolingBox solid CBN inserts and suitable CBN grades for different machining process.

The main performance characteristics of CBN tools(Including Solid and tipped):

(1) Extremely high hardness and wear resistance. The hardness of CBN tools can reach 3000~5000HV. When cutting wear-resistant materials, its wear resistance is 50 times that of cemented carbide tools, 30 times that of coated cemented carbide, and 25 times that of ceramic tools. Also It is the one of the best tools for grinding.

(2) It has high thermal stability. The heat resistance of CBN tools can reach 1400~1500℃, which is almost twice as high as that of diamond. Therefore, CBN tools can cut high-temperature alloys and hardened steel at a speed 3 to 5 times higher than that of cemented carbide tools.

(3) Excellent chemical stability. CBN tools have high oxidation resistance, and will not oxidize at a high temperature of 1000 ℃, so CBN tools are suitable for cutting hardened steel and chilled cast iron, and can be widely used for high-speed cutting of cast iron.

(4) Better thermal conductivity. The thermal conductivity of CBN tools is 3.2 times that of pure copper and 20 times that of cemented carbide. Good thermal conductivity can reduce the temperature at the tip of the tool, reduce tool wear, and improve machining accuracy.

(5) Lower friction coefficient. The coefficient of friction between CBN tools and different materials is about 0.1~0.3, which is much smaller than that of cemented carbide, so it can reduce the cutting force during cutting, lower the cutting temperature, and improve the quality of the machined surface.

What material is suitable for machining with CBN inserts(Solid and tipped)?:

(1) High-hardness cast iron parts. It is a type of cast iron with increased hardness that is made by adding ordinary cast iron to certain alloy elements by certain means, including high chromium cast iron, alloy cast iron, nickel hard cast iron, white cast iron, etc. The common industrial parts include Rolls, industrial pumps and so on. the most suitable CBN grade for alloyed cast iron machining is our solid CBN grade TB400.

(2) High-hardness steel parts. It is steel with high carbon content and high hardness but relatively brittle steel, such as high manganese steel, high speed steel, hardened steel, etc. The more common industrial parts include rolling mortar wall, high speed steel rolls, hardened gears/gear shafts, bearings, Ball screws, molds, etc. If there are heavy-interrupted cutting when machining, it will be better to use tipped CBN inserts compared to solid or brazed solid CBN inserts, but solid CBN grade TB200 is fully competitive performace comparing to other suppliers.

(3) Ordinary gray cast iron. Refers to cast iron with flake graphite, which is called gray cast iron because the fracture is dark gray when it breaks. It is the most widely used type of cast iron. The more common industrial parts include engine block/cylinder head, brake disc, brake drum, belt pulley, clutch pressure plate and so on. the most suitable CBN grade for gray cast iron machining is our solid CBN grade TB100.

(4) Other difficult machining materials. In addition to the above-mentioned materials, there are other materials with hardness greater than 250 and tensile strength greater than 1000MPa, which are collectively referred to as difficult machining materials, such as powder metallurgy, high-temperature alloy materials, CoCrMo material and nickel-based, iron-based, cobalt-based and other high-hardness materials.

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