Polycrystalline Cubic Boron Nitride (PCBN) is a polycrystalline cutting tool material made by pressing fine particles of cbn (CBN) single crystals (0.5~1.6mm thick) along with a binder onto a carbide substrate under high temperature (1400~2600℃) and high pressure (7~9Gpa).
Due to the small grain size of single crystal CBN and its cleavable "cleavage plane", it cannot be directly used for manufacturing cutting tools. Therefore, most cutting tools used in industrial applications are made of polycrystalline cubic boron nitride (PCBN).
PCBN Blanks Have High Hardness and Excellent Wear Resistance
CBN is artificially synthesized, with a hardness second only to that of diamond. The hardness of its grains can reach HV8000~ HV9000, which is much higher than that of ceramics and carbide. The hardness of PCBN composite sheets (usually HV3000 ~HV5000) mainly depends on the CBN content, which generally ranges between 40% and 95%.
As the CBN content increases, the hardness of PCBN increases. However, wear resistance does not have a monotonous relationship with CBN content; it varies under different processing conditions. When processing heavy-duty steel molds, a CBN content of about 55% results in the most wear-resistant tool.
PCBN Blanks Have Very High Thermal Stability
PCBN Blanks have a heat resistance temperature of up to 1400 ~1500℃, nearly double that of diamond (700-800℃). PCBN Blanks only begin to convert from cubic to hexagonal crystalline forms and start to soften above 1370℃. Tools made from this material can cut high-temperature alloys at high speeds, with cutting speeds 3-5 times higher than carbide tools.
PCBN Blanks Have Extremely Strong Chemical Stability
PCBN Blanks are chemically inert substances that remain stable in neutral and reducing gas media, resistant to acids and bases. They only react with carbon at 2000℃ and do not react with iron-based materials below 1200~1300℃. The bonding and diffusion interactions between PCBN Blanks and various materials are much smaller compared to carbide, making them suitable for cutting steel materials that cannot be cut by diamond.
PCBN Blanks have excellent thermal conductivity
The thermal conductivity of PCBN Blanks is 79.54w/m.k, second only to diamond (146.5w/m.k). As the temperature increases, the thermal conductivity of PCBN Blanks also gradually increases, aiding temperature control in the cutting zone and reducing tool wear from diffusion.
PCBN Blanks Have a Low Friction Coefficient
The friction coefficient of PCBN with different materials ranges from 0.1 to 0.3. A lower friction coefficient reduces cutting force and cutting temperature, minimizes the formation of built-up edges, and helps improve the surface quality of the machined material.
PCBN Blanks Tools Can Be Re-Ground
The polycrystalline cutting edges of PCBN tools are firmly embedded using advanced inlaying technology. Users can conveniently re-sharpen these tools on standard tool grinders using 180-240 mesh artificial diamond resin wheels, thus lowering tool costs.
PCBN is composed of numerous tiny, randomly arranged CBN single crystals without a cleavage plane and macroscopically exhibits no directionality. This greatly reduces the impact of cleavage and continuously exposes fresh crystals as the cutting tool wears. PCBN shares a similar structure and properties with PCD and PDC tool materials but is less wear-resistant.
Thanks to PCBN's good resistance to chemical corrosion and excellent thermal stability at 1200℃, the high temperature at the tool's tip does not adversely affect it. On the contrary, it can accelerate cutting when machining hard iron alloys. With ongoing advancements in cutting technology, PCBN Blanks tools are widely used for processing materials that are hard and difficult to machine.
PCBN Blanks Tools Can Replace Grinding with Turning for Hard Machining of High-Hardness Materials
With higher hardness and wear resistance, as well as red hardness, integral polycrystalline cubic boron nitride tools can replace grinding with turning for machining high-hardness materials.
Suitable for High-Speed and Ultra-High-Speed Cutting
PCBN tools are best suited for high-speed cutting of cast iron and hardened steel. The relationship between the wear of the tool's rear face and the cutting distance when PCBN tools cut cast iron and hardened steel shows that as the cutting speed exceeds a certain limit, the wear rate of the rear face of the PCBN tool decreases, thereby increasing the tool's lifespan. This is particularly advantageous for modern high-speed cutting processes.
Dry Cutting
Using PCBN Blanks tools for dry cutting reduces environmental pollution. Coated or ceramic tools require wet cutting, which makes iron chips hard to clean. With PCBN Blanks tools, large volumes of high-hardness cast iron can be cut without cutting fluid, ensuring a cleaner workspace and facilitating the recycling of iron chips.
Suitable for Automated and Difficult-to-Machine Material Processing
PCBN tools have high hardness and wear resistance, allowing for the long-term high-speed machining of high-precision parts, significantly reducing the frequency of tool changes and the downtime needed for tool wear compensation. Therefore, PCBN tools are ideal for CNC machines and highly automated processing equipment, maximizing the efficiency of these machines.
In recent years, with the rapid development of CNC (Computer Numerical Control) machining technology and the widespread use of CNC machines, the application of PCBN tools, which offer high efficiency, high stability, and long tool life, has become increasingly common. Many advanced machining concepts such as high-speed cutting, hard machining, replacing grinding with turning, and dry cutting have also been introduced. PCBN tool materials have become indispensable in modern cutting processes.
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