CBN turning tools are tightly sintered from boron nitride and tungsten carbide bases. The hardness of boron nitride is next to PCD. It has excellent chemical stability and will not produce affinity with iron, cobalt, and nickel-based metals. Therefore, it is especially suitable for work hardening steel, with a hardness above HRC45. Chilled cast iron and heat-resistant steel (Inconel) are also suitable.
In the machining industry, CBN tools and CBN inserts are often mentioned cutting tools, which are mainly used for the cutting and processing of difficult-to-machine materials and superhard materials. So what kind of tool can be called a CBN tool? What does CBN mean?
What Does CBN Mean?
The full name is Cubic Boron Nitride, which translates to: cubic boron nitride, and its color is generally black. It is an insulator and an excellent heat conductor. At present, the natural existence of this substance has not been found in nature. It is a synthetic superhard material.
CBN (cubic boron nitride) is a material whose hardness is next to diamond. It is a new type of inorganic superhard material, which has been widely used in the processing fields of different industries.
As the name suggests, CBN tool is a kind of tool made of CBN material, which is a new type of tool material developed in the early 1970s. Since cubic boron nitride can withstand high temperature of 1300~1500℃, CBN tools can perform high-speed cutting of iron-based metals under high temperature conditions without reacting, with high machining accuracy, low surface roughness, and 10 times higher cutting speed than cemented carbide tools.
CBN tools can cut and process quenched high-hardness steel and other high-hardness materials, and realize the function of turning grinding instead of grinding, which has a significant practical effect on small and medium-sized machining enterprises that do not have grinding machines. For example, Bot CBN tool not only has high processing efficiency, but also can avoid surface burn and surface hard force caused by grinding, which greatly improves the surface quality of the workpiece.
CBN tools are widely used in many metal cutting industries due to their excellent properties such as high thermal hardness, high wear resistance and not easy to stick to the tool. The applicable scope mainly includes the following difficult-to-machine materials: various quenched steels, such as carbon tool steel, alloy steel, bearing steel, die steel, high-speed steel, etc.; thermal spray materials, such as Ni-based, Fe-based two series products; Grinding cast iron: such as V-Ti cast iron, high phosphorus cast iron and chilled cast iron, etc.; some workpieces such as titanium alloys and heat-resistant alloys.
The CBN blade can be fixed on the tool holder by mechanical clamping or welding, or the CBN sheet and cemented carbide can be pressed together to form a composite PCBN tool. For example, installing a CBN tool on a machine tool with better rigidity can give full play to the performance of the CBN tool and use it in various machining processes, saving costs and improving production efficiency.
At present, CBN tools are widely used in many machining processes in the automotive, aerospace and medical equipment industries. If you encounter difficult-to-machine materials with high hardness, you may try it with a CBN tool.
Which Materials Are CBN Tools Suitable for Machining?
As mentioned above, CBN tools are often used for cutting ferrous metals, mainly including high-hardness cast iron/cast steel/forged steel, quenched steel, ordinary gray cast iron, powder metallurgy and other difficult-to-machine materials (hardness of steel requires HRC45 or more).
- High hardness cast iron/cast steel/forged steel: such as high chromium cast iron, alloy cast iron, nickel hard cast iron, white cast iron, high manganese steel, high speed steel and other materials can be processed, such as rollers, slurry pump casings, impellers, guard plate, lining plate, etc. are all typical parts. The overall polycrystalline CBN tool is mainly used for machining such workpieces, with a large allowance for cutting blanks, which improves production efficiency and reduces total production costs.
- Hardened steel: parts such as hardened gears/gear shafts, bearings, molds, synchronizers, ball cage universal joints, and hardened rolls are typical hardened parts with a hardness of around HRC60. High surface finish.
- Ordinary gray cast iron: such as engine block/cylinder head, brake disc, brake drum, pulley, clutch pressure plate, etc. are all gray cast iron materials. The use of CBN tools can advantageously replace the high-speed cutting of carbide inserts, and its cutting speed can be several times higher than that of carbide tools, and on the basis of ensuring high surface quality, the tool life is 10-20 times that of carbide inserts.
Which Processing Methods Are CBN Tools Suitable For?
- High-speed cutting: It is mainly reflected in the field of ordinary gray cast iron. Due to the rising price of gray cast iron raw materials, the competition with enterprises has gradually increased. Initially, the maximum linear speed of gray cast iron with carbide inserts cannot exceed 350m/min, otherwise, severe wear will occur. However, using CBN tools to process gray cast iron can reach a maximum linear speed of 1500m/min (without considering the rigidity of the machine tool), and ensure high wear resistance and high workpiece surface quality.
- Heavy-duty cutting: It is mainly reflected in the fields of high hardness cast iron/cast steel, such as rollers and pumps used in large equipment, and the machining allowance of blanks is large, and cutting tools with excellent wear resistance and impact toughness are required. Machining, and the CBN tool can reach a cutting depth of 10mm at a time, which greatly improves the production efficiency.
- Dry cutting: No matter what kind of material is processed, CBN tools are firstly processed by dry cutting. CBN tools have strong red hardness at high temperature and can withstand normal cutting at a high temperature of 1200 °C to ensure excellent durability. In addition, unnecessary costs caused by using cutting fluid to process workpieces are reduced, and a good production environment is guaranteed.
