Definition
It has high hardness, thermal stability and chemical inertness, its thermal stability is much higher than diamond, and it has greater chemical stability to iron-based metal elements Therefore, it is often used in the cutting of ferrous metals. The use of cubic boron nitride blades is a major contribution to metal processing, leading to revolutionary changes in cutting, which is the second leap in cutting technology.
Types
According to the structure, it can be divided into welded composite cubic boron nitride blades and integral polycrystalline cubic boron nitride blades; the former is welded by cubic boron nitride composite layer to hard The alloy matrix is composed of various turning inserts or other boring tools, and the latter is an integral polycrystalline structure insert. The difference is shown in the figure "Cubic Boron Nitride Welding Composite Sheet" and "Cubic Boron Nitride Integrated Blade":
Material
According to the added components: directly from CBN single crystal Sintered PCBN and PCBN sintered body with a certain proportion of binder; according to the manufacturing compound method: there are two types of PCBN sintered block and PCBN composite sintered with cemented carbide. The PCBN composite sheet with adhesive is widely used. The hardness of PCBN is different according to the ratio of the added adhesive. The more the content of the adhesive, the lower the hardness and the better the toughness; the different types of adhesives, then The uses of PCBN are also different, as shown in Table 1 are common adhesive PCBN cutters and their uses.
CBN content (%)-binder type-main use
The tipped PCBN tool structure can be used for high-speed finishing and is suitable for intermittent processing of hardened steel.
～60－TiN－Quenched steel
～70－TiC－cast iron
～70－Al2O3－cast iron
～90－ AlN-high-strength cast iron
～80-Co-heat-resistant alloy steel cast iron
Development
The early cubic boron nitride blades were mainly welded composite sheets. Mainly, it is still widely used, and its characteristic is that it can realize high-speed and high-efficiency machining and even "turning instead of grinding". However, in the actual production of cutting, there are many intermittent machining of hardened steel, hard cast iron, gray cast iron, sand, In the fields of white cast iron, compound-welded cubic boron nitride (PCBN) blades are often chipped and punched, so integral cubic boron nitride blades have appeared.
Performance characteristics
Cubic boron nitride blades are mainly used in gray cast iron, wear-resistant cast iron, various high hardness materials (such as cold and hot work tool steel, high-speed steel, bearing steel, Powder metallurgy steel, powder smelted metal, martensitic stainless steel, high-strength steel, high-manganese steel, white cast iron, austenitic iron, etc.).
Application characteristics of welding compound cubic boron nitride inserts
Welding compound cubic boron nitride cutting tools are mainly used for finishing, due to their poor toughness , Impact resistance (brittle) is insufficient, can not withstand a slightly larger cutting force (related to the size of the tool angle), easy to collapse during intermittent processing, the depth of the tool (unilateral machining allowance) is best 0.2mm or less is better. High-speed cutting is used (low speed cannot be selected). This material has good wear resistance and heat resistance, but requires high sharpening.
The application characteristics of monolithic cubic boron nitride inserts
The monolithic cubic boron nitride inserts can be processed intermittently. Castings do not collapse. In actual production applications, if the welding compound cubic boron nitride tool collapses, or requires rough machining and finishing with a single knife, the integral cubic boron nitride (PCBN) blade is often used.
Outlook
As we all know, the three elements of the performance of decidingcutting tools are matrix material, tool coating and Geometric groove shape. Because of this, although China is a resource country of cemented carbide minerals, in terms of finished tool products, due to the technical gap in coating technology and groove design at home and abroad, although the same material is used for bar stock and tool blanks , The performance of domestic cemented carbide has always been constrained by large foreign tool brands. According to the physical properties of the cubic boron nitride material and the preparation process of the cubic boron nitride blade, it does not require any coating and complex geometries, and its performance is completely determined by the properties of its matrix, and its physical properties determine its unsurpassed advantages! Therefore, it is bound to bring a new cutting technology revolution, and as a pioneer in the localization of cutting tools.