Performance advantages and applications of the hot

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Performance advantages and application industry of PCD tools and PCBN tools

PCBN mainly processes ferrous metals with high hardness, such as hardened steel and cast steel (iron), powder metallurgy, which can withstand high temperature (above 1000 ℃), and the hardness is always 8000hv. It is a better tool material to improve production efficiency and process difficult materials. However, this material is not suitable for processing steel below 45hrc, which is prone to bonding wear and cracking

pcd is mainly used to process non-ferrous metals and non-metallic parts. Compared with aluminum parts, copper parts, etc., it can grind a very sharp edge and get a better processing surface. Generally, it can achieve a finish of 0.2. It is also the preferred material for processing new non-metallic materials. It has high wear resistance, low friction, and the hardness can reach more than 10000hv. It can cut high hardness products such as cemented carbide and industrial ceramics

performance characteristics of PCD tools

diamond tools have high hardness, high compressive strength, good thermal conductivity and wear resistance, and can obtain high machining accuracy and efficiency in high-speed cutting. The above characteristics of diamond tools are determined by the state of diamond crystal. In diamond crystal, the four valence electrons of carbon atom form bonds according to tetrahedral structure, and each carbon atom forms covalent bonds with four adjacent atoms, thus forming diamond structure. The demand of this international market is gradually increasing, and the structure has strong binding force and directivity, so that diamond has extremely high hardness. Because the structure of polycrystalline diamond (PCD) is a fine grain diamond sintered body with different orientations, its hardness and wear resistance are still lower than that of single crystal diamond, although the binder is added. However, because the PCD sintered body is isotropic, it is not easy to crack along a single cleavage plane

the main performance index of PCD tool material

the hardness of D can reach 8000hv, which is 80-120 times that of cemented carbide

The thermal conductivity of

d is 700w/mk, which is 1.5-9 times that of cemented carbide, and even higher than that of PCBN and copper, so the heat transfer of PCD tools is rapid

The friction coefficient of

d is generally only 0.1-0.3 (the friction coefficient of cemented carbide is 0.4-1), so PCD tools can significantly reduce the cutting force

The coefficient of thermal expansion of

d is only 0.9 × 10^-6——1.18 × 10 ^-6, which is only equivalent to 1/5 of cemented carbide, so PCD tools have small thermal deformation and high machining accuracy

d the affinity between the tool and non-ferrous and non-metallic materials is very small, and the chips are not easy to bond on the tool tip during the processing process to form chip nodules

Application of PCD tools

at present, the processing range of PCD tools has expanded from traditional metal cutting to stone processing, wood processing, metal matrix composites, glass, engineering ceramics and other materials. Through the analysis of the application of PCD tools in recent years, it can be seen that PCD tools are mainly used in the following two aspects: ① the processing of difficult to process non-ferrous metal materials: when using ordinary tools to process difficult to process non-ferrous metal materials, the defects of easy wear of tools and low processing efficiency often occur, while PCD tools can show good processing performance. ② Processing of difficult to process non-metallic materials: PCD cutters are very suitable for processing difficult to process non-metallic materials such as stone, hard carbon, carbon fiber reinforced plastic (CFRP), artificial board, etc. Processing these materials with PCD tools can effectively avoid defects such as easy wear of tools

cutting performance of PCBN tools

because CBN crystal and diamond crystal belong to sphalerite type, with similar lattice constants and the same chemical bond type, CBN has the hardness and compressive strength close to diamond, and because it is composed of N and B atoms, it has higher thermal stability and chemical inertia than diamond. The main properties of PCBN tool material are as follows:

it has high hardness and wear resistance

the microhardness of CBN single crystal is HV800, which is injected into the oil tank with 0-9000 oil. It is the second highest hardness material known at present. The hardness of PCBN composite is generally hv3000-5000. Therefore, when it is used to process high hardness materials, it has higher wear resistance than cemented carbide and ceramics, which can reduce the dimensional deviation or dimensional dispersion in the processing of large parts. It is especially suitable for high automation equipment, which can reduce the auxiliary time of tool change and tool adjustment, and give full play to its efficiency

has high thermal stability and high-temperature hardness

cbn's heat resistance can reach 1400-1500 ℃, and the hardness at 800 ℃ is the normal temperature hardness of al2o3/tic ceramics. Therefore, when the cutting temperature is high, the processed material will soften, and the hardness difference between the material and the tool will increase, which is conducive to cutting processing, but has little impact on the tool life

has high chemical stability

cbn has high antioxidant capacity, and does not produce oxidation at 1000 ℃, nor does it have chemical reaction with iron-based materials at 1200-1300 ℃, but it will hydrolyze with water at about 1000 ℃, causing a large amount of CBN to be worn out. Therefore, when wet cutting with PCBN tools, attention should be paid to the selection of cutting fluid types. Generally, wet cutting does not significantly improve the service life of PCBN tools, so dry cutting is often used when using PCBN tools

it has good thermal conductivity

the thermal conductivity of CBN material is lower than that of diamond but much higher than that of cemented carbide. With the increase of cutting temperature, the thermal conductivity of PCBN tool continues to increase. Therefore, the heat at the tool tip can be quickly transmitted, which is conducive to the improvement of workpiece machining accuracy

the best tool material for hard cutting technology

the finishing of hardened hardware (hardness above HRC55) is usually completed by grinding. However, with the development of tool materials and the improvement of machining accuracy of lathes (especially CNC lathes), it has become a new way of finishing parts by replacing grinding with hard cutting, This process method of turning instead of grinding has the following advantages:

(1) it can improve the processing flexibility, break through the limitation of grinding wheel grinding, and can process workpieces with different geometric shapes by changing the cutting edge and the way of cutting

(2) the environmental protection problem in cutting is becoming more and more serious. The waste liquid and waste produced by grinding are becoming more and more difficult to treat and remove, and are harmful to human body. It is of great significance that there is no need to add coolant in hard cutting

(3) high cutting efficiency, short processing time and low equipment investment cost can reduce the processing cost

(4) the energy consumed by cutting the same volume is only 20% of that of grinding, so the cutting heat is less, the machined surface is not easy to cause burns and micro cracks, and it is easy to maintain the integrity of the surface performance of the workpiece

(5) under the same metal removal rate, hard cutting saves energy compared with grinding

ideal tool material for dry cutting process

due to economic and environmental reasons, dry cutting method has become a key research topic in the field of mechanical manufacturing in recent years. Dry cutting technology has been widely used in western industrial developed countries

the tool materials suitable for dry cutting process include ceramics, cermet, coated cemented carbide, PCBN tool materials, etc., but in terms of red hardness and thermal stability, PCBN material is the most suitable tool material for dry cutting process

suitable for automatic machining and machining of difficult to machine materials

pcbn tools have high hardness and wear resistance, and can process high-precision parts for a long time at high cutting speed (small size dispersion), greatly reducing the number of tool changes and the time spent in tool wear compensation downtime. Therefore, when reversing, it is very suitable for CNC machine tools and processing equipment with a high degree of automation, and can give full play to the efficiency of the equipment

in the application of difficult to machine materials, PCBN tools also show their excellent performance, such as the processing of surface spray welding (coating) materials, processing with other materials tools, the tool life is very low, and the grinding method cannot be used for processing, while PCBN is the only suitable tool material; For another example, for high alloy wear-resistant cast iron used in oil power station equipment, the cutting efficiency of PCBN tool is more than 4 times higher than that of cemented carbide tool, and the cost of a single tool is reduced to 1/5 of the original. In addition, PCBN tools also show good cutting performance in the cutting of cemented carbide and other materials, which then convert the pressure signal into 4 ~ 20mA DC signal and output sintered materials

application examples of PCBN tools

because PCBN has high hardness and wear resistance, and does not react with ferrous metals at high temperatures, it is mainly used for cutting high hardness materials and difficult to machine materials, such as hardened steel, high alloy wear-resistant cast iron, high temperature alloy, high speed steel, surface spray welding materials, sintered metal materials and other difficult to machine materials

(1) machining hardened steel can achieve the effect of turning instead of grinding. Because the cutting depth is more than ten times greater than the grinding depth, the machining efficiency is high and the surface does not burn. For example, when the variable-speed sliding gear (20CrMnTi, hardness HRC58-62) is machined by turning instead of grinding, the cutting efficiency is more than 4 times higher than that of the original grinding

(2) machining high alloy (containing 18% tungsten or chromium) wear-resistant cast iron, the cutting speed is more than 10 times higher than that of cemented carbide tools, and the cutting efficiency is more than 4 times higher

(3) when machining high cobalt chromium molybdenum corrosion-resistant and heat-resistant alloy, the cutting speed of PCBN tool is 160m/min, which is 8 times that of cemented carbide tool

(4) when processing thermal spraying (spray welding) materials, the surface spray weldments cannot be ground, but the cutting efficiency of cemented carbide tools is very low. After using PCBN tools, the processing efficiency can be improved and the processing cost can be saved by more than 50%. PCBN tools can also be used for precision cutting of non-ferrous metals and machining of sintered metals

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