Application status and development trend of the ho

2022-08-10
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Application status and development trend of coated tools

coating technology is one of the main means to improve tool performance. The coating improves the ability of cutting tools to resist wear with a compound annual growth rate (CAGR) of 20.6%, extends the service life of cutting tools, improves the surface accuracy of machined parts, and also improves the cutting speed and feed speed, thereby improving the metal cutting efficiency. Today, among the cemented carbide of the mainstream materials of cutting tools, coated cemented carbide tools account for 80%, of which CVD (chemical coating) accounts for 60% - 65%, and the rest are PVD (physical coating)

in terms of CVD coating, the multilayer composite coating of various compounds including TiCN, tic, tin, zrcn and Al2O3 has a good effect on improving the comprehensive properties of the coating, such as bonding strength, toughness, wear resistance, wear resistance and corrosion resistance. Now the typical vcdtin (outer layer) + Al2O3 (middle layer) + TiCN (inner layer) multilayer structure is further improved in terms of coating technology and film thickness. Mtcvd (medium temperature chemical coating) has low process temperature and fast deposition rate, which makes the interface between the coating and the substrate brittle η At the same time, it reduces the tensile cracks caused by high temperature, which are common in high temperature CVD coatings. Therefore, mtcvd TiCN coating has become a major component of CVD multilayer coatings. This mtvcd has been used in α- Al2O3 coating, such as iscar's α- IC9150、 α- IC9250、 α- Ic9350 and α- Ic4100, etc., improve the bonding strength between the coating and the substrate and the ability to resist rear wear, front wear and adhesion

in terms of PVD coating, it has also developed from a single tin or TiCN or TiAlN coating to the current composite coating, namely hard coating + soft coating. In order to meet the requirements of higher cutting speed and dry cutting, the red hardness of coated tools has become a hot spot in the development of PVD technology in recent years. The improved coating of TiAlN AlTiN increases the content of Al in the film (Al content is more than 50%), and improves the red hardness, chemical stability and oxidation resistance of the coating, such as iscar al-ic910 (processing cast iron and steel), al-ic900, al-ic930 (processing steel, stainless steel, hard steel, cast iron, superalloy, etc.)

an important feature of the development of modern tool coating is compounding. In order to improve its comprehensive performance, coating material compounding, coating layer compounding and CVD and PVD compounding, such as iscar dt7150 (k05-k25) through mtcvd Al2O3 and PVD TiAlN composite coating, improve the comprehensive performance of the material, which is used for high-speed processing of gray cast iron and ductile iron. Diversification is another trend in the development of tool coatings, including various nitride and oxide coating materials, as well as TiB, Sn coating, diamond coating, cubic boron nitride coating and so on. The deep-seated reason for diversification is specialization, that is, different coatings are adopted for different needs, and the composition, percentage, structure and thickness of the coating can be controlled in a wider range. These extrusion equipment will soon become indispensable or irreplaceable equipment and changes due to special technology, so as to adapt to different processed materials and different cutting conditions, so as to significantly improve the cutting performance of tools. For example, CrAlN coating, which replaces Ti with Cr, has a hardness of 3200hv and an oxidation temperature of 1100 ℃. Compared with TiAlN, it has better toughness and is more suitable for intermittent cutting and machining of difficult to machine materials; The coating with Si element instead of Al element can obtain TiSiN for hard cutting and CrSiN with lubricity, which is more suitable for processing materials with strong adhesion such as aluminum and stainless steel. In addition, the refinement of coating materials is another interesting trend in the development of modern tool coatings. Nanocomposite coatings are being applied in more and more places. In the future, the tool coating will be a systematic concept, that is, the tool coating must be combined systematically according to the changing modern cutting application conditions. This is a system engineering method that is completely different from the traditional concept of "coating a layer of film on the tool", which requires us to think systematically

overview of the progress of tool coating

modern cutting is facing the continuous development of high-speed, high-efficiency, high-precision machining requirements and more and more high-level materials such as high strength, high toughness and difficult to cut. In addition, the cutting requirements such as hard machining and dry cutting are changing with each passing day, which makes it difficult for cutting tool materials to meet the increasingly complex requirements of comprehensive cutting performance. If the overall performance of the material meets the requirements, it is not only extremely uneconomical in the use of resources, but also highly difficult and even difficult to achieve in terms of material technology. Considering that the surface effect is the primary characteristic in the cutting process, the comprehensive cutting performance of cutting tools can be given by the method of material surface modification technology. Practice shows that chemical vapor deposition (CVD) and physical vapor deposition (PVD), as one of the surface modification technologies of tool materials, have achieved very ideal results in the application of modern cutting tools. Especially PVD, because its process temperature is lower than CVD, it will not affect the performance of tool substrate, and the change of process scheme is flexible. Its application is becoming more and more extensive, and it has become one of the core technologies of modern tool manufacturing. Therefore, it can be said that the development of modern tools has become the driving force for the development of tool coating, and created an extraordinary development space for it, And almost all enterprises engaged in coating equipment manufacturing and coating services in developed countries have been attracted to China, forming a situation in which a group of Heroes rise together. This is why the tool coating has developed rapidly both in quantity and technical level in the past two years, and has indeed promoted the development of coating technology and production in China

at present, a single coating obviously cannot meet the requirements of modern tool performance. Multicomponent composite coating with high wear resistance and low friction coefficient, multilayer coating and gradient coating with high toughness and impact resistance, composite coating with oxide film thermal barrier top layer and heat resistance and thermal shock resistance, multilayer coating of nano components (particles) with comprehensive properties of wear resistance, heat resistance, low friction and high toughness, pure diamond coating for processing fiber reinforced composites, As well as all kinds of proprietary technologies (patents) with special functions of personalized coatings (such as human implant coatings) have emerged. On the other hand, the tool coating also reacts on modern tools, making the technical level of modern tools constantly leap to a new level, achieving the effect of mutual promotion and common development

in terms of coating equipment, the highly integrated, modular structure and intelligent operation not only realize the modernization of the equipment; At the same time, it can make the process fine, adjust freely, have high stability and high reliability, so it can achieve lean production and clean (green) production of coating, which is an effective means to ensure that modern cutting tools become high-tech products, leading to the continuous emergence of new materials, and putting forward higher requirements for the design of fixtures

it can be expected that the tool coating of our country will enter a rapid development period in the near future, and there will be more and more high-performance coated tools processed by our country, which will play an increasingly important role in continuously improving the cutting technology level of our country and developing our modern manufacturing industry

the latest development of tool coating

from CVD tin/tic/TiCN first adopted in 1970 to PVD coating technology since 1980, modern coating technology has been widely used in tools, molds, parts and decorative products. The use of coating technology can effectively improve the service life of cutting tools, make the tools obtain excellent comprehensive mechanical properties, and greatly improve the machining efficiency. Therefore, coating technology, together with materials and cutting process, is called the three key technologies in the field of cutting tool manufacturing. Compared with tic, TiCN, CrN, TiAlN and tialcn, which are widely used now, in order to meet the requirements of modern machining for high efficiency, high precision and high reliability, the next generation of coating technology will develop to high-performance coating technology. The latest generation of high-performance coating developed by it is specifically for high-end tools, especially cemented carbide tools; High precision, high speed and large cutting quantity machining tools of modern CNC machine tools; Dry cutting; High efficiency processing, mass production and other occasions. Milling cutter and gear hob have good performance. The composite coating (tin+dlc, ticn+dlc, altin+dlc) developed for drilling cutters adds DLC coating (diamond-like carbon coating) on the basis of the original coating, so as to obtain an extremely smooth surface, reduce the friction coefficient, and fundamentally solve the problem of chip removal in deep hole machining, which leads to the occurrence of out of tolerance of hole size. AlTiN can reduce the machining torque by more than 50%, thus greatly improving the performance of tools. Based on TiSi coating materials, it is aimed at high-speed cutting of hard and difficult to machine materials

the application of high-performance coating on hobs includes high-performance coating containing Si, which is specifically aimed at Gear Hobbing with processing speed greater than 120m/min and requires high-speed and efficient batch production. The coating is for high-speed dry cutting; Coating refers to the coating required in. In a group of dry cutting hobbing experiments with a processing speed of 180m/min, the number of gears that ordinary AlTiN can produce is 980/cutter, while the number of gears that can be produced is 2000, and the tool life is doubled

coating manufacturers should provide customized coating parameter design according to the actual situation of customers on the basis of fully understanding the customer's product application, demand, processing parameters and equipment conditions, so as to maximize the performance of the coating, achieve the best service life of tools, and enhance the communication and cooperation with customers. It is extremely important in the actual coating service process

reduce cutting pollution

about 70% of the premature failure of various electromechanical products is caused by wear and corrosion, and these two failure modes are closely related to the surface state of materials (physical, chemical, stress state, etc.). Therefore, the key to improve the performance of these materials is to improve their surface properties

with the development of science and technology, the requirements for surface properties of materials are becoming higher and higher. In recent decades, with the rise of various vapor deposition technologies, the research and application of surface engineering technology have made rapid progress. These technologies not only meet the requirements of mechanical properties, such as wear resistance, friction reduction and corrosion resistance, but also play an important role in the field of functional materials related to the surface layer, such as electromagnetism, optics, optoelectronics, thermology, superconductivity and biology. Surface engineering not only makes low-cost metal materials play a greater advantage in performance and efficiency, but also has become an important means to develop various new coating and film materials, which has great application potential

with the improvement of machining industry, new requirements are put forward for cutting tools. In addition to improving the service life, it is also required to reduce the pollution during cutting and use dry cutting as much as possible. When the cutting fluid cannot be completely eliminated, try to make it contain only rust inhibitor and no organic matter, which can greatly reduce the cost of recycling

the diversity of cutting tools and the working state characteristics during use determine the difference in the selection of tool coating. Turning and drilling are different, and the characteristics of intermittent impact of milling cutter should be considered. The coating developed in the early stage takes wear resistance as the main focus and hardness improvement as the main index. This kind of coating, represented by titanium nitride, has a high friction coefficient (0.4 ~ 0.6), and continuous friction with the workpiece during processing will produce a lot of heat energy. To avoid over cutting

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