Current situation and Prospect of the hottest tool

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The present situation and Prospect of tool coating technology

coating the tool is a great change on the way forward in the machining industry. It is to coat a layer, two layers or even multiple layers of wear-resistant refractory compounds on the matrix with high toughness of the tool, so as to greatly improve the performance of the tool. Coated cutting tools can improve machining efficiency, machining accuracy, prolong service life and reduce cost, so they are widely concerned by countries all over the world

current situation

since the first generation of CVD vapor deposition tic cemented carbide cutters shared the achievements of innovative development in the late 1960s, the coating technology has played a great role in promoting the development of cemented carbide cutters. In the early 1980s, PVD vapor deposition tin was successfully applied to high-speed steel tools, which is known as a revolution in the performance of high-speed steel tools. Since then, the coating technology has made rapid development, the coating process is more and more mature, and the application range of coated tools is more and more extensive

the proportion of coated tools used in western industrial developed countries in indexable blades has increased from 26% in 1978 to 90% in 2005. About 80% of the tools used in new CNC machine tools are coated tools. The proportion of coated blades of Swedish Sandvik Clement and American Kenner metal company has reached more than 85%, the proportion of cemented carbide coated blades used in American CNC machine tools is 80%, and the coated tools used in turning in Sweden and Germany are more than 70%. Japan and Russia also take the lead in the development and application of coating technology in the world. China's coated cutting tools started late, but made rapid progress. The coating points are all over the country. Many cities have their own coating centers to undertake foreign processing business, and the factories and mines are not willing to be outdone. Several large domestic tool factories have more than 10 coating machines, but most of them are used in low-end products such as fried dough twist drills. Coating companies from Germany and other industrial developed countries have camped in China to engage in external processing of coated cutting tools. Due to the lack of resources and the high efficiency of machining, as well as the progress of numerical control technology and the increase of difficult to machine materials, coated cutting tools are moving forward passively at an alarming rate of development

new development of coating technology

looking at the development process of CVD and PVD technology, we can find several common laws. When the first generation of coating products enter the market, the first thing to be solved is the localization of coating equipment to meet the needs of the market; The second is to develop a new generation of coating components to improve the machining efficiency of cutting tools; The third is to develop multi-layer coating and control technology, so that the coated tool surface has the comprehensive mechanical properties of a variety of materials, and implement personalized services for cutting, pull milling and other different processing objects. The new development of coating technology is mainly manifested in the following three aspects:

1) diversification of film materials. At present, the coating materials most used are tic, tin, TiCN and Al2O3. And key strategic material technology, TiAlN ternary coating, which is the most widely used in cemented carbide coated tools, can obtain different film properties by adjusting the composition ratio of Al element. The coating material has developed from the original tic and tin monolayer to the current composite coating. With the emergence of composite coating and related technologies, the coating can not only improve the bonding strength with the matrix, but also have the composite properties of a variety of materials. The multi-component composite thin materials such as tin/nbn and tin/cnx developed in recent years have greatly improved the service life of coated tools. The diversification of coating process combination has brought multiple composite coatings such as TiAlN, tialcn, CrSiN, etc., which enable the tool to obtain excellent comprehensive properties such as high wear resistance, low friction, good thermal stability and oxidation resistance

2) the high hardness of soft coating layer is the main goal of the development of early coating technology with an operating profit margin of 5% in the fourth quarter. However, not all materials are suitable for hard coating. For example, high-strength aluminum alloy, titanium alloy and some valuable materials are not suitable for machining with hard coated tools, while soft coating can better solve the difficult machining problem of the above materials. Soft coatings mainly include MoS2, WS2, tas2, etc

3) nano coating recently, American scholars have developed nano coated tools. This coated tool can adopt different combinations of a variety of coating materials to meet different functional and performance requirements. A reasonably designed nano coating can make the tool material have excellent friction reduction and anti-wear functions and self-lubricating properties. It is suitable for high-speed dry cutting, especially for use in beds where plastic deformation of numerical control machines will be preserved for a long time. The nano hybrid film composed of AlTiN grains and amorphous Si3N4 nano components is representative. Its hardness can reach 45gpa, and the stability and oxidation resistance of the film can reach 1000 ℃

pvd and CVD will coexist for a long time

as early as more than 20 years ago, since PVD coating was put into industrial production, people have been exploring the problem of replacing CVD with PVD. After several twists and turns, imagination and practice have come to naught

although PVD has the incomparable advantages of CVD and can also carry out a variety of hard coatings other than a-Al2O3, the facts show that CVD turning and milling tools are still better than PVD. In the future, the two coatings will coexist and complement each other for a long time in the coating of cutting tools, and occupy their own share in the coating products because of their respective advantages. The two technologies can also be combined with each other, such as the PCVD coating technology currently applied

application of coated cutting tools

coating technology is widely used in machinery, electronics, optics, aerospace, chemical industry, light textile and food industry. The use of high-tech means can not only deposit all kinds of metals and alloys, but also deposit a variety of compounds, not only on the metal matrix, but also on non-metallic materials such as ceramics, diamonds, glass and even plastics. It is no exaggeration to say that coating technology has penetrated into all fields of the national economy, and its role and efficiency are obvious to all. People will see a wide variety of coatings at both domestic and foreign machine tool fairs The application examples of coating tools with different methods are numerous

several problems that should be paid attention to in coating

1) ideal tool material. The tool material used for coating must be ideal and good material, and cannot stay at the qualified level. As the saying goes, good steel should be used on blades. At present, the market of cutting tool materials is not standardized, good and evil people are mixed, and counterfeits and shoddy are rampant. When selecting and using materials, we should strengthen inspection and control all levels, otherwise all previous efforts will be wasted

2) hardness check if the tool with improper hardness is coated, the coating technology is no better than the world. For example, the coating effect is not necessarily good for high-speed steel cutters below 65hrc, 501 steel end mills with hardness greater than 68hrc, and so-called low-alloy high-speed steel drills. Through proper heat treatment, the hardness of the tool is controlled within the range of customer satisfaction, and then the ideal coating is applied, which will be the icing on the cake

jb/t "technical specification for titanium nitride coated tools" requires that the coating hardness of high-speed steel tools is ≥ 2000hv, but at present, many coating products in the market cannot reach this value, often decorative plating with low hardness, or the coating thickness cannot meet the requirements

3) demagnetization treatment should be carried out before demagnetization coating, because magnetism will affect the coating effect. (end)

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