Classification of CNC tool coating Traditional tool coating technology can be divided into two major categories, but due to changes in market demand and the characteristics of the coating technology itself, the development of physical coating technology has received greater attention. While PVD technology has achieved rapid development, its application market has also been extensively expanded. Compared with the initial development, there are not only a wide variety of coating components, but also a breakthrough in coating structure in recent years, which has been accepted by the market. As PVD technology becomes more and more widely used in the market, it is becoming more and more important to understand the characteristics and applicable fields of various coatings. Therefore, this article intends to classify the current PVD coatings and analyze the applicable fields of various types of films. The purpose is to allow users to have a more systematic understanding of various coatings and to use coated tools more reasonably. From the perspective of the development and application of PVD technology, the author believes that PVD coatings can be classified in two ways. 1. Classification by coating composition The classification of coatings by coating composition is concise and clear. Based on the understanding of material properties, users can easily understand the function of the coating and it is easy to be accepted by the market. Therefore, there are more coating companies at present. It is based on different coating components to introduce and recommend its technology and products to users. The distinction of coatings by composition can usually be divided into two categories, namely hard coatings and soft coatings. Hard coatings are represented by TiN, TiCN, TiAlN, etc., including single-layer films and composite films. With the changes in market demand and the development of coating technology, new coating components have been continuously developed, and they have been applied so far. There are dozens of hard coating components; the soft coating, as the name implies, the hardness of the film is relatively low, usually about 1000HV. There are not many types of soft coatings, mainly MoS2 and carbon-based films. In the field of cutting processing, the purpose is to cover a layer of this film on the hard coating surface to try to increase the lubricity of the coating surface and improve The surface quality of the workpiece to be processed can meet the needs of certain application fields. 2. Classification by coating structure Although the classification of coatings by composition has a good market foundation, from the perspective of the development of PVD technology, changes in the internal structure of the coating have increasingly affected the application effect of coated tools . The same coating composition and different structural forms can lead to completely different effects of coated tools. Therefore, understanding the current structure of PVD coating films is of great significance to the practical application of this technology. With regard to the current development status of PVD technology, the coating film structure can be roughly classified as follows: a. Single-layer coating The coating is composed of a certain compound or solid solution film. Theoretically speaking, the coating composition is constant in the longitudinal growth direction of the film. Yes, the coating of this structure can be called ordinary coating. If it is related to the development history of PVD, in fact, this technology has been used for a long time in the past, including the well-known TiN, TiCN, TiAlN , etc. With the continuous improvement of application market requirements, people are increasingly aware of the limitations of this kind of coating. Whether it is microhardness, high temperature performance, film toughness, etc., it is difficult to greatly improve, but this kind of coating still occupies the market. A certain percentage. b. Composite coating c. The structure composed of a variety of films with different functions (characteristics) can be called a composite coating structure film. The typical coating is the current hard coating + soft coating, and each layer of film has its own difference. The characteristics of the coating, so that the coating has a better comprehensive performance. d. The composition of the gradient coating changes gradually along the longitudinal growth direction of the film. This change can be a change in the ratio of each element of the compound, such as the change in the content of Ti and Al in TiAl-CN, or it can gradually transition from a compound to Another compound, such as the gradual transition from CrN to CBC. It can be foreseen that this structure can effectively reduce the increase of internal micro-stress caused by the sudden change of the composition. e. Multi-layer coating
What types of CNC machine tools are there? Advertisement
Classification of CNC lathes CNC lathes can be divided into two categories: horizontal and vertical. Horizontal lathes have two kinds of horizontal guide rails and inclined guide rails. High-grade CNC sleeping cars generally use inclined guide rails. According to the number of tool rests, it can be divided into single tool rest CNC lathes…
The multi-layer coating is composed of multiple films with different properties, and the chemical composition of each film is basically constant. At present, most of the practical applications are composed of two different films. Due to the differences in the processes used, the size of each layer of the multi-layer coating tools of different companies is not nearly the same, usually composed of more than a dozen layers of films, each The film size is larger than tens of nanometers, and the most representative ones are AlN+TiN, TiAlN+TiN coatings and so on. Compared with single-layer coating, multi-layer coating can effectively improve the coating structure and inhibit the growth of coarse grain structure. F. Nano multilayer coating The coating of this structure is similar to the multilayer coating, except that the size of each layer of the film is on the order of nanometers, which can also be called an ultramicrostructure. Theoretical studies have confirmed that in the nano-modulation period (several nanometers to tens of nanometers), compared with traditional single-layer films or ordinary multi-layer films, such films have super-hardness and super-modulus effects, and their micro-hardness exceeds 40 GPa It can be expected that the film can still retain very high hardness at relatively high temperatures. Therefore, this type of film has a good market application prospect, and its typical representatives are AlN+TiN, AlN+TiN+CrN coatings and so on. G. Nano-composite structure coating Nano-composite structure coating. Taking (nc-Ti1-xAlxN)(/-Si3N4) nanocomposite phase structure film as an example, under the action of strong plasma, nano TiAlN crystals are embedded in the amorphous Si3N4 body (see Figure 5), when TiAlN crystals When the size is less than 10nm , the source of dislocation multiplication is difficult to start, and the amorphous phase can prevent the migration of crystal dislocations. Even under higher stress, the dislocations cannot cross the amorphous grain boundary. The hardness of the film with this structure can reach more than 50GPa , and can maintain quite excellent toughness, and when the temperature reaches 900℃～1100℃, its microhardness can still be maintained above 30GPa ; in addition, this kind of film can also obtain excellent toughness. Surface quality, so the prospects for industrial applications are broad.
Post time: Aug-23-2021