The hottest optimized coating helps tools improve

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Optimizing coating helps tools improve competitiveness

the quality of coating plays a vital role in tool production. Only by comprehensively considering all factors in tool design and production, such as tool geometry, application conditions, etc., can the overall competitiveness of enterprises be improved

it is worth noting that at present, although coating plays a vital role in tool production, people still know little about the performance of coating, how coating is applied to specific fields, or how to make up for the insufficient tool shape to improve tool performance. Cemecon company has accumulated many years of production practice and experience, from which it is concluded that only by comprehensively considering all factors in the design and production of cutting tools, can producers be able to produce a successful product

at present, the industry still generally believes that coating the tool can prolong the service life of the tool. However, can the degree of tool wear be used as the only standard to judge whether the tool coating is good or bad? As can be seen from Figure 1, the answer is No. For tin coated tools with geometry (a), there is no obvious sign of improvement. By changing the orthogonal inclination of the tool by 1 (b) and changing the size of the clearance, it is not difficult to see that the service life of the tool is significantly prolonged

Figure 1 backward cutting technology and weak innovation ability have become the main obstacles affecting the structural adjustment and transformation and upgrading of China's manufacturing industry. The impact of tool geometry on HSS Tool Wear:

geometry a: s=6, μ= 5. Geometry b:s=5, μ= 6; Vc=67m/min, f=0.25mm, ap=2.5mm

this example shows that the geometry of the tool and the coating have complex interdependence. Another factor affecting performance is cutting speed. Only under the conditions of accelerated cutting speed and the resulting super cutting load, including high temperature thermal stress, can the benefits of coating become obvious. Therefore, only when people pay the same attention to the geometry, matrix material, coating and application conditions of cutting tools, can a successful and economical cutting tool be developed. At the same time, the application of the coating will affect the formation process of chips on the cutting edge, and the friction and thermophysical properties of the coating will change the flow velocity, thickness and curvature of chips. The presence of the coating reduces the heat transferred to the tool. This fact leads to great changes in chip temperature. For example, the application of TiAlN coating with low thermal conductivity will directly affect the formation of chips and raise the temperature of chips

Fig. 2 Effect of HSS Tool Coating on the thickness of deformed debris

material: 34CrMo 4V, vc=30m/min, f=0.2mm, ap=2.0mm

there is a misleading discussion in the industry that some coatings have low thermal penetration values (similar to the concept of thermal conductivity), but the tool actually has no real thermal protection. This shows that even if the thickness of the coating reaches several microns, the cutting edge of HSS Tool is still not protected and has never reached the heat resistance strength of cemented carbide base material. However, in fact, when the coated tool is used, a very low temperature is actually measured on the blade (Fig. 3)

Figure 3 Effect of coating on HSS bit temperature

material: 42CrMo 4V, coating: tin, 2 μ m. F=0.1mm

anti wear coating

a basic function of the coating is to effectively protect the tool and inhibit the tool from various wear. People often say "the harder the better", thinking that the higher the hardness of the coating, the better the effect. However, this generally accepted statement is questionable. Generally speaking, the hardness of the coating depends largely on the temperature. When the temperature exceeds 500 ℃ (this temperature is easy to reach at the cutting edge), the temperature value of many coating materials cannot be compared with the test value at room temperature. In addition, once the temperature rises, the specific coating will no longer have mechanical stability and begin to oxidize

new tool surface shape

nowadays, the usual coating thickness is within the micron size range, and the sixth coating process basically shows the original surface morphology of the tool. In other words, after coating, the original rough tool surface is still rough. But if you observe it through a microscope, the situation will be different. Some special coating processes can produce a smooth coating surface that is virtually free of defects, while others can only produce a rough surface quality with particles (droplets). For many applications, this roughness is not very critical. However, in deep hole drilling, because chip flow is very important, the rough coating will bring problems. There are only two solutions: one is to choose a "smooth" coating; The second is to provide composite coating with lubricating layer for cutting tools

in depth understanding of coating

another factor that cannot be underestimated is the thickness of the coating. Generally, the coating thickness is several microns. However, in specific applications, in order to obtain the best performance of the tool, sometimes it is necessary to coat the tool with an ultra-thick or ultra-thin coating. For example, an ultra thick coating is more resistant to pure abrasion, while an ultra-thin coating can withstand the alternating load when it is strengthened. A few years ago, the typical golden tin coating was just a simple structure with a single component. No one talks about composite coating, nano coating or ladder structure coating. Now the situation has become more complicated. Targeted control in the coating process will lead to changes in the coating structure and components, thereby significantly changing the performance of the coating. The most typical example is tialcn, a multi-component coating. As long as the coating process is adjusted, its hardness and ductility can be directly affected. The residual stress of the coating plays a crucial role. In other words, even the same coating component can obtain different coating quality

today's coating or tool manufacturers must have the ability to adjust the internal structure of the coating. Only in this way can they finally obtain optimized application efficiency

as a popular saying in the industry, the universal coating is actually discounted in the coating design, in order to obtain good efficiency in a wide range of applications. However, for a specific field, such a coating can only be an alternative to significantly improve the reliability level of products. Only those coatings that really meet the specific needs of tools and application conditions can achieve substantial specific application effects. Nowadays, we can't expect to get the best performance just by taking the coated products printed on the product samples into the actual application. The coating has also been shortened and the forming cycle is regarded as an integral part of the tool. Just like the geometry and base material, it should meet the specific application conditions and be optimized. Due to the complexity of modern coating material design and the universality of functions, if we want to truly make the end users fully obtain 100% of its use value, we must rely on the technical knowledge of both tool manufacturers and coating experts

it is certain that the general standard coating will have a foothold for processing applications in the future. However, in modern high-performance production, only the tools with optimized coating can improve the competitiveness of enterprises in the market. (end)

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