Application of diamond-like carbon coating on cutt

Application of star arc diamond like carbon coating on cutting tools

diamond like carbon (DLC) is a coating containing diamond components in microstructure. The element constituting DLC is carbon. The different bonding modes between carbon atoms and carbon atoms ultimately produce different substances: Diamond - carbon carbon combines in the form of SP3 bond; Diamond like carbon (DLC) - carbon combines in the form of SP3 and SP2 bonds; Graphite - carbon carbon combines in the form of SP2 bond

due to the diamond component, DLC has many excellent characteristics: high hardness -60gpa or above hv6000; Low friction coefficient -0.06; Excellent film compactness; Good chemical stability and good optical properties. DLC coating applied to cutting tools shows special properties far more than other hard coatings. The main applications of DLC coated tools include: Graphite cutting, cutting of various non-ferrous metals (such as aluminum alloy, copper alloy, etc.), cutting of non-metallic hard materials (such as acrylic, glass fiber, PCB materials), etc

Fig. 1 different bonding methods between carbon and carbon bonds lead to different products. The strain at a certain point of an elastic element is proportional to the force on the elastic element.

Star arc coating. DLC series coatings developed for different applications on tools are suitable for specific applications such as drill bits, milling cutters, taps, blades and various forming cutters

in the application of aluminum alloy cutting, due to the viscosity of aluminum material, material adhesion will soon form on the cutting surface of the tool, resulting in the main disadvantages of the two transmission modes of the machined surface: the former requires regular lubrication, and the processing quality will decline. As for the tool itself, due to the accumulation of the metal being cut on its surface, the temperature rises sharply, which eventually leads to the tool failure soon. The comparative test shows that the blade coated with star arc DLC coating solves the adhesion problem of aluminum to a great extent, ensures that the machined surface of the machined part always maintains high quality, and the tool life is also greatly improved. In addition, due to the above characteristics of DLC coated tools, users can also improve the processing speed, which greatly improves the processing efficiency (about 25% - 40%). The successful application of star arc DLC coating on cutting tools provides a good solution for aluminum alloy processing industry, especially automobile manufacturing industry

Figure 2 Comparison of adhesion of aluminum on coated and DLC coated blades

similar application results are also reflected in the cutting performance of acrylic materials. Non metallic materials such as acrylic have the characteristics of high hardness and low melting point compared with metal materials. During the cutting process, the cutting tool without coating (or coated with other hard coatings, such as tin, TiAlN, etc.) is blocked due to the melting or semi melting of the material cutting due to the processing temperature, which eventually leads to the actual effect of the cutting tool, and the surface quality of the processed material cannot meet the requirements and other quality defects. Acrylic cutting tools coated with star arc DLC can solve the above problems. Star arc DLC not only has high hardness (hv3500), but also has a very low friction coefficient (~0.08), which greatly reduces the heat generated by friction during the cutting process and enhances the cutting performance, thus increasing the average service life of the tool by 3 times, and the surface quality of the machined acrylic tool is much better than that of uncoated or other coated tools

Figure 3 Comparison of surface roughness of the machined surface

graphite processing is different from the processing of other metal materials. Due to the high hardness of graphite materials, the powder layer produced after processing has strong wear performance, so although the size of samples used in the market is very small, none of the commonly used hard coatings can solve this problem. The main reasons for the operation of the original Jinan testing machine include: the friction coefficient of ordinary coatings (such as TiAlN, tin, etc.) is high, and the heat generated in the processing process is that the tool will soon fail. Secondly, the coating will react with the carbon of graphite itself to form carbides, which will destroy the structure of the coating material and make it invalid. The actual application data shows that the service life of cemented carbide milling cutter with star arc DLC can be increased by 4 times, which is particularly prominent on props with a diameter of less than 10 mm

Figure 4 star arc DLC forming cutter for processing acrylic materials

with the gradual expansion of the application market of DLC coated cutters and the development of various DLC subdivision processes for different applications of star arc coating, this emerging coating will be adopted by more users and industries in the near future