Application Of CVD Diamond Coated Tools In 3D Glass -Ceramics - High-End Materials

The choice of diamond coating thickness is not "the thicker the better", the improvement of wear resistance, the quality of diamond coating is greater than the thickness of the role.

With the full explosion of the 3D glass market, the excellent performance of graphite materials in the application of 3D glass hot bending molds has been unanimously recognized by the industry, and due to the high wear and toughness of graphite materials, the processing environment of graphite molds is very strict, in order to ensure that the graphite molds have good precision, finish and stability, in addition to the need for quiet, In addition to the dust absorption capacity of the fuselage itself, graphite processing tools have also become the top priority in the processing process, and the selection of tools suitable for high-speed processing needs to be considered from the perspective of improving durability, reliability and safety, as well as the matching of the tool holder and coating materials with the tool and workpiece materials.

After continuous experiments and verification of various tool materials, the service life of CVD diamond coated tools is 8 ~ lO times that of cemented carbide, the allowable cutting speed of CVD diamond coated tools is 2 ~ 3 times higher than that of cemented carbide tools, the cutting edge is sharp and the consistency is good, the friction factor is low, and high-speed and high-precision machining of thin-walled graphite molds can be achieved under high speed and low feed. At the same time, the service life of CVD diamond coated tools is favored by various graphite processing manufacturers in many tool materials!

Chemical Vapor Deposition (CVD) diamond coating has many excellent properties close to natural diamond, such as high hardness, high thermal conductivity, low friction and low expansion coefficient, etc. When processing brittle materials such as graphite and carbon fiber composites, it has become the surface coating of cutting tools. It shows excellent performance in improving tool life and machining quality.

According to the grain size, CVD diamond coating can be divided into micron diamond coating and nano diamond coating. The grain size of micron diamond coating is usually between 500 nm and a few microns, which is formed by the competitive growth of columnar diamond grains. It has excellent characteristics such as high hardness and good surface wear resistance, which can significantly reduce the tool wear rate and improve the tool life.

However, the surface of the micron diamond coating is relatively rough (Ra value is usually several hundred nanometers), the toughness of the coating and the ability to crack propagation is poor, the surface crack is easy to spread along the grain boundary region to cause the coating to fall off, so that the tool surface has not reached the blunt standard before the coating has fallen off.

Nano-diamond coating is composed of nanoscale diamond grains distributed in clusters, the grain size is usually below 100 nm, the surface smoothness is good (Ra value is less than 100 nm), and the friction can be significantly reduced during the cutting process, thereby reducing the cutting force and cutting heat, and improving the tool life. Nano-diamond coating has good anti-crack propagation ability, however, compared with micron diamond, its bonding strength with matrix is relatively low, and it is easy to have abnormal failure such as coating falling off during processing.

The application of diamond coated cutting tools is mainly based on the properties of workpiece materials and processing quality requirements.

For EDM graphite mold processing, the essence of the milling process is similar to the "grinding" process, at this time, the number of "micro-cutting edges" on the tool surface is large and wear-resistant, and micron diamond coating with large grains should be selected.

For the mold used in ceramic processing, the surface finish is required to be high, and nano diamond coating should be selected in the finishing stage. In the processing of aluminum alloy, the severity of the "sticking knife" phenomenon is higher than the tool wear, and the requirements for the wear resistance of the tool are relatively low, and the nano-diamond coating with low friction coefficient should be selected.

For carbon fiber composite materials, due to the strong abrasive properties of the fiber material itself, the tool is required to have good wear resistance, but also to reduce the cutting force and cutting heat during the processing process, micro/nano composite diamond coating should be used.

In particular, the choice of diamond coating thickness is not "the thicker the better", the improvement of wear resistance, the quality of diamond coating is greater than the thickness of the effect.