However, so far, foreign coating companies with mature technology and good economy are limited to European companies. 4 Tool edge strengthening The passivation of the tool edge is a very important issue that has not been widely valued by people. The cutting edges of cemented carbide tools after being sharpened with diamond grinding wheels have microscopic gaps (that is, micro chipping and saw teeth) with different degrees.

The high-speed cutting of graphite puts forward higher requirements on the performance and stability of the tool, especially the diamond-coated tool, which must be passivated by the cutting edge before coating to ensure the firmness and service life of the coating. The purpose of tool passivation is to solve the problem of microscopic gaps in the edge of the tool after sharpening, reduce its sharpness, and achieve the purpose of smooth and smooth, both strong and durable. 5 Cutting conditions The choice of cutting conditions has a considerable influence on the tool life. 5.1 Cutting method (Climbing and Up-cutting) The cutting vibration of down-cutting is smaller than that of up-cutting.

During down milling, the cutting thickness of the tool is reduced from the maximum to zero. After the tool is cut into the workpiece, there will be no spring knife phenomenon caused by the chip that cannot be cut, the process system has good rigidity, and the cutting vibration is small. Increase from zero to the maximum. In the early stage of tool cutting, due to the thin cutting thickness, a path will be scratched on the surface of the workpiece. At this time, if the cutting edge encounters a hard point in graphite material or swarf particles remaining on the workpiece surface

, The flutter or chatter of the tool is caused, so the cutting vibration of up milling is relatively large. 5.2 Blowing (or vacuuming) and immersing EDM fluid processing Cleaning the graphite dust on the surface of the workpiece in time is conducive to reducing the secondary wear of the tool, prolonging the service life of the tool, and reducing the impact of the graphite dust on the machine tool screw and guide rail. 5.3 Other matters Select the appropriate high speed and corresponding large feed. Based on the above points, the material, geometric angle, coating, edge strengthening and cutting processing conditions of the tool play different roles in the service life of the tool. They are indispensable and complement each other. A good graphite tool should have a smooth graphite powder flute, a long service life, be able to carry out deep engraving processing, and can save processing costs.