During coating process, the target is vaporized and gasified into tiny particles, these tiny particles deposit on the surface of the workpiece as coating. At the end of the deposition, the final deposited particles will protrude on the surface of the coating. In addition, the particles are in different sizes, so that there will be many particles of varying sizes protruding on the coating surface. As a result, the surface roughness of the coating is obviously increased, and the surface roughness has a great relationship with the size of the frictional resistance generated when the workpiece is working. Therefore, it is meaningful and necessary to remove the protruding particles on the coating surface to improve the surface roughness and reduce friction.
The post-treatment blasting refers to removing these protruded large particles from the coating surface by sandblasting, thereby improving the surface roughness of the coating. And then the cutting resistance encountered during processing will decrease.
The two figures above show the relationship between the drilling depth and the drilling resistance of two drills under the same coating conditions and different post-treatments. Through comparison, it was found that the drill's drilling resistance is high and low during the entire drilling process without post-processing, that is, when the drill bit is drilled, it will generate vibration, which will affect the drilling accuracy, and also the service life of drill bit will be reduced. But after sandblasting treatment, the drilling resistance is very consistent throughout the whole drilling process, and the drill bit has little vibration during the drilling process. This is because consistent surface roughness of the drill bit, low friction resistance and small bounce. In addition, the average roughness of the coating surface is also significantly reduced, and the service life of the tool is obviously increased.