1. The selection principle of cutter tooth material should be based on the load and cutting state of each tooth. The central teeth suffer from large axial force, severe extrusion friction and bad cutting conditions. Therefore, YG or YW cemented carbide blades with high bending strength and impact resistance should be selected; YT alloy with good red hardness and high wear resistance should be selected for outer teeth and intermediate teeth due to higher cutting speed, and YT materials with high wear resistance should be selected for guide block. For general alloy steel processing, all cutter teeth material should choose a kind of comprehensive material, yt798 is currently used.
2. Cutter tooth size selection principle cutter tooth size is mainly selected according to the cutting load of each cutter tooth in the cutting process, and the cutting load is related to the cutter tooth width, and the cutter tooth width should be distributed according to the cutting state of each cutter tooth and the size of drill bit diameter. There are three conditions for the distribution of cutter tooth width: A. ensure that the eccentricity of drill point E = (0.1 ~ 0.2) d0. The value of E is related to the material to be processed and the diameter of the bit, and its size determines the magnitude and direction of the radial resultant force of the bit. The reasonable eccentricity can make the appropriate radial force press on the wall of the machined hole, which can stabilize the drilling, strengthen the guiding and improve the surface quality of the hole. At the same time, it avoids the zero cutting of the drill point and improves the bad cutting conditions at the drill center; B, a + C + e + F > d0 / 2 + (1 ~ 2) mm, that is, there should be a certain amount of overlap between the cutter teeth; C, a + c-e-f > (1 ~ 3) mm, which can make the cutting radial force always press the guide block, and push the guide block close to the machined hole wall, and make full use of the guiding function of the guide block to ensure the straightness of deep hole drilling.