Tungsten carbide step drill is also called as tow drill, which is mainly used in less than 3mm steel sheet drilling and can replace many drills. It can process pores with different diameters and large pore in one step, and do not replace the drill bit or drill positioning hole. According to the shapes of groove: It can be divided into straight groove, circular groove and spiral groove; according to the edges: Single-blade, double-blade, three-blade, four-blade and multi-blade step drill; the step drill has a standard, but most of are the non-standard customized.
Process reference: Straight shank step drills structure is relatively simple, and in the assembled state to work longer large diameter main positioning surface. So a large diameter axis as a reference not only to meet the functional requirements, but also in processing and analog reference checks easier;
Dimensional accuracy: The accuracy of large and small diameter (D, d) has a remarkable effect on the aperture. The process may be subjected to coarse grinding, grinding to control the drill diameter;
Position accuracy: In order to avoid over-tolerance, it should be positioned by the reference axis in sharpening process;
Surface quality: Surface quality mainly refers to the condition of the surface layer of the drill, including surface roughness and surface hardness, if not meet the requirements, it will affect the tool wear resistance, fatigue strength and corrosion resistance.