MICRO STEP DRILL BIT

摘要

Disclosed in the present invention is a micro-step drill bit with a step unit. The disclosed micro-step drill bit comprises: a shank unit mounted on a holder of a drilling device; a main body unit integrally extended from one end of the shank unit; and a step unit integrally extended from the fore-end of the main body unit. The main body unit has a diameter of 75-350 micrometers while the step unit has a diameter of 50-70% of the diameter of the main body unit. A pair of chip discharge grooves is formed in a spiral shape on the outer circumferential surface of the step unit and the main body unit. The fore-end of the step unit includes: a pair of first cutting blades slantly extended toward both sides from a drill point; and a chisel edge formed between the pair of first cutting blades. A pair of second cutting blades which is slantly extended toward the outer circumferential surface of the main body unit from the outer circumferential surface of the step unit is formed between the step unit and the main body unit.