Drill Bit with a Helical Groove Edge for Clean Drilling of Carbon Fiber-Reinforced Plastic

Abstract This paper presents a new drill bit with a helical groove edge for drilling carbon fiber reinforced plastic (CFRP). The drill has double point angles, a helical flute, and a helical groove edge away from the drill point angle. The helical groove edge has the same rotational direction as the flute angle direction of the drill bit. With the help of the additional cutting action of the helical groove edge, the drilled holes showed eliminated burrs, reduced delamination, and decreased tearing. An analysis was conducted for the burr removal mechanism and thrust force model acting on the chip area. The experimental verification assures that the drill can produce good quality of the hole’s surface, entrance, and exit, even after long service life.