Spiral drill for processing e.g. grey cast iron, includes clearance surface arranged in cutting edge direction behind primary cutting edge, where clearance angle of surface in area of corner is twelve degrees

摘要

The drill includes a clearance surface, which is arranged in a cutting edge direction behind a primary cutting edge (2), where a clearance angle (alpha 1) of the surface in an area of a corner is 12 degrees. The cutting edge is rounded by brushing, where the round of the cutting edge has a radius of 0.05 millimeter (mm). The corner is formed as circular arcs with specified radius.