Ceramic bit for high speed drilling

摘要

A ceramic drill bit comprising a cylindrical shank and a shaped portion extending axially in line with the shank and having a free end forming the tip of the bit, a relief face extending from each main cutting edge with a relief angle lying in the range 4° to 10° approximately relative to a plane perpendicular to the axis of rotation of the bit, and two notches forming two secondary cutting faces extending from the central edge with positive cutting angles lying in the range 10 to 70 approximately relative to the axis of rotation of the bit.