Gun drilling is the oldest and most widely used method of deep hole drilling employed by industry today. The drill or “gun drill” is generally a one piece assembly consisting of a hollow cylindrical drill driver that is brazed to a V-shaped crimped tube and finally assembled to a brazed-on solid carbide drill head. Both the crimped drill shank and the brazed-on carbide drill head form a kidney shaped cross section, whereby the open V-shaped section acts as a chip flute.
In all cases, gun drills require filtered, high pressure coolant that is introduced through the center of the crimped gun drill shank and then directed to a coolant orifice in the carbide drill head. The high pressure coolant provides lubrication for the drill head and assures that all of the chips produced by the drill head are exhausted through the V-shaped chip flute of the gun drill shank. Gun drilling is better known as an internal coolant supply / external chip exhaust method of drilling.
Gun drills are generally used on single purpose gun drilling machines as well as on a variety of machining and turning centers that are equipped with sufficient high pressure coolant and filtrations systems. With this system of drilling, one can expect to drill to depths in excess of 100 x dia.
BTA Heller offers gun drills ranging from 0.055 to 2.000” diameter with several different carbide grades, coatings and cutting edge geometry options.