BTA Drilling is a process developed in more recent years, with BTA drilling the coolant is introduced around the drill tube at the pressure head, and chips are evacuated through the center of the drill. The detachable drill head is comprised of individual carbide inserts and guide pads. Very high penetration rates can be achieved with this system along with good surface finish. Diameters as small as 12.7 mm or as large as 75 and counter boring upto 150 + mm can be produced with this type of system.