In drilling, this problem can be caused by using the wrong type of drill or a dull or incorrectly sharpened drill, or by an excessively light or slow drill feed
, among other factors.
When rotated at a high speed and pressed with high axial force into sheet metal or thin walled tube, generated heat softens the metal and lets the drill feed
forward, produce a hole, and form a bushing from the displaced material.
Thereafter, whenever the set torque limit is reached the drill will again retract and return at fast speeds, resuming normal drill feed
speed as it re-enters the workpiece.
The carbide tipped drills were run at a cutting speed of 60 m/min (197 ft/min) and a drill feed
The hydraulic system for operating drill feed
is self-contained and includes an oil reservoir.
Changing from AISI/SAE low carbon mild steel at 20,000 psi tensile to stainless in the 70,000 to 120,000 psi range, alloy steels such as 4130 with 70,000 to 200,000 psi, or titanium alloys with 130,000 to 190,000 psi tensile, drill feed
thrust increases almost directly by this tensile difference.
Positioning speed of 98 ft/min coupled with the two-speed spindle motor and 12"/min variable drill feed
rate assure fast, accurate hole making.
Reaming feeds: Feeds for reaming are usually much higher than those used for drilling, often running 200 to 300 percent of drill feeds