Why Drill Metal with Annular Cutter (Mag Drill Bits) in Magnetic Drill?

Why Drill Metal with Annular Cutter (Mag Drill Bits) in Magnetic Drill?

Since an annular cutter removes only the material at the periphery of the hole, it is 3 to 4 times faster than twist drill bit. Besides, an annular cutter with pilot pin can finish a hole by one operation without pre-drilling for a pilot hole.