Self-drilling screws (also known as tek screws) drill their own hole in thin sheet metal, heavier gauge metals and other materials; then form close mating threads in the hole.  Self-drilling screws are ideal for automated assembly and reduce or eliminate the need for drill bits or taps. Once the hole is drilled, self drilling screws tap the hole in the same way as thread forming or thread cutting screws do in a pre-drilled hole. They are also designed to eliminate paint build-up, weld flash, or foreign material that may occur in pre-drilled or pre-punched holes.