Self-tapping screw is a kind of threaded fastener that taps and drills the mating female thread in the pre-drilled hole of metal or non-metallic material. It has the characteristics of high tensile strength, single piece and single side combination. Since it forms or taps its matching thread by itself, it has high anti-loosening ability in combination and can be assembled and disassembled. On small screws, its size, thread type, head type, and tapping performance are almost limitless in engineering applications.