This kind of screw has a drill tail tip and is named after a twist drill. When assembling, the screw can drill the central hole by itself, and then tap and extrude the matching thread in the hole on the carrier with the help of the adjacent thread part, so it is called self-drilling and self-tapping screw. See the style below.
Its implementation standards are GB/T 15856. 1-2002, DIN7504N- 1995, JIS B 1 124-2003.
According to the purpose and shape, it can also be divided into the following categories:
1) Cross recessed pan head self-drilling self-tapping screw
2) Cross recessed countersunk head self-drilling and self-tapping screws
3) Cross-grooved semi-countersunk self-drilling and self-tapping screws are close to the countersunk screws above.
4) Self-drilling and self-tapping screws with hexagon flange surface
5) Hexagon flange self-drilling
Self-tapping screws can be divided into steel 1022A, stainless steel 4 10 and stainless steel 304 according to materials.