As a common part of fasteners, screws are widely used, and their types can be divided into many types according to different methods. The following small series summarizes and shares the following six types of methods according to the understanding of screw knowledge.
Machine screw: its external thread is screwed with the corresponding internal thread.
Self tapping screw: there are only external threads. The screw itself has high hardness. When there is no thread in the forming hole of the main part, it is self tapped into thread during assembly.
2. According to production standards: American system (ANSI), international standard Huai (ISO), Japanese system (JIS), German system (DIN) and yellow system (BSW). (for non-standard parts, screw manufacturers can generally produce according to customer requirements)
3. By head shape:
Common head types of screws are indicated by the following letters:
(1) Cylindrical head-c (cheese)
(2) Spherical column head-b (binding)
(3) Basin head (flat round head) - P (Pan)
(4) Flat round head-t (truss)
(5) Countersunk head-f (flat)
(6) Oblate countersunk head-0 (oval)
(7) Round head-r (round)
(8) Hexagon-h (hexagon)
(9) Hexagon washer head HW (Hexagon washer)
(10) Basin washer head PW (pan washer)
4. According to the head groove type: i-groove, cross groove, square socket, hexagon socket, I / cross, triangular groove, i-groove, etc.
5. According to the number of screw threads, it can be divided into: A. steel teeth, fast teeth (single wire, double wire), high and low teeth and triangular teeth of self tapping screws; B standard pitch thread of machine screw.
6. According to the screw material, it is divided into plastic screw and metal screw (low and medium carbon steel, alloy steel, copper, aluminum, kick, stainless steel, etc.).