The self-tapping screw is composed of three parts: the head, the shank and the end of the shank from the beginning to the end. The composition of each self-tapping screw has four major elements: head shape, wrenching method, thread type, and end type.
①The shape of the head
There are various shapes of heads. There are round head (semi-round head), flat round head, round head flange (with pad), flat round head flange (with pad), pan head, pan head flange (with pad), countersunk head, semi-countersunk head, Cylindrical head, spherical cylindrical head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with gasket), etc.
②Wrench method
There are various ways of wrenching. External wrench: hexagonal, hexagonal flange surface, hexagonal flange, hexagonal flower shape, etc.; internal wrench: flat groove, cross groove H type, cross groove Z type, cross groove F type, square groove, compound groove, inner flower Key, inner hexagon flower (plum slot), inner triangle, inner hexagon, inner 12 angle, clutch slot, six-blade slot, high torque cross slot, etc.
③Type of thread
There are many types of threads. There are self-tapping threads (wide thread), machine threads, drywall screw threads, fiberboard screw threads, and some other special threads. In addition, the thread can be divided into single lead (single head), double lead (double head), multi-lead (multiple head) and high and low thread double head thread. End type - The end type mainly includes saw end and flat end. However, according to the function of use, grooves, grooves, cuts or drill-like shapes with cutting functions can be processed. In some standards, the same saw end or flat end, there are different forms.
