Common knowledge of screw thread


A thread is a shape having a uniform spiral protrusion […]

A thread is a shape having a uniform spiral protrusion on a section of the outer or inner surface of the solid. According to its structural characteristics and uses, it can be divided into three categories:

1. Ordinary thread: The tooth shape is triangular and used to connect or fasten parts. Ordinary threads are divided into coarse teeth and fine thread according to the pitch, and the connection strength of the fine thread is high.

2. Transmission thread: The tooth shape has trapezoid, rectangle, saw shape and triangle.

3. Sealing thread: for sealing connection, mainly for pipe thread, taper thread and taper pipe thread.

After understanding the classification of the screw thread, we also need to know the size of the screw thread. The standard screw thread has its standard, we only need to be able to produce according to the basic size of the screw.

Ordinary thread screw length (mm)

S—short spin length; N—medium twist length; L—long twist length;

Generally, the medium rotation length is used in most cases;

The medium-convolution length “N” national standard is not marked, and the other two “S” and “N” must be marked with their codes;

When special needs, the value of the length of the rotation can be used instead of the code of the length of the screw.