Types of threads

1. International metric standard threads

The thread adopted by our national standard CNS. The top of the tooth is flat, easy to turn, and the bottom of the tooth is rounded to increase the strength of the thread. The angle of thread is 60 degrees, and the specification is indicated by M. The metric thread can be divided into two kinds: coarse and fine thread. Metric threads can be divided into two kinds: coarse teeth and fine teeth.

2. American Standard Thread

The top and bottom of the thread are flat for greater strength. The thread angle is also 60 degrees and the size is indicated by the number of teeth per inch. These threads are classified as coarse thread (NC), fine thread (NF) and extra fine thread (NEF). Expressed as 1/2 to 10 NC.

3. Unified thread

It is the commonly used British thread. The thread angle is also 60 degrees, and the specification is indicated by the number of teeth per inch. This kind of thread can be divided into coarse thread (UNC), fine thread (UNF) and extra fine thread (UNEF).

4.V-shape thread

Both the top and the root are pointed, weak, and not often used. The thread angle is 60 degrees.

5. Fitch thread

Threads used in British National Standards. The thread angle is 55 degrees and the symbol is "W". Suitable for rolled manufacturing.

6.Round thread

Threads are standard according to DIN, Germany. Suitable for connection of bulbs and hoses. The symbol is "Rd".

7.Pipe Threads

The threads are used to prevent leakage and are often used for gas or liquid pipe connections. The thread angle is 55 degrees, which can be divided into straight pipe thread designation "P.S., N.P.S." and inclined pipe thread designation "N.P.T.", whose taper is 1:16, i.e. 3/4 inch per foot.

8.square thread

Transmission efficiency is large, second only to the ball thread, and after wear can not be adjusted by the nut, its shortcomings. Generally used for vise screws and crane threads.

9.Trapezoidal thread

Also known as Aechem threads. Transmission efficiency is slightly smaller than square thread, but can be adjusted with nut after wear. The thread angle is 30 degrees for metric threads and 29 degrees for imperial threads. It is generally used for lead screws on lathes. The symbol is "Tr".

10.Sawtooth Thread

Also known as oblique thread, only suitable for one-way transmission. Such as screw jacks, pressurizing machine. The symbol is "Bu".

11.Ball thread

For the best efficiency of the transmission of the thread, the manufacturing difficulties, high cost, is used for precision machinery. Such as CNC machine tools such as lead screw.