Thread used in national standard CNS. The top of the tooth is flat, which is easy to turn, and the bottom of the tooth is rounded to increase the thread strength. The thread Angle is 60 degrees and the specification is M. Metric thread can be divided into coarse and fine teeth. For example, m8x1.25. (M: code name, 8: nominal diameter, 1.25: pitch).

The top and root of the thread are flat with better strength. The Angle of thread is also 60 degrees, as indicated by the number of teeth per inch. Such threads may be classified as coarse teeth (NC); Fine thread (NF); Extra fine teeth (NEF) level 3. The representation is 1/2-10NC. (1/2: outside diameter; 10: number of teeth per inch; NC code.

Tip and root are pointed, weak strength, also bad not often used. The thread Angle is 60 degrees.

British national standard thread. The Angle of thread is 55 degrees and the symbol is "W". Suitable for rolling process. The representation is w1/2 -10. (1/2: outside diameter; 10: number of teeth per inch; W).

DIN thread. Suitable for connecting light bulb and rubber tube. The symbol is "Rd".

Threads used to prevent leakage are often used for gaseous or liquid pipe fittings. The Angle of thread is 55 degrees, which can be divided into straight pipe thread code "P.S. N.P.S." and oblique pipe thread code "N.P.T."Its taper is 1:16, or 3/4 of an inch per foot.

Transmission efficiency, second only to ball thread, and after wear can not be adjusted with the nut, for its shortcomings. Generally used for vise screw and crane thread.

Also known as acme threads. Transmission efficiency is smaller than the square thread, but after wear can be adjusted nut. Metric thread Angle is 30 degrees and inch thread Angle is 29 degrees.

Generally used for lathe guide screw. The symbol is "Tr".