Depending on the thread for different purposes can be divided into:

    1 metric standard thread (International Metric Thread System): China's national standard CNS using threads. Crests of the plane, easy turning, compared with arc-shaped teeth at the end, in order to increase the thread strength. The thread angle of 60 degrees, M represents specifications. Metric thread can be divided into Coarse and fine pitch. Notation such as M8x1.25. (M: Code 8: nominal diameter, 1.25: pitch).

    2 standard thread (American Standard Thread): the top and the root of the thread are flat, better strength. The thread angle is also 60 degrees, specifications, said a few teeth per inch. Such a thread can be divided into Coarse (NC); fine pitch (NF); special fine tooth (NEF) three. Notation such as 1/2-10NC. (1/2: OD; 10: every inch of the number of teeth; NC Code).

    Unified thread (Unified Thread): developed jointly by the United States, Britain, Canada, the three countries for inch thread. The thread angle is also 60 degrees, specifications, said a few teeth per inch. Such a thread can be divided into coarse thread (UNC); fine pitch (UNF); special fine tooth (UNEF). Notation such as 1/2-10UNC. (1/2: OD; 10: every inch of the number of teeth; UNC Code).

    A 4.V shaped thread (Sharp V Thread): top roots tip shape, intensity is weak, also bad infrequently used. The thread angle of 60 degrees.

    5 Hui-style threads (Whitworth Thread): British Standard thread. Thread angle of 55 degrees, which means that the symbol for the "W". Suitable for the manufacture of rolling method. Notation such as W1/2-10. (1/2: OD; 10: the number of teeth per inch; W Code).

    6 round thread Knuckle Thread: German DIN standard thread. Apply to light bulbs, rubber tubing connection. Symbol for "RD".

    7 the tubular threaded (Pipe Thread): To prevent the leakage threaded, often used for gas or liquid, the tube member Quick. Thread angle of 55 degrees and can be divided into straight pipe thread, code-named "PS, NPS and inclined pipe thread Code for" NPT taper 1:16, feet 3/4 inch.

    8 square thread (Square Thread): transmission efficiency, second only to the ball screw, and can not wear nut to adjust its shortcomings. Generally used for the vise screw and the thread of the crane.

    Trapezoidal thread (Trapezoidal Thread): also known as ACME thread. Transmission efficiency than the square thread is somewhat smaller, but wear available nut tune

Whole. Metric thread angle of 30 degrees, the inch thread angle of 29 degrees. Generally used for the lead screw of the lathe. Symbol for "TR".

    10 serrated thread (Buttress, Thread): also known as buttress thread is only suitable for one direction of transmission. Such as screw jack, pressurized machine. Symbol for "BU".

    11 ball screw: the best thread of the transmission efficiency of its manufacturing difficulties and high costs, are used in precision machinery. Such as CNC machine tools lead screw.