Thread Specifications

Metric Thread:

Metric thread is one of the most commonly used thread types, and the main standards include:
ISO Metric Thread: Developed by the International Organization for Standardization (ISO), it is widely used in various industries around the world.
Coarse Thread: For example, M6×1, which means the nominal diameter is 6 mm and the pitch is 1 mm.
Fine Thread: For example, M6×0.75, which means the nominal diameter is 6 mm and the pitch is 0.75 mm.
JIS Metric Thread: Developed by the Japanese Industrial Standard (JIS), it is applicable to Japan and its affected areas.
In millimeters, common specifications include M4, M6, M8, M10, etc.
The expression method is such as M8×1.25, where M8 means the nominal diameter is 8 mm and 1.25 means the pitch is 1.25 mm.

Imperial Thread:
Imperial threads are mainly used in the United States and some Commonwealth countries. Common standards include:

Unified Thread Standard (UTS): includes unified coarse thread (UNC) and unified fine thread (UNF).
UNC thread: such as 1/4-20 UNC, indicating a nominal diameter of 1/4 inch and 20 threads per inch.
UNF thread: such as 1/4-28 UNF, indicating a nominal diameter of 1/4 inch and 28 threads per inch.
British Standard Whitworth (BSW): Developed by the British Standards Association, mainly used for old mechanical equipment.
BSW thread: such as 1/4 BSW, indicating a nominal diameter of 1/4 inch.
British Standard Fine (BSF): A finer thread used for precision machinery.

Common specifications in inches include 1/4-20, 3/8-16, etc.
Expression methods such as 1/4-20 UNC, where 1/4 indicates a nominal diameter of 1/4 inch and 20 indicates the number of threads per inch.