Screw Thread Types (ISO, BSF, JIS)
- Posted: 2013-11-11
ISO Metric Screw Threads
The ISO metric screw threads are the world-wide most commonly used type of general-purpose screw thread. ISO threads can be divided into two types, UNC and UNF. They are commonly specified like this: M8x1.25 (M: code, 8: outer diameter, 1.25: thread distance)
British Standard Fine (BSF) is a screw thread form, as a fine-pitch alternative to British Standard Whitworth (BSW) thread. It was used for steel bolts and nuts on much British machinery, including cars, prior to adoption of Unified, and later Metric, standards.
BSF threads can be classified as UNC, UNF and UNEF. They are commonly specified like this: 1/2-10UNC (1/2: outer diameter, 10: threads per inch, UNC: code)
JIS (Japanese Industrial Standards) specifies the standards used for industrial activities in Japan. There are four popular thread coupling styles in Japan. Click here to read more >
Notes: UN=Unified National; UNC=Coarse; UNF=Fine; UNEF=Extra Fine