戻る
It refers to the introduction of ISO grades in 1973.
Conventional JIS standards were operated as Japan's own standards with classifications of first, second, and third grades, but in response to the trend of eliminating industrial barriers and deregulation due to internationalization, we have introduced an overseas grading system into JIS.
ISO threads, sometimes referred to as new JIS.
The notation rule is a combination of a number representing the tolerance grade and an alphabet representing the tolerance position, and the allowable limit dimensions and tolerances are not necessarily the same.
The alphabet for tolerance positions is uppercase for internal thread and lowercase for external thread .
* Due to the revision of the law on July 1, 2019, the name of JIS has been changed from "Japan Industrial Standards" to "Japan Industrial Standards".