Limit gauges (such as plug gauges, ring gauges, and snap gauges) are physical inspection tools used to verify whether a manufactured part's dimension falls within its acceptable tolerance limits. They do not give an exact measurement, but rather provide a straightforward "go/no-go" verdict. Key Details of the Standard Plain limit gauges
C-shaped gauges used to quickly check the thickness or external diameter of a part. 4. Manufacturing Tolerances
As it wears down from repeated use, it approaches the true limit line.
The PDF document (JIS B 7420) is dense with technical data. When you obtain the official copy, you should expect to find:
If your laboratory or factory is accredited to ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories), you cannot guess tolerances. You must have the reference standard on hand. The serves as your master document for defining acceptance limits during gauge calibration.
Features a longer cylinder to check the minimum allowable diameter of the hole.
Must smoothly enter the hole under its own weight or light pressure. It checks the minimum allowable size of the hole.
If you are looking for the official JIS B 7420-1997-1.pdf, you can purchase and download it directly from the Japanese Standards Association (JSA) Web Store or specialized technical document providers like PhysicsNorm and NormSplash . JIS-B-7420-1997-en.pdf - NormSplash