In the thread gauges system, the limit type is most common. Thread of work piece is ensured by controlling the GO and NOT GO limit. The types of limit thread gauges systems are broadly divided into ISO class and conventional class 1,2,3.
Differences listed below
1. GO and NOT GO of the ISO gauge system is made with same dimensions for both inspection and working.
2. Pass/Fail assessment of a NOT GO gauge for the ISO class gauge system has been set as not be screwed in more than two revolutions.
For class 1,2,3 gauge system it is not to be screwed in more than two revolutions, included two revolutions.
3. For the ISO class gauge system, the thread gauge for check fitting of the thread ring gauge is the GO and NOT GO limit type.