Glossary Thread plug gauges

Thread plug gauges are thread gauges and are used to check the production accuracy of internal threads.

The mating dimension of the internal thread is examined for this purpose. The pitch diameter of the thread must comply with a minimum dimension, and a deviation in the thread pitch is only permitted with a narrow tolerance. The minimum dimension of the outer diameter is also checked. However, the core diameter of the thread is not checked.

The check is carried out by screwing the full length of the thread plug gauge into the internal thread by hand. No special force may be required. If this screwing-in is not possible without problems, the thread does not meet the requirements and is considered to be a reject.

Thread plug gauges are subjected to mechanical stress during testing and wear out over time. Particularly resistant materials are therefore used in the production of these CNC turned parts, and surfaces can also be hard-coated.

Due to unavoidable wear, thread plug gauges must be regularly checked for dimensional accuracy to ensure continuous quality assurance.

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