Definition of Ring Gauge

 

Definition of Ring Gauge

 

Ring gauge is a metrology tool that is used for verifying the outer diameter of pins, shafts, splines, fasteners, dowels, studs, and other machined cylindrical parts. It is typically cylindrical in shape and is fabricated from a stable material (usually tool steel) with a highly precise (very high tolerance) bore in the center. The primary function of a ring gauge is to establish on a go-go basis whether the part being tested falls within the dimensional tolerance that was specified for it. The use of a ring gauge enables the user to make accurate assessments during the acceptance inspections very quickly without the need to use micrometers, calipers, thickness gauges, or other measuring instruments that could take longer to generate a result.

 

It important to acknowledge that the ring gauge is used to quickly determine if a part falls within the accepted tolerances based on the test. It is not a measuring instrument in the sense that it is not providing an actual value of the part’s diameter – it simply tests whether the part falls within permissible limits and therefore can be accepted in terms of quality control.

 

 

To learn more about other varieties of gauges, see our related guide covering the different types of gauges.

 

Types of ring gauge

There are three primary types of ring gauge from the functional perspective:

 

● Go ring gauge

● No-go ring gauge

● Master or set ring gauge

 

Go ring gauge is designed to verify the upper tolerance limit of the outer diameter of a part. If the go ring gauge fits over the outer diameter of the part, then this indicates that the maximum allowable material condition for that part has not been exceeded, meaning that the diameter of the part falls within the upper limit of its tolerance, and therefore, the part is acceptable.

 

No-go ring gauge checks the lower tolerance limit on the outer diameter of a part. If the no-go ring gauge does not fit over the outer diameter of the part, then this indicates that the minimum allowable material condition for the part has been satisfied, meaning that the diameter of the part exceeds the minimum or lower limit of its tolerance, and therefore, the part is acceptable.

 

If the go ring gauge will not fit over the part being tested, the part diameter is too large, meaning that it contains excess material and should be rejected. Similarly, if the no-go ring gauge fits over the part being tested, then too much material has been removed and the part falls below its minimum tolerance value and similarly should be rejected.

 

When a ring gauge is used to directly assess the acceptability of parts, the practice is known as direct gauging.

 

Master ring gauge, also known as set ring gauge, is used for the mastering of other metering instruments. It may be used to calibrate other measuring instruments such as bore gauges or internal micrometers, for example, by providing a measurement standard or reference standard for calibration purposes. The practice is known as indirect gauging.