In the quality world, air gaging ranks with micrometers, calipers, comparators, scales, CMMs and many other instruments in that they are all considered measurement and test equipment (M&TE).
Air gauging gives you a fast measurement device that provides superior reliability in the dirtiest shop environment, but you give up things such as measurement range and a clear delineation of surface. Air gauging has about 10 to 20 percent of the range of a typical electronic transducer with similar resolution.
Under quality standards such as ISO 9000, ISO 13485, AS9100 and IATF 16949A, a complete air gauging program will be comprised of not only the physical components that make up the gauge but also the maintenance and calibration programs necessary to keep those components in an accurate operating state.
The basic components of any air gauge system include the air gauge, setting master(s) and electronic/pneumatic readout. Each one of these components will require periodic calibration by in-house personnel or by an outside laboratory, both of which must meet the quality system’s requirements.
- The measurement ‘point’ is really the average area of the surface the jet is covering. Now consider the finish, or roughness, of that surface.
- The measurement point of the air jet is actually the average of the peaks and valleys to which the jet is exposed.
- This is not the same measured point you have if a contact-type probe is used. This difference is a source of real gauging error, and one that is most often apparent when two different inspection processes are used.
Air Gauges and Their Operation
Air gauges are a comparative type of measurement device. They operate in a two system world: single master and dual master systems, where each requires the use of one or two setting masters respectively, to either set the zero offset or to set the gain. The term “calibration” has been used very loosely to describe these two operation.