Mr Michel L Dechape
Pages in Print Edition:
The basic principle of blowing a jet from a nozzle against the surface of a workpiece to be measured has been known to scientists since the 19th century and was mentioned in the literature as far back as 1917. Liquid was the first medium, followed by compressed air, with the first well-known application in standardizing jets for carburetors. Military demands in the 1940s spurred further development of air gaging instruments to determine the dimensional relationship between a nozzle and the surface of a workpiece. Calibration was nonlinear (curved). A new flow system with air electronic converter (patented 2010) uses a differential back pressure circuit with solid state differential transducer (patented 1985), and the calibration is linear. Although many applications have been taken over by electronic gaging, some forms of measurement are still ideally performed pneumatically. In view of recent improvements in air electronic converters, engineers and designers will realize the potential in simplified tooling and the ability to perform measurements that were not possible even with electronic gages. Air gaging has lower cost, ruggedness, and advantages for in-process gaging, such as for grinding or lapping, and in harsh environments such as heat, cold, caustic, explosive, or nuclear.
By Philip D Rufe
By Ahmad K Elshennawy, Gamal S Weheba, PhD