A precise pneumatic co-axial jet gauging system for surface roughness measurements

Surface texture measurements have an anomalous position in the science of metrology. The property of surface texture is essentially qualitative. A quantitative index can only be assigned indirectly by reference to instrumentation operating in accordance with geometric parameters. The development of more refined production techniques, more exacting design requirements, and more precise measuring methods, coupled with the desire for a better understanding of the relationship between surface properties and surface functions, has stimulated the search for quantitative methods of assessment.Expensive electronic, optical and holographics instruments are available, but are time consuming, complicated, and if not correctly operated, confusing. Correctly used, they can provide the very certain, accurate results imperative for research and development work. For most production and workshop requirements, however, this high accuracy is unnecessary and wasteful.Considerable research effort has been expended on conventional single measuring nozzle gauging systems. No work has been done on coaxial jet gauging system.