Hi, Gage Guy here checking in with another Mahar Metrology Blog!
Our subject this time around is Air Gages, or as they are now commonly referred to; Air to Electronic Gages. What’s the diff? Well boys and girls, glad you asked…
The principle of checking parts with non-contact precision gages was invented, as was many metrology instruments, during World War II. Soon after the war, Sheffield Measurement perfected this type of gaging and hit the ground running by the 1950’s. The concept is air back pressure…uh? Take some air, filter it through a small orifice or opening, and place an object about .003” away from it and wha-la…back pressure. Technically, it’s a little more complicated…the air orifice or jet as it is known in the business, is a precision made opening that is hand honed to exact size and is working in conjunction with a very precise air escape groove that allows for the perfect back pressure to give a repeatable reading. The object, or part, must also be relatively smooth, otherwise the air flow may be interrupted. The concept may be somewhat simple, however, this form of measuring is almost an art more than a science. The gage maker must be able to work with the orifice opening as well as the air escape to perfectly balance the air jet to the part or master to get the precise location and pressure. Getting the correct balance will guarantee the even flow and hence repeatability that is required. In the original applications this concept was what is known as “Pure Air” or without any electronic assistance. The pure air gage worked by receiving the back pressure from the gage checking the part to a glass cylinder or tube that contained a rubber floatation stopper. The tube was located directly in front of a scale that was designed for that particular measurement. When the gage was working properly, the stopper floated between the maximum and minimum points on the scale to show that the part was in tolerance. In the beginning the air gage was commonly used to check diameters, both ID and OD, air spindles checked ID and air rings checked OD. We’ve come a long way from those original air gages…now days we use electronic air converters that allow for an electronic signal or in most cases an actual digital dimension readout. The original concept is the same. Now we use air/electronic gages to check many different features of a part, including but not limited to diameters, thickness, taper, perpendicularity and camber to name a few.
At Mahar we have great air gage suppliers that we go to for anything from concept, to design and build of precision air/electronic gaging. These gages are used as simple hand held measurement devices or as automatic arbors located directly in modern day CNC machining centers. The Gage Guy has many years of experience selling this type of measurement technology and continues to see it used in all industries Mahar is associated with.
I called air gaging “Ol’ Reliable” for a reason…the gages are self-cleaning because of the constant air flow…and because of the non-contact aspect, last a long time…an old concept still used today! Ask your Mahar sales person for more info…the Gage Guy is at your service!