High-production manufacturers are moving air gage checks from a stand-alone bench, where an operator checks parts by hand, to automated in-process gaging. The benefits are 100% inspection of the required callouts, and a handshake between gage and machine so each part is as good as or better than the last, with bad parts removed.
Why air instead of a contact in-process gage?
In-process gaging usually means a contact gage close to the grinding wheel or cutting tool. That works well but is limited, usually to a single outside diameter. When air gaging is used in-process, a simple handling system typically moves the part from the chuck or centers into the air gage; on some machines the part can be gaged while still clamped.
Air gaging handles more complex features: multiple diameter steps, tapers, perpendicularity, straightness and parallelism, as well as inside diameters, including very small bores. You also get the standard air gaging benefits: non-contact measuring that doesn't mark parts or wear gages quickly, high repeatability, and a gage built for your specific feature.
A typical setup
A lathe or grinder finishes the part. A handling device, often a robot that already loads the machine and can simply be reprogrammed, places the part in the air gage or the gage on the part. The readout and the PLC or robot handshake through digital I/O: the PLC signals that the part is in place, and the readout measures and returns good or bad. It also sends offset values to the machine, usually over RS232 or Ethernet, so the next part is as good or better. The handler sorts the part, and data can go to any standard SPC system, with serial-number tracking as an option.
Return on investment
Payback comes faster than most people expect. You inspect 100% of parts and sort them automatically, so a bad part doesn't reach your customer. Automatic offsets reduce scrap. You save the labor of manual checks across shifts. And spindle time and output go up, because the next part is being made while the last one is measured. If a robot already loads the machine, the payback is quicker still.
If you're measuring mid- to high-volume parts offline with air gaging today, automating the check is worth a serious look. Tell us about your part.