Dave, the two I referred to were in different parts of the USA, though one was automotive, and had a lot of dealings with Ontario suppliers...so, maybe.
The use of hard gages is diminishing as more shops move from very large / continuous runs to smaller batches and essentially one-offs. The costs just can't be justified in many cases, unless the tolerances are grossly sloppy, in which case I'd use a surface profile anyway. I've dealt with automotive specialty suppliers that do still use hard-gaging, so I'm not saying it's dead, just diminishing from what I've seen. I've been in engine foundries and fabrication lines, worked with component suppliers (including large assemblies) that gave up hard-gaging over a decade ago. They CMM on a statistical basis typically, and with increasing frequency use SPC to minimize / eliminate final article inspection. This allows a plant to detect and correct a problem before it becomes an issue. I'm also seeing more widespread use of vision systems, which lend themselves nicely to profile controls, particularly for relatively thin pieces. As for cost of using a CMM to check a profile vs a fixture to check a BOUNDARY; consider the size/cost and handling issues associated with a half-ton workpiece engaging multiple features on a checking fixture simultaneously ... a CMM (gantry or arm-style) is more cost effective & easier in many cases. Of course, operators & programmers need to understand the CMM and its software ... that's another story...
While I was an early advocate of CMMs, I came to recognize the issues associated with them (establishing datums from points on a selected surface, sine error, averaging algorithms, sampling rate, etc.) and like to point them out to students who rely exclusively on them for their results. Each situation may warrant different methodologies & equipment, and inspectors need to think things over before jumping in with their usual practice.
Jim Sykes, P.Eng, GDTP-S
Profile Services
TecEase, Inc.
