The plants have 2 CMM machines on the floor, one is Bridge type and the other is gantry type both from Hexagon. There is no AC on the floor, so summer is hot and winter a little bit cold, I wonder which one has better accuracy against temperature variation?
Why not test them?
ring gages and gage blocks. Measure both a handful of times throughout the day when temps change and report your deviation/variation.
I would suggest storing the 'masters' in a controlled environment, then 'run out and measure them' as well, this will show the machine movement over the temp spread.
Run a second test storing the 'masters' on the machines all day for the same thing to see how accurate the TEMP-COMP works on the machines if they are setup for it.
yeah, that machine is not in a good place, and should be in a (more) controlled environment. I'm surprised (well, not really) that Hex didn't warn the moneybags that the placement was not going to be any good for the machines. Maybe they did and the moneybags just figured they knew best.....
68°±2°F I believe is the optimal temp for CMM's. Machines should be set up in a fairly clean environment as well. Portable white rooms equipped with environmental control are fairly cheap vs the cost of repairs that will be coming if your running in a dirty dust filled atmosphere.