Howdy folks,
Need to monitor the temperature of my CMM surface plate. Accuracy is about ±1 degree F, and budget is about $200. Any suggestions?
Arigato.
Monitoring is one thing, remember to work out ahead of time calibration, too, for something that critical. Some temperature sensing systems (like IR) work great, but are tough to calibrate.
Put another way: how are people monitoring the temperature of their cmm surface plates? I have a 36.000" ±.001" dimension on a 6061-T6 aluminum part. Uncertainty of 3 degrees F eats my entire tolerance. Ideas?
I've never monitored the surface plate itself or heard of anyone doing that. If you control and monitor your environment the surface plate should not be changing. The granite probably has one of the lowest coefficents of the whole machine.
Now the aluminum part on the other hand is going to be rather sensitive, and should be allowed to "soak" in the environment that the CMM is in before being measured. I would allow a minimum of 4 hours for that part.
Put another way: how are people monitoring the temperature of their cmm surface plates? I have a 36.000" ±.001" dimension on a 6061-T6 aluminum part. Uncertainty of 3 degrees F eats my entire tolerance. Ideas?
Are you trying to measure a part that will not be the same temperature as the CMM? If so, you can measure the part several times over time and see the change get smaller over time, eventually you'll reach a point where it's not changing in a way you'd consider significant and then you have a rough idea of your soak time. The problem with this on aluminum (if scanning) is you may make barely visible rings on the part.
As mentioned by others the TCE affects the plate and the part. The best way to ensure that you are minimizing the effect of temperature variation is to allow for proper "soak" time prior to inspection. This will assure that the part and the surface plate are at the same temperature if you are inputting a temp comp into your CMM inspection or complying with a defined range for temperature durring inspection.
For metrology equipment we go with 24 hrs stabalization at temp but you can determine what is approprate for your case by checking the part. The time is affected by temperature differantial material and mass.
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