Manual Temperature Compensation

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  • Manual Temperature Compensation

    I'm trying to use temperature compensation in the manual mode, our CMM does not have a part sensor.
    Is there a way to set this temperature reading using variables?

    I'd like to keep the off shift operators from touching the code to enter the part temperature.

    Mike E
    Pcdmis Cad++ 2013 Mr1

  • #2
    We have an in-house-made temperature calibration fixture. It is aluminum (and therefore only applies to aluminum tooling being measured) and has a series of tooling balls in a 3-D 'pattern'. Some TB's measure in X, some in Y, and some in Z. It is calibrated out-of-house. We have run it on the CMM at various temps between ~60F and ~90F. When our thermometer reads out of temp (temp = 68 +/-3), we break out the cal fixure (we keep it next to the CMM, so it is always near temperature-soaked), run our program on it, and the #'s tell us how much we need to compensate in X, Y, and Z. Basically, we end up with a multiplication factor for each axis. We then run the tool/part, and for every dimension needed, we multiply by the appropriate factor --- if the dimension is purely in X, we multiply by the X factor. If the dimension is a combo of X/Y/Z, then we have to multiply by a dimensionally appropriate combo-factor. You, or your company, will have to decide when and how to apply this and how to implement it. We only use it on aluminum (steel/nickel/titanium/etc are exempt), only on tools larger than a certain size (.0001% expansion on a 6" long item is usually meaningless in our world, but on a 6 FOOT long item, it may have some bearing), on tools with a certain 'tightness' of tolerance, etc.

    All in all, our system is a pain in the ****, but it keeps our customers satisfied. I've discovered that the simplest solution is to not run ANYTHING when temps are extreme (Seattle area, so summer temps never terribly hot (no building A/C) and winter temps are offset by the heat in the building) or just run non-aluminum things when things are hot/cold. Yes, I am aware of the shortfalls of the system --- a temperature controlled environment would negate pretty much everything I've written, but try to get the boss (of where I work, anyway) to sign up for an isolated, temperature/humidity controlled room. I mean, one that he doesn't sit in. Good luck with that.


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