CMM Lab Temp & Humidity

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  • CMM Lab Temp & Humidity

    Hello,

    I was wondering if anyone could point me in the right direction? I work in a metal stamping automotive lab. I have always been told that the temp/humidity gage in the lab must be certified and calibrated. Our corporate Quality Director says this is not true. Does anyone know of an ASME, ISO, NIST standard that specifies this? If you could tell me so and where to find it, I would greatly appreciate it. Or if you can tell me that I'm wrong, that will be appreciated as well.

    Thank You!
    Chris

  • #2
    newsitechris

    The correct answer to your question is situationally dependent.

    You said "I have always been told that the temp/humidity gage in the lab must be certified and calibrated". I agree with you that CMMs SHOULD be in a lab environment. However, this can't always be the case.

    There are shop floor CMMs that are designed to work in environments that have varying temp & humidity. I have a SF7107 and a SF454 out in the shop right next to the CNC machines. This shop is 68°F-85°F depending on the time of year yet stays within a 5° range on a day-to-day basis. The CMMs work great, hitting tight tolerances (±0.0003 with TP20s). As long as the parts are temperature normalized to the environment and the machine's tips are qualified before you run a part program, we get good results. Our temp does fluctuate throughout the day but not to a degree that would prevent Hex from properly calibrating the machine when they come in for the yearly cal because these machines are built to "take it".

    The larger the machine, the more susceptible to environmental factors!! In my experience, I would not put anything in the shop that is larger than a 9129.

    We ALSO have two large CMMs (9159 and 152614) in our lab (68°±1° with less than 50RH). This room had to be built specifically for these CMMs. The machines are so large that if they were in an uncontrolled environment, the temperature fluctuations that occur throughout Hex's calibration process are enough to microscopically twist & contort the cmm's position (which would invalidate the calibration as it is occurring) which means that Hex would "fail" the machine.

    All of the above being said....

    The #1 desired state for your CMM is to be in a lab. No doubt about it.

    If you don't have a lab environment, you'll be fine just as long as you don't get a machine that is too large, keep what you have clean (FOD free), qualify your tips often, and be cognizant of part temp (and its effect on metrology).

    You're both half right!


    Hope this helped. Goodluck!
    Last edited by DAN_M; 01-29-2021, 11:16 AM.
    SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

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    • #3
      Thanks Dan!

      I have a Mistral 7105 and use a TP20 in an environment controlled lab. The CMM manual says the temp should be 20 deg +/-2 and humidity to be max 90% non-condensing. We are required to keep a temp/humidity log, but don't get the point of this if our temp/humidity gage doesn't have to be certified/calibrated. Do you know of any standard that addresses this?

      Thanks for all your input!
      Chris

      Comment


      • #4
        newsitechris

        This is also situationally dependent.

        It all boils down to your customer's requirements. If there isn't a customer requirement to keep a log, yet you have an internal requirement driving you to do this, can you remove the procedure from your quality manual? I am also a trained AS9100 QMS auditor, nowhere in that or any other industry standard does it drive anybody to keep a CMM temp log.

        My company ships direct to the large aircraft companies (full gear box assemblies, no source inspectors, took us a WHILE to get here). Per their quality requirements, CMM activities for FINAL ACCEPTANCE of their product must occur in an environment that follows the NIST guidelines. Which is why we provide that environment for THOSE CMMs and pay to have temp control AND monitoring equipment calibrated so we can provide objective evidence that we're doing what we promised if ever audited.

        Based off of what you're telling me.....my two cents would be that IF you have nothing REQUIRING you to record and control this stuff, you could probably change your requirements & stop keeping the log. You have a machine that isn't too large and it sounds like the environment is controlled better than 80% of other CMMs environments that I have seen. As previously stated keep it FOD free & be mindful of part temp and you should be golden.
        Last edited by DAN_M; 01-29-2021, 10:28 AM.
        SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

        Comment


        • #5
          Understood - I appreciate all the info!
          We have 15 different auto customers - I would just need to research and see if any of those require us to do this.

          Thank You Sir!
          Chris

          Comment


          • #6
            Originally posted by newsitechris View Post
            Understood - I appreciate all the info!
            We have 15 different auto customers - I would just need to research and see if any of those require us to do this.

            Thank You Sir!
            Chris
            Happy to help
            SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

            Comment


            • #7
              IMNSHIO any device used to report or record ANY TYPE of measurement needs to certified. I also believe that if an auditor comes in and asks your boss may be in for a surprise. If your company policies and procedures state that the lab is to be maintained to specific range for temp and humidity you need to have a certified measuring device to do so.
              Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
              Contura Calypso 5.4

              Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

              Comment


              • #8
                “Say what you do; do what you say.”
                If your quality manual says you have to track those parameters; that is what you must do. Your quality manual should also list all calibrated equipment and instructions on calibration. If that device is not listed, that could be a finding in an audit. Unless you have customers requirements (many do), you get to pick the environment you are operating in and the procedure for proving you “do what you say”.
                CAD++ 2017 R1, Catia Translator
                B&S Xcel, Renishaw PH10MQ

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