Temperature effect on part measurement.

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  • Temperature effect on part measurement.

    Hello everyone,

    This is a duplicate thread that I have originally posted on CMM board and someone suggested me to post in portable.

    So far the companies I have worked for, always have a temperature and humidity controlled quality lab like most of you guys are working. But in my current company, I am working with a ROMER ABSOLUTE ARM 7525 6-AXIS ARM AND WE USE TOUCH TRIGGER PROBES (PHYSICAL CONTACT PROBES). I was so shocked when I see the arm on the shop floor in a dirty environment where people work with drills, sand papers and abrasives to do rework or to make holes and other regular stuff with hand held devices. At the time of posting this thread, the temperature on the shop floor would be 37C or 38C thanks to our ovens that bake the composite parts. I used a temperature gun pointing on my Romer arm and reading 36.1C and humid work environment. (that's insane). I have never used temperature compensation but as the temperature keeps varying to a lot depending on the duration the ovens stay open and running at 50 Celsius. I was told that the Romer absolute arm can compensate results to outside temperature, but the parts cannot compensate. I want to know from you guys that how accurate our results can be? I definitely know this is not ideal condition to even measure the parts. Our parts are made from a combination of carbon fiber, resin and fiber glass. and most of our tools are made of aluminium.

    Just for information, our Romer arm holds accuracy of 0.020mm or 0.0008". Also to add in, the building don't seem to have any HVAC system on the shop floor except the CNC room and LAMINATION room. I have tried to explain the need of a controlled Quality Lab not only for CMM but for inspection also (because many parts just go to inspection area to do manual inspections and not come to CMM) but management might not thinking about it for our NEW facility as we are moving to bigger place. So I want to explain what kind of terrible accuracy we can hold at 36C or even more.

    Your help is much appreciated guys. Thanks.

  • #2
    I am surprised that we have exactly same condition for working but I am the only guy working at CMM so no we are not in same company. My arm is also on 3/4" steel plate mounted on granite table. We never move the arm and everyone knows here that arm is designed for shop floor but ARM cannot compensate for the CTE of part itself. it can work and give good results for arm itself but no the part. and there have times when we made a part all in tolerance and shipped to customer, they use the part after 6 months and found it was twisted and cannot mate with its mate. So temperature rising to 36C would definitely produce these kind of effects.

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    • #3
      What we both can suggest is to atleast put the arm in the office area where dust is relatively low and less chances of vibrations and temperature is almost always 22-23C (atleast in our engineering offices.) Its portable arm and that would be best alternative I can think for accuracy purpose.

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      • #4
        Wow... yours is much worse than mine. I work relatively in silent place where people hardly bang things. its kind of noise here but may be twice or 4 times a day you find it loud as your air compressors. mosquitos??? where do you work? in a jungle? my arm usually don't get much dust as people use vacuum here when they grind something with a machine but it still get dirty here. Jesus... all the best for your conditions..!! I hope you use some sort of respirator at work.

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