What is proper temperature for a QC lab? ISO requirement? Best practices?
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    Default What is proper temperature for a QC lab? ISO requirement? Best practices?

    I think I know the answer to this, but I'm going to ask anyway.

    In general, it's a assumed a QC lab is temperature controlled.

    Is there anything in ISO requirements that mandate this? or specific temperature? does the thermostat need to be locked out to prevent anyone from messing around with it?

    or is maintaining a constant temperature merely in the category of "best practice"?

    our ring gage standards are engraved with 20C on them...which makes me think if they are to be valid, we should do our best to maintain a temperature of 68F (same as 20C).

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    Quote Originally Posted by qc_tech View Post
    I think I know the answer to this, but I'm going to ask anyway.

    In general, it's a assumed a QC lab is temperature controlled.

    Is there anything in ISO requirements that mandate this? or specific temperature? does the thermostat need to be locked out to prevent anyone from messing around with it?

    or is maintaining a constant temperature merely in the category of "best practice"?

    our ring gage standards are engraved with 20C on them...which makes me think if they are to be valid, we should do our best to maintain a temperature of 68F (same as 20C).
    {nonsense remark removed - TRL} ISO doesn't specify a specific temperature but 20C is generally regarded as "standard" because it is a "comfortable" temperature to work in.
    Last edited by The real Leigh; 06-05-2019 at 03:51 PM.

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    I'll assume your ring gage is made of steel, what are the parts you measure made of?
    Which ISO "requirements" are you asking about? In ISO-9000 and variants you get to write the rules.
    Even if you lock the thermostat can you control the same temp from floor to ceiling?
    Yes 68 is the goal for a calibration room, maybe not for an inspection room.
    You can hold inspection at 90 degrees if you want. It just makes life more complicated if your product mix is differing materials.
    Any part that comes into inspection has to "soak" to contract or expand so a temp closer to the shop floor can be faster to work with.
    You can't take a 10 lb. part off of a 90 degree floor, plop it on a cmm in a 68 degree room and expect good measurements.
    Bob

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    20 C—A Short History of the Standard
    Reference Temperature for Industrial
    Dimensional Measurements

    https://nvlpubs.nist.gov/nistpubs/jr...12.N01.A01.pdf

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    often keep ring gages and large gage block setups in a cnc so at coolant temperature. even when its only a 2degree F difference its has a effect. same with holding measuring gages in your bare hands.
    .
    even a micrometer at 75F if you have a 10" gage block at 75F and 68F you will see a difference. point is measuring tools calibration changes many times a days on temperature exposure.
    .
    i have seen one end of large parts get .0003" smaller cause coolant only touching one end of a large part. stop coolant and wait a hour and it grows taller .0003". how much size change depends on temperature variations
    .
    same as machining one end of a large part and getting it hot it will grow and later shrink when it cools back off to room temperature. a aluminum boring bar often will change size boring a cast iron part while boring cause coolant is causing the aluminum to change size more than the cast iron. easily get tapered bores that way.
    .
    thats why aluminum can be tough to measure as it changes size differently than steel measuring instruments and gage blocks and ring gages. what size you want aluminum part at at what temperature ? cause it will be a different size at 50F and at 75F
    .
    invar that doesnt change size is often the worst you can use for gage blocks and ring gages. usually better to use aluminum to measure aluminum and steel to measure steel, that is if gage and part same material they change size at the same rate

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    Quote Originally Posted by mhajicek View Post
    20 C—A Short History of the Standard
    Reference Temperature for Industrial
    Dimensional Measurements

    https://nvlpubs.nist.gov/nistpubs/jr...12.N01.A01.pdf
    that's a great article. thanks.

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    Quote Originally Posted by CarbideBob View Post
    I'll assume your ring gage is made of steel, what are the parts you measure made of?
    Which ISO "requirements" are you asking about? In ISO-9000 and variants you get to write the rules.
    Mostly alumunimum and stainless and mild steel is what we work with. But we also do some delrin with tight tolerances and some other composites that have fussy requirements (imagineers at work!)

    We are ISO 9001:2015.

    It's our habit to let parts sit and "soak" like you say before we check any tight-tolerance bores. And for some parts that may be more sensitive to
    Our A/C unit for our lab is separate from the larger HVAC system..and hence is somewhat underpowered. I consider 68F a goal for our QC lab since the since our ring stanadards for our bore mics have 20C stated on them. And since we need to zero those bore mics with those standards every time we use them. (you can't always assume the last person did it right or replaced the battery without re-zeroing).

    Consistentcy and repeatedability would be my rationale for leaving the temp set at 68F, regardless if the AC unit can keep up.

    What I want to avoid is people arbitrarily messing around with the thermostate based on personal comfort. And well, having some auditor walk in the the door, whether's it's our own ISO guy or a customer audit and failing us because we don't have a solid policy regarding who controls the temp in the lab.

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    Quote Originally Posted by Gordon B. Clarke View Post
    If you know the answer why ask? .
    why did I ask?

    1) I don't know everything. I could be wrong. Other opinions that align with mine can only bolster my argument for stricter control of the thermostat in our QC lab.
    2) It' always fun see how many people in a forum attack and criticize the post without actually offering any real information.

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    Dealing with AL you need to keep the calibration temp or comp for it. The problem with comp is it is so messy to keep track of.
    You should put this into your ISO 9001:2015 book as a rule along with a procedure for checking the temp in the room and allowed tolerance. (IE: not just a thermostat setting)
    If tight parts or working near the edge this check might even be a line on the daily layered audit and I hate layered audits as BS paperwork.

    Maybe even a documented check on the temp of parts before measuring if coming from a "hot" floor if your tolerances are tight.
    (problems here as the skin cools faster than the core)

    "Consistentcy and repeatedability would be my rationale for leaving the temp set at 68F, regardless if the AC unit can keep up" bothers me.
    What happens when the AC won't? Shut down all inspection? Actually you should.
    Also stirring the air in a QC room can matter a lot so don't miss that floor to ceiling or other dead spots.
    Lighting with IR output can also do weird things to granite plates and cmms.

    You wanted to climb down inside this rabbit hole so expect advice and opinions from all sides.
    Nobody is criticizing you.
    So many ways to skin the cat and by the post I wonder if you have 30-40+ years of mistakes and knowledge. Maybe there is no attack.
    Bob

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    In rooms we need constant temp in we have in wall duct work and fans to continuously cycle air between floor and ceiling. Ground slabs are tough too, cold in the winter.

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    {argument deleted in its entirety - TRL}
    Last edited by The real Leigh; 06-05-2019 at 03:56 PM.

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    A few thoughts-
    You mention Delrin; when measuring this and most plastics, the humidity coefficient of expansion can be ten times more than the thermal, so now you have something new to worry about.

    Where I work we are setting up as a 17025 calibration lab (think 9001 requirements on steroids). They do not specify a temperature, but do require temperature logging.

    As part of calculating uncertainty the possible deviations from 20C/68F must be considered.

    We have one area that is temperature controlled and state 65-70F as the allowed measuring range. The other are is more office and has an allowed range of 66-76F.

    When you get a calibration from someplace (NIST, Webber Gauge, etc.) the stated dimensions are typically corrected to 68F, even though their labs are controlled within tenths of degrees.

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    >>>You should put this into your ISO 9001:2015 book <<<

    actually, no. the more requirements you add to your own quality manual makes it that much harder to maintain and that much easier to fail.

    shutting down QC when it can't keep up with the heat wave? impractical and impossible for a family-owned job shop in the age of JIT manufcature and delivery. I doubt you could do that at larger shops.

    the latest flavor-of-the-month theme for this iteration of ISO is that ANYTHING and EVERYTHING we do should be customer driven. So, if that's the case...we should not make any requirements of ourselves that our customers do not make of us. Which is probably a good rule of thumb...if I were inclined to dig through our contractual obligations, there might be some language about having a temperature controlled QC lab and/or regularly calibrated IMTE, etc.. I doubt anything gets specific enough to dictate temperature and who controls it.

    and PS: I never claimed to have 30-40+ years or mistakes or knowledge. (However, I do have my AARP card). I know there are many ways to skin the cat as you put it...which is why I solicited opinions from the peanut gallery.

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    {argument deleted in its entirety - TRL}
    C'mon, guys. Get back on topic.

    - Leigh
    Last edited by The real Leigh; 06-05-2019 at 03:57 PM.

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    >>>>Where I work we are setting up as a 17025 calibration lab (think 9001 requirements on steroids). I do not envy anyone who has stricter requirements that ISO 9001.<<<<

    I don't even like the idea of AS9100 (but that's where we're headed).

    As I mentioned elsewhere, I think we are in the position of adding requirements to our system only if a customer requires it. It all has to be customer-driven or else we make things too unwieldy for a shop our size.

    It actually does help us when our ISO auditor asks "do you do X, Y, or Z" and we are able to say, only if our customer requests X, Y or Z. (of course it's some basic aspect of robust quality system that we are lacking).

    it also helps us if a customer asks us to do X, Y or Z...and we charge them money for it.

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    Quote Originally Posted by qc_tech View Post
    >>>You should put this into your ISO 9001:2015 book <<<

    actually, no. the more requirements you add to your own quality manual makes it that much harder to maintain and that much easier to fail.

    shutting down QC when it can't keep up with the heat wave? impractical and impossible ......
    I'm so very against any extra or unneeded in a ISO manual. Most are so overwritten and I've argued that since the first days.
    The documents should be short and sweet. The intention of the all this has been long since lost.

    Yet you seem to be okay with my checking parts is meaningless, wrong or questionable.
    Why spend the time and money to do the checks if you know dam well the results are guesses?
    Good money thrown after bad.

    Why can't QC be shut down if its results are unknown?
    No process control on the floor? No way to go back and pick up the slack when the AC is working?
    Bob

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    {Off-topic posts WILL be deleted - TRL}
    Last edited by The real Leigh; 06-05-2019 at 03:59 PM.

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    Quote Originally Posted by CarbideBob View Post
    Yet you seem to be okay with my checking parts is meaningless, wrong or questionable.
    Why spend the time and money to do the checks if you know dam well the results are guesses?
    .....Why can't QC be shut down if its results are unknown?
    because the temperature isn't kept within a strict range does not mean we are purely "guessing". That's quite an overstatement. Does that mean any in-process done on the shop floor are merely guesses as well? then why do in-process inspection at all?

    We have a regular calibration program. Anything the cal service can't do on-site and we send in to their lab. I personally have a ASQ cert. (can't speak for others that work in the lab). Not to mention all the experience that the rest of the employees bring to the table (machinists, engineers, managers, etc) to plan, make and check parts. That all has to mean something. It doesn't all evaporate if the temp is 72F instead of 68F.

    many of the certs for our standards that were checked at a cal lab and sent back to us have varying temperatures under which they were verified. They dont all say "68F", even if that is the best case scenario. Some are at 72F. some at 70F. Depends on what lab we used and when.

    Not all of of our work is done to tight tolerances. Not all of our jobs are for certified customers or require traceability or inspection reports. Some of our jobs don't even have real drawings. Some of our jobs don't even have drawings.

    On intensive days, we may have several jobs on the machines with tight tolerances that make us a little cranky. Some days we have nothing tighter than +/-.010"

    I'm trying to abide by what are reasonable practices to maintain consistency and quality. (can't say the same for the guy who keeps messing with the thermostat who is ABOVE me in the food chain). I am not the quality manager, by the way. I'm just a peon.

    Shutting down for a day or two...let alone two weeks during the hottest part of the summer? would put us out of business. First articles are brought in every 30 minutes sometimes, sometimes they're brought in 5 at a time (a conspiracy by the machinists some say

    Inspections for parts going to outside service or final inpections for parts going to customers fill up the day eaisly. There really is no room for delays. What wiggle room we have for delivery is easily eaten up by machines going down, supply chain issues for material and tooling or finishers that overcook our parts.

    Shutting down the the QC lab would be like going on strike. Don't think the owner would be too happy if I said we were shut down because it's 75F in the QC lab instead of 68F. And then our customers dump us because we can't meet deadline.

    at the end of the day, what is supposed to drive our quality system are customer requirements. We have no NCRs on file that attribute any non-comformance or rejection due to poor calibration or checking parts under temp conditions that give us bad or false readings.

    We are also supposed to make decisions and/or changes to the system based on evidence. Again, no evidence that our weak A/C system is actually hurting us....It certainly doesn't help us, but there is no data to suggest that the fluctuations in lab temperature is putting things so out of whack that we are not meeting our customer requirements.

    Is this a perfect situation? no. I don't like it one bit. which is why I asked the original question. I"d rather put a padlock on the thermostat and tell people to wear a sweater if they are cold. But if ISO doesn't say 68F is a hard and fast rule, and if our auditor hasn't busted us on it...and if our customers don't have a problem with it (so far). I can't just tell the owners we're closed. I just have to live with a manager who doesn't understand the relationship between temperature and different materials. And believe me, there's a lot more that this guy doesn't understand.

    so thanks for all the advice. But I have to live with the situation as-is if it's not stated explicitly by ISO or by our customers as a requirement. thanks again all.

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    A couple more things to keep in mind;
    -If the measuring tool is the same material, and they have reached equal temperature, measurements will be accurate.
    -Materials and tools must be the same temperature and it can take a surprising tome to acclimate.
    -The longer the measurement, the more temperature matters (at 0.5 inch error is very small, at 20 inches errors happen fast.
    -Once acclimated you can calculate the expansion of the tool and of the part and subtract out that error.


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