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FAQ for calibration

Discussion in 'ISO 17025 - Calibration and Test Laboratories' started by BradM, Dec 16, 2015.

  1. BradM

    BradM Moderator Staff Member

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    This discussion began on the Ohio Bay Specialists (OBS) LinkedIn site. So since I have the ability to edit/ clean things up here, I would like to build a decent FAQ for calibration. Hopefully, it can increase some traffic to the site.

    Note: This is not just my endeavor; this is a group thing. Many of the points below and such were added by others at OBS.


    • What is calibration?

      The comparison of a measurement system of unverified uncertainty to a measurement system of quantified uncertainty to detect or correct any deviation from required performance specifications using standards traceable (in SI units) to an international recognized standards lab.

    • Calibration is not to be confused with adjustment:

      Adjustment of a measuring system is the practice of adjusting and standardizing critical measurement equipment performance (accuracy) to appropriate traceable standards.

    • What does “traceability” mean?
    • What is the difference between Calibration and Verification?
    • Does equipment used in the Design/Development process need calibrating or only for final inspection?
    • Can I calibrate my devices in-house? What is involved?
    • Why the 4:1 or 10:1 rule?
    • What is "Uncertainty" and how does it influence the decision to accept/reject the Instrument based on Calibration result?
    • What are the appropriate intervals between calibration periods?
    • How often does it need to be calibrated?
    • Why are most calibration frequency intervals kept to an annual cycle ?
    • What does it mean when an instrument fails? What steps should be taken?
    • I have a Go/NoGo gauge. Must I calibrate or verify ?
    • Can a matching part be used as a valid verification traceability ?
    • When do I need to have a procedure for calibration, verification ?
    • What is the relationship, if any, between calibration and MSA
    • What role do records have in an effective calibration program?

    I think once we have a good listing of the top issues, we can start writing up sections for each.

    I look forward to your feedback/input!
     
    Last edited: Jan 27, 2016
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  2. Ganesh Sundaresan

    Ganesh Sundaresan Active Member

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    What is "Uncertainty" and how does it influence the decision to accept/reject the Instrument based on Calibration result?
     
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  3. Jennifer Kirley

    Jennifer Kirley Moderator Staff Member

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    Why calibrate/verify an instrument when it is not used for final inspection?
     
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  4. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Does equipment used in the Design/Development process need calibrating?
     
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  5. BradM

    BradM Moderator Staff Member

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    Andy/ Jennifer, I took your more detailed suggestions and combined into one. I removed the more generic/general one.
    Thanks for the feedback.
     
  6. MarkMeer

    MarkMeer Well-Known Member

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    Great idea! One quick clarification though...

    I'm not familiar with the specifics of ISO 17025, but wouldn't such an FAQ be largely dependent on application and risk?

    In otherwords, is this FAQ intended for ISO 17025 test labs, or for manufacturers in general?
    If the latter, then the answers would be dependent on the nature of their activities, and applicable regulations, no?
     
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  7. BradM

    BradM Moderator Staff Member

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    Hello, Mark! Thanks for contributing.
    You make a couple of good points here. First, I'm not sure how separate it would need to be from 17025. My intent (at least from my perspective) is to create a general approach to the field of calibration. Many people get thrown into roles (QA/ metrology/ responsible for calibration dept.) usually before an audit or before their organization is planning to maintain compliance to an ISO specification. And... they really don't know where to start. How do they approach what should be calibrated? Do they need it "calibrated" every week; or is every five years OK?

    etc. So to your point, part of this endeavor is to instruct them how important application and risk is, and that they will need to account for such things.
     
  8. MarkMeer

    MarkMeer Well-Known Member

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    "Application of risk" could be a whole other FAQ! ;)

    Again, great idea though. I think it would be a very valuable resource!

    Depending on how detailed you intend to get, I'd suggest using some common examples throughout to illustrate the principles in practice.

    I seem to recall several very lengthy threads back on the Elsmar Cove to the effect of "should a ruler be calibrated?". Perhaps starting with such a (seemingly) simple question might be a good starting point for a lot of the answers. It'd really help illustrate how the nature of the tool, its intended use, and risk considerations are all critical factors to consider...
     
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  9. BradM

    BradM Moderator Staff Member

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    I added a definition for calibration. Let me know your thoughts.
     
  10. MCW8888

    MCW8888 Well-Known Member

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    Although I like this approach- saves company money, how would one verify at every stage of production that the product is on-spec if we have to wait for the final inspection?
     
  11. Jennifer Kirley

    Jennifer Kirley Moderator Staff Member

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    You have cracked the code. Verifying feature conformance to requirements using reliable instrumentation has always been a risk-based pursuit to keep cost of poor quality low and customer needs met.

    Some standards require a control plan, to list (among other things) the verifications done at places in the process in order to ensure product meets requirements.

    We can otherwise define it ourselves in an effort to reduce wasted materials, human time, machine wear and overhead costs that can be impacted by cycle time/time to market. This latter set of considerations can provide justification, given a review of relative costs, for calibrating/verifying production equipment too.
     
  12. MCW8888

    MCW8888 Well-Known Member

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    Ahh!! Another risk-based thinking approach. Thank you Jennifer.
     
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  13. Jennifer Kirley

    Jennifer Kirley Moderator Staff Member

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    It absolutely is a risk-based thinking approach - arguably one of the best because this type of risk is easy for most of us to understand and acknowledge as real.

    By the way, I put a quality cost calculator in the Resources forum.
     
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  14. MCW8888

    MCW8888 Well-Known Member

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    I like this post. We have some improvement to do in calibrating the process equipment out there at some of the location. I can introduce this quality cost calculator. Thank you Jennifer.
     
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  15. MCW8888

    MCW8888 Well-Known Member

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    If the Prototype Control Plan defines measuring equipment the Controls the Design at different stages to verify that outputs meets input requirements, would they nit need calibration? Again refer to the DFMEA for this one (8.3.4). I do not know but I would look at it this way. Thanks.
     
  16. James

    James Active Member

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    We got away from final "dock" inspections last year and now do our inspections in-process at the machines at every operation. Getting away from a final inspection after it's all done has increased our quality and helps with situations like this.
     
  17. Jennifer Kirley

    Jennifer Kirley Moderator Staff Member

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    I know of someone who got a major nonconformity from a CB (to TS 16949) because of calibration in the design process. While we might debate whether it was appropriate to list it as a major (I did not see the writeup) it makes sense to align the instrumentation's performance at both design and inspection so as to reduce the chance of product nonconformity to specification and all the resulting actions and costs that entails.
     

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