I'm working in an automotive company that must follow IATF (International Automotive Task Force) requirements.

I administrate a test-bench that performs RF (radio frequency) tests using an appropriate measure instrument.

As IATF requires, the test-bench has been successfully validated using MSA (Measurement System Analysis) procedures for the production process where the test is performed.

After one year without changes both in production process and test-bench measure chain the instrument must be calibrated (and adjusted accordingly if necessary) from the producer (calibration lasts one year).

IATF requires that every change in the process must be verified with the MSA. The problem is that "change" is too much generic, and I can't find the proper IATF documentation.

Have I to re-perform MSA after the calibration/adjustment of the instrument?

Facts are:

  • the instrument is the same as before (same serial number) or is the same model (different serial number)
  • the instrument is fresh calibrated (like when I performed the MSA first validation)
  • the instrument is plugged out, calibrated or replaced with a calibrated one (same model) and than plugged in.

so, my opinion is that the measurement test chain is the same as before so I don't need to provide MSA documentation to auditors. The calibration + optional adjustment process don't modify the instrument, it restores the instrument to the conditions of the previous calibration.

I'm not able to find official IATF documentation or others sources about that: does calibration + optional adjustment procedure modify the measure process?

This is the calibration definition from the MSA AIAG manual:

A calibration system is a set of operations that establish, under specified conditions, the relationship between a measuring device and a traceable standard of known reference value and uncertainty. Calibration may also include steps to detect, correlate, report, or eliminate by adjustment any discrepancy in accuracy of the measuring device being compared.

so, by definition, a calibration process is a check between instrument actual characteristics and nominal characteristics that comprises adjustments to align real and nominal characteristics. In any case after this process real characteristics are compliant to nominal.

  • $\begingroup$ Don't have experience with the kit or regs specifically so not qualified to answer, but when I've sent items to be 'calibrated' 95% of the time it's just a verification and changes are only made if it's out of tolerance (which may answer your question if so). I've only ever done MSA to determine uncertainty in a system and our auditors have been happy as long as one has been done, regardless of any changes. $\endgroup$
    – Kagekiba
    Dec 19, 2018 at 17:26
  • $\begingroup$ The problem is the 5% and that our QC dept keeps the production blocked until a proper MSA documentation is provided. My opinion is that MSA is not needed even with instrument adjustments and I'm searching evidences that prove my opinion. $\endgroup$
    – Andrea
    Dec 20, 2018 at 15:07
  • $\begingroup$ In that case I would use the arguement that the MSA is a qualifaction of the whole process (including operator variance) and the calibration of the equipment is just to keep the equipment working within limits, so it does not alter the MSA. Also if you can demonstrate any corrections just offset the readings, then you could apply you're uncertainty from the MSA and show it just shifts the range and doesn't change the size of it. $\endgroup$
    – Kagekiba
    Dec 21, 2018 at 9:34
  • $\begingroup$ Another approach would be to agree with QC that MSA will be redone every 5 years or so instead of every year and include/treat it as a seperate item on your calibration schedule. $\endgroup$
    – Kagekiba
    Dec 21, 2018 at 9:34

1 Answer 1


A change may be that the target measurement is different, or that the hardware you're testing is different, or you move the machine into a different location in the shop and there may be different interference level in that area(if some type of electronic testing). Use your judgement or ask someone who knows more about it.

Unless there is a specification or customer requirement for MSA, or something defined in your quality manual, you should determine your MSA frequency. I don't know how long the MSA takes or if there's some cost etc, so take with a grain of salt. You could perform an MSA at the start of each shift, or each lot of parts, or once a week, or once a month, every 3 months, whatever. If the MSA fails, your containment lot size of possible affected parts is all of the parts made since the last MSA. Larger frequency, larger containment lot and more risk.

If you're unsure of the reliability of the inspection equipment, start at a higher frequency initially and then gradually reduce frequency to where you're comfortable. Once a day, for a 1 week. Once a week for 3 weeks, once a month, etc.

Prove and document that your equipment is reliable. If it fails, this way you have data to back your decision on MSA frequency.


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