Calibration Questions

Automotive inspection, TS 16949, IATF 16949


I work at a hydraulic cylinder manufacturer. The company has homemade thread and ring gages in house that we are using for production that are not sent out for calibration but have a homemade master that is used to check them with once a year which does not get sent out either. I have been here six months and am thinking these gages and masters are a violation of ISO. Am I correct?


The short answer is yes. The intent of ISO 9001:2015’s subclause 7.1.5 is to ensure that your company determines and provides suitable resources to ensure valid and reliable monitoring and measuring results, when evaluating the conformity of your products; and’s that is to ensure that your company provides measurement traceability when it is a requirement or when your company determines it to be necessary to have confidence in the validity of the measurement results. It seems that your practice for controlling the homemade thread and ring gages cannot fully fulfill those purposes. This is how I would address the situation:

  1. Assign a unique identifier to each homemade thread and ring gage. Maybe you can do that through your Document Control process.
  2. Ensure that those gages are protected from deterioration or damage when they are not in use.
  3. Have the homemade master measured by a service able to provide you with reliable certified measurements. That will make that gauge traceable to national or international standards. It will also allow you to demonstrate that the piece is fit for its intended purpose.  That means, you will be able to use this piece as the standard during the in-house calibration of the rest of the gages.
  4. Conduct an “in-house calibration” of each gage you use in production. You will need to issue an in-house calibration certificate for each one of those pieces, indicating on those documents how you achieve traceability to NIST or equivalent. If possible, identify the error for each one of those individual measurements you perform during calibration. Do not forget to include a statement indicating that the gauge was found suitable/unsuitable for use. That will demonstrate that each gage is fit for its intended purpose.
  5. Include ALL the gages in your calibration program. Make them subject to all the applicable provisions of your Quality System.

This approach will allow you to demonstrate that your thread and ring gages are properly controlled and maintained. If controlling those gages has not been an issue in the past, there is no guarantee that the situation will remain the same in the future. That is managing risk 😉

Aura Stewart

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TS 16949 Calibration Management

Automotive inspection, TS 16949, IATF 16949

Q: Under the standard ISO/TS 16949:2009 Quality management systems – Particular requirements for the application of ISO 9001:2008 for automotive production and relevant service part organizations — is it acceptable to allow an instrument user to request a calibration extension under certain circumstances?

Here are just a couple of examples:

The user is in the middle of a test that they don’t want to disrupt until completed.
Equipment is installed on a test vehicle that is at a remote location and is not readily available.

I should note we are an automotive supplier engineering facility doing advanced product development.

A: Here is my usual advice about calibrations:

1. The calibration frequency is both a matter of use and criticality of measures. Instrument companies err on the side of frequent recalibrations.

2. As with most standards based on ISO 9001:2008, the calibration frequency is an internal company decision as the requirement is:

•    Process for calibration management
— Records need to show (7.6.2):
> Equipment identification, including the measurement standard against which the equipment is calibrated
> Revisions following engineering changes
> Any out-of-specification readings as received for calibration/verification
> An assessment of the impact of out-of-specification condition
> Statements of conformance to specification after calibration/verification
>  Notification to the customer if suspect product or material has   been shipped

Therefore, it is the supplier who determines the frequency of the calibration, as well as the standard to which they are using. If the supplier sets a frequency schedule they should follow it unless they get a concession from their customer.

I have done a large calibration study where an engine plant did the statistical analysis, which saved them millions of dollars to set optimal gauging schedules for an engine plant. I recommend that such a study be conducted by this company as soon as possible.

Ron Berglund
Voting member of the U.S. TAG to ISO/TC 176
ASQ Fellow
Canton, MI

For more on this topic, please visit ASQ’s website.