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 6 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

For more information about calibration, please see the resources here.

ISO Requirements or Good Documentation Practices?




Are these standard for ISO or just good documentation practices?

1. All entries, except IPQA, should be made with blue ball pen in clear and legible handwriting.
2. IPQA entries shall be done in black ball pen.

I can sense what it is happening at the place where this question originated. In the past, I saw a company where the person in charge of the Quality System was saying “this is a ISO requirement” to enforce what in this person’s opinion was a best practice. Nobody questioned those statements because “it is an ISO requirement”. So, the answer to the question is, those are best practices, not ISO requirements. Please see below the ISO 9001:2015’s clause pertaining to this question.

7.5.3 Control of documented information Documented information required by the quality management system and by this International Standard shall be controlled to ensure:

  1. a)       it is available and suitable for use, where and when it is needed;
  2. b)       it is adequately protected (e.g. from loss of confidentiality, improper use, or loss of integrity). For the control of documented information, the organization shall address the following activities, as applicable:

  1. a)       distribution, access, retrieval and use;
  2. b)       storage and preservation, including preservation of legibility;
  3. c)       control of changes (e.g. version control);
  4. d)       retention and disposition.

Documented information of external origin determined by the organization to be necessary for the planning and operation of the quality management system shall be identified as appropriate, and be controlled.

Documented information retained as evidence of conformity shall be protected from unintended alterations.

NOTE  Access can imply a decision regarding the permission to view the documented information only, or the permission and authority to view and change the documented information.

As you can see, no reference to any ink color whatsoever. Legal documentation tends to be completed by using blue ink to differentiate originals from Xerox copies. However, today’s technology allows us to have color copies.


Aura Stewart

Relocation Requires Audit?


One of my contract manufacturers who is ISO 9001: 2008 certified, submitted a Supplier Change Notice to relocate their factory to a new site/location. This will trigger many activities including re-qualification, etc. My question is, for their ISO 9001 certificate, do they simply refresh their company location / address in their ISO 9001 certificate with the Notified Body or they actually need to go through a full scale quality system audit by the NB?


Yes. They do need to have a full scale audit. The reason is very simple, a business is a system. When you change the environment, you alter that system. A full audit will be an adequate representation of the scope and magnitude of the change, and will indicate if this supplier is still a reliable manufacturer. Think about your most recent home move, the family is the same, your belongings are the same; however, everything is different at the same time.

Aura Stewart

Cleanrooms, Classes, and Control Charts


My question has to do with cleanroom monitoring, specifically particle counts. Using ISO 14644-1: 1999, (we are still transitioning to the new standard).
We have 27 test sites in our cleanroom. Our Particle Counter takes 10 readings per minute and averages those readings into one value. This is the number we record at each of the 27 test sites. Since an ISO Class 8 Cleanroom can have no more than 3,520,000 particles greater than 0.5 micron in size per cubic meter, for the room, do you add all 27 results and compare to the acceptance criteria? Do you average all 27 results and compare to the acceptance criteria? or as long as each individual result is below the acceptance criteria we are in compliance? what makes me think you add all results together is that the acceptance criteria states: ISO Class 8 Cleanroom can have no more than 3,520,000 particles greater than 0.5 micron in size per cubic meter, for the room. Your input would be greatly appreciated!

The way for analyzing these data is very straightforward. Considering you have continuous data, the most appropriate way for accomplishing this is by using a control chart. Use the 27 readings for constructing the averages needed for a control chart. Identify control limits and respond to special cause variation only. You will know that you are in compliance as long as your control charts remain under control. If you ever find any points out of control, you may want to quarantine the product processed during that time and conduct the appropriate corrective actions. As your regular housekeeping, keep the cleanroom certification current. The same for the particle counter system calibration.

If you are new to control charts, the easiest/simplest reference I have ever found is Understanding Variation – The Key to Managing Chaos by Donald J. Wheeler.

Based on your data performance, you may also be able to identify areas within your cleanroom that perform better than class 8 (7 or better). Knowing where those areas are may be handy.