Auditing ISO 9001/AS 9100, sec. 7.1.5 (Calibration)

Test your knowledge and auditing skills to properly assess ISO 9001 / AS9100, sec. 7.1.5 by reviewing the following series of common scenarios encountered by both internal and external ISO 9001 / AS9100 auditors. Most of the technical information provided would be obvious to any 1^st year (entry-level) metrologist (calibration technician). Also, ALL of the scenarios presented are taken from real-world situations I have personally encountered.

Read the below scenarios and decide whether each is a nonconformity. And if so, decide whether it is a minor or a major nonconformity (Ref. "Classifying Nonconformities (ISO 9001 & AS9100)").
Click on the individual “Scenario” link (below) to “jump” to a discussion of that scenario and my opinions.

Scenario #1: You discover that the calibration status label on a micrometer is past its expiration (due) date.

Scenario #2: You observe production personnel in a machine shop verifying products using instruments marked “For Reference Only”. Upon asking why none of these instruments have been calibrated, the company guide informs you that production personnel are required to take the 3 items to the “Quality Inspectors”, located in a lab. Using calibrated instruments, the “Quality Inspectors” verify the first piece from each production run, then a random piece (near the middle of the production run), and then verify the final piece. Therefore, there is no need for the production personnel to have calibrated instruments.

Scenario #3: While visiting an inspection area in a powder processing plant, you observe a number of test sieves labeled “Special Calibration” with no calibration due date. Upon asking what a “special calibration” is, the company guide informs you that the test sieves consist of a stainless steel mesh that is more than sufficient to withstand any wear that the product being tested might exert on it. Therefore, the sieves are considered “single calibration devices”. However, the inspectors visually verify that there has not been any breakage or distortion of the mesh prior to each use. The company guide then presents you with a sampling of the small calibration certificates, some of which are several years old, that accompany each test sieve. You see that each test sieve has been calibrated according to ASTM E11, ISO 565 & ISO 3310-1.

Scenario #4: Upon reviewing a calibration certificate, you discover that it does not contain NIST “traceability” number(s).

Scenario #5: You observed a micrometer being used in the production area. Upon reviewing its calibration record, you see that it was calibrated in-house using a set of Gage Blocks. In order to verify metrological traceability, you review the calibration record for the Gage Blocks and discover that they too, had been calibrated in-house… using a Precision Micrometer. Continuing to investigate metrological traceability, you review the calibration record for the Precision Micrometer and discover that it had been calibrated in-house… using that same Gage Block set. The Precision Micrometer and Gage Blocks were being used to calibrate each other.

Scenario #6: Similar to the above scenario, but at a different company, you discover that the company is using a Starrett W733.1XFL-1 Wireless Electronic Micrometer to calibrate their class AS-2 Gage Block set (stainless steel, rectangular 0.010“ to 2”). While the Starrett W733.1XFL-1 Micrometer Calibration certificate contains minimal information, you notice that it has a digital display with a resolution of 0.00005“. To verify that the Test Accuracy Ratio (T.A.R.) is sufficient, you see that the Gage Blocks Calibration Certificate indicates an accuracy of ±10 μin.” (0.00001).

Scenario #7: You observed a weighing scale with a calibration status label. Upon examining its associated Calibration Certificate, you notice that the certificate was issued to a different address than the location where the audit is being performed. Upon asking about this discrepancy, you're informed that the weighing scale was calibrated at a different location and shipped to the current location.

Scenario #8: You observed calipers being used throughout the production process, and observed that the majority of these calipers supported the “Step” dimensional measurement. Upon interviewing multiple operators, you learned that some use the “Step” feature while others do not. You took note that NONE of these calipers with a “Step” feature had a “Limited Calibration“ status label… and you were told that the calipers are calibrated in-house. Upon examining the Calibration record, you noticed that the “Step” feature was not included in the calibration results. It appears that the company has not been calibrating the “Step” feature on calipers that support this dimensional measurement.

Scenario #9 (AS 9100 ONLY): You observed micrometers being used throughout the production process, and you were told that the micrometers are calibrated “in-house”. Upon Reviewing the Calibration Method, you noticed that neither the “flatness” nor “parallelism” of the anvil with the spindle had been calibrated.

Scenario #10 (AS 9100 ONLY): Upon reviewing the company's “register of the monitoring and measuring equipment”, which was maintained in an Excel spreadsheet, you discovered it did not include the:

• calibration or verification method, and
• acceptance criteria.

The company explained that, since all of their calibrations are outsourced, this information can be found in the calibration certificates provided by the external calibration lab.

Situation: You discover that the calibration status label on a micrometer is past its expiration (due) date.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: It depends.

The auditor should ask whether the company has a “Calibration Management System” (CMS), or equivalent, procedure.
If the answer is yes, then the auditor should review the CMS procedure because many companies provide themselves an automatic extension to the calibration interval/cycle/period (e.g., 30 days); or a conditional calibration due-date extension based upon management approval (to accept the increased risk). There are many good reasons why a company may choose to extend a calibration interval/cycle/period. However, the reason is typically to complete existing work in progress—accepting slightly greater risk in exchange for ensuring on-time completion/delivery of the product/service, or completion of a Project. This is perfectly acceptable.

I've seen CMS procedures that state: “Calibration is due during the month identified on the calibration status label, without regard for the specific day identified.” or “Calibration is due within 45 days past the date identified on the calibration status label.” This certainly satisfies the requirement in ISO 9001/AS9100, sec. 7.1.5.2a relating to specifying an “interval”.

The auditor should understand and recognize that a measuring instrument does not magically go “Out of Tolerance” on a certain date. The calibration interval (cycle) is merely a “risk control” to mitigate:

1. the likelihood of an instrument drifting out of tolerance during the calibration period, and
2. the impact/significance that an “Out-of-Tolerance” condition could have resulted in the shipment of nonconforming product(s) due to errors in measurements.

There are many factors that can contribute toward an instrument drifting out of tolerance, which include, but are not limited to:

• Wear (due to frequent use—which is most common for dimensional measurement devices)
• Use in an environment containing gritty or dirty substances (which will accelerate wear of most dimensional measurement devices)
• Misuse, mishandling, and/or neglect
• Use in an unstable environment (e.g., changes in temperature or humidity, vibration, wind)
• Exposure to harsh conditions, such as corrosive substances or extreme temperature changes (causing rapid degradation of the instrument)
• An unstable electrical source (e.g., “brown-outs) contributing to the degradation of electronic components
• Natural instrument degradation over time (e.g., aging of electronic components)

While many quality auditors incorrectly believe that a calibration status label is required by ISO 9001 / AS 9100; that is merely the most popular way in which to address the requirement. ISO 9001 / AS 9100, sec. 7.1.5.2 “Measurement Traceability” states:

When measurement traceability is a requirement, or is considered by the organization to be an essential part of providing confidence in the validity of measurement results, measuring equipment shall be:
b) identified in order to determine their status;

Prior to determining whether a nonconformity exists, the auditor must:

1. determine whether there are clearly defined provisions to extend a calibration interval/cycle; then determine whether the company complied with these provisions; and
2. determine whether these provisions allow for superseding any sort of calibration status label (or equivalent).

If the company is in compliance with its defined provisions to extend a calibration interval/cycle and the device is ”identified in order to determine“ it's status; then there is no nonconformity.

However, if the company either has no such provisions or has violated its own requirements relating to extending a calibration interval/cycle and/or there are no defined provisions for superseding the calibration due date on a calibration status label (or equivalent), then a clear nonconformity exists (i.e., contrary to 7.1.5.2a, the instrument was not calibrated or verified at its specified interval).

In order to classify a device that is past its calibration due date as a major nonconformity, the auditor must confirm that this is a ”Nonconformity where the effect is judged to be detrimental to the integrity of the product or service” and/or is a “nonconformity that can result in the probable shipment of nonconforming outputs; and a condition that can result in the failure or reduce the usability of the product or service and its intended purpose.”

How can the auditor conclusively reach this determination?

There are several ways in which to do this. However, if the company is either unwilling or unable to provide any evidence that would mitigate the nonconformity from a major nonconformity to a minor nonconformity, then the auditor should assume that a major nonconformity exists.

The auditor “could“ ask the operator to measure a finished part at 2 or 3 different dimensions using the micrometer that is past its calibration due date, and then ask the operator to measure those same dimensions using a micrometer within its calibration interval. If the measurements are the same (or very similar), AND both micrometers indicate that the part is within tolerance, then a Minor nonconformity is justified. However, if there is a significant difference between the readings OR the micrometers disagreed whether the part was within tolerance, then a Major nonconformity is justified.

If you're unfamiliar with “accuracy ratios”, read the linked article titled ”What are Accuracy Ratios“.

If the calculated “accuracy ratio” is greater than 4:1, this could be justification for identifying the nonconformity as a minor.

However, if the “accuracy ratio” is below 4:1, then this could be justification for a major nonconformity.

Depending upon the audit schedule, if the company has the capability to calibrate a micrometer “in-house”, they may opt to do so. If the results of that calibration indicate that the instrument was within tolerance, then a minor nonconformity is justified. However, if the results indicate an “Out-of-Tolerance” condition, then a Major nonconformity is justified.

Situation: You observe production personnel in a machine shop verifying products using instruments marked “For Reference Only”. Upon asking why none of these instruments have been calibrated, the company guide informs you that production personnel are required to take the 3 items to the “Quality Inspectors”, located in a lab. Using calibrated instruments, the “Quality Inspectors” verify the first piece from each production run, then a random piece (near the middle of the production run), and then verify the final piece. Therefore, there is no need for the production personnel to have calibrated instruments.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: More information is required.

You visit the “Quality Lab” and confirm that Inspectors are using calibrated instruments to inspect 3 pieces from each “job” run. You ask about the statistical basis for the sample size of 3, and the company guide informs you that the Inspectors are performing acceptance sampling using “Table 1” from "Zero Acceptance Number Sampling Plans", Fifth Edition by Nicholas L. Squeglia.

Interviews with Inspection personnel reveal that none of them have, nor are aware of “Table 1” from "Zero Acceptance Number Sampling Plans". The company guide explains that there is no need for the Inspectors to be trained in the use of “Table 1” because, when referencing that Table, the required sample of quantities of 25 and below (for an AQL of 4.0) is always 3. Therefore, it is sufficient to only train the Inspectors to verify the first piece, a random piece (near the middle of the production run), and the final piece for each job.

The guide then explains that, because this is a “job shop” handling small orders, none of their order quantities ever exceed 25. Therefore, calibrated instruments are used to inspect the required 3 samples (indicated in “Table 1” when the AQL is 4.0).

If you review the completed jobs and find no instance of a quantity exceeding 25, then there is no nonconformity because calibrated instruments are being used on the required sample size (even though this is a poor practice). However, if you find any instances where the order number exceeds 25 (referencing “Table 1” with an AQL is 4.0, the sample size increases to 7 for lot quantities of 26-50) then this becomes a major nonconformity citing ISO 9001/AS9100, sec. 7.1.5.1 “General”, which states:

The organization shall determine and provide the resources needed to ensure valid and reliable results when monitoring or measuring is used to verify the conformity of products and services to requirements.

Situation: While visiting an inspection area in a powder processing plant, you observe a number of test sieves labeled “Special Calibration” with no calibration due date. Upon asking what a “special calibration” is, the company guide informs you that the test sieves consist of a stainless steel mesh that is more than sufficient to withstand any wear that the product being tested might exert on it. Therefore, the sieves are considered “single calibration devices”. However, the inspectors visually verify that there has not been any breakage or distortion of the mesh prior to each use. The company guide then presents you with a sampling of the small calibration certificates, some of which are several years old, that accompany each test sieve. You see that each test sieve has been calibrated according to ASTM E11, ISO 565 & ISO 3310-1.

(1) Is this a nonconformity?

Answer: No.

ISO 9001 / AS9100, sec. 7.1.5.1, “Measurement traceability” states:

When measurement traceability is a requirement, or is considered by the organization to be an essential part of providing confidence in the validity of measurement results, measuring equipment shall be:
a) calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards; when no such standards exist, the basis used for calibration or verification shall be retained as documented information;

ISO 9001 / AS9100, sec. 7.1.5.1a requires measuring devices to be calibrated EITHER ”at specified intervals“ OR ”prior to use“. Also, note that ”prior to use“ does NOT mandate ”prior to EACH use“. Since the test sieves were calibrated prior to being placed into service, they satisfy the requirements of ISO 9001 / AS9100, sec. 7.1.5.1a.

Companies have taken this same approach toward stainless steel rulers (in a low-wear environment) and graduated glass cylinders (for non-abrasive & non-corrosive materials). Key considerations for these types of devices are:

1. no adjustments of the readout are possible,
2. the devices are made of material that is resistant to wear (e.g., stainless steel), and
3. exposed to extremely low wear (e.g., minimal or no contact).

IF the above test sieves had been used to filter particle sizes of highly abrasive material, then this approach may not have been justified.

Situation: Upon reviewing a calibration certificate, you discover that it does not contain a NIST “traceability” number(s).

(1) Is this a nonconformity?

Answer: No… because there is no such thing as a NIST “traceability” number. I understand that this may come as quite a shock to some auditors who were taught to always verify that NIST Test numbers appear on calibration certificates. However, much like sasquatch, the NIST “traceability” number is a persistent myth… that came into existence due to a misunderstanding of the NIST “Test Number”; which is used for administrative purposes only. This is supported by official interpretations from NIST.

And

This is further noted in the:

Situation: You observed a micrometer being used in the production area. Upon reviewing its calibration record, you see that it was calibrated in-house using a set of Gage blocks. In order to assure metrological traceability, you review the calibration record for the Gage blocks and discover that they too, had been calibrated in-house… using a Precision Micrometer. Continuing to investigate metrological traceability, you review the calibration record for the Precision Micrometer and discover that it had been calibrated in-house… using that same Gage block set. The Precision Micrometer and Gage blocks are being used to calibrate each other.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: This is a major nonconformity.

ISO 9001 / AS9100, sec. 7.1.5.1, “Measurement traceability” states:

When measurement traceability is a requirement, or is considered by the organization to be an essential part of providing confidence in the validity of measurement results, measuring equipment shall be:
a) calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards; when no such standards exist, the basis used for calibration or verification shall be retained as documented information;

Since these two devices are being used to calibrate each other, they've lost metrological traceability to “measurement standards traceable to international or national measurement standards”.

As the Gage blocks wear, that gradual change will be transferred to the Precision Micrometer during its calibration. As these two devices are alternated in their use to calibrate each other, the Precision Micrometer will be adjusted to correlate with the Gage blocks. Over time, the two will drift further away from their true values… and, more significantly, this “drift” is being flowed down to all of the other instruments calibrated using the Gage blocks. Consequently, this is a Major nonconformity because:

• there is a significant doubt that effective process control is in place to ensure that products or services will meet specified requirements;
• the effect of this nonconformity is detrimental to the integrity of the product or service;
• this nonconformity indicates a total breakdown of a system to meet an ISO 9001 or AS9100-series standard requirement;
• this nonconformity could result in the probable delivery of a nonconforming product or service

Situation Similar to the above scenario, but at a different company, you discover that the company is using a Starrett W733.1XFL-1 Wireless Electronic Micrometer & Starrett W733.1XFLZ-2 Wireless Electronic Micrometer a to calibrate their class AS-2 Gage Block set (stainless steel, rectangular 0.010“ to 2”). While the Starrett W733.1XFL-1 Micrometer Calibration certificate contains minimal information, you notice that it has a digital display with a resolution of 0.00005“ (50 μin.). To verify that the Test Accuracy Ratio (T.A.R.) is sufficient, you see that the Gage Blocks Calibration Certificate indicates an accuracy of ±10 μin. (±0.00001”).

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: More research would be required in order to make this determination.

You would need to access and review the specifications for the Starrett W733.1XFL-1 Wireless Electronic Micrometer. Upon doing this, you would discover that the accuracy of this particular micrometer is much less than its resolution. Its stated accuracy is ±0.0001“. If the company assumed that the resolution and the accuracy were the same, they would have been wrong.

In calculating the Test Accuracy Ratio (T.A.R.), we take the Gage Block tolerance of 0.00001” and divide it by the accuracy of the Starrett W733.1XFL-1 micrometer, which is actually stated in its specifications as 0.0001“ (±100 μin.). This results in: 0.00001 ÷ 0.0001 = 0.1 (or 1:10). This means that the Gage blocks are 10x more accurate than the micrometer! This ratio is the inverse of what we would like to have seen!

A major nonconformity is clearly justified.

Situation A weighing scale was calibrated at a different location and then shipped to its current location. And there is no evidence that the calibration was repeated to verify that the weighing scale remained in-tolerance following the move.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: The proper follow-up question is whether there is any documentation or record indicating that this specific model of weighing scale is immune from possible effects of

1. the difference in local gravity acceleration,
   
2. variation in environmental conditions, and/or
   
3. mechanical and thermal conditions during transportation that likely altered the performance of the instrument?
   

If the answer is no, and there is no other evidence to the contrary, this should be a Major nonconformance because we must assume that there is a high degree of probability that product quality (or quantity) has been affected. However, if the auditee has appropriate test weights (mass) providing an acceptable calibration accuracy ratio, and can verify that the weighing scale is in-tolerance during the audit, then this can be graded as a Minor Nonconformity (for not having a record of calibration AFTER the weighing scale was re-located).

The basis for this nonconformity is found in EURAMET Calibration Guide No. 18 (Version 4.0 (11/2015)), page 5, which states:

4.1.2 Place of calibration
Calibration is normally performed in the location where the instrument is being used.

If an instrument is moved to another location after the calibration, possible effects from

1. difference in local gravity acceleration,
   
2. variation in environmental conditions,
   
3. mechanical and thermal conditions during transportation are likely to alter the performance of the instrument and may invalidate the calibration.
   

Moving the instrument after calibration should therefore be avoided, unless immunity to these effects of a particular instrument, or type of instrument has been clearly demonstrated. Where this has not been demonstrated, the calibration certificate should not be accepted as evidence of traceability.

Situation: You observed calipers being used throughout the production process; and observed that the majority of these calipers supported the “Step” dimensional measurement feature. Upon interviewing multiple operators, you learned that some use the “Step” feature while others do not. You took note that NONE of these calipers with a “Step” feature had a “Limited Calibration” status label… and you were told that the calipers are calibrated in-house. Upon examining the Calibration record, you noticed that the “Step” feature was not included in the calibration results. It appears that the company has not been calibrating the “Step” feature on calipers that support this dimensional measurement.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: This is a Major nonconformity.

ISO 9001 / AS 9100, sec. 7.1.5.1 states:

The organization shall retain appropriate documented information as evidence of fitness for purpose of the monitoring and measurement resources.

The auditor should have sufficient knowledge in using a caliper to understand that the “Step” feature can be “Out of Tolerance” due to wear on a point not otherwise calibrated. By recognizing that this feature had not been included in the calibration process, the auditor can justify a Major nonconformity because:

• there is a significant doubt that effective process control is in place to ensure that products or services will meet specified requirements;
• the effect of this nonconformity is detrimental to the integrity of the product or service;
• this nonconformity could result in the probable delivery of a nonconforming product or service

Situation: You observed micrometers being used throughout the production process; and you were told that the micrometers are calibrated “in-house”. Upon reviewing the company's “register of the monitoring and measuring equipment” you discovered that they identify a calibration/verification method. Upon reviewing that calibration/verification method, you noticed that neither the “flatness“ nor “parallelism” of the anvil with the spindle had been calibrated. You confirm this by examining calibration records for a sampling of the micrometers you observed in use. None of these records indicate that the “flatness” or “parallelism” of the anvil with the spindle had been calibrated.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: This is a major nonconformity.

ISO 9001 / AS 9100, sec. 7.1.5 states:

…the organization shall retain appropriate documented information as evidence of fitness for purpose of the monitoring and measurement resources.

The auditor should have sufficient knowledge of using a micrometer to understand that a failure to verify the anvil and spindle Flatness & Parallelism could result in measurement errors due to wear patterns OR dirt / small metal chips embedded in the anvil or spinal. Therefore, checking the flatness & parallelism should be the first step in calibrating a micrometer.

In the video below, a metrologist from Mitutoyo discusses using an optical flat for verifying both micrometer anvil Flatness & Parallelism at: 1:44 to 2:15 (Intro) and 17:50 to 24:55 (detailed discussion).

ASME B86-1-13, “Micrometers”, page 10 “Nonmandatory Appendix C - Test Methods” specifies verification of flatness using an optical flat and a monochromatic light source (in C-2.2). T.O. 33k6-4-15-1 "Calibration Procedure for Micrometers Micrometer Heads and Depth Micrometers-General” also specifies verification of flatness using an optical flat and a monochromatic light source (in 4.1.1)

ASME B86-1-13, “Micrometers” describes using a precision sphere (metal ball) to verify Parallelism (in C-2.4) and using gage blocks (in C-2.5) for larger micrometers (i.e., micrometers designed for larger measurements where the anvils do not touch). It also describes how you can use optical flats to verify Parallelism (in C-4.6).

Auditors should take note that Mitutoyo, ASME & the USAF all agree that calibration of micrometer anvil Flatness & Parallelism is important. And should watch the below video from Mitutoyo describing, step-by-step, how a common outside micrometer is “supposed” to be calibrated.

Situation: Upon reviewing the company's “register of the monitoring and measuring equipment”, which was maintained in an Excel spreadsheet, you discovered it did not include the:

• calibration or verification method, and
• acceptance criteria.

The company explained that, since all of their calibrations are outsourced, this information can be found in the calibration certificates provided by the external calibration lab.

(1) Is this a nonconformity? And if so, (2) is it a minor or a major nonconformity?

Answer: This is NOT a nonconformance.

The following question was submitted to IAQG (through OASIS) for an official clarification (i.e., interpretation):

The 9100:2009-series verbiage require a calibration register and the definition of processes for calibration/verification (including equipment type, ID, frequency, methods and acceptance criteria), but didn’t seem to require them to be one in the same. The 9100:2016 standard appears to mandate these definitions be incorporated into the register itself, as opposed to just being defined. Is this required to be taken literally that the register is required to have this information is absolute?

The IAQG "Official" AS 9100:2016 Series Clarifications contains the following response:

The 9100-series clause 7.1.5.2 was not intended to force organizations to have the register specifically include the “equipment type, unique identification, location, and the calibration or verification method, frequency, and acceptance criteria.” The organization is required to have this information for equipment listed on the calibration register but not specifically in the register.

To further clarify, if the documented information is available, and not necessarily in the “register”, IAQG considers the requirement to have been adequately addressed.

The entire IAQG "Official" AS 9100:2016 Series Clarifications is available online.

To contact the SDR (Sector Document Representative) for AS 9100-series in your region, Reference: Contact info. for AS Standard IDRs (IAQG Document Representatives) & SDRs (Sector Document Representatives) - Updated Oct. 2021.