ISO 9001/AS 9100 Calibration Requirements and Procedure

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Both AS 9100 and ISO 9001 calibration requirements are quite extensive, and special attention is required to meet them. Any tiny failure in this part of the QMS will trigger questions about the impacts on the product.

This post introduces step-by-step the different activities that are required to satisfy (in an efficient manner) ISO 9001 and AS 9100 calibration requirements for control/measuring equipment used for product and process verification.

AS 9100 Calibration Requirements: The Foundations

Whether you are establishing a new calibration system from scratch or revamping an existing one, below are the key considerations to meet ISO 9001 or AS 9100 calibration requirements. These are necessary pre-requisites before we start the second part of this post.

If you familiar with these requirements, feel free to skip the explanations and directly download our Calibration Procedure and Excel Calibration Database that meets ISO 9001 and AS 9100 Calibration Requirements.

Does your system have clear scope and boundaries?

Start by imagining the big picture of your calibration system. It is important to define the scope by asking yourself some key questions such as:

        • What are the major instrument/equipment groups of my calibration system?
          The purpose is to have a helicopter view of what equipment can be grouped together. The most common categories are the following :
            • Measurement instruments: Vernier Calipers, Rulers, Filler Gauges, Torque Wrenchs, …
            • Process Equipment: CNC, CMM, Ovens, Galvanization Baths, Freezers, Power Screw Drivers, …
            • Manufacturing Tools: Stamping Tools, Injection Molds, Lay-Up Tools, …
            • Environmental Control: temperature, humidity, pressure, particle counter, light, noise level, …
            • Reference Instruments: instruments that will be solely kept in the QA Lab to conduct in-house calibrations
            • etc
        • Who will be in charge of the calibration activities for each family/group?
          QA will most probably be in charge of most of the calibration activities but it is frequent that some complex areas are covered by other departments such as maintenance or engineering. Understanding stakeholders will support their involvement from the early stages of implementing or revamping the calibration system.
        • What will be excluded from the calibration system?
          At this stage, you may consider large groups of equipment that will not be part of the calibration system. For example measuring equipment that does not influence the quality of the product (facilities equipment, equipment that needs separate verifications by certified bodies,  …). You may also decide to exclude completely some areas for example a laboratory if it covered by a separate process or procedures.

What are past failures and lessons learned?

It can appear obvious, but learning from past failures is interesting at the early stages of any project. Asking people around you this question will help you implement a better system. For example, people may complain about the software system to track calibration due dates, or the sticker attached to every tool gets worn too easily, or the current system led to AS 9100 findings in the past.

Is the current calibration database accurate and up to date?

The next step is to have an accurate and up-to-date database with an inventory of all equipment that requires calibration. Inventory means also the identification of every piece of equipment with an id number. At this stage, a simple calibration database is fine. You don’t need a complex one. The purpose is only to assess the current condition versus the ideal situation and understand which gaps need to be closed.

Is the current numbering system appropriate?

My advice here is to not make a complex numbering system. I have seen organizations that allocate for each instrument family a prefix to the id number and they end up with a complex system that only the person in charge understands. Make the system so easy that anyone can support this activity in case of absence or leave. The baseline is to have a unique number for every piece of equipment or instrument. Hence, you don’t need to number every oven OVEN1, OVEN2, etc, and calipers CAL1, CAL2, CAL2, etc. Numbering all your equipment regardless of their type: ID-00001 until ID-99999 is perfect. Having said that, you may want to develop a little bit more the numbering system, this is also fine but just keep in mind to not make it too complex.

While talking about numbering, keep in mind that you will definitely face from time to time worn stickers or detached ones. Therefore, in addition to the usual calibration sticker, it is recommended (where possible) that you engrave the id number on the instrument/equipment itself (particularly the small or frequently used ones). You can do it using a grinder/engraving pen such as Dremel or equivalent.

Are calibration reports available and archived?

Once you have a list of all equipment, every single entry must be supported with a calibration report. Calibration report can be electronic or hard copy. If not done yet, organize them in one location (a shared drive or physical folder).There is no requirement to have all the reports scanned and available in electronic format. As long as you can provide them to an auditor, it is fine. Discuss with your service provider to have them in electronic format to ease the archiving. If only hard copies are available, you may decide to scan the most important ones that are often requested by auditors (e.g.: pyrometry, process equipment, …) and keep the rest (and the vast majority) in paper format.

Are the service providers selected and appropriate?

Make a list of service providers that are used in your company to perform calibration activities. You may need different service providers for the different categories and or equipment. Make sure they are certified ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories. This requirement towards service providers shall be included in your calibration procedure or purchasing procedure as well as tracked and checked on a yearly basis in your Approved Supplier List.Your calibration database shall at this stage include the information for every instrument if calibration is done in-house or by an external service provider. Don’t worry too much about internalizing calibration activities for the easier equipment (e.g. vernier caliper, time counters, rulers, …). Get first your system up to speed and running then introduce group by group in-house calibrations.

Consolidating your Calibration System:

Now that you have put in place the skeleton of your system, you can make the ball rolling. Between the start of these activities until the system reaches the cruising speed, there might be ups and downs: past due equipment, service provider unable to meet a deadline, equipment that is out of calibration, lost and damaged instruments, etc. It is part of the activity to manage exceptions. Don’t be afraid of such issues and handle them with a continuous improvement approach: update your forms if necessary, your calibration excel tracker, your procedure, provide feedback to the buyer about low-quality instruments, etc.

The foundations that we discussed so far are the most critical part of the system. Weak foundations will lead to many issues at a later stage or even “Scrap & Build”. In this chapter, we will cover additional items of the calibration system.

Calibration Procedure:

The calibration procedure will combine into one location all the considerations you taught about so far. You shall keep the procedure large enough that you don’t have to update it often and at the same time specific enough to cover most situations that will arise.

You can download our AS 9100 Calibration Procedure. It complies with AS 9100 Calibration Requirements as well as ISO 9001 ones.

Calibration Extension Form:

This is a key pillar of the calibration procedure and you will have to define precisely the approval flow. The calibration extension form will help you overcome unplanned situations where some equipment shall be used while the calibration due date is passed.

The extension request form shall include fields to record properly the risk assessment that will support an informed judgment. Also, it shall include a tick box to check past calibrations history.

You can download our calibration extension form which is compliant to AS 9100 calibration requirements.

MTE (Maximum Tolerated Error) and Instrument Range per AS 9100 CALIBRATION RequirementS

Every equipment shall have an MTE and usage range defined and communicated to the calibration service provider. You may include this information in the calibration database or eventually gather these details in a separate documented information to ease the updates and avoid different MTE for the same type of equipment. The MTE is straightforward and shall be defined based on the product you are producing/measuring.

For example, a vernier caliper used to measure a diameter of 100 +/- 5mm can be calibrated to an MTE of 0.5 or 0.1mm while if used to measure 2 +/- 0.1mm it shall be calibrated to 0.01mm. As a general rule, MTE shall be to the tenth of the tolerance or 1/4 if allowed by stakeholders. There are no specific requirements for MTE in the AS 9100 but these shall be defined based on the internal constraints.

AS 9100 CALIBRATION RequirementS for RecordS Retention

While the AS 9100 does not specifically mention a duration for the retention of old calibration reports, it is common practice to keep them for few years. The purpose of the retention is first to keep evidence of product conformance (even after delivery) and secondly to keep evidence that there was no time between two calibration periods where the equipment was out of calibration. Pay attention that this is a common question during ISO or AS audits.

In general, the retention period is between 7 to 10 years but a detailed matrix of how long every quality record is retained shall be included in the document control procedure.

Calibration Excel Database

Once all your procedures and forms established, they will require little updates and improvements over the years. The most critical part of your system is your calibration database. Any audit will assess how well you maintain your calibration database up to date and how does is help you to keep track and trigger the calibration activities.

You will notice that it is the calibration database and its management that will be often reviewed in case a departure or near-miss is noticed. Below are some information that you shall consider including in your calibration database. Some of the information below is not a must-have from AS 9100 calibration requirements point of view but they are good practices in the industry:

      • Instrument details: brand, type, range, manufacturer serial number
      • Dates tracker: date of purchase or date of first use, calibration date, calibration due date, calibration frequency, the time required to perform calibration, …
      • Calibration type: in-house, external calibration with eventually the service provider(s) name(s) and approximative costs as well as if the outsourced calibration is done in the service provider offices or in-house.
      • Location and status: the area where it is used or stored, the exact station where it is used, status (in use, stored and calibrated, stored only, out of use, lost, etc)
      • Dashboard and visual telltales: in the same way as a car dashboard, your database shall provide you telltales that show equipment that is not due, due, past due. This judgment shall be made based on the above information.  You may decide also to develop a dashboard that shows a summary of this information.

Feel free to download our free Calibration Tracker that meets AS 9100 Calibration Requirements. You may also consider downloading our Calibration Procedure.

Download Section

Download our ready-to-use Calibration Procedure and Tracker Templates. This compressed file contains the procedure, calibration tracker with formulas to trigger calibration activities as well as a calibration extension form.

These documents are meeting AS/ISO requirements and will require a little adjustment to be adapted to your organization’s QMS. Support can be provided by email after purchase.

Download our AS9100 / ISO 9001 Calibration Procedure & Tracker on Sellfy

Free Excel Calibration Database Template meeting AS9100 Calibration Requirements

Free Excel Calibration Database Template meeting AS9100 Calibration Requirements


In conclusion, AS 9100 calibration requirements are quite extensive, and special attention is required to meet them. This part of the QMS can be self-sustaining but on the other hand, can lead to significant troubles in case a tiny failure is noticed during an audit. You will have to demonstrate that there was no impact on the product in such situations. I hope the above ideas will help you design a system that meets AS 9100 calibration requirements as well as your stakeholders’ expectations.

Feel free to ask any question you may have in the comments sections.


For further resources related to AS9100 Rev D or ISO9001:2015 implementation, refer to the below posts:

Defining internal and external issues per AS9100 – ISO 9001 (SWOT/PEST)

Defining interested parties per AS9100 – ISO 9001

Document Control Procedure per AS9100 – ISO 9001

Management Review Procedure per AS9100 – ISO 9001

Process Map and Process Cards per AS9100 – ISO9001

Calibration Procedure and Tracker per AS9100 – ISO9001

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