Selecting a Calibration Supplier

When selecting an outside calibration supplier, it is critical to have confidence in the supplier’s abilities to calibrate your measuring equipment properly and to maintain quality in the services they provide. Your measuring equipment provides the basis for the quality and performance of your organization. An incorrect calibration of one of your primary measurement standards can lead to significant errors in your measurements and can lead to misleading results, a lack of confidence in your equipment and even recalls of critical items.

Investing time in conducting some preliminary research can ensure that the provider will meet your calibration needs and keep your equipment performing within its specified tolerances. It is very important that you work towards building a close working relationship with your calibration supplier and create a partnership where requirements, results, improvements and concerns are freely communicated.

Although cost and turnaround times are the first, and sometimes only, things companies look for when considering a calibration supplier, there are several other things that are very important to ensure that you are getting the calibration results you are expecting.

Any calibration supplier that is chosen should be accredited to ISO/IEC 17025. By the performance of periodic audits by national accreditation bodies and through proficiency testing, accreditation confirms that the calibration laboratory has the proper quality systems in place and has demonstrated the technical competence in their measurements to provide increased confidence in their results.

The calibration laboratory should have the capabilities to calibrate most of the equipment that you require. Having one, or a few, calibration suppliers can reduce shipping hassles and costs and will incur less overall downtime.

All calibration laboratories accredited to ISO/IEC 17025 have a Scope of Accreditation available which lists the accredited technical capabilities of the laboratory. That is an excellent way to compare the capabilities between differing calibration suppliers. Special attention needs to be made to the measurement uncertainty values associated with the measurement capabilities. The measurement uncertainty is a measure of the combined equipment specifications and error sources during a specific calibration. Two calibration laboratories could have similar technical capabilities, but widely different measurement uncertainty values depending on the methods and standards used for the calibration.

Clear agreements should be established with the calibration supplier on expected turnaround times. The average turnaround time for your equipment can be a significant determination of a laboratory’s efficiency and must be weighed against the organization’s expected downtime. Shipping times must also be factored into the expected timeframe. Expedited service should be available from the supplier when requested.

Selecting a calibration supplier based on price alone can be detrimental to an organization’s quality system and end up costing more in the long run. If the calibration quality is compromised, the reliability of the equipment must be questioned and recalibrations or monitoring of equipment is required. Sometimes the quoted calibration cost is only a base cost. Other costs, such as fees for an accredited calibration, expedited service or adjustments and repairs could be added. Shipping and insurance costs will also need to be factored into the total cost of the calibration.

Can the laboratory perform adjustments on the types of equipment you will be sending them? Some equipment manufacturers consider adjustment and repair information proprietary so that only the manufacturer or authorized repair facilities can perform the adjustments. If the calibration supplier can calibrate the equipment, but cannot perform any adjustments if the equipment is out-of-tolerance, they would need to send the item somewhere else which would increase the turnaround time and likely add additional costs to the calibration. The calibration supplier should also provide proper documentation concerning out-of-tolerance readings, such as before and after adjustment data.

What calibrations can the laboratory perform on-site? Some items, such as ovens, environmental chambers, surface plates and floor scales cannot be moved so a technician needs to calibrate the items on-site. Calibrating some high use equipment onsite and scheduling those items together annually can reduce the downtime for those items and eliminate the need for purchasing spare equipment.

Does the laboratory use an online calibration management system? An online system will have all of the calibration history and documentation in one place and help simplify the management of an organization’s test equipment. This is especially useful for companies that have a large amount of equipment and when equipment audits are conducted. Those systems can also provide notifications when equipment is due and reminders when equipment is overdue for calibration.

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