Hexagon metrology calibration for CMMs and portable systems

What Hexagon metrology calibration means

Hexagon metrology calibration is more than a due-date label on a coordinate measuring machine, portable arm or scanning system. It is the documented check that a measuring system still performs within defined requirements, that the result is traceable to recognized standards, and that the reported uncertainty is suitable for the parts being inspected. Hexagon Manufacturing Intelligence states that measuring machines should be inspected, certified and, where necessary, recalibrated on a yearly basis. It also recommends annual calibration for portable systems that are regularly relocated.

For quality teams, the practical question is not simply whether the equipment has a current certificate. The certificate, method, uncertainty statement and operating environment all need to support the measurement risk in production, inspection and audit work. This guide fits broader calibration and metrology planning for laboratories, manufacturers and quality departments.

Why calibration matters beyond the annual due date

Hexagon CMMs, Absolute Arms, laser scanners and machine-tool verification workflows are often used to make product conformity decisions. A small measurement error can affect acceptance of aerospace components, automotive fixtures, medical parts, molds, precision tooling or reverse-engineered surfaces. Calibration provides evidence that the measuring system has been checked against a defined method and a recognized reference chain.

Calibration should not be treated as a blanket guarantee. NIST policy on metrological traceability emphasizes that traceability requires an unbroken chain of calibrations, with each step contributing measurement uncertainty. It also notes that traceability alone does not prove fitness for purpose. A CMM can have traceable calibration and still be unsuitable for a task if its uncertainty is too large relative to the tolerance, if the measurement program is weak, or if the shop environment differs from the calibration conditions.

This distinction matters in audits. A certificate may show that the machine met a performance specification on the day of service, but production measurement depends on more than the machine frame. Probe qualification, fixture stability, temperature control, part cleanliness, software settings, operator practice and the selected inspection strategy all affect the result. Calibration is the foundation, not the whole measurement system analysis.

What a Hexagon calibration may cover

The phrase Hexagon metrology calibration can apply to several equipment types. The relevant standard, artifact and report format depend on the system being calibrated. Hexagon documentation says its service centers perform calibration procedures traceable to national and international standards, including ISO 10360, and that several service centers hold ISO/IEC 17025 accreditation. ISO/IEC 17025 is the laboratory competence standard used by testing and calibration laboratories to demonstrate that they operate competently and can generate valid results.

In practice, calibration, certification, verification and compensation should not be used as interchangeable terms. Calibration compares measured values with reference values and reports error or correction information. Verification checks whether the equipment meets a requirement. Certification documents the outcome. Compensation applies corrections, often through controller or software tables. One service visit may include more than one of these steps, but the certificate should make clear what was actually performed.

Standards that shape calibration evidence

For CMM users, ISO 10360 is central because it defines acceptance and reverification tests for coordinate measuring systems. ISO 10360-2 addresses CMMs used for measuring linear dimensions and specifies acceptance and periodic reverification tests for demonstrating stated performance requirements. ISO 10360-12 addresses articulated arm CMMs and their performance verification using calibrated test lengths. These standards do not replace a full measurement uncertainty analysis for every inspection task, but they provide a common framework for comparing equipment performance.

ISO/IEC 17025 adds a different layer of evidence. It is not a machine performance standard; it is a competence and quality standard for laboratories. When calibration is performed under an accredited scope, the user has stronger evidence that the laboratory’s method, uncertainty evaluation, traceability and technical competence have been assessed by an accreditation body. The scope still has to match the job. A laboratory can be accredited for some dimensional measurements and not others, so the certificate should be checked against the accredited measurand, range and calibration method.

NIST traceability policy is also relevant for U.S. manufacturers. It clarifies that organizations claiming traceability are responsible for supporting that claim, and users are responsible for assessing its validity. In practice, a certificate should not stop at the phrase NIST traceable. It should identify standards, procedures or reference artifacts clearly enough to show a documented chain, with uncertainty information included.

How often should Hexagon systems be calibrated

Annual calibration is a common baseline. Hexagon’s calibration and certification guidance explicitly recommends yearly inspection, certification and recalibration when needed for measuring machines. It also recommends annual calibration for portable systems that are regularly relocated. That is a useful starting point, but it should not be the only rule in a calibration program.

Quality teams should shorten the interval, or trigger an immediate check, when risk increases. Examples include a probe crash, suspected collision, controller repair, encoder issue, relocation, foundation movement, major temperature event, software or compensation change, scanner replacement, unusual measurement drift, failed interim check or customer requirement. Portable arms and scanners can carry additional risk because they are moved between cells, exposed to shop-floor conditions and mounted in different positions.

Intervals may sometimes be extended, but only with evidence. That evidence can include stable historical results, low drift, low measurement risk, successful interim checks, low usage and documented approval under the company’s quality system. Extension should not be based only on service cost or machine availability. If a CMM is used for tight tolerances, regulated production or final acceptance, documented confidence is usually worth more than the short-term savings from delaying service.

How to read the calibration certificate

A useful certificate should help a quality engineer answer five questions: what was tested, how it was tested, what limits applied, what the measured results were, and what uncertainty affects those results. If any of these points are missing or unclear, the document may still be a service record, but it may not be enough for a demanding customer audit. See also: analytical methods.

• Accreditation and scope. Confirm whether the work was performed under ISO/IEC 17025 accreditation and whether the scope covers the relevant equipment, range and method.
• As-found results. These show the condition before adjustment. They are critical for deciding whether previous inspection results may need review.
• As-left results. These show the condition after adjustment or compensation. They support release of the equipment back to use.
• Measurement uncertainty. Compare uncertainty with the tolerance and internal decision rules. Avoid assuming a certificate is adequate simply because it is traceable.
• Environmental conditions. Temperature, vibration and cleanliness can affect dimensional results, especially for long measurements and tight tolerances.
• Standards and artifacts. The report should identify the method and reference artifacts sufficiently for traceability and audit review.
• Pass or fail criteria. A pass statement is more useful when the applicable MPE, decision rule and uncertainty treatment are clear.

The as-found section deserves close attention. If the machine was out of tolerance before adjustment, the quality team should assess product measured since the last known good check. That does not automatically mean every part is suspect. It means the organization should complete a documented risk review based on the affected measurement programs, tolerances, measured deviations, feature types and any available interim checks.

Practical workflow before and after service

Calibration outcomes are stronger when the user prepares both the equipment and the records. Before service, collect the previous certificate, maintenance history, probe and stylus list, software version, error map records, recent alarms and any measurement concerns from operators. For CMMs, confirm that the machine is clean, the air supply is stable, scales and ways are not contaminated, and the room has reached normal operating temperature. For portable arms, gather the probes, scanner, certified sphere, length bar and mounting hardware used in normal work.

After service, do not return the system to production based only on the new sticker. Review the certificate, file it with the asset record, update the calibration due date, and run practical checks on representative artifacts or known production features. If compensation tables or controller parameters changed, verify key inspection programs before relying on them for final acceptance. A short internal check after calibration often catches issues that a formal machine test may not show, such as a wrong probe file, incorrect stylus build, fixture shift or outdated inspection routine.

For high-value inspection processes, consider an interim verification plan. This may include measuring a calibrated artifact weekly, checking a master part at shift start, trending probing repeatability or comparing selected features across two independent methods. Interim checks do not replace accredited calibration, but they can provide early warning between annual services.

Questions to ask before scheduling calibration

Before choosing an OEM service center, accredited laboratory or qualified third-party provider, define the evidence your quality system and customers require. The provider should be able to explain what standards apply, whether the work is under an accredited scope, what artifacts will be used, whether adjustments are included, and how out-of-tolerance findings are handled.

• Which standard or internal procedure will be used for this equipment model and configuration?
• Is the calibration covered by ISO/IEC 17025 accreditation, and can the scope be matched to this service?
• Will the report include both as-found and as-left data?
• Will probing, scanning, rotary axes, temperature sensors or accessories be included or excluded?
• How will measurement uncertainty and pass or fail decisions be reported?
• What preparation is required for room temperature, compressed air, foundations, fixtures and software access?
• If the system fails, will adjustment, compensation or repair be performed during the same visit?

The best provider is not always the one with the shortest visit time. For audit-critical equipment, report quality, traceability chain, uncertainty statement and service competence are often more important than convenience.

Frequently asked questions

Is yearly calibration enough for a Hexagon CMM

Yearly calibration is a common and manufacturer-supported baseline, but it is not automatically enough for every application. Tight tolerances, frequent use, harsh environments, relocation, crashes, repairs or failed interim checks can justify a shorter interval or an immediate verification.

Does ISO/IEC 17025 accreditation mean the machine is accurate for every part

No. ISO/IEC 17025 supports confidence in the competence of the laboratory and the validity of the calibration result within the accredited scope. It does not prove that every production measurement is fit for purpose. The user still needs to consider uncertainty, tolerance, measurement strategy, fixturing, environment and operator practice.

What is the difference between calibration and probe qualification

Calibration evaluates the measuring system against reference standards or artifacts. Probe qualification establishes the probe tip size, position and behavior for a specific stylus, angle or sensor setup. A calibrated CMM can still produce poor results if the wrong probe file is used or if probe qualification is outdated.

Should scanners be calibrated separately from portable arms

It depends on the system and certificate. For arm and scanner combinations, users should confirm whether the report covers the arm, the scanner or the complete combined system. This is especially important when scanning data is used for final acceptance rather than reverse engineering or visualization.

Sources and standards referenced

• Hexagon Manufacturing Intelligence calibration and certification documentation, including its guidance on yearly inspection and accredited service centers.
• Hexagon ISO 17025 accredited laboratory certificate listings for regional service centers.
• ISO information pages for ISO/IEC 17025, ISO 10360-2 and ISO 10360-12.
• NIST policy on metrological traceability and measurement uncertainty.