Frequently Asked Questions

Interval depends on usage, environment and the shop's own risk assessment. Many shops verify annually; higher-use machines or those coming off a crash may be checked more often. The basis for the interval is set at quotation, not assumed.

Calibration establishes the relationship between a machine's readings and reference values, with a stated uncertainty. Performance verification confirms the machine still meets its specification. Most CMM work sold under the word calibration is verification against ISO 10360 or ASME B89.

Length measurement error, E0 and E150, tested with five calibrated lengths measured three times each in seven positions, 105 measurements total. Repeatability range R0 is checked against its own stated limit alongside the error result.

Bridge and gantry machines are typically verified on-site. Portable arms and smaller machines can ship. Time on site depends on axis count and working volume and is confirmed at quotation.

ISO 1 sets 20°C as the reference temperature. CMM environments are commonly specified with a permissible excursion and a gradient per hour and per metre; the gradient matters more than the absolute reading. Thermal soak of the artifacts is required before testing.

As-found data is recorded before any adjustment. Under reverification, a length exceeding the limit on one of three repeats is re-measured three times, and all repeats must then pass. The finding is reported before correction, with enough detail to support an impact assessment back to the last passing calibration.

The certificate should state the standard used, the reported uncertainty and a traceability statement. The performing laboratory's scope of accreditation, checked in the accreditation body's public directory, determines whether the specific measurement is covered.

Calibration and measurement capability is the smallest uncertainty a laboratory can claim within its scope. It needs to support the tolerance being inspected; a reported uncertainty smaller than the scope CMC is a finding, not an advantage.

Auditors under IATF 16949 clause 7.1.5.3 and AS9100 look for an accredited scope covering the measurement, a traceability statement, and evidence that out-of-tolerance findings were assessed for impact on prior results. Certificate content is built to support that review.

The volumetric error compensation map corrects for geometric errors across the working volume. Whether it can be updated depends on the controller; some OEM controllers lock the map to factory access. This is confirmed against the specific machine at quotation.