Frequently Asked Questions

Most shops run an annual interval, tightened where usage, crash history or audit findings warrant it. The basis for the interval should be documented, not assumed from habit.

Calibration states the relationship between indication and reference value with an uncertainty. Verification confirms the machine still meets a stated specification. Most shop-floor work is verification.

Five calibrated test lengths are measured three times each across seven positions in the volume, 105 measurements, checking length measurement error E0 against the manufacturer's stated MPE.

On-site verification is standard for bridge and gantry machines. Time on site depends on volume, axis count and whether repair is needed, and is confirmed at quote.

ISO 1 sets 20°C as reference temperature. Gradient matters more than absolute value: 1°C of error over a 1-meter steel scale already exceeds many machines' specification.

As-found data is recorded before adjustment. Under reverification, a failing length may be re-measured; all repeats must then fall within limit before the machine is accepted as-left.

The performing laboratory's scope of accreditation is published by its accreditation body and should list the specific measurement, range and uncertainty, not just the laboratory's name.

Calibration and measurement capability is the smallest uncertainty a laboratory can claim within scope. It should support a 4:1 test uncertainty ratio against the tolerance being inspected.

Auditors check accredited scope, traceability statements, decision rules and out-of-tolerance handling, not the word 'calibrated' on an invoice. Certificates are built to carry that detail.

The volumetric error map compensates for known geometric deviations. Whether it can be updated depends on controller access; some OEM controllers lock the map to factory service.