Overview
ISO 15530-3:2011 - Geometrical product specifications (GPS) - Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement - Part 3 - defines an experimental method to evaluate the measurement uncertainty of CMM results by using calibrated workpieces or measurement standards. The standard describes a substitution-style approach where calibrated artefacts of similar geometry and dimension are measured under the same conditions as production parts to derive realistic, task‑specific uncertainty estimates.
Key topics and requirements
- Scope: Applies to both substitution measurements (using a check standard to correct systematic CMM errors) and non‑substitution measurements (using the raw CMM indication).
- Similarity conditions: Calibrated workpiece must be similar to the production part in dimension, geometry, material and measuring strategy. Examples:
- Dimensions: within 10% for features > 250 mm; within 25 mm for features < 250 mm
- Angles: within ±5°
- Form, surface texture, material and probe configuration: functionally similar
- Operating conditions: Require CMM initialization, probe qualification, and adequate thermal equilibrium between CMM and artefact. Environmental and operational conditions specified by the manufacturer or quality manual must be observed.
- Measurement procedure: Repeat the actual measurement procedure on calibrated standards. The difference between measured values and known calibrated values is used to estimate uncertainty contributions.
- Uncertainty components: Includes contributions from the measurement procedure, the calibration of the standard, and variations among uncalibrated workpieces (form, thermal expansion, surface).
- Equipment: Task‑related stylus setup and at least one calibrated workpiece with sufficiently low calibration uncertainty.
- Reverification & interim checks: Procedures for periodic reverification and interim checks of the evaluated measurement uncertainty are specified to ensure ongoing traceability and validity.
Applications and users
Who benefits from ISO 15530-3:2011:
- Metrology and calibration laboratories establishing CMM measurement uncertainty
- Quality managers and inspectors in aerospace, automotive, medical devices and precision manufacturing
- CMM operators and process engineers performing task‑specific calibrations or gauge calibrations
- Organizations seeking mutual recognition of calibration results and traceability to national/international standards
Practical uses:
- Generating realistic, task‑specific uncertainty budgets for CMM inspection routines
- Validating CMM performance for specific part geometries and measurement strategies
- Supporting conformity assessment, supplier quality control and audit evidence
Related standards
- ISO 15530-1 (overview and metrological characteristics)
- ISO 15530-4 (simulation-based task‑specific uncertainty)
- ISO 10360-1 (CMM vocabulary and acceptance tests)
- ISO/IEC Guide 98-3 (GUM - expression of uncertainty)
- ISO 14978 (GPS measuring equipment concepts)
Keywords: ISO 15530-3:2011, CMM, coordinate measuring machines, measurement uncertainty, calibrated workpieces, substitution method, GPS, task‑specific uncertainty.