Overview
ISO/TR 230-9:2005 - "Test code for machine tools - Part 9: Estimation of measurement uncertainty for machine tool tests according to series ISO 230, basic equations" is an informative Technical Report from ISO that explains practical methods for estimating measurement uncertainty in machine‑tool testing carried out under the ISO 230 series. The document follows the Guide to the Expression of Uncertainty in Measurement (GUM) and provides basic equations, evaluation approaches (type A and mainly type B), and worked guidance for common test parameters.
Key Topics
- Purpose and scope: Guidance on estimating measurement uncertainty for tests described in ISO 230 (e.g., positioning accuracy, repeatability, reversal values).
- Uncertainty framework: Use of GUM principles - identification of contributors, expression as standard uncertainties, combination into a combined standard uncertainty, and reporting an expanded uncertainty (U).
- Combination rule: Combined standard uncertainty is formed from strongly correlated and uncorrelated contributors; the expanded uncertainty U is calculated using a coverage factor (k = 2 is recommended in the report).
- Evaluation methods: Type A (statistical) and type B (knowledge/experience) evaluations; the report emphasizes practical type B assessments for industrial use.
- Black‑box and transparent‑box methods: Black‑box for whole-measurement uncertainty, transparent‑box for parameters computed from measured values (e.g., functions Y = f(Xi)) where propagation of uncertainties is applied.
- Annexes with focused formulae:
- Annex A: uncertainty of a mean value (treatment of correlated vs. uncorrelated repeat measurements).
- Annex B: uncertainty of an estimator of standard deviation.
- Annex C: detailed contributors and practical estimation for linear positioning measurements per ISO 230‑2 (includes contributors like calibration, alignment, temperature compensation, environmental variation error, and repeatability of setup).
Applications / Who Uses It
- Machine tool manufacturers - for documenting performance and verifying compliance with ISO 230 test methods.
- Metrology and calibration laboratories - to estimate and report measurement uncertainty for machine‑tool tests and calibrations (laser interferometers, linear scales).
- Quality and test engineers - to support acceptance testing, supplier verification and process capability studies involving positioning accuracy and repeatability.
- Research and R&D teams - when developing measurement procedures or uncertainty budgets for machine‑tool experiments.
Practical examples include linear positioning tests using laser interferometry, repeatability and reversal measurements, and routine factory acceptance tests.
Related Standards
- ISO 230 series (Test code for machine tools) - Parts 1–7 and ongoing parts (notably ISO 230‑2 for positioning tests).
- Guide to the Expression of Uncertainty in Measurement (GUM).
- ISO/TR 16015 (thermal influences on length measurement).
- ISO/TS 14253‑2 (uncertainty in GPS measurement and verification).
Keywords: ISO/TR 230-9:2005, measurement uncertainty, machine tools, ISO 230, positioning accuracy, repeatability, GUM, uncertainty estimation, laser interferometer, linear positioning measurement.
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