Overview
EN ISO 20170:2019 - Geometrical product specifications (GPS) defines principles and tools for the decomposition of geometrical characteristics to support manufacturing control. Published by CEN as the European adoption of ISO 20170:2019, the standard describes how to convert a univariate GPS result (global size, form, location, orientation) into a multivariate, process‑relevant set of components - called a collected characteristic - that map to manufacturing process parameters and the manufacturing datum/coordinate system. The standard focuses on macro‑geometry (does not cover surface texture or micro‑geometry). Its main objectives are to provide correction values for process control and to enable meaningful statistical analysis of production processes.
Key topics and technical focus
- Decomposition concept: transforming a univariate GPS characteristic into a multivariate characteristic whose components are independent and related to machine/process axes.
- Collected characteristic: a vector combining the global (univariate) result and the multivariate components required to derive it.
- Independent characteristics: size, form, orientation and location characteristics that are complementary and independent for manufacturing control.
- Manufacturing datum system: alignment of decomposition components to the manufacturing process coordinate system so components correlate with machine adjustments.
- Presentation and use: guidance on presenting collected characteristic results and using decomposition outputs for correction and statistical evaluation.
- Statistical analysis: using decomposed components (e.g., X and Y position components for a hole) to calculate meaningful capability indices tied to the manufacturing kinematics.
- Scope limits: explicitly excludes micro‑geometry (surface texture) and contains no normative references.
Practical applications and users
Who benefits:
- Manufacturing engineers seeking to derive actionable machine correction values from inspection data.
- Quality engineers and metrologists performing process capability studies that reflect machine kinematics.
- Production planners and tool setters optimizing tooling offsets and fixture locators.
- OEMs and suppliers implementing GPS‑based control loops on CNC machines, coordinate measuring machines (CMMs), and automated inspection systems.
Typical uses:
- Decomposing a positional tolerance into X/Y/Z components to feed CNC offset changes.
- Translating form or orientation deviations into axis‑specific adjustment values.
- Performing statistical control and capability analysis on process‑relevant components rather than on aggregated univariate results.
Related standards
Using EN ISO 20170:2019 helps bridge metrology results and practical manufacturing interventions by making geometrical specifications actionable and statistically meaningful for process control.
