Overview
EN ISO 22432:2011 - Geometrical product specifications (GPS) - Features utilized in specification and verification - defines standardized terms and types of geometrical features used when specifying and verifying workpieces. Developed from concepts in ISO/TS 17450‑1 and endorsed by CEN as a European adoption, this standard acts as a road map describing the interrelationships between nominal geometry, specification representations and verification models. It is primarily intended to guide future standardization, software developers and metrology experts rather than to be applied directly by designers on the shop floor.
Key topics
- Three “worlds” of geometry: nominal definition (designer’s ideal), specification (designer’s intended representations), and verification (representations used in measurement).
- Surface models: clear distinction and definitions for nominal surface model, skin model, discrete surface model and sampled surface model - important for translating ideal geometry to measurable data.
- Feature types and definitions: nominal feature, real feature, discrete feature, sampled feature, and ideal features (with attributes such as shape, size, situation and skeleton).
- Feature of size: formal definition and its role in specifying material and dimensional requirements (e.g., shafts, holes, grooves).
- Verification concepts: separation of physical operations (mechanical, optical, electromagnetic) and mathematical operations (sampling, interpolation, computation) used in coordinate metrology and inspection.
- Relations and mapping: diagrams and examples (normative Annex A and informative Annexes B–C) that map relationships between features and the GPS matrix model.
Applications
- Standardizing terminology for CAD/CAM, coordinate metrology, and inspection software development to ensure consistent interpretation of features across tools.
- Providing a reference model for metrologists, measurement labs and QA engineers to link measured data (sampled/discrete models) back to design intent (nominal models).
- Guiding standards committees and software makers in creating interoperable feature-based specification and verification workflows.
- Supporting definition of verification operators and decision rules used in measurement reports and conformity assessments.
Who should use this standard
- Standards developers (ISO/CEN technical committees)
- Metrology and quality assurance professionals
- Developers of CAD/CAM, metrology and inspection software
- Technical writers and educators preparing GPS-compliant documentation
Related standards
EN ISO 22432:2011 is a foundational GPS document for harmonizing how geometrical features are described, modeled and verified across standards, tools and measurement practices.