Overview
EN ISO 18183-3:2024 - Geometrical product specifications (GPS) - Partition - Part 3: Methods used for specification and verification (ISO 18183-3:2024) is a CEN-endorsed international standard that specifies the procedure for the partition operation used in GPS specification and verification workflows. Published February 2024 and adopted as a European Standard, it defines how to divide nominal, skin and sampled surface models into meaningful features for specification and metrological verification.
Note: this document does not apply to profile and areal surface texture.
Key topics
- Default partition: Describes the default rule that partitions the skin model (specification), nominal model and sampled surface model (verification) into single features (single surfaces or single lines) of maximum extent.
- Single surface / single line definitions: A connected and finite entity determined by invariance class ordering (degree of invariance), maximum area (surfaces) or maximum length (lines).
- Invariance classes: Uses a partial ordering of invariance classes to determine subdivisions; includes guidance for revolute surfaces where generatrix/axis intersections affect partitioning.
- Real-world criteria: For measured (real) surfaces and lines, curvature and slippable motion concepts are recommended to identify single surfaces/lines and determine partition boundaries (Annexes A and B provide further information and implementations).
- Explicit partition: Covers partitioning for united features, restricted single features and restricted compound features, noting that all explicit partitions build on the default partition.
- Supporting material: Annex C explains the relationship to the GPS matrix model; normative references include ISO 18183-1 (vocabulary) and other GPS system standards (ISO 14638, ISO 8015, ISO 14253-1).
Applications
- Standardizes how CAD/CAM models, skin models and sampled measurement data (e.g., CMM point clouds) are partitioned for:
- Geometrical specification drafting and interpretation
- Measurement planning and verification (CMM programming, inspection routines)
- Metrology software algorithms for feature recognition and decomposition
- QA/quality assurance processes where consistent feature partitioning affects tolerance evaluation
Who uses this standard
- Metrology and quality engineers, inspection laboratories, and manufacturing quality teams
- CAD/CAM and inspection software developers (feature-extraction, partitioning algorithms)
- Standards committees and technical consultants working on GPS chain links (size, form, orientation, location, run-out)
Related standards
Keywords: EN ISO 18183-3:2024, GPS partition, geometrical product specifications, default partition, explicit partition, curvature, slippable motion, feature partitioning, verification, metrology.