Overview
EN ISO 21920-1:2022 - Geometrical Product Specifications (GPS) - Surface texture: Profile - Part 1 - establishes the rules for indicating surface texture by profile methods on technical product documentation using graphical symbols. Endorsed by CEN and aligned with ISO 21920-1:2021, this standard supersedes EN ISO 1302:2002 and provides the canonical way to communicate profile-based surface texture requirements on engineering drawings and documentation.
Key topics and requirements
- Graphical symbols: Defines the symbol set, proportions and placement rules (see normative Annex A) for clear indication of profile surface texture on drawings.
- Specification elements: Lists mandatory and optional elements to be shown, including parameter type, tolerance limit values, tolerance type, and tolerance acceptance rules.
- Tolerance acceptance rules: Describes acceptance options such as the maximum, 16%, and median rules and references annex guidance for inspection procedures.
- Profile parameters: Covers R-, P- and W-parameter families and how to indicate them (evaluation length, section length, number of sections).
- Filters and operators: Specifies profile S-filter and L-filter types, nesting indices, and F-operator association methods and elements for unambiguous parameter extraction.
- Evaluation and section lengths: Rules for indicating evaluation length, section length and related measurement setup.
- Profile direction and surface lay: How to specify surface lay, direction of lay and profile direction relative to workpiece features.
- Positioning on documentation: Guidance on symbol placement and orientation on technical product documentation.
- Simplified & restrictive indications: Options for simplified symbols, general tolerances, and specifying identical requirements for multiple features.
- Annexes: Includes normative annexes for symbol dimensions, filter symbols, association methods, and informative guidance for unambiguous specifications and inspection methods.
Applications and who uses it
EN ISO 21920-1:2022 is essential for:
- Design and mechanical engineers creating drawings that require precise surface texture control.
- Manufacturing and process engineers specifying machining, grinding or finishing process parameters.
- Quality, metrology and inspection labs implementing measurement protocols and acceptance checks.
- CAD/CAM and PLM teams embedding standardized surface texture symbols in digital models and documentation.
- Standards writers and procurement who need consistent contract specifications and acceptance criteria.
Practical uses include detailed engineering prints, inspection reports, supplier specifications, and traceable product acceptance criteria where profile-based surface texture affects function, fit, friction, sealing or appearance.
Related standards
Keywords: EN ISO 21920-1:2022, surface texture, profile, GPS, graphical symbols, profile parameters, tolerance acceptance rule, evaluation length, S-filter, L-filter, technical product documentation.
