Overview
EN ISO 22081:2021 (ISO 22081:2021) is a GPS (Geometrical Product Specifications) standard published by CEN/ISO that defines rules for the definition and interpretation of general geometrical specifications and general size specifications as referenced in ISO 8015:2011, clause 5.12. It provides a consistent framework for indicating general tolerancing on technical product documentation (TPD) and 3D models, reducing repetitive individual annotations while clarifying scope and applicability.
Key topics and requirements
- Scope and applicability
- Applies to general geometrical specifications and general size specifications (linear and angular) for integral features only (including features of size).
- Does not apply to derived features, integral lines, or non-linear/non-angular dimensions (see ISO 17450-1 and ISO 14405-2).
- Rules for definition and interpretation
- Specifies how to indicate general specifications in TPD and how they are interpreted when attached to multiple features.
- Clarifies datum-system rules and how general specifications interact with individual feature specifications.
- Indication tools
- Introduces tools and conventions to reduce the number of repeated annotations on drawings and models (an evolution from ISO 2768-2).
- Designer responsibilities and decision rules
- Emphasises that designers must define functional requirements and select appropriate tolerances to avoid overlooking functions or over-constraining parts.
- Default decision rules from ISO 14253-1 apply unless otherwise stated.
Practical applications
- Use ISO 22081 to:
- Apply uniform tolerance rules across multiple similar features (holes, slots, faces) to simplify drawings and 3D annotations.
- Improve clarity in technical product documentation for manufacturing, inspection and quality control processes.
- Ensure consistent interpretation of general tolerances in CAD models and downstream verification workflows.
- Benefits include reduced drafting time, fewer drawing errors, and clearer communication between design, manufacturing and metrology teams.
Who should use this standard
- Mechanical designers and CAD modelers preparing TPD or 3D annotations
- Quality and metrology engineers responsible for verification and inspection
- Technical drafters and manufacturing engineers standardizing tolerancing practices
- Standards committees and organizations aligning GPS implementation across enterprises
Related standards
Keywords: EN ISO 22081:2021, ISO 22081, GPS, geometrical tolerancing, general size specifications, integral features, technical product documentation.