Overview
ISO 1660:2017 - Geometrical product specifications (GPS) - Geometrical tolerancing - Profile tolerancing - is the ISO rule set for specifying line profile and surface profile geometric tolerances. Published as the third edition (2017), this standard gives formal rules for defining the nominal geometry (the theoretically exact feature, TEF), the toleranced feature, and the tolerance zone for both integral and derived features. ISO 1660:2017 is a rule‑based GPS standard that works with symbols defined in ISO 1101 and is intended for use on 2D drawings and 3D CAD models.
Key topics and technical requirements
- Scope and character symbols: Applies to line profile and surface profile characteristic symbols (per ISO 1101) for straight and non‑straight lines and flat and non‑flat surfaces.
- Definition of TEF (Rule A): Makes explicit how the nominal (theoretically exact) geometry is defined.
- Toleranced feature identification (Rule B): Clarifies which real feature is constrained by the profile tolerance following the feature principle.
- Tolerance zone definition (Rule C): Specifies how the profile tolerance zone is defined and applied normal to the toleranced feature.
- Additional specification tools (Rules D–L): Provide mechanisms for:
- Specifying toleranced feature elements (D)
- Unequally disposed tolerance zones (E)
- Linear and angular tolerance zone offsets (F, G)
- Variable tolerance zone width (H)
- Filtered feature specification (I)
- Association, parameter and associated feature specification elements (J, K)
- Non‑rigid part considerations (L)
- Annexes and guidance: Informative annexes cover compound features, illustrative examples, historical practices and the GPS matrix relation.
- Normative references: Works in concert with ISO 1101, ISO 5459, ISO 8015, ISO 16792 and other GPS standards.
Practical applications and who uses it
ISO 1660:2017 is essential for professionals who specify, model, manufacture or verify complex shapes:
- Design and CAD engineers - to create unambiguous profile tolerances in 2D drawings and 3D CAD models.
- Tolerance and drafting specialists - to apply rule‑based tolerancing for lines and surfaces.
- Manufacturing and tooling engineers - to understand allowable form and shape variation for parts and assemblies.
- Quality, inspection and metrology teams - to verify parts against profile tolerance zones and interpret filtered or variable tolerance rules.
- Technical authors and standards practitioners - for consistent documentation of geometrical specifications.
Related standards
Keywords: ISO 1660:2017, profile tolerancing, geometrical tolerancing, GPS, line profile, surface profile, tolerance zone, theoretically exact feature, ISO 1101.
Open preview (PDF)Geometrical product specifications (GPS) — Geometrical tolerancing — Profile tolerancing
