Overview
ISO/TS 17863:2013 - Geometrical product specification (GPS) - Geometrical tolerancing of moveable assemblies specifies how to indicate constraint conditions between parts of movable assemblies when applying geometrical tolerancing. It fills gaps left by general GPS standards (e.g., ISO 1101, ISO 14405-1) by defining graphical symbols and rules to remove specification uncertainty where one part shows tolerance indications and another part shows corresponding datum indications.
Key topics and requirements
- Scope and purpose
- Applies to assemblies where relative mobility and interaction between parts must be constrained and explicitly described for tolerancing.
- Intended as a general GPS technical specification; references the GPS matrix model and foundational rules (ISO 8015, decision rules ISO 14253-1).
- Graphical language and symbols
- Defines a force indicator (F1, F1 A, F1 A B C, etc.) to show applied forces and their relation to datums.
- Defines a gravity symbol (G) when only gravity acts on the movable part, with orientation indications.
- Introduces flags to invoke constraint conditions that make specific tolerance values valid under the stated conditions.
- Rules for leader lines, contacting features (drawn with long-dashed double-dotted narrow lines), and use of TEDs (theoretical exact dimensions) for points/lines/areas where forces are applied.
- Mobility and degrees of freedom
- Requires locking all degrees of freedom not necessary for the toleranced characteristic (example: run-out locks translational and two rotational DOFs).
- Per default, the part with tolerance indications is considered movable, the part with datums fixed; item numbering follows ISO 6433.
- Force application rules
- Forces are typically applied to the movable part and are evenly distributed over the concerned integral feature unless otherwise specified.
- Default force direction is perpendicular to the concerned feature unless a specific direction is indicated.
Practical applications and users
- Useful for design engineers, tolerancing specialists, CAD/drawing authors, quality engineers, and technical drafters who prepare assembly drawings involving movable parts (bearings, hinges, sliding fits, rotary assemblies).
- Helps eliminate ambiguity when specifying tolerances that depend on how parts are constrained in real application or test conditions (e.g., run-out, size tolerances under load, assembly preloads).
Related standards
This specification is essential when you need precise, unambiguous geometrical tolerancing of movable assemblies and graphical conventions to document constraint conditions on engineering drawings.
