TS ISO 1101

TS ISO 1101 is a foundational standard within Geometrical Product Specifications (GPS) that addresses how form, orientation, location and run-out tolerances are defined and understood. In practice, it helps engineers express not only the size of a feature, but also how a surface, axis or derived median line is allowed to deviate in geometry.

The core logic behind geometrical tolerancing

Geometrical tolerancing manages how far a manufactured feature may depart from its ideal geometry. It brings together concepts such as straightness, flatness, parallelism, perpendicularity, position and circular run-out. Unlike size tolerances, which limit only dimensional variation, geometrical tolerances describe the feature’s spatial behaviour as well. That distinction matters when fit, assembly function, motion quality or contact conditions depend on the relationship between surfaces and datums.

What this standard covers

According to the supplied scope, this standard provides basic information and requirements for geometrical tolerancing and serves as the initial basis for the subject. Its emphasis is on the foundational principles of the GPS tolerancing system and the common technical language used to specify and interpret it on drawings and in product definition. Rather than focusing on a single product family, it establishes the general framework that makes geometrical indications consistent and meaningful across mechanical engineering practice.

• Form tolerances control how closely a feature follows its intended ideal shape.
• Orientation tolerances define the angular or spatial relationship of a feature to a reference.
• Location tolerances limit where a feature may be positioned in relation to a datum system.
• Run-out tolerances are used to control variation on rotating parts.
• The GPS approach creates a shared basis for design, inspection and interpretation.

This standard is relevant to design, metrology and quality engineering where the meaning of tolerances must be communicated precisely. In mechanical products, correct functional performance often depends on geometry as much as on size, and TS ISO 1101 is one of the core references that structures that shared language.