TS EN ISO 12181-1

TS EN ISO 12181-1 defines the core vocabulary and parameters used for roundness within the Geometrical Product Specifications (GPS) system. It addresses the roundness of individual integral features and explains the subject through complete roundness profiles, giving a common technical language for describing and comparing roundness.

Why roundness is treated as a distinct concept

Roundness describes how far a circular section deviates from an ideal circle. It is not the same as broader form characteristics such as cylindricity, where the geometry of a full surface feature is considered. In practical metrology, that distinction matters because the interpretation of diameter, coaxiality, fit, and surface-related measurements can depend on how roundness is defined and evaluated.

Parameters and technical use

In GPS terminology, parameters are the numerical way of expressing geometric deviation. For roundness, consistent use of terms such as reference circle, profile deviation, and evaluation concept helps ensure that drawings, inspection reports, and quality records carry the same meaning. In general engineering practice, vocabulary standards like this one support consistent communication between design, manufacturing, and inspection; this document itself is a terminology-and-parameters standard, not a product performance specification.

• Focuses on the roundness of individual integral features.
• Covers concepts related to complete roundness profiles.
• Defines the terms and parameters used for roundness.
• Supports consistent interpretation within GPS terminology.