TS EN ISO 1660

TS EN ISO 1660 addresses the rules for stating profile tolerancing within geometrical product specifications (GPS). Using the line profile and surface profile characteristic symbols defined in ISO 1101, it sets out how geometrical specifications for integral and derived features are expressed. In practical terms, it helps define the permitted deviation of a part from its intended geometry in a way that is consistent and readable on technical drawings and related documentation.

What profile tolerancing describes

Profile tolerance does not describe a single size alone; it defines the allowable form deviation of an entire contour or surface. A line profile applies to a two-dimensional section curve, while a surface profile applies to a full three-dimensional surface. This makes profile tolerancing especially useful for curved or freeform geometries, where size tolerances alone may not adequately capture the functional shape requirement.

Use with integral and derived features

The scope of the standard covers profile-based geometric specifications for integral and derived features. In general technical terms, an integral feature is the actual geometric element of the part as manufactured, while a derived feature is an idealized element obtained from it by geometric or mathematical means. That distinction matters when applying profile tolerances to edges, grooves, curves, or surfaces, because it affects how the feature is identified and interpreted in the drawing.

In engineering practice, profile tolerances are widely used for freeform surfaces, complex contours, aerodynamic shapes, moulded components, and other parts where precise form control is important. TS EN ISO 1660 provides the common rule set for presenting these characteristics with the appropriate profile symbols, supporting clearer communication between design, manufacturing, and inspection disciplines.