Materials, geometry and pressure

ISO 1101: Geometrical product specifications (GPS), geometrical tolerancing

The language of geometrical tolerances on ISO drawings.

01Purpose

ISO 1101 defines the symbolic language and rules for specifying geometrical tolerances of form, orientation, location and run-out on technical drawings.

02Scope

Part of the ISO GPS system together with ISO 5459 (datums), ISO 2692 (material requirements) and ISO 8015 (fundamental principles). ASME Y14.5 is a different, though similar, system.

03Main requirements

Tolerance characteristics: straightness, flatness, roundness, cylindricity, profile, parallelism, perpendicularity, angularity, position, concentricity, symmetry, run-out
Tolerance frame structure and tolerance zones
Reference to datums and datum systems
Modifiers and specification elements

04Typical applications and industries

All machined and fabricated parts drawn to ISO standards. See dimensional inspection.

CNC and Precision Machining Casting and Foundry Aerospace and Defence

05Audit and inspection considerations

Is the drawing ISO or ASME based?
Are datums established as intended in measurement?
Is the principle of independency (ISO 8015) understood?

06Common nonconformities

Datum set-up differs between supplier and buyer
Position evaluated without datum reference frame
ASME interpretation applied to ISO drawing

07How QUALITAS TR can support

Our engineers interpret GD&T in drawing reviews and first article inspections.

Discuss ISO 1101