Overview
ISO 13385-2:2020 - part of the ISO GPS (Geometrical Product Specifications) family - defines the design and metrological characteristics of calliper depth gauges. It covers both analogue indications (vernier scale or circular/dial scale) and digital displays, focusing on the essential parameters required for design, testing, calibration and specification of these dimensional measuring instruments.
Key topics
- Scope and definitions: Clear definition of a calliper depth gauge and measuring-face contact (full vs partial).
- Design characteristics: References general design rules in ISO 14978 and requires manufacturers to state key dimensions (e.g., measuring-base length, hook dimensions for hook-ended gauges). Scale intervals: main beam scale interval is 1 mm for vernier; for circular scales it is 1 mm or 2 mm.
- Metrological characteristics:
- Maximum Permissible Error (MPE) values and their application to all permitted indications.
- MPEs apply at rated operating conditions, defaulting to 20 °C unless otherwise stated, and cannot be smaller than the digital step or scale interval.
- Reference point / zero setting: digital and circular-scale gauges must provide an adjustable zero; conditions for evaluation depend on proper zero-setting against a flat surface.
- Test methods and conformity:
- Errors of indication are tested using suitable standards (for example gauge blocks per ISO 3650 and a surface plate).
- Test points must adequately cover the instrument’s scale (including various pointer orientations for circular scales) and consider local or cyclic errors.
- Includes guidance on measurement uncertainty, decision rules and acceptance testing.
- Annexes: Calibration guidance (Annex A), default MPE values (Annex B), and relation to the GPS matrix model (Annex C).
Applications and users
ISO 13385-2:2020 is practical for:
- Manufacturers specifying design dimensions, scale intervals, zeroing capability and rated operating conditions.
- Calibration laboratories using standardized test methods and MPE criteria.
- Quality and metrology engineers selecting or specifying calliper depth gauges for inspection tasks.
- Procurement and inspection personnel defining acceptance tests and conformity criteria.
Typical applications include instrument design verification, acceptance testing on delivery, routine calibration, and specifying instrument capability in quality control procedures.
Related standards
Use ISO 13385-2:2020 when you need authoritative requirements for designing, testing or specifying calliper depth gauges in production inspection and laboratory calibration workflows.
Open preview (PDF)Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 2: Design and metrological characteristics of calliper depth gauges