ISO 13385-1:2019

Overview

ISO 13385-1:2019 - "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Design and metrological characteristics of callipers" defines the essential design and metrological requirements for callipers (calipers) with analogue indication (vernier or circular/dial scales) and digital indication (digital display). This second edition (2019) updates design figures, clarifies metrological characteristics, adds test method requirements and default maximum permissible error (MPE) values. The standard is part of the ISO GPS system and interfaces with general GPS rules.

Key topics and requirements

• Scope: Applies to external, internal, depth and step measurements using callipers with vernier, circular (dial) or digital displays.
• Design characteristics: Follows general GPS design guidelines (see ISO 14978). Specifies main-scale intervals (vernier: 1 mm; circular scale: 1 mm or 2 mm) and requires manufacturers to state key dimensions (e.g., jaw lengths, widths, depth-rod cross-section).
• Metrological characteristics:
  • Defines the measurement characteristics and associated Maximum Permissible Error (MPE) values; MPE cannot be smaller than the instrument’s digital step or scale interval.
  • Rated operating conditions: MPEs apply at a reference temperature of 20 °C; test values should be corrected to this temperature or uncertainty increased accordingly.
  • Reference point: Digital and circular-scale callipers shall provide an adjustable zero; digital models must allow zero setting at any position within the range.
  • Includes requirements for test methods, shift and partial-contact errors, and special cases.
• Conformity and uncertainty: Guidance on determining conformity, accounting for measurement uncertainty, and decision rules (linked to ISO 14253 series).
• Annexes: Calibration guidelines (Annex A), default MPE values (Annex B), and relation to the GPS matrix model (Annex C).

Applications and who uses it

ISO 13385-1:2019 is used by:

• Manufacturers of callipers for product design, specification and marking.
• Calibration laboratories and test houses for establishing calibration procedures and MPE verification.
• Quality managers, metrologists and inspection teams to set procurement specifications, acceptance criteria and inspection/test methods.
• Design and production engineers who need reliable dimensional measurement tools for shop-floor or laboratory use.

Practical uses include creating supplier specifications, defining acceptance criteria for incoming inspection, establishing calibration intervals, and ensuring measurement traceability and compliance with GPS.

Related standards

• ISO 14978 (GPS measuring equipment general concepts)
• ISO 14253 series (decision rules and uncertainty in verification)
• ISO/IEC Guide 98-3 (GUM) and VIM for measurement uncertainty and terminology

Keywords: ISO 13385-1:2019, callipers, calipers, geometrical product specifications, GPS, dimensional measuring equipment, vernier, dial, digital calipers, MPE, calibration, metrological characteristics.