Overview
EN ISO 5059-1:2025 - "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Design and metrological characteristics of two-point inside micrometers (ISO 5059-1:2025)" - defines the principal design and metrological requirements for two-point inside micrometers used in precision internal-diameter measurement. The standard applies to instruments with scale intervals or digital steps of 0.001 mm and 0.01 mm, available with analogue or digital indication, and with or without interchangeable extensions. It excludes micrometers fitted with a dial gauge and jaw micrometers.
Key topics
- Design characteristics
- General design, nomenclature and main dimensions
- Thermally insulating grips, measuring faces and adjustment devices
- Requirements for interchangeable extensions
- Metrological characteristics
- Rated operating conditions and reference point definition
- Test methods and procedures for verification
- Determination of length measurement error (E) and Maximum Permissible Error (MPE)
- Conformity and calibration
- Measurement uncertainty, decision rules and conformity assessment
- Marking and information to be supplied with the instrument
- Supporting material
- Normative Annex A with default MPE values
- Informative Annex B relating to the GPS matrix model
Keywords: EN ISO 5059-1, two-point inside micrometers, dimensional measuring equipment, GPS, metrological characteristics, MPE, interchangeable extensions.
Applications
EN ISO 5059-1:2025 is intended for organizations and professionals involved in precision internal measurement and quality assurance:
- Calibration laboratories and metrology labs performing verification and calibration of inside micrometers
- Manufacturers and suppliers of inside micrometers who need to design and certify instruments to GPS requirements
- Quality managers and inspection engineers in manufacturing sectors (automotive, aerospace, hydraulics, bearing and precision engineering) who use inside micrometers for internal-diameter control
- Standards and compliance officers who implement metrological traceability and conformity assessment procedures
Practical uses include bore and internal-diameter inspection, in-process control, instrument specification selection, and establishing calibration routines that reference MPE and measurement uncertainty principles.
Related standards
- ISO 5059 series (other parts covering different types of inside micrometers and verification methods)
- ISO/TC 213 publications on geometrical product specifications (GPS) and measurement verification
- Annex B connects this part to the GPS matrix model, aligning instrument characteristics with GPS requirements
This standard helps ensure consistent design, reliable calibration, and traceable measurement results for two-point inside micrometers used in precision metrology.