ISO 25178-601:2025

Overview

ISO 25178-601:2025 - published by ISO - is the second edition of the Geometrical Product Specifications (GPS) standard that specifies the design and metrological characteristics of contact (stylus) instruments used for areal surface topography measurement. The standard covers instrument architecture, nominal characteristics and performance requirements for contact stylus scanning. Because areal data can be converted to profiles, the document and its methods are also applicable to profiling measurements.

Key topics and technical requirements

The standard defines essential technical content for contact stylus instruments, including:

• Instrument requirements

  • Mandatory components for areal measurement: probing system, areal reference guide, lateral scanning system, drive unit x, drive unit y (y optional for profile-only systems), and lateral position sensor.
  • Data acquisition by moving a stylus tip in contact with the surface to generate height data relative to the areal reference guide.

• Metrological characteristics

  • References metrological characteristics listed in ISO 25178-600 and clarifies which characteristics apply to stylus instruments.

• Design features and nominal characteristics

  • Descriptions of stylus geometry and nominal values (e.g., stylus tip geometry, static measuring force) are included to support consistent instrument specification and procurement.
  • Guidance on probe, stylus, stylus-changing interfaces, and reference guides.

• Terminology and definitions

  • Harmonized terms for probing systems, probes, stylus tips, lateral scanning systems, and critical dynamic behavior.

• Informative annexes:

  • Annex A: principles of contact stylus instruments
  • Annex B: sources of measurement error and influence on uncertainty
  • Annex C: background on changes from ISO 3274
  • Annex D: relationship to the GPS matrix model

Applications and who uses it

ISO 25178-601:2025 is used by professionals and organizations that need reliable, comparable areal surface texture data:

• Metrology laboratories defining instrument acceptance and calibration criteria
• Quality engineers specifying measurement methods and procurement requirements for stylus instruments
• Manufacturers of metrology equipment designing or validating stylus probes and scanning systems
• R&D teams working on surface characterization, tribology, and functional surface design
• Standards writers and conformity assessors aligning inspection processes with GPS requirements

Practical applications include surface roughness and texture control, functional surface assessment (wear, friction, sealing), and transfer of areal data to profile analysis.

Related standards

• ISO 25178-600 - Metrological characteristics for areal topography measuring methods (normative reference)
• ISO GPS framework references: ISO 14638, ISO 8015 and decision rules in ISO 14253-1
• This edition replaces the earlier ISO 25178-601:2010 and incorporates content from ISO 3274:1996

Keywords: ISO 25178-601:2025, surface texture areal, contact stylus instrument, stylus scanning, metrological characteristics, surface topography, geometrical product specifications (GPS).