Overview
ISO 25178-70:2014 - Geometrical product specification (GPS) - Surface texture: Areal - Part 70: Material measures specifies the characteristics of material measures (physical measurement standards) used for the periodic verification and adjustment of areal surface texture measurement instruments. As part of the ISO 25178 series, this standard defines what material measures are, their intended uses (calibration and user adjustment), and the types suitable for assessing and correcting systematic errors in areal surface texture measurement.
Key topics and technical requirements
- Scope and purpose: Material measures are dedicated workpieces that provide assigned quantity values to verify metrological characteristics and/or to adjust instruments (calibration vs user adjustment).
- Design and material constraints: Material characteristics (reflectivity, hardness, refractive index, colour) and geometric features (flatness, groove form, slope) shall not significantly affect measurements. Real-surface scale limitations are defined so out-of-scale features are excluded.
- Metrological intent: The measures are designed to allow verification and correction of coordinate scale and instrument adjustment coefficients (Cx, Cy, Cz) and squareness between X and Y drives on areal instruments.
- Types of material measures: The standard enumerates profile (prefix P) and areal (prefix A) types. Examples include:
- Profile: PPS (Periodic sinusoidal), PPT (Periodic triangular), PGR (Groove, rectangular), PRO (Irregular profile), PCS (Contour standard), PDG (Double groove)
- Areal: AGP (Grooves, perpendicular), AGC (Grooves, circular), ASP (Hemisphere), APS (Plane‑sphere), ACG (Cross grating), ACS (Cross sinusoidal)
- Documentation and certification: Material measures should be uniquely identified (serial number, type, nominal measurands) and supplied with measurement method and characteristics. A material measure certificate format is covered.
- Limitations: This Part does not separate errors introduced by instrument hardware from those due to filtering/computation algorithms - software measurement standards address that.
Practical applications and users
Who uses ISO 25178-70:2014:
- Metrology and calibration laboratories (ISO/IEC 17025 contexts)
- Surface metrology instrument manufacturers and suppliers
- Quality engineers in automotive, aerospace, medical devices, precision manufacturing
- Calibration service providers and R&D teams developing surface-measurement methods
Practical benefits:
- Reliable periodic verification and adjustment of areal surface texture instruments
- Improved measurement traceability and reduced systematic error
- Clear identification and specification of physical calibration standards for surface texture
Related standards
- ISO 25178 series (Parts 1, 2, 3, 6, 71, 601, etc.)
- ISO 25178-71 (software measurement standards)
- ISO 25178-600 series (instrument adjustment coefficients)
- ISO 3274 (stylus instrument characteristics)
- ISO 10012 and ISO/IEC 17025 (measurement and laboratory management)
For implementation or procurement of material measures, consult the full ISO 25178-70:2014 text and associated annexes for measurement requirements, types, and certification details.