prEN ISO 25178-70

• Abstract:

  ISO 25178-70:2014 specifies the characteristics of material measures used for the periodic verification and adjustment of areal surface texture measurement instruments.

• Status: Not Published
• Publication Date: 11-Jan-2028
• ICS: 17.040.20 - Properties of surfaces
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: CEN/TC 290 - Dimensional and geometrical product specification and verification
• Drafting Committee: CEN/TC 290 - Dimensional and geometrical product specification and verification
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Start Date: 10-Sep-2026
• Completion Date: 10-Sep-2026
• Ref Project: oSIST prEN ISO 25178-70:2026 - Geometrical product specification (GPS) - Surface texture: Areal - Part 70: Material measures (ISO/DIS 25178-70:2026)

• Revises: EN ISO 5436-1:2000 - Geometrical Product Specifications (GPS) - Surface texture: Profile method; Measurement standards - Part 1: Material measures (ISO 5436-1:2000)
• Effective Date: 26-Mar-2025
• Revises: EN ISO 25178-70:2014 - Geometrical product specification (GPS) - Surface texture: Areal - Part 70: Material measures (ISO 25178-70:2014)
• Effective Date: 25-Sep-2024

Overview

prEN ISO 25178-70:2026, titled Geometrical Product Specification (GPS) - Surface Texture: Areal - Part 70: Material Measures, is an international draft standard developed by CEN and ISO (ISO/DIS 25178-70:2026). This document specifies the characteristics and applications of material measures intended for the calibration, verification, and adjustment of instruments that measure areal surface texture. These material measures play a vital role in ensuring the accuracy and reliability of metrology equipment used for profile and areal surface topography assessment in manufacturing and quality control environments.

Key Topics

• Material measures for surface texture: The standard defines dedicated calibration artifacts (material measures) designed for checking and adjusting metrological performance of instruments utilized for areal and profile surface texture measurements.
• Scope: Covers the characteristics, categories, and requirements of material measures, including their design constraints, metrological attributes, and suitable measurement parameters.
• Types of material measures: Outlines several types, classified for both profile (line-based) and areal (surface-based) calibration, such as sinusoidal, triangular, rectangular, and special patterns.
• Requirements: Specifies the design and material requirements that ensure stability and repeatability during instrument calibration and verification routines, aiming to minimize influences from material properties or geometry not relevant to the calibration process.
• Use in calibration, verification, and adjustment: Describes the multifunctional nature of material measures, supporting initial calibration, user adjustment (by establishing correction coefficients), and periodic verification to validate ongoing measurement accuracy.

Applications

The standard is highly applicable to industries and laboratories involved in precision engineering, manufacturing, quality control, and metrology that require consistent and traceable areal surface texture measurements. Key applications include:

• Calibration of surface texture measurement instruments such as contact stylus profilometers and optical areal topography measuring systems. Proper calibration using specified material measures is essential to ensure instrument compliance with international traceability and accuracy standards.
• Adjustment and verification: Material measures from this standard are used to fine-tune and periodically check the accuracy of metrology equipment, supporting ongoing instrument maintenance and ISO-compliant QA/QC procedures.
• Assessment of performance: Enables manufacturers, laboratories, and instrument operators to assess systematic errors, instrument squareness, coordinate calibration, and measurement uncertainty.
• Support for traceability: By specifying standardized material artifacts, the document enhances measurement traceability, supporting quality management requirements such as those outlined in ISO 10012.

Related Standards

prEN ISO 25178-70:2026 is interconnected with several key standards within the Geometrical Product Specification (GPS) family, ensuring coherence in metrological procedures:

• ISO 25178 series: Provides the comprehensive framework for areal surface texture measurement, including parameter definitions and instrumental requirements (e.g., ISO 25178-2, ISO 25178-600).
• ISO 14660-1: Defines general GPS terms and is essential for uniform terminology.
• ISO/IEC 17025: Relates to general requirements for testing and calibration laboratory competence.
• ISO 10012: Addresses quality management for measurement management systems.
• ISO 5436-1 (superseded, content incorporated): Previously defined material measures for profile surface texture instruments.
• ISO 8015 and ISO 14253-1: Establish fundamental GPS principles and decision rules for specification compliance and uncertainty.

Implementing prEN ISO 25178-70:2026 ensures that manufacturers, laboratories, and quality professionals can confidently calibrate and verify areal surface texture measuring instruments, supporting robust, consistent, and globally recognized practices in dimensional metrology.

SLOVENSKI STANDARD
01-september-2026
Specifikacija geometrijskih veličin izdelka (GPS) - Tekstura površine: ploskovna -
70. del: Meritve materiala (ISO/DIS 25178-70:2026)
Geometrical product specification (GPS) - Surface texture: Areal - Part 70: Material
measures (ISO/DIS 25178-70:2026)
Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Flächenhaft -
Teil 70: Maßverkörperungen (ISO/DIS 25178-70:2026)
Spécification géométrique des produits (GPS) - État de surface: surfacique - Partie 70:
Mesures matérialisées (ISO/DIS 25178-70:2026)
Ta slovenski standard je istoveten z: prEN ISO 25178-70
ICS:
17.040.20 Lastnosti površin Properties of surfaces
17.040.40 Specifikacija geometrijskih Geometrical Product
veličin izdelka (GPS) Specification (GPS)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 25178-70
ISO/TC 213
Geometrical product specification
Secretariat: BSI
(GPS) — Surface texture: Areal —
Voting begins on:
Part 70: 2026-06-18
Material measures
Voting terminates on:
2026-09-10
Spécification géométrique des produits (GPS) — État de surface:
surfacique —
Partie 70: Mesures matérialisées
ICS: 17.040.20; 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 25178-70:2026(en)
DRAFT
ISO/DIS 25178-70:2026(en)
International
Standard
ISO/DIS 25178-70
ISO/TC 213
Geometrical product specification
Secretariat: BSI
(GPS) — Surface texture: Areal —
Voting begins on:
Part 70:
Material measures
Voting terminates on:
Spécification géométrique des produits (GPS) — État de surface:
surfacique —
Partie 70: Mesures matérialisées
ICS: 17.040.20; 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 25178-70:2026(en)
ii
ISO/DIS 25178-70:2026(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
5 Requirements for the material measures . . 2
6 Types of material measures . 3
7 Profile material measures . 4
7.1 Type PPS: Periodic sinusoidal shape .4
7.1.1 Design characteristics .4
7.1.2 Measurands .4
7.2 Type PPT: Periodic triangular shape.5
7.2.1 Design characteristics .5
7.2.2 Measurands .5
7.3 Type PPR: Periodic rectangular shape .6
7.3.1 Design characteristics .6
7.3.2 Measurands .6
7.4 Type PPA: Periodic arcuate shape .7
7.4.1 Design characteristics .7
7.4.2 Measurands .7
7.5 Type PGR: Groove, rectangular . .8
7.5.1 Design characteristics .8
7.5.2 Measurands .8
7.6 Type PGC: Groove, circular .11
7.6.1 Design characteristics .11
7.6.2 Measurands .11
7.7 Type PRO: Irregular profile . 12
7.7.1 Design characteristics . 12
7.7.2 Measurands . 13
7.8 Type PCR: Circular irregular profile . 13
7.8.1 Design characteristics . 13
7.8.2 Measurands .14
7.9 Type PRI: Prism .14
7.9.1 Design characteristics .14
7.9.2 Measurands . 15
7.10 Type PRB: Razor blade . 15
7.10.1 Design characteristics . 15
7.10.2 Measurands .16
7.11 Type PAS: Approximated sinusoidal shape .16
7.11.1 Design characteristics .16
7.11.2 Measurands .16
7.12 Type PCS: Contour standard.16
7.12.1 Design characteristics .16
7.12.2 Measurands .17
7.13 Type PDG: Double groove .17
7.13.1 Design characteristics .17
7.13.2 Measurands .18
8 Areal material measures .18
8.1 Type AGP: Grooves, perpendicular .18
8.1.1 Design characteristics .18
8.1.2 Measurands .19

iii
ISO/DIS 25178-70:2026(en)
8.2 Type AGC: Grooves, circular .19
8.2.1 Design characteristics .19
8.2.2 Measurands . 20
8.3 Type ASP: Hemisphere. 20
8.3.1 Design characteristics . 20
8.3.2 Measurands .21
8.4 Type APS: Plane-sphere .21
8.4.1 Design characteristics .21
8.4.2 Measurands .21
8.5 Type ACG: Cross grating . 22
8.5.1 Design characteristics . 22
8.5.2 Measurands . 22
8.6 Type ACS: Cross sinusoidal . 22
8.6.1 Design characteristics . 22
8.6.2 Measurands . 23
8.7 Type ARS: Radial sinusoidal . 23
8.7.1 Design characteristics . 23
8.7.2 Measurands .24
8.8 Type ASG: Star-shape grooves .24
8.8.1 Design characteristics .24
8.8.2 Measurands .24
8.9 Type AIR: Irregular .24
8.9.1 Design characteristics .24
8.9.2 Measurands . 25
8.10 Type AFL: Flat plane . 26
8.10.1 Design characteristics . 26
8.10.2 Measurands . 26
8.11 Type APC: Photochromic pattern. 26
8.11.1 Design characteristics . 26
8.11.2 Measurands .27
9 Material measure certificate .27
Annex A (normative) Requirements for measurements .28
Annex B (normative) Calibration of sensitive and insensitive material measures to stylus tips .29
Annex C (informative) Changes to previous documents (ISO 25178-70:2014 and ISO 5436-
1:2000) .30
Annex D (informative) Equivalence table for material measure names .31
Annex E (informative) Evaluation of a spacing measurand on an areal instrument .32
Annex F (informative) Irregular material measures .35
Annex G (informative) Relationship to the GPS matrix model.38
Bibliography .39

iv
ISO/DIS 25178-70:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
This second edition cancels and replaces the first editions (ISO 25178-70:2014), which have been technically
revised and cancels and replaces ISO 5436-1:2000, whose contents have been revised and incorporated into
this document.
The main changes are as follows:
— revison of Clause 7, which now include most of the contents of ISO 5436-1:2000;
— revison of Clause 8 on Areal material measure;
— revison of Clause 9 on material measure certificate;
— addition of Annex B on the calibration method of sensitive and insensitive material measures to check
the stylus tip condition, which was addressed in ISO 5436-1:2000;
— addition of Annex C describing changes to the previous documents (ISO 25178:2014 and ISO 5436-1:2000);
— revision of Annex D on equivalence table for material measure names; the corresponding material
measure with PGC has been added;
— revision of Annex E on evaluation of a spacing measurand on an areal instrument.
A list of all parts in the ISO 25178 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO/DIS 25178-70:2026(en)
Introduction
This document is a geometrical product specification (GPS) standard and is to be regarded as a general GPS
[1]
standard (see ISO 14638 ). It influences chain link G of the chain of standards on profile and areal surface
texture.
[1]
The ISO GPS matrix model given in ISO 14638 gives an overview of the ISO GPS system of which this
[2]
document is a part. The fundamental rules of ISO GPS given in ISO 8015 apply to this document and
[3]
the default decision rules given in ISO 14253-1 apply to the specifications made in accordance with this
document, unless otherwise indicated.
For more detailed information on the relation of this document to other standards and the GPS matrix model,
see Annex G.
The material measures for profile surface texture instruments were previously defined in ISO 5436-1. Based
on this, this document for areal surface texture instruments was published in 2014. Since this is the more
modern international standard and more inclusive material measures for the profile method and the areal
method differ only in the presence of a Y-axis, this edition of this document replaces not only the previous
version of ISO 25178-70 but also ISO 5436-1:2000.
This document introduces material measures that can be used for calibration, verification and adjustment of
profile and areal surface texture measurement instruments.
NOTE Portions of this document, particularly the informative sections, describe patented systems and methods.
This information is provided only to assist users in understanding the operating principles of contact stylus
instruments. This document is not intended to establish priority for any intellectual property, nor does it imply a
license to proprietary technologies described herein.

vi
DRAFT International Standard ISO/DIS 25178-70:2026(en)
Geometrical product specification (GPS) — Surface texture:
Areal —
Part 70:
Material measures
1 Scope
This document specifies the characteristics of material measures used for the calibration, adjustment and
verification of profile and areal surface texture measurement instruments.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 10012, Quality management — Requirements for measurement management systems
ISO 14660-1:1999, Geometrical Product Specifications (GPS) — Geometrical features — Part 1: General terms
and definitions
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 25178-600:2019, Geometrical product specifications (GPS) — Surface texture: Areal — Part 600:
Metrological characteristics for areal topography measuring methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12780-1, ISO 12781-1, ISO 21920-2,
ISO 25178-2, ISO 25178-600, ISO 25178-601, ISO 25178-701 and ISO/IEC Guide 99 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
material measure
dedicated manufactured workpiece intended to reproduce or supply, in a permanent
manner during its use quantities of one or more given kinds, each with an assigned quantity value
Note 1 to entry: The indication of a material measure is its assigned quantity value.
Note 2 to entry: A material measure can be a measurement standard.
Note 3 to entry: A material measure is sometimes called calibration sample, calibration specimen, calibration standard,
standard artefact, physical measurement standard or physical standard.
[SOURCE: ISO/IEC Guide 99:2007, 3.6, modified — A domain has been added and the definition modified.
The examples are not reproduced.]

ISO/DIS 25178-70:2026(en)
4 General
A material measure can be used for three different purposes:
— calibration of the metrological characteristics, followed by assessment of the measurement uncertainty;
— user adjustment of the instrument, which establishes corrections of the measured quantities;
— verification of the measurement instrument to test the validity of calibration and adjustment.
These purposes depend on the metrological characteristics of the material measures (see the ISO 25178-700
series).
The material measures presented in this document are suitable for all three purposes; nevertheless, they
have been especially designed for the assessment and correction of systematic errors. This is due to the fact
that the characteristics of those material measures permit the calibration of coordinates such as x, y and
z through the assessment and verification of adjustment coefficients C , C and C (see the ISO 25178-600
x y z
series).
These material measures are generally not useful for separating the errors introduced by the instrument
from those due to the filtering and computation algorithms. The algorithms can be tested using software
[4] [5] [6]
measurement standards (see ISO 5436-2 , ISO 25178-71 and ISO 25178-72 ).
Most of the material measures presented below permit the verification and the correction of the squareness
between X- and Y- drive units on areal instruments.
The measurement method, the instrument settings, especially concerning the filter settings and/or
the required topographic spatial resolution W (see Clause 9, and also ISO 25178-600:2019, 3.1.20). This
R
information is usually specified by the manufacturer of the material measure, the calibration certificate or
calibration instructions.
In ISO 21920-2 and ISO 25178-2, each term is followed by its parameter (abbreviated term), then its symbol.
Throughout this document, parameters are written as abbreviated terms with lower-case suffixes (as in
Rq) when used in a sentence, and are written as symbols with subscripts (as in Rq) when used in formulae,
to avoid misinterpretations of compound letters as an indication of multiplication between quantities in
formulae. The parameters with lower-case suffixes are used in product documentations, drawing and data
sheets.
5 Requirements for the material measures
The design characteristics of material measures shall be compatible with the considered application. See
also Annex A.
The material characteristics of the material measure shall not significantly influence the measurement
carried out on it.
The lateral scale-limits of the integral real surface (defined in ISO 14660-1:1999, 2.4.1) of the material
measure shall be specified. Features, or components of features, with length scales entirely outside the
bandwidth of these scale-limits, shall be considered not to affect the measurement. Similarly, features
or parts of features located outside the area involved in the analysis shall be considered not to affect the
measurement.
Examples of such features are:
— flatness deviation of the real integral surface of the standard;
— form deviation of the groove(s) (i.e. for PGR, PGC, PDG, AGP, AGC, etc.);
— groove bottom radius (i.e. for PGC, PCS, PDG, AGP, AGC, etc.);

ISO/DIS 25178-70:2026(en)
— form deviation of the flanks of the triangles (i.e. for PPT, PCS, PDG, AGP, etc.);
— parallelism errors between grooves (i.e. for PDG, AGP, etc.);
— squareness between grooves (i.e. for AGP, etc.);
— local slope at any point (when using an optical instrument);
— bisector of the groove(s) or the triangles (line, plane or cylinder), which shall be nominally perpendicular
to the reference plane of the standard;
— reflectivity of the surface (when using an optical instrument);
— hardness of the material (when using a stylus instrument);
— refractive index of the material;
— colour of the material.
The measurement standards should be uniquely identified. Serial number, type and nominal values of the
measurands are recommended to be engraved on the standard and/or standard’s casing.
6 Types of material measures
The different types of material measures covered by this document are given in Table 1 and Table 2.
NOTE 1 The prefix P is used for the profile material measures type.
NOTE 2 The prefix A is used for the areal material measures type.
Annex D gives the equivalence between names defined in other standards (e.g. ISO 5436-1 and ISO 25178-701).
Table 1 — Types of profile material measures
Type Name
PPS Periodic sinusoidal shape
PPT Periodic triangular shape
PPR Periodic rectangular shape
PPA Periodic arcuate shape
PGR Groove, rectangular
PGC Groove, circular
PRO Irregular profile
PCR Circular irregular profile
PRI Prism
PRB Razor blade
PAS Approximated sinusoidal shape
PCS Contour standard
PDG Double groove
ISO/DIS 25178-70:2026(en)
Table 2 — Types of areal material measures
Type Name
AGP Grooves, perpendicular
AGC Groove, circular
ASP Hemisphere
APS Plane – sphere
ACG Cross grating
ACS Cross sinusoidal
ARS Radial sinusoidal
ASG Star-shape grooves
AIR Irregular
AFL Flat plane
APC Photochromic pattern
7 Profile material measures
7.1 Type PPS: Periodic sinusoidal shape
7.1.1 Design characteristics
This material measure reproduces a sinusoidal shape along one direction. The shape is defined by the period
p and the depth d (see Figure 1).
NOTE Particular cases of PPS material measures, commonly called chirps, have increasing or decreasing periods.
They enable the assessment of instrument bandwidth or lateral resolution.
Key
d depth
p period
Figure 1 — Sinusoidal shape
7.1.2 Measurands
See Table 3.
Table 3 — Measurand of material measures — Type PPS
Profile Areal
Z-axis Ra, Rq, Rt and/or Rz Sa, Sq and/or Sz
X-axis (and Y-axis) Rsm averaged Psm
This material measure can be primarily used for calibrating vertical profile component for contact stylus
instruments, and can also be used for calibrating horizontal profile components, if the period p is held within
limits acceptable for this purpose. The material measure is chosen, so that the values of Ra, Rq and Rsm are
not affected by attenuation due to the stylus tip or S-filter with a nesting index N (cut-off λs).
is
ISO/DIS 25178-70:2026(en)
When used in conjunction with sensitive groove pattern to stylus tips (see 7.2), Type PPS can be used for
checking stylus tip condition. For this purpose, Type PPS with large enough p is chosen so that Ra value
is not affected by attenuation due to the stylus tip (insensitive groove pattern to the stylus tip). For the
calibration of Type PPS for this purpose, see Annex B.
Other parameters, such as Rdq, Rp, Rv can be used, but less commonly used.
NOTE 1 Ra is the arithmetic mean height of the roughness profile, Rq is the root mean height of the roughness
profile, Rt is the total height of the roughness profile, Rz is the maximum height of the roughness progfile and Rsm is
the mean profile element spacing of the roughness profile (see ISO 21920-2).
NOTE 2 Rsm is equal to the period p of the sinusoid.
NOTE 3 Sa is the arithmetic mean height of the aerial surface, Sq is the root mean square height of the areal surface
(see ISO 25178-2).
NOTE 4 Ra and Rq can be calculated using Formula (1) and Formula (2), assuming the effect of the L-filter with a
nesting index N (cut-off λc) and the S-filter with a nesting index N is negligible:
ic is
(1)
and
(2)
NOTE 5 Psm is the mean profile element spacing of the primary profile (see ISO 21920-2).
NOTE 6 For the definition of “averaged Psm”, see Annex E.
NOTE 7 The maximum slope on this material measure is given by the ratio .
NOTE 8 Rdq is the root mean square gradient of the roughness profile, Rp is the mean peak height of the roughness
profile and Rv is the pit depth of the roughness profile.
7.2 Type PPT: Periodic triangular shape
7.2.1 Design characteristics
This material measure reproduces a triangular shape along one direction. The shape is defined by the period
p and the depth d, or by the depth d and the angle α between opposing flanks (see Figure 2).
Key
α angle
d depth
p period
Figure 2 — Triangular shape
7.2.2 Measurands
See Table 4.
ISO/DIS 25178-70:2026(en)
Table 4 — Measurand of material measures — Type PPT
Profile Areal
Z-axis Ra, Rq, Rt and/or Rz Sa, Sq and/or Sz
X-axis (and Y-axis) Rsm averaged Psm
This material measure can be primarily used for calibrating vertical profile component for contact stylus
instruments, and can also be used for calibrating horizontal profile components if the period p is held within
limits acceptable for this purpose. The material measure is chosen, so that the values of Ra, Rq and Rsm are
not affected by attenuation due to the stylus tip or S-filter with a nesting index N (cut-off λs).
is
Type PPT can be used for checking stylus tip condition. For this purpose, Type PPT shall have isosceles
triangular grooves with sharp peaks and pits, with Rsm and angle α proportioned to make Ra dependant
the size of the stylus (sensitive groove pattern to the stylus tip). For the calibration of Ra ratio of Type PPT
and insensitive material measures, see Annex B.
Other parameters, such as Rdq can be defined, but are less commonly used.
NOTE 1 Rsm is equal to the period p of the triangular motif.
NOTE 2 Ra and Rq can be calculated using the Formula (3) and Formula (4), assuming the effect of the L-filter with
a nesting index N (cut-off λc) and the S-filter with a nesting index N (cut-off λs) is negligible:
ic is
(3)
and
(4)
NOTE 3 For the definition of “averaged Psm”, see Annex E.
7.3 Type PPR: Periodic rectangular shape
7.3.1 Design characteristics
This material measure reproduces rectangular grooves along one direction. The shape is defined by the
groove width w, the shape period p, and the groove depth d (see Figure 3).
Key
d groove depth
p shape period
w groove width
Figure 3 — Rectangular shape
7.3.2 Measurands
See Table 5.
ISO/DIS 25178-70:2026(en)
Table 5 — Table 5 — Measurand of material measures — Type PPR
Profile Areal
Z-axis Ra, Rq, Rt and/or Rz Sa, Sq a/or Sz
X-axis (and Y-axis) Rsm averaged Psm
Other parameters can be defined, but are less commonly used.
NOTE 1 Rsm is equal to the period p of the rectangular motif.
NOTE 2 Ra and Rq can be calculated using the Formula (5) and Formula (6), assuming the effect of the L-filter with
a nesting index N (cut-off λc) and the S-filter with a nesting index N (cut-off λs) is negligible:
ic is
(5)
and
(6)
NOTE 3 For the definition of “averaged Psm”, see Annex E
7.4 Type PPA: Periodic arcuate shape
7.4.1 Design characteristics
This material measure reproduces an arcuate shape along one direction. The shape is defined by the period
p and the radius r of arcs, or by the period p and the depth d (see Figure 4).
Key
d depth
r radius of arcs
p period
Figure 4 — Arcuate shape
7.4.2 Measurands
See Table 6.
Table 6 — Measurand of material measures – Type PPA
Profile Areal
Z-axis Ra, Rq, Rt and/or Rz Sa, Sq and/or Sz
X-axis (and Y-axis) Rsm averaged Psm
This material measure can be primarily used for calibrating vertical profile component for contact stylus
instruments, and can also be used for calibrating horizontal profile components, if the period p is held within
limits acceptable for this purpose. The material measure is chosen, so that the values of Ra, Rq and Rsm are
not affected by attenuation due to the stylus tip or S-filter with a nesting index N (cut-off λs).
is
ISO/DIS 25178-70:2026(en)
When used in conjunction with sensitive groove pattern to stylus tips (see 7.2), Type PPS can be used for
checking stylus tip condition. For this purpose, Type PPA with large enough p and r is chosen, so that Ra
value is not affected by attenuation due to the stylus tip (insensitive groove pattern to stylus tip). For the
calibration of Type PPA for this purpose, see Annex B.
Other parameters can be defined, but are less commonly used.
NOTE 1 Rsm is equal to the period p of the arcuate shape.
NOTE 2 For the definition of “averaged Psm”, see Annex E.
7.5 Type PGR: Groove, rectangular
7.5.1 Design characteristics
This material measure has a wide groove with a flat bottom or a number of separated grooves of equal or
increasing depth, each groove being wide enough to be insensitive to the lateral resolution limitations of the
instrument (for example the stylus tip).
Each groove is characterized by its width w and its depth d (see Figure 6).
Key
d depth
w groove width
Figure 5 — Rectangular groove
Key
d depth
w groove width
Figure 6 — Trapezoidal groove
7.5.2 Measurands
The measurand is the depth d.
epresentThe default area used to determine the depth d of a rectangular groove is shown in Figure 7
, while the corresponding area for a trapezoidal groove is shown in Figure 8. A pair of reference areas A
and B represent the level of the outer surface. Area C represents the level of the groove. The equivalent
constructions for profile analysis of a rectangular groove and a trapezoidal groove are shown in Figure 9
and Figure 10, respectively.
ISO/DIS 25178-70:2026(en)
To avoid the influence of any rounding of the corners, the upper surface on each side of the groove shall be
ignored for a length equal to one-third of the width of the groove. The surface at the bottom of the groove is
assessed only over the central third of its width.
For areal method, least-square parallel plane shall be fitted to the data points of areas A, B and
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