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Denkmalgeschützte Bauwerke im Clouth Quartier

DIN ISO 25178
Bereich Geometrische Produktspezifikation (GPS)
Titel Surface texture : areal
Kurzbeschreibung: Geometrische Produktspezifikation, flächenhafte Oberflächenparameter
Letzte Ausgabe 2007
Übernahme von ISO 25178
Karte

Die Norm ISO 25178 mit dem vollständigen Titel „Geometric Product Specifications (GPS) – Surface texture : areal“ (deutsch: „Geometrische Produktspezifikation (GPS) – Oberflächenbeschaffenheit: Flächenhaft“) ist eine Sammlung internationaler Normen zur Analyse von 3D-Oberflächentexturen.

Diese Norm wurde vom Technischen Komitee TC213 der Arbeitsgruppe WG16 der ISO (Internationale Organisation für Normung) erarbeitet.

Es ist die erste internationale Norm die Messung und Spezifikation von 3D-Oberflächentexturen berücksichtigt. Im Einzelnen definiert die Norm 3D Texturparameter und die zugehörigen Operatoren zu deren Bestimmung. Sie beschreibt auch die anwendbare Messtechnik, Kalibriermethoden und physikalische Kalibrierstandards, sowie die dafür nötige Kalibriersoftware.

Eine grundlegend neuer Bestandteil der Norm ist die Abdeckung der Berührungslosen Messmethoden, die zwar schon weit in der Industrie verbreitet sind, denen aber bisher eine Norm fehlte um Qualitätsaudits nach ISO 9000 durchzuführen. Die Norm führt zum ersten mal 3D Oberflächencharakterisierung in Bereiche ein, in denen die 2D-Profilometer seit über 30 Jahren durch Normen standardisiert wurde. Das gleiche gilt für die damit verbundene Oberflächenmesstechnik, die nicht auf mechanisch abtastende Verfahren beschränkt ist, sondern auch Konfokalmikroskope oder Interferometer umfasst.

Aufbau der Norm

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Documents constituting the standard

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  • Part 1: surface texture indications
  • Part 2: terms, definitions and surface texture parameters
  • Part 3: specification operators
  • Part 6: classification of methods for measuring surface texture
  • Part 601: nominal characteristics of contact (stylus) instruments
  • Part 602: nominal characteristics of non-contact (confocal chromatic probe) instruments
  • Part 603: nominal characteristics of non-contact (wavefront interferometric microscope) instruments
  • Part 701: calibration and measurement standards for contact (stylus) instruments

Other documents are in draft or being drafted and will been published in the next few years. A number of documents that are in draft concern, in particular, other optical measurement technologies (3D confocal microscope, white light interferometric microscope, digital holographic microscope).

New definitions

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The ISO 25178 standard is considered by TC213 as first and foremost providing a redefinition of the foundations of surface texture, based upon the principle that nature is intrinsically 3D. It is anticipated that future work will extend these new concepts into the domain of 2D profilometric surface texture analysis, requiring a total revision of all current surface texture standards (ISO 4287, ISO 4288, ISO 1302, ISO 11562, ISO 12085, ISO 13565, etc.)

A new vocabulary is imposed:

  • S filter: filter eliminating the smallest scale elements from the surface (or of the shortest wavelength for a linear filter)
  • L filter: filter eliminating the largest scale elements from the surface (or of the longest wavelength for a linear filter)
  • F operator: operator suppressing nominal form.
  • S-L surface: surface obtained after S and L filtering. Equivalent to a roughness or waviness surface.
  • S-F surface: surface obtained after S filtering and application of the F operator.
  • Primary surface: surface obtained after S filtering.
  • Nesting index: index corresponding to the cut-off wavelength of a linear filter, or to the scale of the structuring element of a morphological filter.

The new authorized filters are described in the series of technical specifications included in ISO/TS 16610. These filters include: the Gaussian filter, the spline filter, robust filters, morphological filters, wavelet filters, cascading filters, etc.

3D areal surface texture parameters

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3D parameters are written with the capital letter S (or V) followed by a suffix of one or two small letters. They are calculated on the entire surface and no more by averaging estimations calculated on a number of base lengths, as is the case for 2D parameters. In contrast with 2D naming conventions, the name of a 3D parameter does not reflect the filtering context. For example, Sa always appears regardless of the surface, whereas in 2D there is Pa, Ra or Wa depending on whether the profile is a primary, roughness or waviness profile.

Height parameters

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These parameters quantify the z axis perpendicular to the surface only.

Parameter Description
Sq Root mean square height of the surface
Ssk Skewness of height distribution
Sku Kurtosis of height distribution
Sp Maximum height of peaks
Sv Maximum height of valleys
Sz Maximum height of the surface
Sa Arithmetical mean height of the surface

Spatial parameters

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These parameters quantify the lateral information present on the x and y axes of the surface.

Parameter Description
Sal Fastest decay auto-correlation rate
Str Texture aspect ratio of the surface
Std Texture direction of the surface

Hybrid parameters

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These parameters combine the information present on the x, y and z axes of the surface.

Parameter Description
Sdq Root mean square gradient of the surface
Sdr Developed area ratio

Functional parameters

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These parameters are calculated from the Abbott-Firestone curve obtained by the integration of the height distribution on the whole surface.

Parameter Description
Smr Surface bearing area ratio
Smc Height of surface bearing area ratio
Sxp Peak extreme height
Vm Material volume at a given height
Vv Void volume at a given height
Vmp Material volume of peaks
Vmc Material volume of the core
Vvc Void volume of the core
Vvv Void volume of the valleys
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These parameters are derived from a segmentation of the surface into motifs (dales and hills). Segmentation is carried out using the watersheds method.

Paramètre Description
Spd Density of peaks
Spc Arithmetic mean peak curvature
S10z 10 point height
S5p 5 point peak height
S5v 5 point valley height
Sda Closed dales area
Sha Closed hills area
Sdv Closed dales volume
Shv Closed hills volume

3D surface texture measurement instruments

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Part 6 of the standard divides the usable technologies into three families:

  1. Topographical instruments: contact and non-contact 3D profilometers, interferential and confocal microscopes, structured light projectors, stereoscopic microscopes, etc.
  2. Profilometric instruments: contact and non-contact 2D profilometers, line triangulation lasers, etc.
  3. Instruments functioning by integration: pneumatic measurement, capacitive, by optical diffusion, etc.

and defines each of these technologies.

Next, the standard explores a number of these technologies in detail and dedicates two documents to each of them:

  • Part 6xx: nominal characteristics of the instrument
  • Part 7xx: calibration of the instrument

Contact profilometer

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Parts 601 and 701 describe the contact profilometer, using a diamond point to measure the surface with the assistance of a lateral scanning device.

Chromatic confocal gauge

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Part 602 describes this type of non-contact profilometer, incorporating a single point white light chromatic confocal sensor. The operating principle is based upon the chromatic dispersion of the white light source along the optical axis, via a confocal device, and the detection of the wavelength that is focused on the surface by a spectrometer.

25178