ČSN EN ISO 25178-73 - Geometrické specifikace produktu (GPS) - Textura povrchu: Plocha - Část 73: Termíny a definice pro povrchové vady na ztělesněných mírách

3.3.6 ignoring

measuring the surface of the measurement standard while paying no regard to whether the portion of the surface being measured includes any defects or not

Note 1 to entry: Without the definition in 3.3.6, three possible interpretations of the term to ignore a defect would present themselves a priori: a) to measure the surface while deliberately avoiding areas which are visibly defective; b) to measure the surface and then to discard either all the data or else just the portion which corresponds to the defect; c) to measure the surface and to retain all the resulting data as though there were no defect at all.

In terms of the definitions presented in this document, case a) above corresponds to avoiding the defect as defined in 3.3.2, and case b) corresponds to removing the defect as defined in 3.3.1. Case c) is the only instance of ignoring a defect as defined in 3.3.6.

Note 2 to entry: The six ways of responding to defects defined above (3.3.1 to 3.3.6) are exhaustive, because outside these alternatives there is no other way to deal with a defect. The six ways are also mutually exclusive, with the exception of 3.3.5 and 3.3.6: it is possible for a defect to be both ignored and measured. However, it is also possible for a defect to be ignored and not measured; and it is possible for a defect to be measured and not ignored.

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(informative) Stains and discolorations

General

The presence of stains and discolorations (i.e. areas which are coloured differently than the rest of the measuring area) on the measuring surface of a material measure often causes concern. Sometimes this is because they are assumed to be the effect of corrosion of ferrous metal and therefore associated with distortions of the surface profile. This assumption is wrong in the case of any object made from a non-ferrous material.

Classes of stains

It is important to consider whether the change in colour of the stained area corresponds to any measurable distortion of the profile. There are three cases to consider:

1) some stains can be seen under magnification to consist of small irregularities much smaller than the scale of interest;

2) other stains will correspond to Gestalt defects (3.2.10);

3) some stains will be seen under magnification to coincide spatially with an area which is a geometrical defect.

The first class of stains are ineffective defects, and when the small irregularities are smaller than the scale limitation (see 3.1.2, Note 4 to entry) they are not even defects at all. The second class are cosmetic defects. Neither of these two types of defect will influence any measurement of surface texture. The third class of stains might be either effective or ineffective. If they are visible to the naked eye and ineffective, then they are cosmetic. The only stains which will influence a measurement are those which belong to the third class and are, in addition, effective.

Treatment of stains

If an attempt is made to repair (3.3.3) the stain by mechanical rubbing (for example, with a soft cloth) then it is highly likely that the defect will be altered (3.3.4). The overall consequence will be some combination of the effects described below:

1) the desired effect of reducing the visibility or area of the stain might be achieved;

2) a stain which was originally an ineffective (cosmetic) defect might be altered to an effective defect (see 3.3.4, Note 2 to entry);

3) a stain which was originally an effective defect might be altered, by reducing the size of the corresponding deviation, to an ineffective defect;

4) a stain which was originally an effective defect might be altered, by increasing the size of the corresponding deviation, to a worse defect.

(informative) Relation to the GPS matrix model

General

For full details about the GPS matrix model, see ISO 14638.

Information on this document and its application

See Introduction.

Position in the GPS matrix model

This document is a general ISO GPS standard which influences chain link F of the chains of standards on profile and areal surface texture in the GPS matrix model. The rules and principles given in this document apply to all segments of the ISO GPS matrix which are indicated with a filled dot (•).

Table B.1 — ISO GPS standards matrix modelN IF "x_+3" " N " N 0 ,N COMPARE N 0 ) !Syntax Error, , = 1 " QUOTE "" " IF N N ">" " " QUOTE "" " IF "x_-3" "N IF N " N ">" " ""

 

Chain links

A

B

C

D

E

F

G

Symbols and indications

Feature requirements

Feature properties

Conformance and nonconformance

Measurement

Measurement equipment

Calibration

Size

 

 

 

 

 

 

 

Distance

 

 

 

 

 

 

 

Form

 

 

 

 

 

 

 

Orientation

 

 

 

 

 

 

 

Location

 

 

 

 

 

 

 

Run-out

 

 

 

 

 

 

 

Profile surface texture

 

 

 

 

 

•

 

Areal surface texture

 

 

 

 

 

•

 

Surface imperfections

 

 

 

 

 

•

 

Related standards

The related standards are those of the chains of standards indicated in Table B.1.

Bibliography

[1] ISO 5436-1, Geometrical Product Specifications (GPS) — Surface texture: Profile method; Measurement standards — Part 1: Material measures

[2] ISO 8785:1998, Geometrical Product Specification (GPS) — Surface imperfections — Terms, definitions and parameters

[3] ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories

[4] ISO 22432:2011, Geometrical product specifications (GPS) — Features utilized in specification and verification

[5] ISO 25178-70, Geometrical product specification (GPS) — Surface texture: Areal — Part 70: Material measures