Plastics — Quantitative evaluation of scratch-induced damage and scratch visibility

ISO 17541:2014 deals with quantitative evaluation of scratch-induced damage and scratch visibility in polymers. ISO 17541:2014 specifies two methods to assess scratch damage and scratch visibility expressed by three colour coordinates of a 3-D colour model. Method A uses a scratch tip capable of area-contact or line-contact with material surfaces under a constant load condition. It is represented by scratch damage index (SDI). Method B uses a scratch tip capable of line-contact under a linearly increasing load condition. It is represented by scratch visibility index (SVI). The methods are suitable for use with coated and uncoated thermoplastic and thermosetting moulding materials. The methods specify the preferred dimensions of testing specimens and the preferred scratch-tip geometry.

Plastiques — Évaluation quantitative des dommages induits par rayure et visibilité des rayures

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Status
Published
Publication Date
01-Sep-2014
Current Stage
9093 - International Standard confirmed
Start Date
23-Nov-2020
Completion Date
23-Nov-2020
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ISO 17541:2014 - Plastics -- Quantitative evaluation of scratch-induced damage and scratch visibility
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INTERNATIONAL ISO
STANDARD 17541
First edition
2014-09-01
Plastics — Quantitative evaluation of
scratch-induced damage and scratch
visibility
Plastiques — Évaluation quantitative des dommages induits par
rayure et visibilité des rayures
Reference number
ISO 17541:2014(E)
ISO 2014
---------------------- Page: 1 ----------------------
ISO 17541:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

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Published in Switzerland
ii © ISO 2014 – All rights reserved
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ISO 17541:2014(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 General description ............................................................................................................................................................................. 3

5.2 Scratch tip .................................................................................................................................................................................................... 3

5.3 Load and position sensors ............................................................................................................................................................ 4

5.4 Test load ........................................................................................................................................................................................................ 4

5.5 Test speed .................................................................................................................................................................................................... 4

5.6 Specimen stage ....................................................................................................................................................................................... 4

6 Test specimens........................................................................................................................................................................................................ 5

6.1 General ........................................................................................................................................................................................................... 5

6.2 Shape and dimensions ...................................................................................................................................................................... 5

6.3 Preparation ................................................................................................................................................................................................ 5

6.4 Conditioning .............................................................................................................................................................................................. 5

6.5 Number of test specimens ............................................................................................................................................................. 5

7 Procedure..................................................................................................................................................................................................................... 5

7.1 Test atmosphere .................................................................................................................................................................................... 5

7.2 Scratch tip .................................................................................................................................................................................................... 5

7.3 Method A (constant load condition) .................................................................................................................................... 5

7.4 Method B (linearly increasing load condition)............................................................................................................ 6

7.5 Scratch testing ......................................................................................................................................................................................... 6

8 Interpretation of result.................................................................................................................................................................................. 7

8.1 General ........................................................................................................................................................................................................... 7

8.2 Scratch strength and scratch resistance............................................................................................................................ 7

8.3 Single-damage (SD) ............................................................................................................................................................................. 7

8.4 Multiple-damage (MD) ..................................................................................................................................................................... 8

9 Test report ................................................................................................................................................................................................................10

Annex A (informative) 3-D colour model .....................................................................................................................................................12

Annex B (informative) Example for quantitative determination of scratch damageand

scratch visibility .................................................................................................................................................................................................13

Bibliography .............................................................................................................................................................................................................................17

© ISO 2014 – All rights reserved iii
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ISO 17541:2014(E)
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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical

properties.
iv © ISO 2014 – All rights reserved
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INTERNATIONAL STANDARD ISO 17541:2014(E)
Plastics — Quantitative evaluation of scratch-induced
damage and scratch visibility
1 Scope

This International Standard deals with quantitative evaluation of scratch–induced damage and scratch

visibility in polymers.

This International Standard specifies two methods to assess scratch damage and scratch visibility

expressed by three colour coordinates of a 3-D colour model.

Method A uses a scratch tip capable of area-contact or line-contact with material surfaces under a

constant load condition. It is represented by scratch damage index (SDI).

Method B uses a scratch tip capable of line-contact under a linearly increasing load condition. It is

represented by scratch visibility index (SVI).

The methods are suitable for use with coated and uncoated thermoplastic and thermosetting moulding

materials.

The methods specify the preferred dimensions of testing specimens and the preferred scratch-tip

geometry.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 291, Plastics — Standard atmospheres for conditioning and testing

ISO 294-1, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 1: General

principles, and moulding of multipurpose and bar test specimens

ISO 294-2, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 2: Small

tensile bars

ISO 294-3, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 3: Small

plates
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 19252, Plastics — Determination of scratch properties
ISO 20753, Plastics — Test specimens
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
scratch

visual surface damage such as cutting and whitening, which is generated by sliding of the scratch tip

over the surface of the test specimen under defined conditions
© ISO 2014 – All rights reserved 1
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ISO 17541:2014(E)
3.2
normal force

load applied by the scratch tip in a direction perpendicular to the material surface

Note 1 to entry: It is expressed in newtons.
3.3
tangential force

load applied by the scratch tip in a horizontal direction on the material surface

Note 1 to entry: It is expressed in newtons.
3.4
scratch path

connected line of scratch damage induced on the material surface by the scratch tip

3.5
whitening

visual damage which is generated on the material surface along the scratch path such as micro-cracking,

crazing, voiding, and debonding
3.6
single-damage

simple surface damage which is generated in a single direction on the material surface

3.7
multiple-damage

latticed damages which are generated in two perpendicular, horizontal directions on the material

surface
3.8
scratch force

resultant force applied to the material surface as the summation of the normal and tangential force

vectors
Note 1 to entry: It is expressed in newtons.
3.9
scratch strength
scratch force per unit contact area of area-contact scratch tip
Note 1 to entry: It is expressed in newtons per square millimetre.
3.10
scratch resistance
scratch force per unit contact length of line-contact scratch tip
Note 1 to entry: It is expressed in newtons per millimetre.
3.11
degree of scratch damage

euclidean distance between the color coordinates of the scratched and unscratched surfaces

2 © ISO 2014 – All rights reserved
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ISO 17541:2014(E)
3.12
percent difference in luminance
norm

percent difference between the luminance values of the scratched and unscratched surfaces

3.13
scratch damage index (SDI)
[ΔD, S (or R )] or [L , S (or R )]
s s norm s s

set of the relative severity of scratch damage and scratch strength (or scratch resistance) values, which

are quantitative values obtained under a constant normal load
3.14
critical intensity value
threshold intensity value where the onset of scratch visibility occurs
3.15
critical saturation value
threshold saturation value where the onset of scratch visibility occurs
3.16
scratch visibility index (SVI)
[I , S , R ]
c c s

set of the relative intensity, saturation, and scratch resistance values, which is the onset of scratch

visibility obtained under a linearly increasing normal load
4 Principle

This test method provides a quantitative evaluation of scratch damage and visibility on polymer and

coated surfaces. Scratching is generated by a scratch tip capable of area-contact or line-contact on the

material surface and can be induced under a constant normal load or a linearly increasing load.

The scratch damage index (SDI), the severity of surface damage caused by scratching under a constant

normal load condition, is determined by comparing the Euclidean distance or percent difference in the

luminance between colour coordinates of the scratched surface and the ones of the unscratched surface.

SDI is defined as a set of the degree of scratch damage (or percent difference in luminance) and scratch

strength (or scratch resistance) values, as a quantitative determination.

The scratch visibility index (SVI), the onset point of scratch visibility where the surface damage can be

perceived by the naked eye, is determined under a linearly increasing load condition and defined as a set

of intensity, saturation, which are two of three coordinates in HSI colour model, and scratch resistance

value.
5 Apparatus
5.1 General description

The instrumented scratch machine consists of a load device, position sensor, specimen stage, clamping

devices, and scratch tip with a preferred geometry. An environmental chamber can also be added for

testing at non-ambient condition. For evaluation after scratching, tools such as optical microscopes,

flatbed scanners, profilometer, and colour analysis software are used.
5.2 Scratch tip

The scratch tip shall be made from stainless steel or tungsten carbide having a hardness greater than

Rockwell HRC 64 value, as specified by ISO 6508-1, and a roughness less than 0,20 μm, in accordance

with ISO 19252.
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ISO 17541:2014(E)

Two scratch tips with a preferred geometry are used in this method. Type 1 is used to induce an area-

contact with the material surface (see Figure 1). Type 2 is used to induce a line-contact with the material

surface (see Figure 2). It is permissible to use other sizes of the scratch tip but this shall be noted in the

report.
Dimensions in millimetres
Figure 1 — Schematic of area-contact scratch tip, Type 1
Dimensions in millimetres
Figure 2 — Schematic of line-contact scratch tip, Type 2
5.3 Load and position sensors

The instrumented scratch machine shall be equipped with devices to monitor the normal force, tangential

force, instantaneous scratch depth, and horizontal position. The forces acting on the scratch tip shall be

measured with an accuracy of ±1 % of actual value. The data acquired for depth and horizontal position

of the scratch tip shall have an accuracy of ±10 μm or better.
5.4 Test load

The instrumented scratch machine shall be capable of maintaining the test load within a tolerance

of ±1 %, for any test load chosen as specified in 7.3 and 7.4, and shall be capable of applying the load

perpendicular to the test specimen within a tolerance of ±1°.
5.5 Test speed

The instrumented scratch machine shall be capable of maintaining the test speed within a tolerance of

±1 %, except for the first stage and the end stage of 10 mm for the total scratch distance, for any test

speed chosen as specified in 7.3 and 7.4, and shall be capable of reaching the test speed within 10 mm

and stopping within 10 mm.
5.6 Specimen stage

The specimen stage shall be flat, smooth, and free of holes in the area where the test specimen will be

placed.
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ISO 17541:2014(E)
6 Test specimens
6.1 General

Test specimens having homogeneous surface in texture, colour, and flatness shall be prepared and

tested.

The specimen shall be cleaned to remove any contaminants or residues which can alter surface

characteristics. The reagent used for cleaning shall not affect the inherent surface properties of the

specimen.
6.2 Shape and dimensions

Bars, plaques, discs, or other specimen types of sufficient size for testing can be used.

For only single-damage tests, standard multipurpose test specimens as specified in ISO 20753 can be

used. If the scratch length is taken to be 100 mm, the specimen shall be at least 150 mm in length to

provide enough area for clamping.

For both multiple-damage and single-damage tests, injection-moulded test specimens shall be acceptable.

It is recommended to use plaques having dimensions of at least 150 mm wide by at least 150 mm long.

6.3 Preparation

Prepare test specimens as required by the relevant moulding materials standard, or, if none exists,

following the conditions in ISO 294-1, ISO 294-2, and ISO 294-3, as applicable, and the recommendations

of the
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