Testing method for steel tyre cord

This document specifies test methods of steel cords which are used for tyre reinforcement. Dimension, process properties, mechanical properties and coating test method are all included.

Méthode d'essai pour les câbles de pneumatiques en acier

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Published
Publication Date
09-Feb-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
30-Dec-2020
Completion Date
29-Dec-2020
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INTERNATIONAL ISO
STANDARD 23475-1
First edition
2021-02
Testing method for steel tyre cord —
Part 1:
General requirements
Méthode d'essai pour les câbles de pneumatiques en acier —
Partie 1: Exigences générales
Reference number
ISO 23475-1:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23475-1:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23475-1:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

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

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

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

4 Dimension ................................................................................................................................................................................................................... 1

4.1 Cord diameter .......................................................................................................................................................................................... 1

4.1.1 Measure with micrometre ....................................................................................................................................... 1

4.1.2 Measure with profile projector ........................................................................................................................... 3

4.2 Unravelled filament diameter .................................................................................................................................................... 4

4.2.1 Principle .................................................................................................................................................................................. 4

4.2.2 Apparatus ............................................................................................................................................................................... 4

4.2.3 Procedure ............................................................................................................................................................................... 5

4.2.4 Expression of results .................................................................................................................................................... 5

4.2.5 Test report ............................................................................................................................................................................. 5

4.3 Linear density .......................................................................................................................................................................................... 5

4.3.1 Principle .................................................................................................................................................................................. 5

4.3.2 Apparatus ............................................................................................................................................................................... 5

4.3.3 Procedure ............................................................................................................................................................................... 6

4.3.4 Test report ............................................................................................................................................................................. 6

4.4 Lay direction and lay length ........................................................................................................................................................ 6

4.4.1 Lay direction/direction of lay ............................................................................................................................... 6

4.4.2 Trace method for lay length ................................................................................................................................... 6

4.4.3 Untwisting method for lay length ..................................................................................................................... 8

5 Process property .................................................................................................................................................................................................. 9

5.1 Straightness ............................................................................................................................................................................................... 9

5.1.1 Principle .................................................................................................................................................................................. 9

5.1.2 Apparatus ............................................................................................................................................................................... 9

5.1.3 Procedure ............................................................................................................................................................................... 9

5.1.4 Test report ............................................................................................................................................................................. 9

5.2 Arc height ..................................................................................................................................................................................................... 9

5.2.1 Principle .................................................................................................................................................................................. 9

5.2.2 Apparatus ............................................................................................................................................................................10

5.2.3 Procedure ............................................................................................................................................................................10

5.2.4 Test report ..........................................................................................................................................................................10

5.3 Flare ...............................................................................................................................................................................................................10

5.3.1 Principle ...............................................................................................................................................................................10

5.3.2 Apparatus ............................................................................................................................................................................10

5.3.3 Procedure ............................................................................................................................................................................10

5.3.4 Test report ..........................................................................................................................................................................11

5.4 Residual torsion ..................................................................................................................................................................................11

5.4.1 Principle ...............................................................................................................................................................................11

5.4.2 Apparatus ............................................................................................................................................................................11

5.4.3 Procedure ............................................................................................................................................................................11

5.4.4 Test report ..........................................................................................................................................................................11

6 Mechanical property .....................................................................................................................................................................................12

6.1 Breaking load and elongation at fracture .....................................................................................................................12

6.1.1 Principle ...............................................................................................................................................................................12

6.1.2 Apparatus ............................................................................................................................................................................12

6.1.3 Procedure ............................................................................................................................................................................12

6.1.4 Test report ..........................................................................................................................................................................13

6.2 Elongation between defined forces (EDF) ...................................................................................................................13

6.2.1 Principle ...............................................................................................................................................................................13

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23475-1:2021(E)

6.2.2 Apparatus ............................................................................................................................................................................14

6.2.3 Procedure ............................................................................................................................................................................15

6.2.4 Test report ..........................................................................................................................................................................15

6.3 Loop test (Elasticity) .......................................................................................................................................................................15

6.3.1 Principle ...............................................................................................................................................................................15

6.3.2 Apparatus ............................................................................................................................................................................15

6.3.3 Procedure ............................................................................................................................................................................16

6.3.4 Test report ..........................................................................................................................................................................17

7 Determination of mass and composition of coating by X-Ray fluorescence spectroscopy ...17

7.1 Principle .....................................................................................................................................................................................................17

7.2 Apparatus .................................................................................................................................................................................................17

7.2.1 WDXRFS or EDXRFS ...................................................................................................................................................17

7.2.2 Analytical balance, which can be read to the nearest 0,001 g. ..............................................17

7.2.3 Dispenser, with the accuracy of 25,00 ml ± 0,05 ml. ......................................................................17

7.2.4 X/Y shaker, with variable frequency. ...........................................................................................................17

7.3 Reagents.....................................................................................................................................................................................................17

7.3.1 Acetone or diethyl ether .........................................................................................................................................17

7.3.2 Ammonium persulphate (mass fraction >98 %) ..............................................................................17

7.3.3 Ammonia (mass fraction >25 %, not more than “d=0,91” at temperature 20 °C) 17

7.3.4 Stripping solution, for 1 l: weigh 16 g ammonia persulphate into a
beaker of 600 ml and dissolve in 400 ml demineralized water. Transfer
quantitatively into a 1 l volumetric flask. Add 120 ml ammonia. Fill up to

the mark with demineralized water. Shake well. ..............................................................................17

7.3.5 Standard, the matrix and range should cover the sample range. Prepare
the calibration standards according to the XRFS user’s manual or

according to an example in Table 1. .............................................................................................................17

7.4 Preparation of test samples ......................................................................................................................................................18

7.5 Procedure .................................................................................................................................................................................................18

7.6 Expression of results .......................................................................................................................................................................18

7.7 Test report ................................................................................................................................................................................................19

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23475-1:2021(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 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 17, Steel, Subcommittee SC 17, Steel wire

rod and wire products.
A list of all parts in the ISO 23475 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.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 23475-1:2021(E)
Testing method for steel tyre cord —
Part 1:
General requirements
1 Scope

This document specifies test methods of steel cords which are used for tyre reinforcement. Dimension,

process properties, mechanical properties and coating test method are all included.

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 17832, Non-parallel steel wire and cords for tyre reinforcement
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 17832 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Dimension
4.1 Cord diameter
4.1.1 Measure with micrometre
4.1.1.1 Principle

Hold the sample between two parallel circular faced anvils of a micrometre. Close the movable anvil

gradually and gently until it is in contact with the specimen. Read the value on the micrometre.

4.1.1.2 Apparatus
4.1.1.2.1 Micrometre

A precision disk micrometre with non-rotate spindle is suggested. This micrometre may have a hole

(maximum 8 mm) in the centre of the anvils (see Figure 1).
Measuring range is from 0 mm to 25 mm. Resolution is 0,001 mm.

Anvil type: the diameter of the anvils shall be greater than one lay length (min. 20 mm in diameter).

Measuring force range: <10 N. It is suggested from 3 N to 5 N.
© ISO 2021 – All rights reserved 1
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ISO 23475-1:2021(E)
The anvils shall be plane within 0,002 mm and parallel within 0,005 mm.
Figure 1 — Disk micrometre
4.1.1.2.2 Fusing machine
4.1.1.3 Procedure

a) Clean the surface of the anvils with clean paper. Verify whether the micrometre reads 0,000 when

the anvils are closed for each measurement.

b) Fuse a specimen to a length about 150 mm and ensure that cord end is well secured with no

unravelling. Place the sample in the centre of the anvils.

c) Close the movable anvil gradually and gently until it is in contact with the specimen. For normal

cords, stop rotating the spindle when 3 ‘click’ are heard and for HE, HI and OC constructions only 1

“click” is heard.

d) Axially rotate the sample between repeated measurements in order to find the maximum diameter

(D ) and minimum diameter (D ).
1 2
Figure 2 — Diameter test diagram
4.1.1.4 Expression of results
Calculate the average diameter (D) with Formula (1):
DD+
D= (1)
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 23475-1:2021(E)
where
D is the maximum diameter, expressed in millimetres (mm);
D is the minimum diameter, expressed in millimetres (mm);
D is the average diameter, expressed in millimetres (mm).
4.1.1.5 Test report
Report the average diameter to the nearest 0,001 mm.
4.1.2 Measure with profile projector
4.1.2.1 Principle

Specimens of a cord sample are successively put on the optical microscope. A silhouette of the cord is

projected on the screen. The thickness of the specimen is measured by moving the abscissa axis of the

projector.
4.1.2.2 Apparatus
4.1.2.2.1 Profile projector, with
— magnification possibility: × 10 or × 20;
— micrometre stage table: resolution 0,001 mm.

4.1.2.2.2 Sample holder, a frame on which two magnets are fixed in order to position the test

specimen.
4.1.2.2.3 Fusing machine
4.1.2.3 Procedure

a) Fuse a specimen to a length about 100 mm, ensure that fuse is securely tied in order to prevent the

cord ends from any unravelling. Put the specimen on the sample holder and ensure that is fixed by

magnets.

b) Bring the sample into sample holder and adjust the focal distance. Make the sample being projected

on the screen.

c) Rotate the sample until the maximum profile is being projected on the screen. Move the micrometre

table until the horizontal reference line contacts two consecutive waves (see Figure 3).

Figure 3 — X-axis contacts the two consecutive waves
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 23475-1:2021(E)

d) Reset the micrometre. Move the stage until the X-axis contacts the opposite wave (see Figure 4).

Record the reading as maximum diameter (D . If there are two waves on the opposite side, measure

the bigger one.
Figure 4 — X-axis contacts the other side wave

e) Turn the specimen through 90° until a minimum diameter is obtained, record the minimum

diameter D . Repeat the steps c) and d) and record the reading as minimum diameter (D ). If there

2 2
are two waves on the opposite side, measure the bigger one (see Figure 5).
Figure 5 — Minimum diameter
4.1.2.4 Expression of results
Calculate the average diameter (D) of the two readings with Formula (1).
4.1.2.5 Test Report
Report the average diameter to the nearest 0,001 mm.

NOTE This test method is generally used for open cords and HI cords or for other cord types that are

sensitive to radial compression when using a micrometre.
4.2 Unravelled filament diameter
4.2.1 Principle

A sample is held between two parallel blade anvils of a micrometre. The movable anvil is closed

gradually and gently until it is in contact with the specimen. Read the value on the micrometre.

4.2.2 Apparatus
4.2.2.1 Blade micrometre (see Figure 6)
— Measuring range is from 0 mm to 25 mm. Resolution is 0,001 mm.
— Anvil type: blade.
— Measuring force: <10 N. It is suggested from 3 N to 5 N.
4 © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 23475-1:2021(E)
Figure 6 — Blade micrometre
4.2.2.2 Nipper pliers
4.2.3 Procedure

a) Clean the surface of the anvils with clean paper. Verify whether the micrometre reads 0,000 when

the anvils are closed for each measurement.

b) Cut the wire approximately 100 mm in length. Position the specimen in the centre of the anvils.

c) The movable anvil is closed gradually and gently until it is in contact with the specimen. Read the

value after 3 ‘click’ are heard.

d) Measure on the same section of the specimen until the maximum diameter (D ) and minimum

diameters (D ) are found.
4.2.4 Expression of results
Calculate the average diameter (D) of the two readings with Formula (2):
D +D
D= (2)
where
D is the maximum diameter, expressed in millimetres (mm);
D is the minimum diameter, expressed in millimetres (mm);
D is the average diameter, expressed in millimetres (mm).
4.2.5 Test report
Report the average diameter to the nearest 0,001 mm.
4.3 Linear density
4.3.1 Principle

A straight section of the cord of a predefined length, generally 1 m, is weighted using an analytical

balance.
4.3.2 Apparatus
4.3.2.1 Analytical balance, which can be read to the nearest 0,001 g.
© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 23475-1:2021(E)
4.3.3 Procedure

a) Fuse a specimen approximately 1 200 mm in length. Cut into (1 000 ± 1) mm, and make sure the

cord is straightened before cutting.

NOTE For normal construction, the pretension is 10 N +/-1 N, for HE/HI/OC constructions, the

pretension is 2 N +/- 0,5 N.

b) Verify the balance, coil the sample and weigh it, record the mass as linear density.

4.3.4 Test report
Report the linear density to the nearest 0,001 g/m.
4.4 Lay direction and lay length
4.4.1 Lay direction/direction of lay
4.4.1.1 Principle

Hold the cord vertically and verify whether the filaments or strands around the central axis are having

an “S” direction or “Z” direction.
4.4.1.2 Procedure

The cord, strand or wrap has an “S” or left-handed lay if, when held vertically, the spirals around the

central axis of the cord or strand conform in direction of the slope to the central portion of the letter

“S”; and “Z” or right-handed lay if the spirals conform in direction of the slope to the central portion of

the letter “Z” (see Figure 7).
S direction lay Z direction lay
Figure 7 — Illustration of the S and Z direction of lay
4.4.1.3 Test report
Report the direction of lay as “S” or “Z”.
4.4.2 Trace method for lay length
4.4.2.1 Principle

Through the impacted trace of the wire, calculate the lay length by measuring the distance of multiple

lay length.
6 © ISO 2021 – All rights reserved
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ISO 23475-1:2021(E)
4.4.2.2 Apparatus
4.4.2.2.1 Pencil
4.4.2.2.2 Paper

4.4.2.2.3 White paper or carbon paper, Vernier calliper (which can be read to the nearest 0,5 mm).

4.4.2.3 Procedure

a) Fuse a specimen of cord approximately 300 mm in length. Place the specimen on the clean and

flat table.

b) Place a sheet of white paper or carbon paper over a straight-length section of the specimen and rub

the paper with a pencil to form a relief impression (see Figure 8).
Key
1 sample with wrap wire
2 pencil
3 white paper
Figure 8 — Trace method for lay length test
c) Measure the distance between the first and eleventh node on the impression.
4.4.2.4 Expression of results
Calculate the lay length with Formula (3):
L = (3)
where
L is the lay length, expressed in millimetres (mm);

L is the distance between the first and eleventh node, expressed in millimetres (mm).

4.4.2.5 Test report
Report the lay length to the nearest 0,01 mm.
NOTE The trace method is usually used to measure the lay length of wrap wire.
© ISO 2021 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 23475-1:2021(E)
4.4.3 Untwisting method for lay length
4.4.3.1 Principle

A specified length of specimen of cord or strand is untwisted until the elements to be determined are

parallel. The length of lay can be calculated by the specified length divided by the untwisted turns.

4.4.3.2 Apparatus
4.4.3.2.1 Lay length tester, whose gauge length is (500 ± 1) mm.
4.4.3.3 Procedure

a) Place a straight specimen in the lay length tester being clamped in such a manner that no slippage

will occur. The specimen shall be placed under a tension just enough to keep the specimen straight,

but no more than 20 N. If the cord has a wrap then this filament shall be cut in the middle of the

specimen and near each jaw and removed.

b) Set the counter at zero. The twist is removed by turning the rotatable clamp until the components

of the external layer of the specimen are complete separated. These components shall be parted

with a needle or the blade of a spatula (starting at the non-rotatable clamp and moving to the

rotatable clamp) to avoid the entanglement of components and to confirm that all the twist has

been removed. The number of revolutions is recorded as n .

c) If the multiple layers construction and the lay length of core strand need to be measured, the

operation as described above shall be repeated without unloading the cord. The number of turns to

untwist this filament is recorded as n .
d) The above procedure is then repeated if necessary.
4.4.3.4 Expression of results
Calculate the lay length with Formulae (4), (5) and (6):
500
L = (4)
500
L = (5)
500
L = (6)
where

500 is the gauge length of lay length tester. For M x N constructions, after untwisting the first layer

of the cord, there is
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23475-1
ISO/TC 17/SC 17
Testing method for steel tyre cord —
Secretariat: SAC
Voting begins on:
Part 1:
2020-11-03
General requirements
Voting terminates on:
2020-12-29
Méthode d'essai pour les câbles de pneumatiques en acier —
Partie 1: Exigences générales
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 23475-1:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 23475-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23475-1:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

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

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

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

4 Dimension ................................................................................................................................................................................................................... 1

4.1 Cord diameter .......................................................................................................................................................................................... 1

4.1.1 Measure with micrometer ....................................................................................................................................... 1

4.1.2 Measure with profile projector ........................................................................................................................... 3

4.2 Unravelled Filament diameter ................................................................................................................................................... 4

4.2.1 Principle .................................................................................................................................................................................. 4

4.2.2 Apparatus ............................................................................................................................................................................... 4

4.2.3 Procedure ............................................................................................................................................................................... 5

4.2.4 Expression of results .................................................................................................................................................... 5

4.2.5 Test report ............................................................................................................................................................................. 5

4.3 Linear density .......................................................................................................................................................................................... 5

4.3.1 Principle .................................................................................................................................................................................. 5

4.3.2 Apparatus ............................................................................................................................................................................... 5

4.3.3 Procedure ............................................................................................................................................................................... 6

4.3.4 Test report ............................................................................................................................................................................. 6

4.4 Lay direction and lay length ........................................................................................................................................................ 6

4.4.1 Lay direction/direction of lay ............................................................................................................................... 6

4.4.2 Trace method for lay length ................................................................................................................................... 6

4.4.3 Untwisting method for lay length ..................................................................................................................... 8

5 Process property .................................................................................................................................................................................................. 9

5.1 Straightness ............................................................................................................................................................................................... 9

5.1.1 Principle .................................................................................................................................................................................. 9

5.1.2 Apparatus ............................................................................................................................................................................... 9

5.1.3 Procedure ............................................................................................................................................................................... 9

5.1.4 Test Report ............................................................................................................................................................................ 9

5.2 Arc height ..................................................................................................................................................................................................... 9

5.2.1 Principle .................................................................................................................................................................................. 9

5.2.2 Apparatus ............................................................................................................................................................................10

5.2.3 Procedure ............................................................................................................................................................................10

5.2.4 Test report ..........................................................................................................................................................................10

5.3 Flare ...............................................................................................................................................................................................................10

5.3.1 Principle ...............................................................................................................................................................................10

5.3.2 Apparatus ............................................................................................................................................................................10

5.3.3 Procedure ............................................................................................................................................................................10

5.3.4 Test report ..........................................................................................................................................................................11

5.4 Residual torsion ..................................................................................................................................................................................11

5.4.1 Principle ...............................................................................................................................................................................11

5.4.2 Apparatus ............................................................................................................................................................................11

5.4.3 Procedure ............................................................................................................................................................................11

5.4.4 Test report ..........................................................................................................................................................................11

6 Mechanical property .....................................................................................................................................................................................12

6.1 Breaking load and elongation at fracture .....................................................................................................................12

6.1.1 Principle ...............................................................................................................................................................................12

6.1.2 Apparatus ............................................................................................................................................................................12

6.1.3 Procedure ............................................................................................................................................................................12

6.1.4 Test report ..........................................................................................................................................................................13

6.2 Elongation between defined forces (EDF) ...................................................................................................................13

6.2.1 Principle ...............................................................................................................................................................................13

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23475-1:2020(E)

6.2.2 Apparatus ............................................................................................................................................................................14

6.2.3 Procedure ............................................................................................................................................................................15

6.2.4 Test report ..........................................................................................................................................................................15

6.3 Loop test (Elasticity) .......................................................................................................................................................................15

6.3.1 Principle ...............................................................................................................................................................................15

6.3.2 Apparatus ............................................................................................................................................................................15

6.3.3 Procedure ............................................................................................................................................................................16

6.3.4 Test report ..........................................................................................................................................................................17

7 Determination of mass and composition of coating .....................................................................................................17

7.1 X-Ray fluorescence spectroscopy .........................................................................................................................................17

7.1.1 Principle ...............................................................................................................................................................................17

7.1.2 Apparatus ............................................................................................................................................................................17

7.1.3 Reagents ...............................................................................................................................................................................17

7.1.4 Preparation of test samples .................................................................................................................................18

7.1.5 Procedure ............................................................................................................................................................................18

7.1.6 Expression of results .................................................................................................................................................18

7.1.7 Test report ..........................................................................................................................................................................19

iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23475-1:2020(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 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/TC17, Steel, Subcommittee SC 17, Steel wire

rod and wire products.
A list of all parts in the ISO 23475 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.
© ISO 2020 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23475-1:2020(E)
Testing method for steel tyre cord —
Part 1:
General requirements
1 Scope

This document specifies test methods of steel cords which are used for tyre reinforcement. Dimension,

process properties, mechanical properties and coating test method are all included.

2 Normative references

The following referenced documents are indispensable for the application 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 17832, Non-parallel steel wire and cords for tyre reinforcement
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 17832 apply.

4 Dimension
4.1 Cord diameter
4.1.1 Measure with micrometer
4.1.1.1 Principle

Hold the sample between two parallel circular faced anvils of a micrometer. Close the movable anvil

gradually and gently until it is in contact with the specimen. Read the value on the micrometer.

4.1.1.2 Apparatus
4.1.1.2.1 Micrometer

A precision disk micrometer with non-rotate spindle is suggested. This micrometer may have a hole

(maximum 8 mm) in the center of the anvils. (see Figure 1)
Measuring range is from 0 mm to 25 mm. Resolution is 0,001 mm

Anvil type: the dimeter of the anvils shall be greater than one lay length (min. 20 mm in diameter).

Measuring force range: < 10 N. It is suggested from 3 N - 5 N.
The anvils shall be plane within 0,002 mm and parallel within 0,005 mm.
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ISO/FDIS 23475-1:2020(E)
Figure 1 — Disk micrometer
4.1.1.2.2 Fusing machine
4.1.1.3 Procedure

a) Clean the surface of the anvils with clean paper. Verify whether the micrometer reads 0,000 when

the anvils are closed for each measurement.

b) Fuse a specimen to a length about 150 mm and ensure that cord end is well secured with no

unravelling. Place the sample in the centre of the anvils.

c) Close the movable anvil gradually and gently until it is in contact with the specimen. For normal

cords, stop rotating the spindle when 3 ‘click’ are heard and for HE, HI and OC constructions only 1

“click” is heard.

d) Axially rotate the sample between repeated measurements in order to find the maximum diameter

(D ) and minimum diameter (D )
1 2
Figure 2 — Diameter test diagram
4.1.1.4 Expression of results
Calculate average diameter (D) with Formula 1 below:
DD+
D= (1)
where
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ISO/FDIS 23475-1:2020(E)
D is the maximum diameter, expressed in millimetres (mm)
D is the minimum diameter, expressed in millimetres (mm)
D is the average diameter, expressed in millimetres (mm)
4.1.1.5 Test report
Report the average diameter to nearest 0,001 mm
4.1.2 Measure with profile projector
4.1.2.1 Principle

Specimens of a cord sample are successively put on the optical microscope. A silhouette of the cord is

projected on the screen. The thickness of the specimen is measured by moving the abscissa axis of the

projector.
4.1.2.2 Apparatus
4.1.2.2.1 Profile projector, with
— Magnification possibility : x 10 or x 20
— Micrometer stage table: resolution 0,001 mm

4.1.2.2.2 Sample holder, A frame on which two magnets are fixed in order to position the test

specimen.
4.1.2.2.3 Fusing machine
4.1.2.3 Procedure

a) Fuse a specimen to a length about 100 mm, ensure that fuse is securely tied in order to prevent the

cord ends from any unravelling. Put the specimen on the sample holder and ensure that is fixed by

magnets.

b) Bring the sample into sample holder and adjust the focal distance. Make the sample being projected

on the screen.

c) Rotate the sample until the maximum profile is being projected on the screen. Move the micrometer

table until the horizontal reference line contacts two consecutive waves (see Figure 3).

Figure 3 — X axis contacts the two consecutive waves

d) Reset the micrometer. Move the stage until X axis contacts the opposite wave (Figure 4). Record

the reading as maximum diameter (D . If there are two waves on the opposite side, measure the

bigger one.
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ISO/FDIS 23475-1:2020(E)
Figure 4 — X axis contacts the other side wave

e) Turn the specimen through 90 degrees until a minimum diameter is obtained, record the minimum

diameter D . Repeat the step c and d and record the reading as minimum diameter (D ). If there are

2 2
two waves on the opposite side, measures the bigger one (Figure 5).
Figure 5 — the minimum diameter
4.1.2.4 Expression of results
Calculate average diameter (D) of the two readings with Formula (1).
4.1.2.5 Test Report
Report the average diameter to the nearest 0,001 mm.

NOTE This test method is generally used for open cords and HI cords or for other cord types that are

sensitive to radial compression when using micrometer.
4.2 Unravelled Filament diameter
4.2.1 Principle

A sample is held between two parallel blade anvils of a micrometer. The movable anvil is closed

gradually and gently until it is in contact with the specimen. Read the value on the micrometer.

4.2.2 Apparatus
4.2.2.1 Blade micrometre (see Figure 6)
— Measuring range is from 0 mm to 25 mm. Resolution is 0,001 mm.
— Anvil type: blade
— Measuring force: <10 N. It is suggested from 3 N - 5 N.
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ISO/FDIS 23475-1:2020(E)
Figure 6 — Blade micrometre
4.2.2.2 Nipper pliers
4.2.3 Procedure

a) Clean the surface of the anvils with clean paper. Verify whether the micrometre reads 0,000 when

the anvils are closed for each measurement.

b) Cut the wire approximately 100 mm in length. Position the specimen in the centre of the anvils.

c) The movable anvil is closed gradually and gently until it is in contact with the specimen. Read the

value after 3 ‘click’ are heard.

d) Measure on the same section of the specimen until maximum diameter (D ) and minimum

diameters (D ) are found.
4.2.4 Expression of results
Calculate average diameter (d) of the two readings with Formula 2 below.
D +D
D= (2)
where
D is the maximum diameter, expressed in millimetres (mm)
D is the minimum diameter, expressed in millimetres (mm)
D is average diameter, expressed in millimetres (mm).
4.2.5 Test report
Report the average diameter to the nearest 0,001 mm.
4.3 Linear density
4.3.1 Principle

A straight section of the cord of a predefined length, generally 1 m, is weighted using an analytical

balance.
4.3.2 Apparatus
4.3.2.1 Analytical balance, which can be read to the nearest 0,001 g
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ISO/FDIS 23475-1:2020(E)
4.3.3 Procedure

a) Fuse a specimen approximately 1 200 mm in length. Cut into (1 000 ± 1) mm, and make sure the

cord is straightened before cutting

NOTE For normal construction, the pretension is 10 N +/-1 N, for HE/HI/OC constructions, the

pretension is 2 N +/- 0,5 N

b) Verify the balance, coil the sample and weight it, record the weight as linear density.

4.3.4 Test report
Report the linear density to nearest 0,001 g/m.
4.4 Lay direction and lay length
4.4.1 Lay direction/direction of lay
4.4.1.1 Principle

Hold the cord vertically and verify whether the filaments or strands around the central axis are having

a “S” direction or “Z” direction.
4.4.1.2 Procedure

The cord, strand or wrap has an “S” or left-handed lay if, when held vertically, the spirals around the

central axis of the cord or strand conform in direction of slope to the central portion of the letter “S”;

and “Z” or right-handed lay if the spirals conform in direction of slope to the central portion of the letter

“Z”.(Figure 7).
S direction lay Z direction lay
Figure 7 — Illustration of the S and Z direction of lay
4.4.1.3 Test report
Report the direction of lay as “S” or “Z”
4.4.2 Trace method for lay length
4.4.2.1 Principle

Through the impacted trace of the wire, calculate the lay length by measuring the distance of multiple

lay length.
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ISO/FDIS 23475-1:2020(E)
4.4.2.2 Apparatus
4.4.2.2.1 Pencil
4.4.2.2.2 Paper

4.4.2.2.3 White paper or carbon paper, Vernier calliper (which can be read to the nearest

0,5 mm)
4.4.2.3 Procedure

a) Fuse a specimen of cord approximately 300 mm in length. Place the specimen on the clean and

flat table.

b) Place a sheet of white paper or carbon paper over a straight-length section of the specimen and rub

the paper with a pencil to form a relief impression (see Figure 8).
Key
1 sample with wrap wire
2 pencil
3 white paper
Figure 8 — Trace method for lay length test
c) Measure the distance between the first and eleventh node on the impression.
4.4.2.4 Expression of results
Calculate the lay length with Formula (3)
L = (3)
where
L Lay length, expressed in millimetre (mm)
L distance between the first and eleventh node, express in millimetre (mm)
4.4.2.5 Test report
Report the lay length to nearest 0,01 mm
NOTE The trace method is usually used to measure the lay length of wrap wire.
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ISO/FDIS 23475-1:2020(E)
4.4.3 Untwisting method for lay length
4.4.3.1 Principle

A specified length of specimen of cord or strand is untwisted until the elements to be determined are

parallel. The length of lay can be calculated by the specified length divided by the untwisted turns.

4.4.3.2 Apparatus
4.4.3.2.1 Lay length tester, whose gauge length is (500 ± 1) mm
4.4.3.3 Procedure

a) Place a straight specimen in the lay length tester being clamped in such a manner that no slippage

will occur. The specimen shall be placed under a tension just enough to keep the specimen straight,

but no more than 20 N. If the cord has a wrap then this filament shall be cut in the middle of the

specimen and near each jaw and removed.

b) Set the counter at zero. The twist is removed by turning the rotatable clamp until the components

of the external layer of the specimen are complete separated. These components shall be parted

with a needle or the blade of a spatula (starting at the non-rotatable clamp and moving to the

rotatable clamp) to avoid the entanglement of components and to confirm that all the twist has

been removed. The number of revolutions is record as n .

c) If it is the multiple layers construction and the lay length of core strand need to be measured, the

operation as described above shall be repeated without unloading the cord. The number of turns to

untwist this filament recorded as n .
d) The above procedure is then repeated if necessary.
4.4.3.4 Expression of results
Calculate the lay length with Formulae below:
500
L = (4)
500
L = (5)
500
L = (6)
where

500: is the gauge length of lay length tester. For M x N constructions, after untwisting the first

layer of the cord, there is a change in length of the remaining elements, the gauge length

should be decided through consultation by buyer and seller.
L : is layer length of outer layer, expressed in millimetre (mm).
L is lay length of the second strand, expressed in millimetre (mm)
L : is lay length of the third core strand, expressed in millimetre (mm)
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ISO/FDIS 23475-1:2020(E)
n : is the revolution number of outer layer when untwist
n : is the revolution number of second layer when untwist
n : is the revolution number of third layer when untwist
4.4.3.5 Test report
Report the lay length to nearest 0,01 mm.
5 Process property
5.1 Straightness
5.1.1 Principle

Keep the cord at natural status, the position of the cord between two parallel straight lines, which are

a prescribed distance apart, is observed, the cord shall be considered straight, when it is not touching

the lines.
5.1.2 Apparatus

5.1.2.1 Spool mounting device, enabling the spool to rotate freely on a horizontal axis

5.1.3 Procedure

Without cutting the specimen from the spool, pull out a 6 m length of cord (or other length agreed

upon between the buyer and selle
...

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