Paper and board -- Determination of bending stiffness -- Resonance method

ISO 5629:2017 specifies a method for the determination of bending stiffness using the resonance method. This method gives only a single result for each test piece tested, although in general, bending stiffness values may depend on which surface of the material forms the inner surface of the arc resulting from bending forces. The bending stiffness of a very wide range of papers and boards can be measured using this method. However, for some materials, such as those listed below, the measured numerical values will not be strictly identical with bending stiffness as defined in 3.1: a) multi-ply papers and boards in which the component plies can move separately during a test; b) papers and boards with appreciable curl, especially if the axis of the curl is in the long direction of the test piece; c) some soft papers with grammage below about 40 g/m2. This method is not applicable to corrugated boards.

Papier et carton -- Détermination de la résistance à la flexion -- Méthode par résonance

General Information

Status
Published
Publication Date
06-Dec-2017
Current Stage
6060 - International Standard published
Start Date
10-Nov-2017
Completion Date
07-Dec-2017
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ISO 5629:2017 - Paper and board -- Determination of bending stiffness -- Resonance method
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INTERNATIONAL ISO
STANDARD 5629
Second edition
2017-12
Paper and board — Determination of
bending stiffness — Resonance method
Papier et carton — Détermination de la résistance à la flexion —
Méthode par résonance
Reference number
ISO 5629:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 5629:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

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

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ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 5629:2017(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Principle ........................................................................................................................................................................................................................ 2

5 Apparatus (see Figure 1) .............................................................................................................................................................................. 2

6 Sampling ........................................................................................................................................................................................................................ 2

7 Conditioning .............................................................................................................................................................................................................. 3

8 Preparation of the test piece .................................................................................................................................................................... 3

9 Procedure..................................................................................................................................................................................................................... 3

9.1 General ........................................................................................................................................................................................................... 3

9.2 Procedure A ............................................................................................................................................................................................... 3

9.2.1 Grammage .............................................................................................................................................................................. 3

9.2.2 Resonant length ................................................................................................................................................................ 3

9.3 Procedure B ............................................................................................................................................................................................... 4

9.3.1 Mean grammage ............................................................................................................................................................... 4

9.3.2 Resonant length ................................................................................................................................................................ 4

10 Expression of results ........................................................................................................................................................................................ 4

10.1 General ........................................................................................................................................................................................................... 4

10.2 Procedure A ............................................................................................................................................................................................... 4

10.3 Procedure B ............................................................................................................................................................................................... 5

10.4 Approximate results ........................................................................................................................................................................... 5

11 Precision — Repeatability .......................................................................................................................................................................... 5

12 Test report ................................................................................................................................................................................................................... 6

Annex A (informative) Theoretical basis of test method ................................................................................................................. 9

Annex B (informative) Precision ............................................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

© ISO 2017 – All rights reserved iii
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ISO 5629:2017(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 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 the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee

SC 2, Test methods and quality specifications for paper and board.

This second edition cancels and replaces the first edition (ISO 5629:1983), of which it constitutes a

minor revision.
The main changes compared with the previous edition are as follows:
— Annex B with precision data has been added;
— Bibliography has been added.
iv © ISO 2017 – All rights reserved
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ISO 5629:2017(E)
Introduction

There are many methods of measuring the resistance of paper and board to bending forces. Because of

the visco-elastic nature of the material, results will depend to a considerable extent on the test method

used. In this method, the bending stiffness is determined under dynamic conditions (vibration) using

only a relatively small bending angle.
© ISO 2017 – All rights reserved v
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INTERNATIONAL STANDARD ISO 5629:2017(E)
Paper and board — Determination of bending stiffness —
Resonance method
1 Scope

This document specifies a method for the determination of bending stiffness using the resonance method.

This method gives only a single result for each test piece tested, although in general, bending stiffness

values may depend on which surface of the material forms the inner surface of the arc resulting from

bending forces.

The bending stiffness of a very wide range of papers and boards can be measured using this method.

However, for some materials, such as those listed below, the measured numerical values will not be

strictly identical with bending stiffness as defined in 3.1:

a) multi-ply papers and boards in which the component plies can move separately during a test;

b) papers and boards with appreciable curl, especially if the axis of the curl is in the long direction

of the test piece;
c) some soft papers with grammage below about 40 g/m .
This method is not applicable to corrugated boards.
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 186, Paper and board — Sampling to determine average quality

ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for

monitoring the atmosphere and conditioning of samples
ISO 536, Paper and board — Determination of grammage
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1
bending stiffness

moment of the resistance per unit width that a paper or board offers to bending in the region of elastic

deformation. It can be defined mathematically by Formula (1):
S= (1)
© ISO 2017 – All rights reserved 1
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ISO 5629:2017(E)
where
E is the modulus of elasticity, i.e. Young's modulus;

I is the second moment of area (moment of inertia) of the cross-sectional area, about an axis

through the centre of that area, in its plane, and perpendicular to the direction of bending;

b is the width of the test piece.
4 Principle

Determination, under standard conditions, of the vibrational resonant length of a test piece clamped at

one end. Calculation of the bending stiffness from this value and the grammage of the material.

The vibrational resonant length of a material, in one direction, when it is subjected to vibration of a

given frequency, depends on its bending stiffness in that direction and its grammage.

5 Apparatus (see Figure 1)
Usual laboratory apparatus and the following.
5.1 Clamping system.

The clamp shall consist of two flat parallel metal plates which can be so adjusted as to give a separation

and a clamping pressure such as to just permit the test piece to be pulled through the clamp. The clamp

shall be so arranged that a test piece can project vertically in both directions through the clamp. The

dimensions of the clamp are not critical, but the width shall be greater than the width of the test piece

used. Generally, a width of slightly more than 25 mm is satisfactory.

The upper edges of the clamp may be rounded, in which case, the radius of curvature shall be less

than 0,1 mm.

5.2 Means of vibrating the clamp in a horizontal plane, perpendicularly to the plane of the paper, at

a frequency of 25,0 Hz ± 0,1 Hz with an amplitude of not greater than 0,2 mm .

5.3 Means of measuring the length of test piece, projecting above the upper edge of the clamp.

5.4 Stroboscopic lamp, operating at the same frequency and in the same phase as the vibrator, for

illuminating the top edge of the test piece.
5.5 Optional components.

5.5.1 Magnifier, which can be adjusted for viewing the top edge of the test piece.

5.5.2 Movable lower clamp, of non-critical construction, so arranged that with its aid, the test piece

can be pulled (and for some materials, pushed) through the vibrating clamp. This clamp may be suitably

coupled to a measuring device, enabling the resonant length to be read directly from a scale.

6 Sampling
Select at least 10 specimens from a sample
...

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