ISO 4646:2022

INTERNATIONAL ISO
STANDARD 4646
Third edition
2022-08
Rubber- or plastics-coated fabrics —
Low-temperature impact test
Supports textiles revêtus de caoutchouc ou de plastique — Essai de
choc à basse température
Reference number
© ISO 2022
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
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus and materials .1
5 Test pieces .3
6 Time – interval between manufacturing and testing . 3
7 Conditioning of test pieces .4
8 Procedure .4
9 Test report . 4
Annex A (informative) Speed calibration of a solenoid-actuated low-temperature impact
tester . 6
Bibliography . 9
iii
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 45, Rubber and rubber products,
Subcommittee SC 4, Products (other than hoses).
This third edition cancels and replaces the second edition (ISO 4646:1989), which has been technically
revised.
The main changes are as follows:
— Clause 3, "Terms and definitions", has been added, and the subsequent clauses have been renumbered;
— in 4.1, another type of impact tester which is generally used in the industries has been added in
Figure 1 as b);
— in 4.3, Dichlorodifuloromethane has been replaced with methylcyclohexane due to its toxicity, and
other heat-transfer mediums have also been updated.
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.
iv
INTERNATIONAL STANDARD ISO 4646:2022(E)
Rubber- or plastics-coated fabrics — Low-temperature
impact test
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions.
1 Scope
This document specifies a procedure for determining the lowest temperature at which rubber- or
plastics-coated fabrics will not exhibit fractures or coating cracks when subjected to specific impact
conditions.
Rubber-or plastics-coated fabrics are used in many applications involving low-temperature flexing
with or without impact. Data obtained by this method can be used to predict the behaviour of these
coated fabrics at low temperatures only in the applications in which the conditions of deformation are
similar to those specified in the method.
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 2231, Rubber- or plastics-coated fabrics — Standard atmospheres for conditioning and testing
ISO 2286-3, Rubber- or plastics-coated fabrics — Determination of roll characteristics — Part 3: Method
for determination of thickness
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Apparatus and materials
Typical two types of impact testers which are generally used in the industries are shown in Figure 1 a)
and b). Some other testers can be commercially available, however, the apparatus used shall meet the
requirements specified below for certain components.
4.1 Test piece clamps and striking arm, it shall be designed to hold the test piece(s) as cantilever
beam(s). Each individual test piece shall be held firmly and securely in the clamp without causing
distortion to the test piece.
The striking edge shall move relative to the test piece(s) along a trajectory normal to the upper surface
of the test piece(s) at a linear testing speed of 1,8 m/s to 2,1 m/s at impact and during at least the
following 6 mm of travel after impact. In order to maintain this velocity consistently within the heat-
transfer medium (4.3), the striking arm shall be positively driven. It may be necessary in some cases to
reduce the number of test pieces tested at one time.
The striking edge shall have a radius of 1,6 mm ± 0,1 mm;
The striking arm and the test piece clamps shall have a clearance at and immediately following impact
in accordance with the dimensions listed in Table 1.
Dimensions in millimetres
a) Straight-line motion b) Rotational motion
Key
1 test piece
2 striker
3 test piece clamp
4 locus described by point on striker closest to test piece clamp
5 locus described by impact point on striker
a
See Table 1.
Figure 1 — Test piece clamps and striking arm
4.2 Insulated tank
4.3 Heat-transfer medium, liquid or gaseous, which remains fluid at the test temperature and which
does not appreciably affect the material being tested shall be used.
CAUTION — Where a flammable or toxic solvent is used as the heat-transfer medium, the
customary precautions in handling such a material shall be exercised.
a) for temperatures down to −60 °C, silicone fluids are usually suitable owing to their chemical
inertness towards rubbers, their non-flammability and their non-toxicity;
NOTE A kinematic viscosity of about 5 mm /s at ambient temperature has been found suitable.
b) for temperatures down to −73 °C, ethanol;
c) for temperatures down to −120 °C, methylcyclohexane cooled by liquid nitrogen (found to be
satisfactory with the use of suitable apparatus).
4.4 Stirrer, to provide thorough circulation of the heat-transfer medium.
4.5 Temperature control, automatic or manual, for controlling the temperature of the heat-transfer
medium to within ±0,5 °C of the desired temperature.
Powdered solid carbon dioxide (dry ice), liquid nitrogen or liquid carbon dioxide are recommended for
lowering the temperature. An electric immersion heater is required for raising the temperature.
4.6 Thermocouple, with associated temperature indicator graduated in 1 °C divisions and having a
range suitable for the temperature at which the tests are to be made.
The thermocouple shall be constructed of copper-constantan wire between 0,2 mm and 0,5 mm in
diameter and shall be fusion-bonded at the junction. It shall be located as near the test piece as possible.
NOTE A thermometer can be used if it is shown to be in agreement with the specified thermocouple.
5 Test pieces
5.1 Test pieces shall be die-punched. Each shall be 6,4 mm ± 0,5 mm wide. Test pieces shall be cut with
the longer dimensions parallel to the lengthwise and traverse direction of the coated fabrics across the
full usable width of the coated fabric unless otherwise specified.
Dimensions in millimetres
Table 1 — Clearance of striking arm and test piece clamps
Thickness of test piece Required clearance
1,65 to 2,15 6,4 ± 0,3
1,05 to 1,64 5,7 ± 0,3
0,55 to 1,04 5,2 ± 0,3
0,10 to 0,54 4,8 ± 0,3
The thickness of the test piece shall be determined in accordance with ISO 2286-3.
The required clearance may be obtained by fabricating an adjustment plate of
individual plates to fit the test piece clamps illustrated in Figure 1.
Apparatus for this test may be powered in any way, provided that it meets the
dimensional and velocity requirements given above and Clause 4. If the striker is
electrically driven, a means of controlling and regulating the voltage is needed to
control the speed when testing light gauge material.
5.2 A minimum of 6 mm of the test pieces shall be held in the clamp, and the length extending from
the clamp shall be 25 mm ± 5 mm.
Sharp dies shall be used in the preparation of test pieces for this test if reliable results are to be
obtained. Light honing of the cutting edges with a jeweller’s honing stone should be carried out daily.
6 Time – interval between manufacturing and testing
6.1 For all test purposes, the minimum time between manufacturing and testing shall be 16 h.
6.2 For non-product test, the maximum time between manufacturing and testing shall be 4 weeks
and, for evaluations intended for purposes, all tests should, as far as possible, be carried out after the
same time-interval.
6.3 For product tests, wherever possible, the time between manufacturing and testing should not
exceed 3 months. In other cases, tests shall be made 2 months of the date of receipt by the customer.
7 Conditioning of test pieces
Condition the test piece in accordance with method 1 of ISO 2231.
NOTE In ISO 2231, three standard atmospheres are defined for method 1 namely:
— temperature 20 °C ± 2 °C, relative humidity 65 % ± 5 % R.H.;
or
— temperature 23 °C ± 2 °C, relative humidity 50 % ± 5 % R.H.;
— for tropical countries only, temperature 27 °C ± 2 °C, relative humidity 65 % ± 5 % R.H.
8 Procedure
8.1 Prepare the insulated tank (4.2) and bring the apparatus to the desired temperature. This may
be accomplished by placing a suitable amount of solid carbon dioxide (dry ice) in the tank and slowly
adding the heat-transfer medium (4.3) until the tank is filled to within 50 mm of the top. During the
test, the temperature of the bath shall be maintained constant by judicious addition of small quantities
of dry ice.
NOTE The desired temperature can also be obtained by filling the tank with
...