IEC 60404-12:2023

Magnetic materials - Part 12: Methods of test for the assessment of the thermal endurance of surface insulation coatings on electrical steel strip and sheet

IEC 60404-12:2023 is applicable to surface insulation coatings on electrical steel strip and sheet classified in IEC 60404-1-1.
This document defines the general principles and technical details of the tests for the assessment of the thermal endurance of surface insulation coatings on electrical steel strip and sheet.
The assessment is made by evaluating the change of a specified property of the surface insulation coating due to a heat treatment at a specified temperature up to 850 °C for a specified duration time up to 2 500 h. The specified property is measured at an ambient temperature of (23 ± 5) °C both without heat treatment and after heat treatment.
This edition includes the following significant technical changes with respect to the previous edition:  
the method of test for adhesion has been modified to match to the method of bend test specified in ISO 1519 using a cylindrical mandrel of 32 mm in diameter instead of the 30 mm diameter mandrel specified in the first edition;
the method of test for interlaminar insulation resistance has been modified to match to the method specified in IEC 60404-11 and the modified Franklin test has been removed;
the method of test for compressibility has been modified to match to the method of test for stacking factor specified in IEC 60404-13;
the concept of "resistance grades" has been removed;
the clamping pressure to be used at temperature ratings above 500 °C has been reduced to (0,01 ± 0,001) N/mm2;
the testing for continuous exposure has been made a subject to an agreement between the manufacturer and the purchaser and the procedure has been moved to an informative Annex A.

Matériaux magnétiques - Partie 12: Méthodes d’essai pour l’évaluation de l’endurance thermique des revêtements isolants superficiels des bandes et tôles en acier électrique

L’IEC 60404-12:2023 s'applique aux revêtements isolants superficiels des bandes et tôles en acier électrique classées dans l’IEC 60404-1-1.
Le présent document définit les principes généraux et les éléments techniques des essais relatifs à l’évaluation de l’endurance thermique des revêtements isolants superficiels des bandes et tôles en acier électrique.
L'évaluation consiste à apprécier la variation d’une propriété spécifiée du revêtement isolant superficiel du fait d’un traitement thermique à une température spécifiée allant jusqu’à 850 °C pendant une durée spécifiée maximale de 2 500 h. La propriété spécifiée est mesurée à une température ambiante de (23 ± 5) °C sans traitement thermique et après un traitement thermique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:  
la méthode d'essai d’adhérence a été modifiée afin de correspondre à la méthode d’essai de pliage spécifiée dans l’ISO 1519, qui utilise un mandrin cylindrique d’un diamètre de 32 mm en lieu et place du mandrin d’un diamètre de 30 mm spécifié dans la première édition;
la méthode d’essai de résistance d'isolation interlaminaire a été modifiée afin de correspondre à la méthode spécifiée dans l’IEC 60404-11 et l’essai de Franklin modifié a été supprimé;
la méthode d’essai de compressibilité a été modifiée afin de correspondre à la méthode d’essai du facteur de foisonnement spécifiée dans l’IEC 60404-13;
le concept de "niveaux de résistance" a été supprimé;
la pression de serrage à utiliser à des températures assignées supérieures à 500 °C a été réduite à (0,01 ± 0,001) N/mm2;
L’essai d’exposition continue a fait l’objet d’un accord entre le fabricant et l’acheteur et la procédure a été déplacée vers une Annexe A informative.

General Information

• Status: Published
• Publication Date: 09-Feb-2023
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Drafting Committee: WG 2 - TC 68/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 15-Mar-2023
• Completion Date: 10-Feb-2023

Standards Content (Sample)

IEC 60404-12
®

Edition 2.0 2023-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Magnetic materials –
Part 12: Methods of test for the assessment of the thermal endurance of surface
insulation coatings on electrical steel strip and sheet

Matériaux magnétiques –
Partie 12: Méthodes d’essai pour l'évaluation de l’endurance thermique des
revêtements isolants superficiels des bandes et tôles en acier électrique

IEC 60404-12:2023-02(en-fr)

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2023 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.


Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Secretariat Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland

About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.

Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: [e-mail].


A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - Découvrez notre puissant moteur de recherche et consultez
webstore.iec.ch/advsearchform gratuitement tous les aperçus des publications. Avec un
La recherche avancée permet de trouver des publications IEC abonnement, vous aurez toujours accès à un contenu à jour
en utilisant différents critères (numéro de référence, texte, adapté à vos besoins.
comité d’études, …). Elle donne aussi des informations sur les
projets et les publications remplacées ou retirées. Electropedia - www.electropedia.org

Le premier dictionnaire d'électrotechnologie en ligne au monde,
IEC Just Published - webstore.iec.ch/justpublished
avec plus de 22 300 articles terminologiques en anglais et en
Restez informé sur les nouvelles publications IEC. Just
français, ainsi que les termes équivalents dans 19 langues
Published détaille les nouvelles publications parues.
additionnelles. Egalement appelé Vocabulaire
Disponible en ligne et une fois par mois par email.
Electrotechnique International (IEV) en ligne.


Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
[e-mail].
IEC Products & Services Portal - products.iec.ch

---------------------- Page: 2 ----------------------
IEC 60404-12

®


Edition 2.0 2023-02




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Magnetic materials –

Part 12: Methods of test for the assessment of the thermal endurance of surface

insulation coatings on electrical steel strip and sheet



Matériaux magnétiques –

Partie 12: Méthodes d’essai pour l'évaluation de l’endurance thermique des


revêtements isolants superficiels des bandes et tôles en acier électrique













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 17.220.01; 29.030 ISBN 978-2-8322-6445-4




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – IEC 60404-12:2023 © IEC 2023
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 General principles . 7
4.1 General . 7
4.2 Preparation of clamped stacks of test specimens . 7
4.2.1 Procedure of stacking test specimens . 7
4.2.2 Clamping stacks for temperature ratings up to 500 °C . 7
4.2.3 Clamping stacks for temperature ratings above 500 °C . 8
4.3 Heat treatment . 8
4.3.1 For time ratings up to 2 500 h . 8
4.3.2 For continuous exposure . 9
5 Standard temperature/time performance designations T/t . 9
6 Method of the test for adhesion . 9
6.1 General . 9
6.2 Test specimens . 9
6.3 Procedure of test . 9
6.4 Test report . 10
7 Method of the test for surface insulation resistance . 10
7.1 General . 10
7.2 Test specimens . 10
7.3 Procedure of test . 10
7.4 Test report . 11
8 Method of the test for stacking factor . 11
8.1 General . 11
8.2 Test specimen . 11
8.3 Procedure of test . 11
8.4 Test report . 11
Annex A (informative) Method of test for the assessment of the thermal endurance for
continuous exposure to elevated temperatures . 12
A.1 General . 12
A.2 Procedure of test . 12
A.3 Temperature/time performance designations T/t for continuous exposure . 12
Bibliography . 13

Figure 1 – Example of clamped stack for 100 mm square test specimens . 8

---------------------- Page: 4 ----------------------
IEC 60404-12:2023 © IEC 2023 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MAGNETIC MATERIALS –

Part 12: Methods of test for the assessment of the thermal endurance
of surface insulation coatings on electrical steel strip and sheet

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60404-12 has been prepared by IEC technical committee 68: Magnetic alloys and steels.
It is an International Standard.
This second edition cancels and replaces the first edition published in 1992. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the method of test for adhesion has been modified to match to the method of bend test
specified in ISO 1519 using a cylindrical mandrel of 32 mm in diameter instead of the 30 mm
diameter mandrel specified in the first edition;
b) the method of test for interlaminar insulation resistance has been modified to match to the
method specified in IEC 60404-11 and the modified Franklin test has been removed;
c) the method of test for compressibility has been modified to match to the method of test for
stacking factor specified in IEC 60404-13;

---------------------- Page: 5 ----------------------
– 4 – IEC 60404-12:2023 © IEC 2023
d) the concept of "resistance grades" has been removed;
e) the clamping pressure to be used at temperature ratings above 500 °C has been reduced
2
to (0,01 ± 0,001) N/mm ;
f) the testing for continuous exposure has been made a subject to an agreement between the
manufacturer and the purchaser and the procedure has been moved to an informative
Annex A.
The text of this International Standard is based on the following documents:
Draft Report on voting
68/698/CDV 68/720/RVC

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 60404 series, published under the general title Magnetic materials,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

---------------------- Page: 6 ----------------------
IEC 60404-12:2023 © IEC 2023 – 5 –
INTRODUCTION
The surface insulation coatings on electrical steel strip and sheet are sometimes exposed to
elevated temperatures in service or during processing by the purchaser. Therefore, the thermal
endurance of the surface insulation coating is important.
Physicochemical models postulated for the aging processes lead to the almost universal
assumption of the Arrhenius equations to describe the rate of aging (see Annex A of this
document and IEC 60216-1).
Since the measurement of the properties of surface insulation coatings at elevated
temperatures is expensive and time-consuming, the thermal endurance of a coating is usually
assessed by evaluating the change of a specified coating property, at an ambient temperature,
due to a heat treatment.

---------------------- Page: 7 ----------------------
– 6 – IEC 60404-12:2023 © IEC 2023
MAGNETIC MATERIALS –

Part 12: Methods of test for the assessment of the thermal endurance
of surface insulation coatings on electrical steel strip and sheet



1 Scope
This part of IEC 60404 is applicable to surface insulation coatings on electrical steel strip and
sheet classified in IEC 60404-1-1.
This document defines the general principles and technical details of the tests for the
assessment of the thermal endurance of surface insulation coatings on electrical steel strip and
sheet.
The assessment is made by evaluating the change of a specified property of the surface
insulation coating due to a heat treatment at a specified temperature up to 850 °C for a specified
duration time up to 2 500 h. The specified property is measured at an ambient temperature of
(23 ± 5) °C both without heat treatment and after heat treatment.
This document is applicable to the following properties of surface insulation coatings:
– adhesion;
– surface insulation resistance;
– stacking factor.
This document is not applicable to other properties of surface insulation coatings, e.g. welding
properties, or to other effects, e.g. discoloration and off-gassing, which can be caused by
exposure to elevated temperatures.
NOTE Some of the tests take a very long time to perform and therefore they are often not appropriate for acceptance
tests of material supplied on a specific order.
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.
IEC 60050-121, International Electrotechnical Vocabulary – Part 121: Electromagnetism
IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials
and components
IEC 60404-1-1, Magnetic materials – Part 1-1: Classification – Surface insulations of electrical
steel sheet, strip and laminations
IEC 60404-11, Magnetic materials – Part 11: Methods of measurement of the surface insulation
resistance of electrical steel strip and sheet
IEC 60404-13, Magnetic materials – Part 13: Methods of measurement of resistivity, density
and stacking factor of electrical steel strip and sheet

---------------------- Page: 8 ----------------------
IEC 60404-12:2023 © IEC 2023 – 7 –
ISO 1519, Paints and varnishes – Bend test (cylindrical mandrel)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121,
IEC 60050-221 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
temperature/time performance designation T/t
designation consisting of a temperature T, expressed in °C, and a duration of time t, expressed
in hours, of a heat treatment that a surface insulation coating can withstand with respect to a
specified coating property
EXAMPLE The designations 200/2500 and 800/2 mean that the surface insulation coating can withstand heat
treatments at 200 °C for 2 500 h and 800 °C for 2 h, respectively, with respect to a specified coating property.
Note 1 to entry: This designation serves for rating of the thermal endurance of a surface insulation coating with
respect to specified coating properties.
Note 2 to entry: More than one designation can be assigned to a coating.
4 General principles
4.1 General
The thermal endurance of a surface insulation coating shall be assessed by evaluating changes
of specified coating properties due to a heat treatment at a specified temperature T °C for a
specified duration time t h. The coating properties shall be measured at an ambient temperature
of (23 ± 5) °C.
The thermal endurance for the following coating properties shall be assessed separately:
– adhesion;
– surface insulation resistance;
– stacking factor.
4.2 Preparation of clamped stacks of test specimens
4.2.1 Procedure of stacking test specimens
The test specimens shall be stacked between two similar sized or larger sheets made of the
same material as the test specimens. The stack shall then be clamped between two steel
pressure plates. The dimensions of the steel pressure plates shall be larger than the size of the
part of the test specimens to be tested, e.g. it is permitted to clamp only the part of the test
specimens that will be bent at the bend test (see 6.3).
4.2.2 Clamping stacks for temperature ratings up to 500 °C
The stack of test specimens shall be clamped homogeneously between the two steel pressure
2
plates under a pressure of (1 ± 0,1) N/mm . Figure 1 illustrates an example of clamped stack
for 100 mm square test specimens for temperature rating up to 500 °C.

---------------------- Page: 9 ----------------------
– 8 – IEC 60404-12:2023 © IEC 2023
The pressure shall be applied using suitable calibrated equipment such as a press, a tensile
test machine or hydraulic jacks. The bolts shall be tightened while applying the pressure. The
disk-springs, the bolts, the nuts and the steel pressure plates shall be made of suitable materials
which can maintain a substantially constant pressure while the test specimens are subjected to
the heat treatment.

Figure 1 – Example of clamped stack for 100 mm square test specimens
In case the clamping method using screws causes problems during the test, the manufacturer
and the purchaser can agree at the time of enquiry and order on using the clamping method for
above 500 °C described in 4.2.3.
4.2.3 Clamping stacks for temperature ratings above 500 °C
The stack of test specimens shall be clamped homogeneously between the two steel pressure
2
plates under a pressure of (0,01 ± 0,001) N/mm .
The pressure shall be applied by using a dead weight or by an externally applied force
transmitted by suitable thermally insulated rods from the outside of the furnace used for the
heat treatment.
4.3 Heat treatment
4.3.1 For time ratings up to 2 500 h
The clamped stack shall be placed in a furnace at near ambient temperature. The furnace shall
be heated to the temperature T °C within ±1,5 % with a heating rate not exceeding 200 °C/h.
When the furnace reaches the temperature T °C, this temperature shall be held for a specified
duration time of t h within ±1 %, where T and t constitute the temperature/time performance
designation T/t.
The furnace shall have enough power and heating capacity to ensure that the surface of the
clamped stack reaches at least 2,5 % below the temperature T °C when the furnace reaches
the temperature T °C. The furnace capacity shall be confirmed, e.g. by means of a thermocouple
applied to the clamped stack. A furnace with forced atmosphere convection is recommended.
After the duration time t h, the clamped stack is removed from the furnace and allowed to cool
to ambient temperature.

---------------------- Page: 10 ----------------------
IEC 60404-12:2023 © IEC 2023 – 9 –
For temperatures up to 500 °C, the heat treatment shall take place in air. For temperatures
above 500 °C, other atmospheres, e.g. inert atmosphere, are recommended to avoid oxidation
of the steel.
4.3.2 For continuous exposure
If agreed between the manufacturer and the purchaser at the time of enquiry and order, the
assessment of the thermal endurance for continuous exposure to elevated temperatures can,
as a guide, be carried out according to the procedure described in Annex A.
5 Standard temperature/time performance designations T/t
The recommended standard temperature/time performance designations T/t are:
150/168, 180/168, 200/168, 250/168, 150/2500, 180/2500, 200/2500, 250/2500, 400/6, 500/0,5,
750/2, 800/2 and 850/2.
6 Method of the test for adhesion
6.1 General
The test for assessment of the thermal endurance for adhesion shall be made by the method of
bend test in accordance with ISO 1519 using the test apparatus with a mandrel with
(32 ± 0,1) mm diameter specified in ISO 1519 at an ambient temperature of (23 ± 5) °C.
The manufacturer and the purchaser can agree at the time of enquiry and order to use a different
diameter of the mandrel, e.g. 30 mm to comply with the requirements according to the first
edition of IEC 60404-12 (IEC 60404-12:1992), or a smaller diameter to increase the severity of
the test.
6.2 Test specimens
The test specimens shall be at least 30 mm in width, 280 mm to 320 mm in length. They shall
be cut parallel to the rolling direction of the strip or sheet, and adjacent to each other, without
causing damage to the coating. Four test specimens shall be cut from the strip or sheet at least
40 mm away from the edges of the strip or sheet.
NOTE A test applied to coated electrical steel sheets of one nominal thickness can be considered to be
representative of the coated electrical steel sheets of other nominal thicknesses.
6.3 Procedure of test
Two of the four test specimens shall be tested without heat treatment. One test specimen shall
be bent with one of the surfaces against the mandrel and another test specimen shall be bent
with the opposite surface against the mandrel.
The test specimens shall be examined immediately after bending by the naked eye under
sufficient illumination. There shall be no cracking and/or detachment of the coating from the
base material visible to the naked eye, ignoring the surface of the coating within 2 mm from the
edges of the test specimen.
The remaining two test specimens shall be stacked and clamped in accordance with 4.2, and
then heat-treated at a specified temperature T °C for a specified duration time t h in accordance
with 4.3.

---------------------- Page: 11 ----------------------
– 10 – IEC 60404-12:2023 © IEC 2023
After cooling the test specimens to (23 ± 5) °C, the test specimens shall be removed from the
clamping device and tested in the same way as the first two test specimens are tested. If there
is no cracking and/or detachment of the coating from the base material visible to the naked eye,
ignoring the surface of the coating within 2 mm from the edges of the test specimen, the coating
has a temperature/time performance designation T/t with respect to adhesion.
6.4 Test report
The test report for each temperature/time performance designation T/t shall include the
following as applicable:
a) the description of the surface insulation coating, including the coating thickness, and the
type of base material (e.g. a steel name specified in IEC 60404-8-4);
b) the number of this document (IEC 60404-12), including the year of publication;
c) the diameter of the mandrel used for the bend test if different from the specified
(32 ± 0,1) mm;
d) the atmosphere used during the heat treatment;
e) the description of any cracks or detachment of the coating from the base material without
heat treatment and after the heat treatment, ignoring the surface of the coating within 2 mm
from the edges of the test specimen;
f) the temperature/time performance designation T/t with respect to adhesion.
7 Method of the test for surface insulation resistance
7.1 General
The test for assessment of the thermal endurance for surface insulation resistance shall be
made in accordance with IEC 60404-11 at an ambient temperature of (23 ± 5) °C.
7.2 Test specimens
A sufficient number of test specimens shall be prepared to provide a total area enabling
10 measurements of surface insulation resistance to fulfil the requirements of IEC 60404-11.
Two sets of such test specimens shall be prepared.
7.3 Procedure of test
The first set of test specimens shall be tested without heat treatment. The value of the
coefficient of the insulation resistance shall be calculated from 10 measurements (five
measurements per side for materials coated on both sides).
The second set of test specimens shall be stacked and clamped in accordance with 4.2, an
...