Magnetic materials - Part 5: Permanent magnet (magnetically hard) materials - Methods of measurement of magnetic properties

IEC 60404-5:2015 is available as IEC 60404-5:2015 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60404-5:2015 is to define the method of measurement of the magnetic flux density, magnetic polarization and the magnetic field strength and also to determine the demagnetization curve and recoil line of permanent magnet materials. This edition includes the following significant technical changes with respect to the previous edition:
- adaption of the measurement methods and test conditions to newly introduced magnetically hard materials with coercivity values HcJ higher than 2 MA/m;
- update of the temperature conditions to allow the measurement of new materials with high temperature coefficients.

Matériaux magnétiques - Partie 5: Aimants permanents (magnétiques durs) - Méthodes de mesure des propriétés magnétiques

L'IEC 60404-5:2015 est disponible sous forme de IEC 60404-5:2015 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 60404-5:2015 a pour objectif de définir la méthode de mesure de l'induction magnétique, de la polarisation magnétique et l'intensité du champ magnétique, mais aussi de déterminer la courbe de désaimantation et la droite de recul des matériaux pour aimants permanents. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- adaptation des méthodes de mesure et des conditions d'essai aux matériaux magnétiquement durs récemment introduits possédant un champ coercitif HcJ supérieur à 2 MA/m;
- mise à jour des conditions de température, afin de permettre la mesure de nouveaux matériaux avec des coefficients de température élevés.

General Information

Status
Published
Publication Date
15-Apr-2015
Current Stage
PPUB - Publication issued
Start Date
16-Apr-2015
Completion Date
16-Apr-2015
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IEC 60404-5
Edition 3.0 2015-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 5: Permanent magnet (magnetically hard) materials – Methods of
measurement of magnetic properties
Matériaux magnétiques –
Partie 5: Aimants permanents (magnétiques durs) – Méthodes de mesure des
propriétés magnétiques
IEC 60404-5:2015-04(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60404-5
Edition 3.0 2015-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 5: Permanent magnet (magnetically hard) materials – Methods of
measurement of magnetic properties
Matériaux magnétiques –
Partie 5: Aimants permanents (magnétiques durs) – Méthodes de mesure des
propriétés magnétiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.030 ISBN 978-2-8322-2593-6

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 60404-5:2015  IEC 2015
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 Electromagnet and conditions for magnetization .............................................................. 6

4.1 General ................................................................................................................... 6

4.2 Geometrical conditions ........................................................................................... 8

4.3 Electromagnetic conditions ..................................................................................... 8

5 Test specimen ................................................................................................................. 9

6 Determination of the magnetic flux density .................................................................... 10

7 Determination of the magnetic polarization .................................................................... 10

8 Measurement of the magnetic field strength................................................................... 11

9 Determination of the demagnetization curve .................................................................. 12

9.1 General ................................................................................................................. 12

9.2 Principle of determination of the demagnetization curve, test specimen

magnetized in the electromagnet .......................................................................... 12

9.3 Principle of determination of the demagnetization curve, test specimen

magnetized in a superconducting coil or pulse magnetizer .................................... 13

10 Determination of the principal characteristics ................................................................. 14

10.1 Remanent flux density .......................................................................................... 14

10.2 (BH) product ................................................................................................... 14

max

10.3 Coercivities H and H ...................................................................................... 14

cB cJ

10.4 Determination of the recoil line and the recoil permeability .................................... 14

11 Reproducibility ............................................................................................................... 15

12 Test report ..................................................................................................................... 15

Annex A (normative) Influence of the air-gap between the test specimen and the pole

pieces ................................................................................................................................... 17

Annex B (informative) Influence of the ambient temperature on measurement results .......... 18

Bibliography .......................................................................................................................... 19

Figure 1 – Demagnetization curve showing (BH) point ...................................................... 7

max

Figure 2 – Schematic diagram of electromagnet...................................................................... 8

Figure 3 – Measuring circuit (schematic) ............................................................................... 13

Figure 4 – Demagnetization curve and recoil loop ................................................................. 15

Figure A.1 – Air-gap .............................................................................................................. 17

Table 1 – Reproducibility of the measurement of the magnetic characteristics of

permanent magnet materials ................................................................................................. 15

Table A.1 – d/l ratios ............................................................................................................. 17

Table B.1 – Temperature coefficients of B and H of permanent magnet materials ............. 18

r cJ
---------------------- Page: 4 ----------------------
IEC 60404-5:2015  IEC 2015 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 5: Permanent magnet (magnetically hard) materials –
Methods of measurement of magnetic properties
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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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.

International Standard IEC 60404-5 has been prepared by IEC technical committee 68:

Magnetic alloys and steels.
This third edition cancels and replaces the second edition published in 1993 and
Amendment 1:2007. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
• adaption of the measurement methods and test conditions to newly introduced
magnetically hard materials with coercivity values H higher than 2 MA/m;

• update of the temperature conditions to allow the measurement of new materials with high

temperature coefficients.
---------------------- Page: 5 ----------------------
– 4 – IEC 60404-5:2015  IEC 2015
The text of this standard is based on the following documents:
FDIS Report on voting
68/497/FDIS 68/505/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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 publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 6 ----------------------
IEC 60404-5:2015  IEC 2015 – 5 –
INTRODUCTION

The previous edition of IEC 60404-5 was issued in October 1993 and amended in 2007. Since

then, new applications of NdFeB sintered magnetic materials with intrinsic coercivity, H ,

higher than 2 MA/m for hybrid electric vehicles and fully electric vehicles have appeared.

Thus, IEC TC68 decided in 2011 at their meeting in Ghent to revise IEC 60404-5.

For the measurement of the coercivity relating to polarization, H , at values higher than

2 MA/m and the measurement of magnetic properties at elevated temperatures, the methods

described in the non-normative Technical Reports IEC TR 61807 and IEC TR 62331 can be

considered.

The ambient temperature previously recommended was (23 ± 5) °C. However, for permanent

magnet materials such as NdFeB and hard ferrites that have large temperature coefficients, it

is strongly recommended that the ambient temperature should be controlled within this range

to ± 1 °C or better. It is desirable to apply this temperature recommendation for

other hard magnet materials. This recommendation was already included in
IEC 60404-5:1993/AMD1:2007.
---------------------- Page: 7 ----------------------
– 6 – IEC 60404-5:2015  IEC 2015
MAGNETIC MATERIALS –
Part 5: Permanent magnet (magnetically hard) materials –
Methods of measurement of magnetic properties
1 Scope

The purpose of this part of IEC 60404 is to define the method of measurement of the

magnetic flux density, magnetic polarization and the magnetic field strength and also to

determine the demagnetization curve and recoil line of permanent magnet materials, such as

those specified in lEC 60404-8-1 [1] , the properties of which are presumed homogeneous

throughout their volume.

The performance of a magnetic system is not only dependent on the properties of the

permanent magnet material but also on the dimensions of the system, the air-gap and other

elements of the magnetic circuit. The methods described in this part of IEC 60404 refer to the

measurement of the magnetic properties in a closed magnetic circuit.
2 Normative references

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

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

undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
http://www.electropedia.org)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-121,

IEC 60050-151 and IEC 60050-221 apply.
4 Electromagnet and conditions for magnetization
4.1 General

For permanent magnet materials, this part of IEC 60404 deals with both the coercivity H

(the coercivity relating to the magnetic flux density) and the intrinsic coercivity H (the

coercivity relating to the magnetic polarization).

The measurements specified in this part of IEC 60404 are for both the magnetic flux density,

B, and the magnetic polarization, J, as a function of the magnetic field strength, H. These

quantities are related by the following equation:
B = µ H + J (1)
______________
Numbers in square brackets refer to the Bibliography.
---------------------- Page: 8 ----------------------
IEC 60404-5:2015  IEC 2015 – 7 –
where
B is the magnetic flux density, in teslas;
µ is the magnetic constant = 4π × 10 , in henry per metre;
H is the magnetic field strength, in amperes per metre;
J is the magnetic polarization, in teslas.

Using this relationship H values can be obtained from the B(H) hysteresis loop and H

cB cJ

values from the J(H) hysteresis loop. The point represented by H and B at which the

a a

modulus of the product BH has a maximum value is called the point of maximum energy

product for (BH) (see Figure 1).
max

The term “squareness” of the demagnetization curve described in this part of IEC 60404

specifies roughly the characteristic shape of the demagnetization curve between the remanent

flux density and the coercivity relating to the magnetic polarization in the J–H curve.

BH = constant
(BH)
max
H H
cB a
IEC
point
Figure 1 – Demagnetization curve showing (BH)
max

The measurements are carried out in a closed magnetic circuit consisting of an electromagnet

made of soft magnetic material and the test specimen. The construction of the yokes shall be

symmetrical; at least one of the poles shall be movable to minimize the air-gap between the

test specimen and the pole pieces (see Figure 2). The end faces of both pole pieces shall be

ground as nearly as possible parallel to each other and as nearly as possible perpendicular to

the pole axis to minimize the air-gap (see Figure A.1).

NOTE For certain measurements, the yoke and the poles can be laminated to decrease eddy currents. The

coercivity of the material is normally not more than 100 A/m.

To obtain a sufficiently uniform magnetizing field in the space occupied by the test specimen,

the conditions described in 4.2 and 4.3 below shall be fulfilled simultaneously.
---------------------- Page: 9 ----------------------
– 8 – IEC 60404-5:2015  IEC 2015
Device for moving the pole
Yoke
Magnetizing winding
Magnetic field
Search coil (B) 1
strength sensor
Pole face
Test specimen
Pole piece
Pole of
electromagnet
IEC
Figure 2 – Schematic diagram of electromagnet
4.2 Geometrical conditions
Referring to Figure 2;
d ≥ d + 1,2 l’ (2)
1 2
d ≥ 2,0 l’ (3)
where

d is the diameter of a circular pole or the dimension of the smallest side of a rectangular

pole piece, in millimetres;
l’ is the distance between the pole pieces, in millimetres;

d is the maximum diameter of the cylindrical volume with a homogeneous field, in

millimetres.

With reference to the magnetic field strength at the centre of the air-gap, condition (2)

/2 is 1 % and condition (3)
ensures that the maximum field decrease at a radial distance of d

ensures that the maximum field increase along the axis of the electromagnet at the pole faces

is 1 %.
4.3 Electromagnetic conditions

During the measurement of the demagnetization curve, the flux density in the pole pieces

shall be kept substantially lower than the saturation magnetic polarization so that the pole

faces shall be brought as near as possible to an equipotential. In practice, the magnetic flux

density shall be less than 1 T in iron and less than 1,2 T in iron alloy containing 35 % to 50 %

cobalt.
---------------------- Page: 10 ----------------------
IEC 60404-5:2015  IEC 2015 – 9 –

The yoke is excited by magnetizing coils which are arranged symmetrically as near as

possible to the test specimen (see Figure 2). The axis of the test specimen shall be coincident

with the axis of the pole pieces.
Before measurement, the test specimen shall be magnetized in a magnetic field H
max

intended to bring the test specimen to saturation. The determination of the demagnetization

curve shall then be made in a magnetic field with the direction opposite to that used for the

initial magnetization.

If it is not possible to magnetize the test specimen to near saturation within the yoke (for

instance if the requirements of formulae (4) and (5) cannot be met), the test specimen shall

be magnetized outside the electromagnet in a superconducting coil or pulse magnetizer.

Recommended values for H for various permanent magnet materials can be found in
max
IEC TR 62517 [2].
Where the product standard or the manufacturer does not specify the value of the

magnetizing field strength, H , it is recommended that before the measurement of the

max

demagnetization curve, the test specimen is magnetized to saturation. The test specimen will

be considered to be saturated if the following relationships hold for two values of magnetizing

field strength H and H :
1 2
0,02454
P ≤ P ⋅ (H /H ) (4)
2 1 2 1
and H ≥ 1,2 H (5)
2 1
where

P is the maximum attainable value of (BH) in joules per cubic metre, or of coercivity H ,

2 max cB
in amperes per metre;

P is the lower value of (BH) , in joules per cubic metre or of coercivity H , in amperes per

1 max cB
metre;
H is the magnetizing field strength corresponding to P , in amperes per metre;
2 2
H is the magnetizing field strength corresponding to P , in amperes per metre.
1 1
In the special case of H / H =1,5, relationship (4) becomes P ≤ 1,01 P .
2 1 2 1

In all cases, the magnetization process shall not cause the test specimen to be heated

excessively.
5 Test specimen

The test specimen shall have a simple shape (for example a right cylinder or parallelepiped).

The length l of the test specimen shall be not less than 5 mm and its other dimensions shall

be a minimum of 5 mm and shall be such that the test specimen and the sensing devices shall

be within the diameter d as defined in 4.2.

NOTE As a consequence of the high (BH) values exhibited by rare earth permanent magnet materials, the

max

length l in the direction of magnetization can be less than 5 mm. When measuring test specimens with such a

length, the homogeneity of the magnetic field between the pole pieces of the electromagnet deteriorates. The effect

of this on the measurements was reported by Chen et al. [3]. It can be considered when evaluating the results and,

if necessary, a contribution included in the measurement uncertainty. At these thicknesses, the influence of air-gap

is also increased. Therefore the air-gap is carefully minimized. Since the magnetic properties of machined surfaces

of sintered REFeB have poorer properties, the magnetic properties of specimens that have a thickness of less than

5 mm and/or higher S/V ratio are carefully evaluated (where S is the surface area of the test specimen and V is the

volume). In this case, a poor squareness of the demagnetization curves is usually observed.

The end faces of the test specimen shall be made as nearly as possible parallel to each other

and perpendicular to the test specimen axis to reduce the air-gap (see Annex A).
---------------------- Page: 11 ----------------------
– 10 – IEC 60404-5:2015  IEC 2015

The cross-sectional area of the test specimen shall be as uniform as possible along its length;

any variation shall be less than 1 % of its minimum cross-sectional area. The mean cross-

sectional area shall be determined to within 1 %.
The test specimen shall be marked with the direction of magnetization.
6 Determination of the magnetic flux density

The changes in magnetic flux density in the test specimen are determined by integrating the

voltages induced in a search coil.

The search coil shall be wound as closely as possible to the test specimen and symmetrical

with respect to the pole faces. The leads shall be tightly twisted to avoid errors caused by

voltages induced in loops in the leads.

The total error of measuring the magnetic flux density shall be not greater than ± 2 %.

The variation of the apparent magnetic flux density ∆B uncorrected for air flux, between the

two instants t and t is given by:
1 2
1 2
∆B = B − B = Udt (6)
ap 2 1
where
B is the magnetic flux density at the instant t , in teslas;
2 2
B is the magnetic flux density at the instant t , in teslas;
1 1
A is the cross-sectional area of the test specimen, in square metres;
N is the number of turns on the search coil;

is the integrated induced voltage, expressed in webers, for the time interval of

Udt
integration (t – t ), in seconds.
2 1

This change in the apparent magnetic flux density ∆B shall be corrected to take into account

the air flux included in the search coil. Thus, the change in magnetic flux density ∆B in the

test specimen is given by:
(A − A)
∆B = ∆B − µ ∆H (7)
ap 0
where
µ is the magnetic constant = 4π × 10 , in henry per metre;
∆H is the change in the measured magnetic field strength, in amperes per metre;
A is the average cross-sectional area of the search coil, in square metres.
7 Determination of the magnetic polarization

The changes in magnetic polarization in the test specimen are determined by integrating the

induced voltages at the terminals of a two-search-coil device composed of COIL 1 and COIL 2

where the test specimen is contained in COIL 2, while COIL 1 is empty. If each of the

individual coils has the same product of cross-sectional area and the number of turns, and if

both are connected electrically in opposition, the output of COIL 1 compensates for the output

---------------------- Page: 12 ----------------------
IEC 60404-5:2015  IEC 2015 – 11 –

of COIL 2 except the magnetic polarization J of the test specimen. The change of magnetic

polarization ∆J in the test specimen is given by:
1 2
∆J = J − J = Udt (8)
2 1
where
J is the magnetic polarization at the instant t , in teslas;
2 2
J is the magnetic polarization at the instant t , in teslas;
1 1
A is the cross-sectional area of the test specimen, in square metres;
N is the number of turns on the search coil;
Udt is the integrated induced voltage, expressed in webers, for the
...

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