IEC 60404-8-1:2015
(Main)Magnetic materials - Part 8-1: Specifications for individual materials - Magnetically hard materials
Magnetic materials - Part 8-1: Specifications for individual materials - Magnetically hard materials
IEC 60404-8-1:2015 specifies minimum values for the principal magnetic properties of, and dimensional tolerances for, technically important magnetically hard materials (permanent magnets). For information purposes only, this part of IEC 60404 provides values for the densities of the materials and the ranges of their chemical compositions. Some additional physical data and mechanical reference values concerning the magnetic materials are given for information and comparison purposes. This edition includes the following significant technical changes with respect to the previous edition:
a) recently developed anisotropic Sm-Fe-N bonded magnets are included;
b) high energy ferrites with La and Co as substituents are included.
Matériaux magnétiques - Partie 8-1: Spécifications pour matériaux particuliers - Matériaux magnétiquement durs
L'IEC 60404-8-1:2015 spécifie les valeurs minimales des principales propriétés magnétiques des matériaux magnétiques durs importants d'un point de vue technique (aimants permanents) ainsi que leurs tolérances sur les dimensions. La présente partie de l'IEC 60404 donne uniquement à titre indicatif des valeurs de masses volumiques des matériaux et les plages de leur composition chimique. Dans un but d'information et de comparaison, quelques données physiques et valeurs mécaniques de référence sur les matériaux magnétiques sont aussi données au Tableau A.1. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) elle inclut les aimants agglomérés Sm-Fe-N anisotropes récemment développés;
b) elle inclut les ferrites haute énergie avec les remplaçants La et Co.
General Information
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Standards Content (Sample)
IEC 60404-8-1 ®
Edition 3.0 2015-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 8-1: Specifications for individual materials – Magnetically hard materials
Matériaux magnétiques –
Partie 8-1: Spécifications pour matériaux particuliers – Matériaux
magnétiquement durs
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IEC 60404-8-1 ®
Edition 3.0 2015-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 8-1: Specifications for individual materials – Magnetically hard materials
Matériaux magnétiques –
Partie 8-1: Spécifications pour matériaux particuliers – Matériaux
magnétiquement durs
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.030 ISBN 978-2-8322-2429-8
– 2 – IEC 60404-8-1:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 7
4 Types of materials and their applications . 7
5 Classification . 8
5.1 General . 8
5.2 Principal magnetic properties . 8
5.3 Additional magnetic properties . 9
6 Chemical composition . 10
7 Densities . 10
8 Designation . 10
9 Mode of shipment and dimensions . 10
10 Testing . 10
10.1 Extent of testing . 10
10.2 Testing methods . 10
11 Grounds for rejection . 11
12 Description of tables of standard properties . 11
12.1 Magnetically hard alloys . 11
12.1.1 Aluminium-nickel-cobalt-iron-titanium alloys (AINiCo) . 11
12.1.2 Chromium-iron-cobalt alloys (CrFeCo) . 12
12.1.3 Iron-cobalt-vanadium-chromium alloys (FeCoVCr) . 12
12.1.4 Rare earth-cobalt alloys (RECo) . 13
12.1.5 Rare earth-iron-boron alloys (REFeB) . 14
12.2 Magnetically hard ceramics (magnetically hard ferrites) . 14
12.2.1 Chemical composition . 14
12.2.2 Manufacturing method . 15
12.2.3 Sub-classification . 15
12.2.4 Magnetic properties and densities . 15
12.2.5 Dimensional tolerances . 15
12.3 Bonded magnets . 15
12.3.1 General . 15
12.3.2 Chemical composition . 15
12.3.3 Manufacturing method . 16
12.3.4 Sub-classification . 16
12.3.5 Magnetic properties and densities . 17
12.3.6 Dimensional tolerances . 17
13 Irreversible demagnetization behaviour . 17
13.1 General . 17
13.2 General definition of demagnetization field strength H . 18
D
13.3 Simplified definition of demagnetization field strength H . 18
D
14 Tables 10 to 23 . 20
Annex A (informative) Physical data and mechanical reference values of AINiCo,
CrFeCo, FeCoVCr, SmCo, NdFeB, hard ferrite and bonded SmFeN magnets . 34
Bibliography . 36
Figure 1 – Graphic representation of B(H) and J(H) demagnetization and recoil curves . 19
Figure 2 – Simplified evaluation of B(H) and J(H) demagnetization and recoil curves . 20
Table 1 – Classification of magnetically hard materials . 8
and units
Table 2 – Magnetic properties — Symbols . 9
Table 3 – Additional magnetic properties — Symbols and units . 9
Table 4 — Chemical compositions of AlNiCo alloys (% mass fraction) . 11
Table 5 — Chemical compositions of CrFeCo alloys (% mass fraction) . 12
Table 6 — Chemical compositions of FeCoVCr alloys (% mass fraction) . 12
Table 7 – Chemical compositions of RECo alloys (% mass fraction) . 13
Table 8 – Chemical compositions of REFeB alloys (% mass fraction) . 14
Table 9 – Chemical compositions of REFeN alloys for bonded magnet (% mass
fraction) . 16
Table 10 – Magnetic properties and densities of AlNiCo magnets . 21
Table 11 – Magnetic properties and densities of CrFeCo and FeCoVCr magnets . 22
Table 12 – Magnetic properties and densities of RECo magnets . 23
Table 13 – Magnetic properties and densities of REFeB magnets . 24
Table 14 – Magnetic properties and densities of hard ferrites . 25
Table 15 – Magnetic properties and densities of isotropic AlNiCo alloys with organic
binder . 26
Table 16 – Magnetic properties and densities of RECo alloys with organic binder . 27
Table 17 – Magnetic properties and densities of isotropic REFeB alloys with organic
binder . 28
Table 18 – Magnetic properties and densities of isotropic and anisotropic hard ferrites
with organic binder . 29
Table 19 – Magnetic properties and densities of anisotropic REFeN alloys with organic
binder . 30
Table 20 – Dimensional tolerances (as cast or as sintered) of magnets made from
AlNiCo alloys . 31
Table 21 – Dimensional tolerances of cold rolled strips of FeCoVCr and CrFeCo alloys
with a maximum thickness of 6 mm and maximum width of 125 mm . 32
Table 22 – Dimensional tolerances of the diameter of cold drawn wires and bars of
FeCoVCr and CrFeCo alloys . 32
Table 23 – Dimensional tolerances on magnets made from hard ferrites . 33
Table A.1 – Physical data and mechanical reference values of AlNiCo, CrFeCo,
FeCoVCr, SmCo, NdFeB, hard ferrite and bonded SmFeN magnets . 35
– 4 – IEC 60404-8-1:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 8-1: Specifications for individual materials –
Magnetically hard materials
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
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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 60404-8-1 has been prepared by IEC technical committee 68:
Magnetic alloys and steels.
This third edition cancels and replaces the second edition published in 2001 and
Amendment 1:2004. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) recently developed anisotropic Sm-Fe-N bonded magnets are included;
b) high energy ferrites with La and Co as substituents are included.
The text of this standard is based on the following documents:
FDIS Report on voting
68/495/FDIS 68/503/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.
– 6 – IEC 60404-8-1:2015 © IEC 2015
INTRODUCTION
This third edition of IEC 60404-8-1 includes the recently developed anisotropic Sm-Fe-N
bonded magnets and high energy ferrites with La and Co as substituents which have become
established in permanent magnet applications. It also includes corrections to the second
edition in order to improve consistency with IEC 60404-5. The squareness of the
demagnetization curve is introduced through the quantity H .
D
MAGNETIC MATERIALS –
Part 8-1: Specifications for individual materials –
Magnetically hard materials
1 Scope
This part of IEC 60404 specifies minimum values for the principal magnetic properties of,
and dimensional tolerances for, technically important magnetically hard materials (permanent
magnets).
For information purposes only, this part of IEC 60404 provides values for the densities of
the materials and the ranges of their chemical compositions.
NOTE Some additional physical data and mechanical reference values concerning the magnetic materials are
given in Table A.1 for information and comparison purposes.
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:
www.electropedia.org)
IEC 60404-5, Magnetic materials – Part 5: Permanent magnet (magnetically hard) materials –
Methods of measurement of magnetic properties
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121 [1],
IEC 60050-151 [2] and IEC 60050-221 [3] apply.
4 Types of materials and their applications
Permanent magnetic materials, also designated as magnetically hard materials, are
classified in IEC 60404-1 [4] as Class R (magnetically hard alloys), Class S (magnetically
hard ceramics) and Class U (bonded magnets).
Permanent magnets have a coercivity relating to the magnetic polarization greater than
1 kA/m. After being magnetized to saturation they produce a material-dependent specific
magnetic energy, which can be used in static or dynamic magnetic circuit applications.
Permanent magnetic materials are used in nearly every area of daily life. They perform
coupling, modulating, or regulating functions in equipment and devices based on
electromagnetic principles, for example in measuring instruments, motors, generators and
_______________
Numbers in square brackets refer to the Bibliography.
– 8 – IEC 60404-8-1:2015 © IEC 2015
loudspeakers. Permanent magnet materials are indispensable in office equipment and
computer hardware, automobiles including propulsion motors for Hybrid Electric Vehicles
(HEV) and Electric Vehicles (EV), entertainment electronics, telecommunications, household
appliances and medical instruments, as well as in mechanical engineering as holding
devices, clamping plates, etc.
Further possible and typical applications for the commercially available permanent magnetic
materials are described in more detail in 3.2 (Class R), 3.3 (Class S) and in 3.5
(Class U) of IEC 60404-1:2000.
5 Classification
5.1 General
Compared to IEC 60404-8-1:2001 and IEC 60404-8-1:2001/AMD1:2004, this revised edition
uses the same classification of permanent magnetic materials for technical applications. The
bonded REFeN magnets are newly added as U5 for the first part of the code number. This
is given in Table 1. The materials are grouped according to their metallurgical
classification
relationships.
Table 1 – Classification of magnetically hard materials
Group Principal constituents First part of code Previous code
number number
1:2001/AMD1:2004
Magnetically hard Aluminium-nickel-cobalt-iron-titanium R1 R1
alloys alloys
(R) Chromium-iron-cobalt alloys R6 R6
Iron-cobalt-vanadium-chromium alloys R3 R3
Rare earth-cobalt alloys R5 R5
Rare earth-iron-boron alloy R7 R7
Magnetically hard Magnetically hard ferrites S1 S1
ceramics
(MO･nFe O ; M = Ba, Sr, and/or Pb, and
2 3
(S)
n = 4,5 to 6,5)
Bonded hard Bonded aluminium-nickel-cobalt-iron- U1 U1
magnetic titanium magnets
materials
Bonded rare earth-cobalt magnets U2 U2
(U)
Bonded rare earth-iron-boron magnets U3 U3
Bonded hard ferrite magnets U4 U4
Bonded rare earth-iron-nitrogen magnets U5
—
The permanent magnetic materials are identified by the principal magnetic properties given
in 5.2.
5.2 Principal magnetic properties
Symbols and units of magnetic properties of magnetically hard materials are given in Table 2.
and units
Table 2 – Magnetic properties — Symbols
Magnetic properties Symbol Unit
Maximum value of (BH) product (BH) kJ/m
max
Remanent flux density B mT
r
H
Coercivity relating to the magnetic flux density kA/m
cB
Coercivity relating to the magnetic polarization H kA/m
cJ
Minimum values at room temperature of magnetic properties, determined after magnetization
to saturation, are given in Tables 10 to 19.
The specified values of magnetic properties are valid only for magnets having a cross
3 3
section invariable along the axis of magnetization, with a volume of 0,125 cm to 200 cm
and with dimensions in the three directions of the coordinate axes of at least 5 mm.
For anisotropic materials, they are valid only along the one preferred direction.
For more details on size limits for measurements, see IEC 60404-5.
For reasons connected with the manufacturing methods, lower values of the magnetic
properties may be obtained if the dimensional conditions mentioned above are not satisfied.
For the method of measurement of the coercivity of magnetic materials in an open magnetic
circuit, see IEC 60404-7 [5].
5.3 Additional magnetic properties
Symbols and units of additional magnetic properties of magnetically hard materials are given
in Table 3.
Table 3 – Additional magnetic properties — Symbols and un it s
Magnetic properties Symbol Unit
Recoil permeability µ —
rec
Temperature coefficient of the remanent flux
den s i ty [it corresponds to the temperature coefficient α(B ) %/°C
r
of the magnetic saturation α(J )]
s
Temperature coefficient of the coercivity relating to
α(H ) %/°C
cJ
the magnetic polarization
T
Curie temperature °C
c
The values given in Tables 10 to 19 are specified minimum values and some typical
values. The typical values are mean values published in the literature and are given as an
indication only and are not guaranteed. The temperature range for the temperature
coefficients in the tables is generally from 20 °C to 100 °C, but this does not preclude the
use of these materials outside this temperature range.
The magnetic field strength necessary for magnetizing magnetically hard materials to
magnetic saturation is defined in IEC 60404-5, IEC 60404-7 [5] and IEC TR 62517 [6].
– 10 – IEC 60404-8-1:2015 © IEC 2015
6 Chemical composition
The composition ranges for the different material groups are given for information purposes
under 12.1.1.1, 12.1.2.1, 12.1.3.1, 12.1.4.1, 12.1.5.1, 12.2.1 and 12.3.2.
7 Densities
Density values are given in Tables 10 to 19 for information purposes only. The density
values can be used for mass and volume calculations.
8 Designation
Magnetically hard materials can be identified by brief designations and by alpha-numeric
symbols (code numbers, see Tables 10 to 19). In so far as chemical symbols are used in
the brief designation, they indicate main constituents. The number before the oblique stroke
in the brief designation denotes the maximum value of the (BH) product expressed in
kilojoules per cubic metre (kJ/m ) and the number after the oblique stroke denotes one tenth
of the coercivity H expressed in kiloamperes per metre (kA/m). Magnetically hard materials
cJ
with a binder (mostly organic, see 12.3.1) are denoted by a suffixed “p” to the brief
designation.
EXAMPLE For the grade AlNiCo 12/6 of Table 10, the integer 12 is obtained from its minimum value (BH) of
max
11,6 kJ/m , and the integer 6 from one-tenth of its minimum value of H i.e. one-tenth of 55 kA/m = 5,5 kA/m on
cJ
rounding up or down to the nearest integer. If rounding down would give the integer zero, the number containing
the first rounded non-zero decimal is maintained.
The code numbers are derived from the classification system used in IEC 60404-1. The
letter in the code number means the class of the magnetically hard material. The first number
designates the kind of material in the respective class, see Table 9. A ‘0’ in the second
position means that the material is magnetically isotropic, a “1”, that the material is
magnetically anisotropic. The number in the third position denotes the different grades.
9 Mode of shipment and dimensions
The materials described in this specification may be delivered either magnetized or
unmagnetized and may be mounted in magnetic circuits.
The dimensions of the magnets have to be agreed upon between supplier and purchaser
when ordering.
10 Testing
10.1 Extent of testing
The extent of testing shall be agreed upon between supplier and purchaser.
10.2 Testing methods
The testing methods shall be agreed upon between supplier and purchaser.
The minimum values of th e magnetic properties of magnetically hard materials having
suitable shape and appropriate dimensions shall be tested according to IEC 60404-5.
If the shape and dimensions do not correspond to the requirement of 5.2, the details of the
test should be agreed upon between the supplier and the purchaser.
11 Grounds for rejection
Grounds for rejection include inferior magnetic quality (Tables 10 to 19 give specified
minimum values of some magnetic properties), physical dimensions and dimensional
tolerances (Tables 20 to 23).
External and internal mechanical imperfections may be considered a cause for rejection, if
these are deleterious to handling and application.
The purchaser’s notification of rejection to the supplier shall be accompanied by samples of
consignment.
the rejected
12 Description of tables of standard properties
12.1 Magnetically hard alloys
12.1.1 Aluminium-nickel-cobalt-iron-titanium alloys (AINiCo)
12.1.1.1 Chemical composition
Permanent magnets based on aluminium-nickel-cobalt-iron-titanium, referred to as AINiCo,
form a broad spectrum of component-rich alloys in the composition ranges given in
Ta b le 4 (values in percentage mass fraction).
Table 4 — Chemical compositions of AlNiCo alloys (% mass fraction)
Al Ni Co Cu Ti Nb Si Fe
AlNiCo 8 to 13 13 to 28 5 to 42 2 to 6 0 to 9 0 to 3 0 to 0,8 balance
12.1.1.2 Manufacturing methods
AINiCo magnets are formed by casting or by a powder metallurgical process. The magnetic
performance of alloys with a Co content higher than 20 % mass fraction can be
increased in a preferred direction by applying a magnetic field during heat treatment. By this
procedure a magnetic anisotropy is generated in the material.
crystal
The best performances of AlNiCo magnets are achieved with columnar or single
structure materials. The magnetic field applied during the heat treatment has to be parallel
to the columnar axis.
12.1.1.3 Sub-classification
Isotropic magnetic alloys, cast or sintered (R1-0-x)
where x = 1, 2, ……….
Anisotropic magnetic alloys, cast (R1-1-x)
where x = 1, 2, ……….
12.1.1.4 Magnetic properties and densities
The magnetic properties and densities are given in Table 10. (See also 5.2, 5.3 and
Clause 7.)
– 12 – IEC 60404-8-1:2015 © IEC 2015
12.1.1.5 Dimensional tolerances
Values of the dimensional tolerances for sintered and cast AINiCo magnets are given in
Table 20.
12.1.2 Chromium-iron-cobalt alloys (CrFeCo)
12.1.2.1 Chemical composition
Permanent magnets based on chromium-iron-cobalt alloys, referred to as CrFeCo, have
compositions within the ranges given in Table 5 (values in percentage mass fraction).
Table 5 — Chemical compositions of CrFeCo alloys (% mass fraction)
Cr Co Other elements Fe
e.g. Si, Ti, Mo, Al, V
CrFeCo 25 to 35 7 to 25 0,1 to 3 balance
12.1.2.2 Manufacturing method
The CrFeCo alloys can be manufactured by casting, followed by hot and cold rolling and
drawing to produce strips and wires. Parts are made from this material by stamping,
turning or drilling. Subsequent to the shaping, a heat treatment has to be provided to obtain
the permanent magnetic properties. The magnets can also be formed by a powder
metallurgical process. The magnetic performance of the cast as well as sintered material
can be increased in a preferred direction by applying a magnetic field during heat
treatment.
12.1.2.3 Sub-classification
Isotropic magnetic alloys (R6-0-x)
where x = 1, 2, …….
Anisotropic magnetic alloys (R6-1-x)
where x = 1, 2, ……
12.1.2.4 Magnetic properties and densities
Magnetic properties and densities of isotropic and anisotropic CrFeCo magnets are given in
Table 11. (see 5.2, 5.3 and Clause 7.)
12.1.2.5 Dimensional tolerances
Values of dimensional tolerances of cold rolled strips and cold drawn wires and bars are
given in Tables 21 and 22, respectively. For sintered magnets, the tolerances shall be
agreed upon between supplier and purchaser.
12.1.3 Iron-cobalt-vanadium-chromium alloys (FeCoVCr)
12.1.3.1 Chemical composition
The ranges of chemical composition are given in Table 6 (values in percentage mass
fraction).
Table 6 — Chemical compositions of FeCoVCr alloys (% mass fraction)
Co V + Cr Fe
FeCoVCr 49 to 54 4 to 13 balance
12.1.3.2 Manufacturing method
The FeCoVCr alloys are manufactured by casting and hot and cold rolling or drawing to
produce strips or wires, respectively. The cold deformation (80 % to 95 %), followed by a
heat treatment in the range from 500 °C to 650 °C, is essential for the production of the
permanent magnet properties.
12.1.3.3 Sub-classification
The recommended sub-classification is based on the coercivity related to the magnetic
polarization H .
cJ
12.1.3.4 Magnetic properties and densities
Magnetic properties and densities are given in Table 11. (See also 5.2, 5.3 and Clause 7.)
12.1.3.5 Dimensional tolerances
Values of the dimensional tolerances of cold rolled strips and cold drawn wires are given in
Tables 21 and 22, respectively.
12.1.4 Rare earth-cobalt alloys (RECo)
12.1.4.1 Chemical composition
Of technical importance are the two types of alloys: and The composition
RECo RE Co .
5 2 17
is used as the generic name for a series of binary and multi-phase alloys with a
RE Co
2 17
number of transition elements partially replacing cobalt. The alloys have a strong uniaxial
magnetic anisotropy and a high magnetic saturation, resulting in a high coercivity H and a
cJ
high remanence B of the magnets. Their main constituents are given in Table 7 (values in
r
percentage mass fraction).
Table 7 – Chemical compositions of RECo alloys (% mass fraction)
Sm Fe Cu Other elements Co
e.g. Zr, Hf, Ti
SmCo 33 to 36 — — — balance
Sm Co 24 to 26 10 to 20 4,5 to 12 0 to 3 balance
2 17
Samarium (Sm) is the main RE metal in these alloys and leads to the best magnetic
properties.
However, cerium (Ce) or praseodymium (Pr) may also be used as the RE component.
12.1.4.2 Manufacturing method
Compacting of the monocrystalline RECo powder is carried out in a magnetic field, thus
obtaining particle-oriented anisotropic magnets. The pressed bodies are sintered under
vacuum or under a protective atmosphere followed by heat treatments.
12.1.4.3 Sub-classification
Anisotropic alloys of the type (R5-1-x)
RECo
where x = 1, 2, ……, 9
Anisotropic alloys of the type (R5-1-x)
RE Co
2 17
where x = 10, 11, 12, ……., 19
– 14 – IEC 60404-8-1:2015 © IEC 2015
12.1.4.4 Magnetic properties and densities
The magnetic properties and densities are given in Table 12. (See also 5.2, 5.3 and
Clause 7.)
12.1.4.5 Dimensional tolerances
The dimensional tolerances have to be agreed upon between producer and purchaser.
12.1.5 Rare earth-iron-boron alloys (REFeB)
12.1.5.1 Chemical composition
The REFeB magnet alloys are based on the compound The RE element is
RE Fe B.
2 14
mainly neodymium (Nd), which may be partially substituted by dysprosium (Dy),
praseodymium (Pr) or other rare earth elements. Iron may be partially substituted by cobalt
(Co). The alloy forms a tetragonal crystal structure and shows both a high
Nd Fe B
2 14
saturation magnetization and a high uniaxial magnetocrystalline anisotropy.
The composition ranges of the REFeB alloys are given in Table 8 (values in percentage
mass fraction).
Table 8 – Chemical compositions of REFeB alloys (% mass fraction)
Total RE Co B Dy, Tb,Pr etc. Other elements Fe
e. g. V, Nb, Al, Ga, Cu
REFeB 28 to 35 0 to 15 0,85 to 1,2 0 to 10 0 to 1 balance
12.1.5.2 Manufacturing methods
Compacting of the monocrystalline REFeB powder is carried out in a magnetic field, thus
obtaining particle-oriented anisotropic magnets. The pressed bodies are sintered under
vacuum or under a protective atmosphere followed by a heat treatment.
12.1.5.3 Sub-classification
Anisotropic alloys of the type RE FeB (R7-1-x)
where x = 1, 2, ……,
12.1.5.4 Magnetic properties and densities
The specified minimum magnetic properties and density of anisotropic materials are given in
Table 13. (See also 5.2, 5.3 and Clause 7.)
12.1.5.5 Dimensional tolerances
Dimensional tolerances shall be in accordance with those for sintered AINiCo magnets
having less than 1 % Ti as specified in Table 20.
12.2 Magnetically hard ceramics (magnetically hard ferrites)
12.2.1 Chemical composition
The chemical composition of the magnetically hard ferrites can be described by the formula
(where M = Ba and Sr). The ratio n can vary from 4,5 to 6,5. The magnetically
MO･nFe O
2 3
hard ferrites have a hexagonal structure with a high uniaxial magnetocrystalline anisotropy,
but a relatively low magnetic saturation.
The magnetic properties can be improved by special substitutions. This is particularly so with
additions of up to 9 % of La and up to 4 % of Co, which can increase the values of H by up
cJ
to 100 % and decrease values of α(H ) by up to 50 %.
cJ
12.2.2 Manufacturing method
Compacting of the monocrystalline hard ferrite powder is carried out in a magnetic field,
thus obtaining particle-oriented anisotropic magnets. The pressed bodies are sintered in air.
12.2.3 Sub-classification
Isotropic magnetically hard ferrites (S1-0-x)
where x = 1, 2, …….
Anisotropic magnetically hard ferrites (S1-1-x)
where x = 1, 2, …….
12.2.4 Magnetic properties and densities
The magnetic properties and the density of the isotropic and anisotropic magnetically hard
ferrites are given in Table 14. (See also 5.2, 5.3 and Clause 7.)
12.2.5 Dimensional tolerances
Values of the dimensional tolerances for isotropic and anisotropic magnetically hard ferrites
are given in Table 23.
12.3 Bonded magnets
12.3.1 General
Plastic bonded permanent magnets are composite materials. They consist of permanent
magnet powders embedded in a plastic matrix. This binder phase determines to a large
extent the mechanical properties of the composite, while the magnet powder determines
the magnetic properties of the composite. The properties of the composite are determined by
the type of permanent magnet material, the matrix material, the fill factor and, for anisotropic
material, the degree of alignment, leading to a wide variety of grades.
In spite of their lower magnetic properties compared with sintered materials, bonded
magnets offer economical and technical advantages in many applications because they are
cost-effective to manufacture and allow a wide scope for shaping and good mechanical
properties.
The expensive and elaborate processing steps required in powder metallurgy are not
needed.
12.3.2 Chemical composition
The magnet materials for producing bonded permanent magnets are powders of AINiCo,
NdFeB and hard ferrite (see 12.1.1.1, 12.1.4.1, 12.1.5.1 and 12.2.1).
SmCo , Sm Co ,
5 2 17
The magnetic material required for producing REFeN bonded magnets is based on a
Sm Fe N intermetallic compound and the chemical composition ranges are given in Table 9.
2 17 3
The REFeN powders are manufactured by the reduction diffusion process using Sm O and
2 3
Fe powders with Ca as a reductant followed by nitrogenation. When the size of the processed
powders is coarse, a subsequent milling is required.
The main matrix materials are elastomers, thermoplastics or thermosets.
– 16 – IEC 60404-8-1:2015 © IEC 2015
Table 9 – Chemical compositions of REFeN alloys for bonded magnet (% mass fraction)
Sm N Fe
REFeN 22 to 27 3,0 to 4,0 balance
12.3.3 Manufacturing method
The methods of manufacturing bonded permanent magnets, frequently referred to as “P
magnets”, are largely similar, irrespective of the magnet material used. The flexible
materials are produced by rolling, extrusion or calendering, while the shape-stable magnets
are made by injection moulding, die pressing or extrusion.
In the injection moulding technique, cold or hot mixing of the magnet powders, depending
on the binder, is carried out in mixers, mixing extruders or kneaders.
The most important matrix materials for injection-moulded magnets are the thermoplastics
polyamide, polyethylene, and polyphenylene sulfide (PPS). The compound mass is processed
in injection moulding machines. Single or multi-cavity dies are used depending on the magnet
shape, size and production volume.
In the manufacture of anisotropic grades, the magnetic values depend critically on the
alignment conditions, which are determined by magnetic field strength in the mould and by
the shape of the magnet.
In the die pressing technique, which is only used commercially for the manufacture of
bonded rare earth magnets, thermosets such as epoxy resins are used as binders.
The compound mixtures are loaded into the die cavities of press tools and pressed into
compacts at pressures from 0,6 GPa to 1 GPa. The compacts are then heat treated to cure
the binder. Anisotropic magnets can also be produced by die pressing anisotropic powders
under an aligning magnetic field.
12.3.4 Sub-classification
Isotropic bonded AlNiCo magnets (U1-0-x)
where
x = [30 + n] for compression moulding
n = 0, 1, 2, ……
Isotropic bonded RECo magnets (U2-0-x)
where
x = [20 + n] for injection moulding
x = [30 + n] for compression moulding
n = 0, 1, 2, … 4 for SmCo
n = 5, 6, 7, ….9 for Sm Co
2 17
Anisotropic bonded RECo magnets (U2-1-x)
where
x = [20 + n] for injection moulding
x = [30 + n] for compression moulding
n = 0, 1, 2, ……, 4 for RECo
n = 5, 6, ……, 9 for RE Co
2 17
Isotropic bonded REFeB magnets (U3-0-x)
where
x = [20 + n]
...
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