IEC Standard Rare earth-iron-boron (REFeB) Magnets

IEC 60404-1:2016 is available as IEC 60404-1:2016 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60404-1:2016 is intended to classify commercially available magnetic materials. The term “magnetic materials” denotes substances where the application requires the existence of ferromagnetic or ferrimagnetic properties. The classification of magnetic materials is based upon the generally recognized existence of two main groups of products:
– soft magnetic materials (coercivity less than or equal to 1 000 A/m);
– hard magnetic materials (coercivity greater than 1 000 A/m). This edition includes the following significant technical changes with respect to the previous edition:
a) Removal of all tables and values describing typical properties of the material to be consistent with the aim of the document to be a classification and not a specification.
b) Enlargement of the Ni content for the classes E1 and E3.
c) Enlargement of the Co content for the classes F3.
d) Addition of a new class: U5 bonded rare earth-iron-nitrogen magnets.

IEC Standard Rare earth-iron-boron (REFeB) Magnets

IEC Standard Rare earth-iron-boron (REFeB) Magnets

Sintered Neodymium magnets (also known as NdFeB magnets) are the most common type of rare earth magnet.
They are composed of a Neodymium, Iron and Boron alloy that forms the Nd2Fe14B tetragonal crystal structure. Neodymium magnets have the strongest magnetic properties currently available on the market.

They are suitable for applications that require high induction and small sized magnets or motors.
They reach their maximum performance when used on:

New generation brushless motors
High performance generators
NEODYMIUM-IRON-BORON
Curie temperature °C > 310
Recoil permeability (µr) – 1.1
Saturation field kOe > 25
Electrical resistivity Ω m 150 X 108
Compressive strength N/mm2 ~ 1050
Density g/cm3 7.5 – 7.6
Flexural strength N/mm2 250
Tensile strength N/mm2 75
Hardness – Vickers HV ~ 600
Young’s Modulus N/mm2 160 X 103
Specific heat kcal/kg.°C 0.12
Thermal conductivity kcal/m/hr/°C ~ 7.7
Coeff. of thermal expansion // 10-6/°C -1.5
Coeff. of thermal expansion_ 10-6/°C 5

MAGNETIC MATERIALS –
Part 1: Classification
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

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with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.
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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

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International Standard IEC 60404-1 has been prepared by IEC technical committee 68:

Magnetic alloys and steels.
This bilingual version (2017-12) corresponds to the monolingual English version, published in

2016-10.
This third edition cancels and replaces the second edition published in 2000 and constitutes a

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

edition:
a) Removal of all tables and values describing typical properties of the material to be

consistent with the aim of the document to be a classification and not a specification.

b) Enlargement of the Ni content for the classes E1 and E3.
c) Enlargement of the Co content for the classes F3.
———————- Page: 6 ———————-
IEC 60404-1:2016 © IEC 2016 – 5 –
d) Addition of a new class: U5 bonded rare earth-iron-nitrogen magnets.
The text of this standard is based on the following documents:
CDV Report on voting
68/533/CDV 68/555/RVC
Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.IEC Standard Rare earth-iron-boron (REFeB) Magnets
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.IEC Standard Rare earth-iron-boron (REFeB) Magnets

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 thestability date indicated on the IEC website under “http://webstore.iec.ch” in the data related tothe specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC Standard Rare earth-iron-boron (REFeB) Magnets
MAGNETIC MATERIALS –
Part 1: Classification
1 Scope
This part of IEC 60404 is intended to classify commercially available magnetic materials.

The term “magnetic materials” denotes substances where the application requires theexistence of ferromagnetic or ferrimagnetic properties.
In this document, the classification of magnetic materials is based upon the generallyrecognized existence of two main groups of products:
• soft magnetic materials (coercivity ≤1 000 A/m);
• hard magnetic materials (coercivity >1 000 A/m).
Within these main groups, the classification when appropriate recognizes the following

characteristics:
• the main alloying element and the metallurgical state and physical properties of thematerial;
• when possible and convenient, the relationship between these characteristics is identified.

A classification by specific areas of application cannot be applied to all materials becausedifferent materials can very often be used for the same application depending on thecharacteristics required.
2 Normative references
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document. For dated references, only the editioncited applies. For undated references, the latest edition of the referenced document (includingany amendments) applies.
IEC 60050-121, International Electrotechnical Vocabulary – Part 121: Electromagnetism

IEC 60050-151, International Electrotechnical Vocabulary – Part 151: Electrical and magneticdevices
IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materialsand components
IEC 60401-3, Terms and nomenclature for cores made of magnetically soft ferrites – Part 3:

Guidelines on the format of data appearing in manufacturers catalogues of transformer and

inductor cores
IEC 60404-2, Magnetic materials – Part 2: Methods of measurement of the magneticproperties of electrical steel sheet and strip by means of an Epstein frame
IEC 60404-3, Magnetic materials – Part 3: Methods of measurement of the magneticproperties of magnetic sheet and strip by means of a single sheet tester
———————- Page: 8 ———————-
IEC 60404-1:2016 © IEC 2016 – 7 –
IEC 60404-4, Magnetic materials – Part 4: Methods of measurement of d.c. magnetic

properties of iron and steel
IEC 60404-6, Magnetic materials – Part 6: Methods of measurement of the magnetic
properties of magnetically soft metallic and powder materials at frequencies in the range

20 Hz to 200 kHz by the use of ring specimens
IEC 60404-7, Magnetic materials – Part 7: Method of measurement of the coercivity ofmagnetic materials in an open magnetic circuit
IEC 60404-8-1, Magnetic materials – Part 8-1: Specifications for individual materials –Magnetically hard materials
IEC 60404-8-3, Magnetic materials – Part 8-3: Specifications for individual materials – Cold-IEC Standard Rare earth-iron-boron (REFeB) Magnets

rolled electrical non-alloyed and alloyed steel sheet and strip delivered in the semi-processed

state
IEC 60404-8-4, Magnetic materials – Part 8-4: Specifications for individual materials – Cold-IEC Standard Rare earth-iron-boron (REFeB) Magnets

rolled non-oriented electrical steel strip and sheet delivered in the fully-processed state

IEC 60404-8-5, Magnetic materials – Part 8: Specifications for individual materials –IEC Standard Rare earth-iron-boron (REFeB) Magnets

Section Five: Specification for steel sheet and strip with specified mechanical properties and

magnetic permeability
IEC 60404-8-6, Magnetic materials – Part 8-6: Specifications for individual materials – Soft magnetic metallic materials
IEC 60404-8-7, Magnetic materials – Part 8-7: Specifications for individual materials –Cold- rolled grain-oriented electrical steel strip and sheet delivered in the fully processed state

IEC 60404-8-8, Magnetic materials – Part 8: Specifications for individual materials –Section 8: Specification for thin magnetic steel strip for use at medium frequencies

IEC 60404-8-9, Magnetic materials – Part 8: Specifications for individual materials –Section 9: Standard specification for sintered soft magnetic materials
IEC 60404-8-10, Magnetic materials – Part 8-10: Specifications for individual materials –Magnetic materials (iron and steel) for use in relays
IEC 60404-10, Magnetic materials – Part 10: Methods of measurement of magnetic properties of magnetic sheet and strip at medium frequencies
ISO 4948-1, Steels – Classification – Part 1: Classification of steels into unalloyed and alloy steels based on chemical composition
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121, IEC Standard Rare earth-iron-boron (REFeB) Magnets
IEC 60050-151, IEC 60050-221 and in the product standards of the IEC 60404-8 series apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
———————- Page: 9 ———————-
– 8 – IEC 60404-1:2016 © IEC 2016
4 Magnetically soft materials (coercivity ≤1 kA/m)
4.1 Class A – Irons
4.1.1 Reference documents
These materials are covered by IEC 60404-8-6 and IEC 60404-8-10.
4.1.2 Chemical composition
The basic constituent of these materials is pure iron, and they are often referred to as
“commercially pure” or “magnetically soft” irons. The material also contains unavoidable impurities that may affect magnetic properties. The amount of impurities that adversely affect the remanence, coercivity, saturation, magnetic polarization and stability of the magnetic properties are limited to produce the required magnetic properties for the proposed application. For information the most significant impurities when they are present in these materials are carbon (up to 0,03 %), silicon (up to 0,1 %), manganese (up to 0,2 %),phosphorus (up to 0,015 %), sulphur (up to 0,03 %), aluminium (up to 0,08 %), titanium (up to 0,1 %) and vanadium (up to 0,1 %).
NOTE For improved free machining capability, the amount of phosphorus and sulphur can be higher than

indicated above.
4.1.3 Basis of subclassification
The recommended subclassification is based on coercivity values.
4.1.4 Available forms
These materials are available in a wide variety of forms. They may be supplied as slabs, billets, ingots or forgings; as hot-rolled bar in rectangular and square cross-sections; as hot-rolled wire rod in round, hexagonal and octagonal cross-sections; in cold-rolled and drawnforms as bar and wire; as hot- or cold-rolled sheet and strip.
4.1.5 Physical characteristics
In addition to the values of coercivity, a more complete definition of these materials can be based on the following characteristics: saturation magnetic polarization, magnetic polarization at various
• magnetic: values of magnetic field strength (from which permeability can be derived), stability of characteristics with time;
• mechanical: hardness, suitability for punching operations, free machining capability, deep drawing properties, tensile strength;
• metallurgical state: hot- or cold-worked, forged, deep drawn, fully processed state, i.e. final annealed.
NOTE For material not delivered in the fully processed state, subclassification is based on the coercivity measured after heat treatment according to the requirements of the product standard or the recommendations of the manufacturer.
Ranges of specified values for the above-mentioned magnetic characteristics in the fully processed state are given in the corresponding product specifications.
4.1.6 Main applications
The main applications are in DC relays, loudspeakers, electromagnets, magnetic clutches, brakes, parts for magnetic circuits in instruments and control apparatus, as well as for polebpieces and other DC parts for generators and motors.

China
grade e+
Magnetic properties and densities of REFeB magnets (IEC 60404-8-1:2015)
Brief designation Code
number
Maximum
BH
product
Remanent
flux
density
Coercivity Coercivity Relative
recoil
permeability
Density
(BH)max Br HcB HcJ μrec ρ
kJ/m3 mT kA/m kA/m Mg/m3
N/A REFeB 170/190 R7-1-1 170 980 700 1900 1.05 7.5
to
7.7
N28H REFeB 210/130 R7-1-2 210 1060 790 1300
N33M REFeB 250/120 R7-1-3 250 1130 840 1200
N38 REFeB 290/80 R7-1-4 290 1230 700 800
N28UH REFeB 200/190 R7-1-5 200 1060 760 1900
N33SH REFeB 240/180 R7-1-6 240 1160 840 1800
N38M REFeB 280/120 R7-1-7 280 1240 900 1200
N42 REFeB 320/88 R7-1-8 320 1310 800 880
N28EH REFeB 210/240 R7-1-9 210 1060 760 2400
N33UH REFeB 240/200 R7-1-10 240 1160 840 2000
N42H REFeB 310/130 R7-1-11 310 1300 900 1300
N33EH REFeB 250/240 R7-1-12 250 1200 830 2400
N35UH REFeB 260/200 R7-1-13 260 1210 840 2000
N45H REFeB 340/130 R7-1-14 340 1330 920 1300
N45 REFeB 360/90 R7-1-15 360 1350 800 900
N50 REFeB 380/100 R7-1-16 380 1420 990 1000
* e+ = equal
or superior
Typical values of the parameters:
Temperature coefficient of remanence α(Br) = -0.1 %/°C to -0.12 %/°C (for 20 °C to 100 °C)
Temperature coefficient of coercivity α(HcJ) = -0.45 %/°C to -0.6 %/°C (for 20 °C to 100 °C)
Curie temperature: 310 °C
Maximum opertating temperature: 200 °C

Sintered Neodymium-Iron-Boron Rod Magnets Magnetized Through Thickness

Excellent Magnetic Technical Block Neodymium-Iron-Boron Magnets N40H

Zinc Plated Sintered Neodymium-iron-boron Ellipse Shape Magnets

Neodymium-Iron-Boron Rectangular Magnet 12 x 4 x 4 mm

Double-Sided Adhesive Strong Neodymium Disc Magnets 1.26″D x 0.08″H

Neodymium Iron Boron Multipole Magnet