ASTM A1101-23

Standard Specification for Sintered and Fully Dense Neodymium Iron Boron (NdFeB) Permanent Magnets

ABSTRACT
This specification covers technically important, commercially available, magnetically hard sintered and fully dense neodymium iron boron (Nd2Fe14B, NdFeB, or “Neo”) permanent magnets. These materials are available in a wide range of compositions with a commensurately large range of magnetic properties. Neodymium iron boron magnets have approximate magnetic properties of residual magnetic induction from 1.08 T (10 800 G) up to 1.5 T (15 000 G) and intrinsic coercive field strength of 875 kA/m (11 000 Oe) to above 2785 kA/m (35 000 Oe). Special grades and isotropic (un-aligned) magnets can have properties outside these ranges.
SCOPE
1.1 This specification covers technically important, commercially available, magnetically hard sintered and fully dense neodymium iron boron (Nd2Fe14B, NdFeB, or “Neo”) permanent magnets. These materials are available in a wide range of compositions with a commensurately large range of magnetic properties. The numbers in the Nd2Fe14B name indicate the approximate atomic ratio of the key elements.  
1.2 Anisotropic (aligned) sintered and fully dense neodymium iron boron magnets have approximate magnetic properties of residual magnetic induction, Br, from 1.08 T
(10 800 G) up to 1.5 T (15 000 G) and intrinsic coercive field strength, HcJ, of 875 kA/m (11 000 Oe) to above 2785 kA/m (35 000 Oe). Fully dense but not sintered magnets include hot-deformed magnets using a plastic deformation technique, such as upsetting or extrusion, at elevated temperatures for the crystallographic alignment, as opposed to magnetic field alignment in sintered magnets. Special grades and isotropic (un-aligned) magnets can have properties outside these ranges (see Appendix X4). Specific magnetic hysteresis behavior (demagnetization curve) can be characterized using Test Method A977/A977M.  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to customary (cgs-emu and inch-pound) units which are provided for information only and are not considered standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2023
• ICS: 29.100.10 - Magnetic components
• ICS: 77.140.40 - Steels with special magnetic properties
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.02 - Material Specifications

Relations

• Replaces: ASTM A1101-16 - Standard Specification for Sintered and Fully Dense Neodymium Iron Boron (NdFeB) Permanent Magnets
• Effective Date: 01-Dec-2023
• Refers: ASTM A977/A977M-07(2020) - Standard Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs
• Effective Date: 01-Jun-2020

Overview

ASTM A1101-23 is the internationally recognized standard specification for sintered and fully dense neodymium iron boron (NdFeB or “Neo”) permanent magnets. Developed under the jurisdiction of ASTM Committee A06 on Magnetic Properties, this standard provides comprehensive guidelines for the classification, properties, ordering, testing, and quality requirements of commercially available NdFeB magnets. These magnets are known for their high magnetic strength and are widely used across multiple industries due to their superior performance and versatility.

Key Topics

• Material Types: The standard encompasses both sintered and hot-deformed NdFeB magnets, each available in a broad range of grades and magnetic properties.
• Magnetic Properties: Includes definitions of key parameters such as residual induction, intrinsic coercive field strength, and maximum energy product. Typical residual induction values range from 1.08 T (10,800 G) to 1.5 T (15,000 G), with intrinsic coercivity values from 875 kA/m (11,000 Oe) to above 2,785 kA/m (35,000 Oe).
• Composition and Classification: NdFeB magnet grades are defined by chemical composition and process methods. Extension to special grades, including isotropic and temperature-stable types, is possible as mutually agreed between producer and user.
• Testing and Evaluation: The standard details procedures for material evaluation, including the use of closed magnetic circuit measurements and referenced ASTM Test Methods such as A977/A977M.
• Quality and Safety: Addresses workmanship, appearance, dimensional tolerances, packaging, marking, and safety practices necessary for handling strong permanent magnets.

Applications

NdFeB permanent magnets specified under ASTM A1101-23 are essential components in numerous demanding applications, including:

• Electric Motors and Generators: Used in high-performance electric motors for automotive, industrial, and renewable energy sectors due to their strong magnetic field and compact size.
• Consumer Electronics: Integral to the miniaturization of devices such as hard disk drives, mobile phones, and audio equipment.
• Medical Devices: Applied in MRI machines, surgical instruments, and other advanced medical technologies requiring reliable and compact magnetic sources.
• Aerospace and Defense: Preferred for their high energy density in guidance systems, actuators, and sensors.
• Automotive: Employed in hybrid and electric vehicle motors, sensors, and actuators.
• Industrial Automation: Widely used in robotics, magnetic separators, and holding mechanisms.

Related Standards

Several standards support and complement the requirements set out in ASTM A1101-23, including:

• ASTM A340: Terminology of Symbols and Definitions Relating to Magnetic Testing - defines key terms used in magnetic materials specification.
• ASTM A977/A977M: Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials - provides methods for accurate magnetic property measurement.
• MMPA Standard No. 0100-00: Standard Specifications for Permanent Magnet Materials - offers further guidance for permanent magnet classification.
• IEC 60404-8-1: Magnetic materials – Specifications for magnetically hard materials at the international level.

Practical Value

The ASTM A1101-23 standard plays a critical role in:

• Ensuring Consistency and Quality: By providing a unified framework for specifying, classifying, and testing neodymium iron boron permanent magnets.
• Enabling Performance Optimization: Allowing users to select appropriate grades for specific application requirements, including magnetic strength, thermal stability, and resistance to demagnetization.
• Facilitating Global Trade: Supporting international procurement and compliance through alignment with widely accepted test methods and classification systems.

By adhering to ASTM A1101-23, manufacturers, engineers, and procurement professionals ensure reliable performance, safety, and compatibility in their use of NdFeB permanent magnets, critical for advanced technological applications and product innovation.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A1101 − 23
Standard Specification for
Sintered and Fully Dense Neodymium Iron Boron (NdFeB)
Permanent Magnets
This standard is issued under the fixed designation A1101; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This specification covers technically important, com-
Barriers to Trade (TBT) Committee.
mercially available, magnetically hard sintered and fully dense
neodymium iron boron (Nd Fe B, NdFeB, or “Neo”) perma-
2 14
2. Referenced Documents
nent magnets. These materials are available in a wide range of
2.1 ASTM Standards:
compositions with a commensurately large range of magnetic
A340 Terminology of Symbols and Definitions Relating to
properties. The numbers in the Nd Fe B name indicate the
2 14
Magnetic Testing
approximate atomic ratio of the key elements.
A977/A977M Test Method for Magnetic Properties of High-
1.2 Anisotropic (aligned) sintered and fully dense neo-
Coercivity Permanent Magnet Materials Using Hyster-
dymium iron boron magnets have approximate magnetic prop-
esigraphs
erties of residual magnetic induction, B , from 1.08 T
r
2.2 Other Standards:
(10 800 G) up to 1.5 T (15 000 G) and intrinsic coercive field
MMPA Standard No. 0100-00 Standard Specifications for
strength, H , of 875 kA ⁄m (11 000 Oe) to above 2785 kA ⁄m
cJ
Permanent Magnet Materials
(35 000 Oe). Fully dense but not sintered magnets include
IEC 60404-8-1 Magnetic Materials Part 8: Specifications for
hot-deformed magnets using a plastic deformation technique,
Individual Materials Section 1 – Standard Specifications
such as upsetting or extrusion, at elevated temperatures for the
for Magnetically Hard Materials
crystallographic alignment, as opposed to magnetic field align-
ment in sintered magnets. Special grades and isotropic (un-
3. Terminology
aligned) magnets can have properties outside these ranges (see
3.1 The terms and symbols used in this specification, unless
Appendix X4). Specific magnetic hysteresis behavior (demag-
netization curve) can be characterized using Test Method otherwise noted, are defined in Terminology A340.
A977/A977M.
3.2 Terms that are not defined in Terminology A340 but are
1.3 The values stated in SI units are to be regarded as in common usage and used herein are as follows.
3.2.1 Recoil permeability, μ , is the permeability corre-
standard. The values given in parentheses are mathematical
(rec)
conversions to customary (cgs-emu and inch-pound) units sponding to the slope of the recoil line. For reference see
incremental, relative, and reversible permeabilities as defined
which are provided for information only and are not considered
standard. in Terminology A340. In practical use, this is the slope of the
normal hysteresis loop in the second quadrant and in proximity
1.4 This standard does not purport to address all of the
to the B-axis. The value of recoil permeability is dimension-
safety concerns, if any, associated with its use. It is the
less. Note that in producers’ product literature recoil perme-
responsibility of the user of this standard to establish appro-
ability is sometimes represented by the symbol μ , which is
r
priate safety, health, and environmental practices and deter-
defined by Terminology A340 as relative permeability.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ization established in the Decision on Principles for the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
This specification is under the jurisdiction of ASTM Committee A06 on This standard is no longer actively maintained but it is still available from the
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on Permanent Magnet Division of A3 (Association for Advancing Automation),
Material Specifications. http://www.automate.org.
Current edition approved Dec. 1, 2023. Published January 2024. Originally Available from International Electrotechnical Commission (IEC), 3, rue de
approved in 2016. Last previous edition was approved in 2016 as A1101 – 16. DOI: Varembé, 1st Floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, http://
10.1520/A1101-23 www.iec.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A1101 − 23
3.2.2 Magnetic characteristics change with temperature. 6.3 There are a number of additional elements included in
Two key metrics of permanent magnet performance are re- the alloy to adjust magnetic, chemical, or mechanical proper-
sidual induction, B , and intrinsic coercive field strength, H . ties. See Appendix X3 for additional information.
r cJ
The change in these characteristics over a defined and limited
temperature range can be reversible, that is, nondestructive.
7. Physical and Mechanical Properties
This change is represented by values called reversible tempera-
7.1 Typical thermal and physical properties are listed in
ture coefficients. The symbol for reversible temperature coef-
Table X2.1 in Appendix X2.
ficient of induction is α(B ) and of (intrinsic) coercivity is
r
7.2 Physical density values are given for information pur-
α(H ). They are expressed in percent change per degree
cJ
poses only and are not mandatory.
Celsius, %/°C, or the numerically equivalent percent per
Kelvin, %/K, and represent the average rate of change of the
7.3 Neodymium iron boron magnets are used for their
characteristic within the specified temperature range. The magnetic characteristics. The end-use application should not
change in magnetic characteristics is nonlinear, so it is neces-
rely on them for structural purposes due to low tensile and
sary to specify the temperature range over which the coefficient flexural strength. These materials are brittle, and can chip or
applies.
break easily. Magnetic properties may also be affected by
3.2.3 The maximum recommended working temperature of
physical stress.
a permanent magnet, T , is a semi-arbitrary value sometimes
w
7.4 Strength testing of brittle materials such as neodymium
assigned by magnet manufacturers to their products. T is not
w
iron boron is difficult, expensive, time-consuming, and there
normative. See Appendix X6 for a more complete discussion.
may be considerable scatter in the measured values. Producers
typically make a complete set of measurements at the onset of
4. Classification
production and they are seldom repeated.
4.1 The classification of sintered neodymium iron boron
permanent magnets is given in Table 1. The classification of
8. Magnetic Property Requirements
hot-deformed neodymium iron boron permanent magnets is
8.1 Magnetic properties of sintered neodymium iron boron
given in Table 2. Cross-reference to MMPA standard No.
permanent magnets are given in Table 1. Magnetic properties
0100-00 and IEC 60404-8-1 is provided in Appendix X1.
of hot-deformed neodymium iron boron permanent magnets
are given in Table 2.
5. Ordering Information
8.2 The values of magnetic properties listed in the table are
5.1 Orders for parts conforming to this specification shall
specified minimum values at 20 °C 6 2 °C (68 °F 6 4 °F),
include the following information:
determined after magnetizing to saturation in closed magnetic
5.1.1 Reference to this specification and year of issue/
circuit.
revision.
5.1.2 Reference to an applicable part drawing.
8.3 The specified values of magnetic properties are valid
5.1.3 Magnetic property requirements, if they are more
only for magnet test specimens with a uniform cross-section
stringent than the minimum values listed in the tables.
along the axis of magnetization. Properties for anisotropic
5.1.4 Quantity required.
(magnetically oriented) magnets are measured along the axis of
5.1.5 The required magnetization state of the provided
preferred orientation. In the case of radially oriented magnets
material (unmagnetized, fully magnetized, magnetized and
where the orientation axes vary along the curvature, care
thermally stabilized, magnetized and then partially demagne-
should be taken to minimize the error arising from the
tized). This information should appear on the part drawing
misalignment between the orientation and measurement field
whenever possible.
axis, for example, to use smaller circumferential length of the
5.1.6 Certification of magnetic property evaluation.
test specimen.
5.1.7 Marking and packaging requirements.
8.4 Because of the nature of permanent magnet production,
5.1.8 Exceptions to this specification or special require-
magnetic testing of each lot is recommended, especially for
ments such as plating, coating, or functional testing as mutually
applications where the magnet performance is closely speci-
agreed upon by the producer and user.
fied. Such magnetic property evaluations shall be conducted in
the manner described below. Where the magnet shape is not
6. Chemical Composition
suitable for magnetic testing, a specimen shall be cut from the
6.1 Neodymium iron boron magnets should be specified
magnet using appropriate slicing and grinding techniques,
primarily by magnetic performance. Chemical composition can
paying attention to any magnetic orientation within the magnet.
have an influence on both magnetic and physical characteristics
8.4.1 The magnetic properties shall be determined in accor-
but should only be specified when other options are insufficient
dance with Test Method A977/A977M, or by using a suitable,
to meet user requirements. Agreement on composition must be
mutually agreed upon magnetometric method.
mutually arrived at by producer and user.
8.4.2 When magnets are being purchased in the fully
6.2 The general chemical composition of neodymium iron magnetized condition, the testing shall determine the magnetic
boron includes the elements neodymium, iron, and boron. properties from the as-received magnetization state, followed
Approximate chemical compositions are listed in Table X3.1 by magnetization to saturation and testing of the magnetic
and are typical but not mandatory. properties from the fully magnetized condition.
A1101 − 23
A
TABLE 1 Sintered Neodymium Iron Boron Permanent Magnets: Classification and Minimum Magnetic Property Requirements
Maximum Residual Coercive Field Intrinsic Coercive
Energy Product Induction Strength Field Strength
B
ASTM Designation
(BH) B H H
max r cB cJ
kJ/m (MGOe) mT (G) kA/m (Oe) kA/m (Oe)
ANISOTROPIC Nd Fe B
2 14
ND-SA-333/875 333 (41.8) 1 325 (13 250) 832 (10 450) 875 (11 000)
ND-SA-355/875 355 (44.6) 1 369 (13 690) 832 (10 450) 875 (11 000)
ND-SA-370/875 370 (46.5) 1 397 (13 970) 832 (10 450) 875 (11 000)
ND-SA-385/875 385 (48.4) 1 426 (14 260) 832 (10 450) 875 (11 000)
ND-SA-407/875 407 (51.1) 1 465 (14 650) 832 (10 450) 875 (11 000)
ND-SA-222/955 222 (27.9) 1 082 (10 820) 820 (10 300) 955 (12 000)
ND-SA-244/955 244 (30.7) 1 136 (11 360) 861 (10 820) 955 (12 000)
ND-SA-259/955 259 (32.5) 1 168 (11 680) 907 (11 400) 955 (12 000)
ND-SA-281/955 281 (35.3) 1 218 (12 180) 907 (11 400) 955 (12 000)
ND-SA-296/955 296 (37.2) 1 250 (12 500) 907 (11 400) 955 (12 000)
ND-SA-311/955 311 (39.1) 1 281 (12 810) 907 (11 400) 955 (12 000)
ND-SA-333/955 333 (41.8) 1 325 (13 250) 907 (11 400) 955 (12 000)
ND-SA-355/955 355 (44.6) 1 369 (13 690) 907 (11 400) 955 (12 000)
ND-SA-370/955 370 (46.5) 1 397 (13 970) 907 (11 400) 955 (12 000)
ND-SA-385/955 385 (48.4) 1 426 (14 260) 907 (11 400) 955 (12 000)
ND-SA-222/1114 222 (27.9) 1 082 (10 820) 820 (10 300) 1 114 (14 000)
ND-SA-244/1114 244 (30.7) 1 136 (11 360) 861 (10 820) 1 114 (14 000)
ND-SA-259/1114 259 (32.5) 1 168 (11 680) 885 (11 120) 1 114 (14 000)
ND-SA-281/1114 281 (35.3) 1 218 (12 180) 923 (11 600) 1 114 (14 000)
ND-SA-296/1114 296 (37.2) 1 250 (12 500) 947 (11 900) 1 114 (14 000)
ND-SA-311/1114 311 (39.1) 1 281 (12 810) 971 (12 200) 1 114 (14 000)
ND-SA-333/1114 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 114 (14 000)
ND-SA-355/1114 355 (44.6) 1 369 (13 690) 1 058 (13 300) 1 114 (14 000)
ND-SA-370/1114 370 (46.5) 1 397 (13 970) 1 058 (13 300) 1 114 (14 000)
ND-SA-385/1114 385 (48.4) 1 426 (14 260) 1 058 (13 300) 1 114 (14 000)
ND-SA-207/1353 207 (26.0) 1 045 (10 450) 792 (9 950) 1 353 (17 000)
ND-SA-222/1353 222 (27.9) 1 082 (10 820) 820 (10 300) 1 353 (17 000)
ND-SA-244/1353 244 (30.7) 1 136 (11 360) 861 (10 820) 1 353 (17 000)
ND-SA-259/1353 259 (32.5) 1 168 (11 680) 885 (11 120) 1 353 (17 000)
ND-SA-281/1353 281 (35.3) 1 218 (12 180) 923 (11 600) 1 353 (17 000)
ND-SA-296/1353 296 (37.2) 1 250 (12 500) 947 (11 900) 1 353 (17 000)
ND-SA-311/1353 311 (39.1) 1 281 (12 810) 971 (12 200) 1 353 (17 000)
ND-SA-333/1353 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 353 (17 000)
ND-SA-355/1353 355 (44.6) 1 369 (13 690) 1 038 (13 040) 1 353 (17 000)
ND-SA-370/1353 370 (46.5) 1 397 (13 970) 1 058 (13 300) 1 353 (17 000)
ND-SA-207/1592 207 (26.0) 1 045 (10 450) 792 (9 950) 1 592 (20 000)
ND-SA-222/1592 222 (27.9) 1 082 (10 820) 820 (10 300) 1 592 (20 000)
ND-SA-244/1592 244 (30.7) 1 136 (11 360) 861 (10 820) 1 592 (20 000)
ND-SA-259/1592 259 (32.5) 1 168 (11 680) 885 (11 120) 1 592 (20 000)
ND-SA-281/1592 281 (35.3) 1 218 (12 180) 923 (11 600) 1 592 (20 000)
ND-SA-296/1592 296 (37.2) 1 250 (12 500) 947 (11 900) 1 592 (20 000)
ND-SA-311/1592 311 (39.1) 1 281 (12 810) 971 (12 200) 1 592 (20 000)
ND-SA-333/1592 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 592 (20 000)
ND-SA-355/1592 355 (44.6) 1 369 (13 690) 1 038 (13 040) 1 592 (20 000)
ND-SA-207/1989 207 (26.0) 1 045 (10 450) 792 (9 950) 1 989 (25 000)
ND-SA-222/1989 222 (27.9) 1 082 (10 820) 820 (10 300) 1 989 (25 000)
ND-SA-244/1989 244 (30.7) 1 136 (11 360) 861 (10 820) 1 989 (25 000)
ND-SA-259/1989 259 (32.5) 1 168 (11 680) 885 (11 120) 1 989 (25 000)
ND-SA-281/1989 281 (35.3) 1 218 (12 180) 923 (11 600) 1 989 (25 000)
ND-SA-296/1989 296 (37.2) 1 250 (12 500) 947 (11 900) 1 989 (25 000)
ND-SA-311/1989 311 (39.1) 1 281 (12 810) 971 (12 200) 1 989 (25 000)
ND-SA-333/1989 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 989 (25 000)
ND-SA-207/2387 207 (26.0) 1 045 (10 450) 792 (9 950) 2 387 (30 000)
ND-SA-222/2387 222 (27.9) 1 082 (10 820) 820 (10 300) 2 387 (30 000)
ND-SA-244/2387 244 (30.7) 1 136 (11 360) 861 (10 820) 2 387 (30 000)
ND-SA-259/2387 259 (32.5) 1 168 (11 680) 885 (11 120) 2 387 (30 000)
ND-SA-281/2387 281 (35.3) 1 218 (12 180) 923 (11 600) 2 387 (30 000)
ND-SA-207/2785 207 (26.0) 1 045 (10 450) 792 (9 950) 2 785 (35 000)
ND-SA-222/2785 222 (27.9) 1 082 (10 820) 820 (10 300) 2 785 (35 000)
ND-SA-244/2785 244 (30.7) 1 136 (11 360) 861 (10 820) 2 785 (35 000)
A
Magnetic properties at 20 °C (68 °F).
B
The ASTM designation conforms to the requirements of this specification. ASTM Designations are of the form MM-TT-XX/YY, where:
MM = material (ND = neodymium iron boron),
TT = type of processing and orientation (S = sintered; I = isotropic (non-oriented), A = anisotropic (oriented)),
XX = energy product in kJ/m rounded to the nearest integer, and
YY = intrinsic coercivity in kA/m rounded to the nearest integer.
A1101 − 23
A
TABLE 2 Hot-deformed Neodymium Iron Boron Permanent Magnets: Classification and Minimum Magnetic Property Requirements
Maximum Residual Coercive Field Intrinsic Coercive
Energy Product Induction Strength Field Strength
B
ASTM Designation
(BH) B H H
max r cB cJ
kJ/m (MGOe) mT (G) kA/m (Oe) kA/m (Oe)
ANISOTROPIC Nd Fe B
2 14
ND-DR-240/1110 240 (30.2) 1 140 (11 400) 830 (10 430) 1 110 (13 949)
ND-DR-230/1590 230 (28.9) 1 080 (10 800) 810 (10 179) 1 590 (19 981)
ND-DR-270/1110 270 (33.9) 1 220 (12 200) 870 (10 933) 1 110 (13 949)
ND-DR-270/1430 270 (33.9) 1 220 (12 200) 880 (11 058) 1 430 (17 970)
ND-DR-300/1110 300 (37.7) 1 280 (12 800) 920 (11 561) 1 110 (13 949)
ND-DR-320/900 320 (40.2) 1 300 (13 000) 840 (10 556) 900 (11 310)
ND-DR-290/1430 290 (36.4) 1 270 (12 700) 920 (11 561) 1 430 (17 970)
ND-DR-310/1350 310 (39.0) 1 290 (12 900) 970 (12 189) 1 350 (16 965)
ND-DR-250/1800 250 (31.4) 1 170 (11 700) 900 (11 310) 1 800 (22 619)
ND-DA-330/1590 330 (41.5) 1 320 (13 200) 1 000 (12 566) 1 590 (19 981)
ND-DA-360/1570 360 (45.2) 1 370 (13 700) 1 050 (13 195) 1 570 (19 729)
A
Magnetic properties at 20 °C (68 °F).
B
The ASTM designation conforms to the requirements of this specification. ASTM Designations are of the form MM-TT-XX/YY, where:
MM = material (ND = neodymium iron boron),
TT = type of processing and orientation (S = sintered; D = hot-deformed; I = isotropic (non-oriented), A = axial (axially oriented); R = radial (radially oriented),
XX = energy product in kJ/m rounded to the nearest integer, and
YY = intrinsic coercivity in kA/m rounded to the nearest integer.
8.4.3 When magnets are being purchased in the unmagne- 9.5 Cracks visible to the naked eye shall not be permitted
tized condition or in an unknown state of magnetization, the unless otherwise agreed to by producer and user.
test laboratory shall magnetize the test specimen(s) to satura-
10. Sampling
tion in the same direction as the received specimen’s indicated
direction of orientation and measure the magnetic properties
10.1 A lot shall consist of parts of the same form and
from this fully magnetized condition.
dimensions, produced from a single mixed powder batch or
8.4.4 When magnets are being purchased in a calibrated,
sintering or hot-deformation run, and from an unchanged
stabilized, or “knocked-down” condition, magnets should be
process, without discontinuity in production, and submitted for
handled with care to prevent exposure to externally applied
inspection at one time.
fields. Refer to Appendix X6 for an explanation of these terms.
10.2 The producer and user shall agree upon a representa-
During testing using Test Method A977/A977M, the measure-
tive number of specimens for testing. Typically, a suitable
ment should proceed in the second quadrant only, without
number of parts, as mutually agreed upon between producer
attempting to saturate the magnet specimen, to avoid changing
and user, shall be randomly selected from each lot. It is
the magnetization state of the material prior to test.
advisable to test a minimum of two parts from each lot, and
8.4.5 Other test methods may be utilized as agreed to
more if there is reason to suspect that the magnetic properties
between producer and user. Such tests may include the open
are not uniform throughout the lot.
circuit magnetization Helmholtz test, field strength measure-
ments in a defined magnetic circuit or adjacent to the magnet
11. Rejection and Rehearing
surface.
11.1 Parts that fail to conform to the requirements of this
specification shall be rejected. Rejection should be reported to
9. Workmanship, Finish, and Appearance
the producer promptly and in writing. In case of dissatisfaction
9.1 Dimensions and tolerances shall be as specified on the
with the results of the test, the producer may make a claim for
magnet drawing and must be agreed upon between the pro-
a rehearing.
ducer and the user.
11.2 The disposition of rejected parts shall be subject to
9.2 Though porosity and voids are uncommon in sintered or
agreement between the producer and user.
hot-deformed neodymium iron boron magnets, their appear-
ance shall not in themselves constitute reason for rejection 12. Certification
unless agreed upon between producer and user. Allowable
12.1 When specified in the purchase order or contract, the
amounts of porosity and voids shall be documented in writing
user shall be furnished certification that samples representing
and included as part of the ordering or contracting process.
each lot have been either tested or inspected as directed in this
9.3 Magnets shall be free of adhered magnetic particles and specification and that the requirements have been met.
surface residue which may interfere with assembly or proper
12.2 When specified in the purchase order or contract, a
device function.
report of the test results shall, at a minimum, include:
9.4 Chips shall be acceptable if no more than 10 % of any 12.2.1 Grade of material.
surface identified as a magnetic pole surface is removed. 12.2.2 Lot or batch number.
A1101 − 23
12.2.3 Magnetic test results. ing upon local, national, and international laws. It is the
12.2.4 Results of any other tests stipulated in the purchase responsibility of the producer to ensure packaging meets all
order or contract. relevant regulations. This may require rearranging the parts
within the shipping container, adding sheets of steel or other
13. Packaging and Package Marking magnetically soft shielding material, or both, or other special-
ized packaging procedures as determined by regulation, carrier
13.1 Packaging shall be subject to agreement between the
policy, or by agreement between producer and user, to reduce
producer and the user.
the magnetic field external to the shipping container below the
13.2 Parts furnished under this specification shall be in a
required levels.
container identified by the name or symbol of the parts
producer. 14. Keywords
13.3 Magnetized parts shall be properly labeled as such for 14.1 coercive field strength; hot-deformed rare earth mag-
safe handling and shipping purposes. net; magnetic field strength; magnetic flux density; magnetic
13.3.1 Magnetized parts to be shipped via aircraft must be properties; maximum energy product; neodymium iron boron
packaged in an appropriate manner to meet applicable require- magnet; neo magnet; permanent magnet; residual induction;
ments for air shipment. These requirements may vary depend- sintered rare earth magnet
APPENDIXES
(Nonmandatory Information)
X1. CLASSIFICATION
X1.1 See Table X1.1.
A1101 − 23
TABLE X1.1 Neodymium Iron Boron Permanent Magnets: Classification and Grade Cross Reference
NOTE 1—“.” indicates that there is no known published data.
ASTM MMPA IEC
ASTM MMPA Brief IEC Brief IEC Code
A
Designation Designation Designation Number
(none) . REFeB 170/190 R7-1-1
ND-SA-207/1592 . REFeB 210/130 R7-1-2
ND-SA-244/1114 . REFeB 250/120 R7-1-3
ND-SA-281/955 . REFeB 290/80 R7-1-4
ND-SA-207/1592 . REFeB 200/190 R7-1-5
ND-SA-244/1592 . REFeB 240/180 R7-1-6
ND-SA-281/1114 . REFeB 280/120 R7-1-7
ND-SA-311/955 . REFeB 320/88 R7-1-8
ND-SA-207/2387 . REFeB 210/240 R7-1-9
ND-SA-244/1592 . REFeB 240/200 R7-1-10
ND-SA-311/135
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A1101 − 16 A1101 − 23
Standard Specification for
Sintered and Fully Dense Neodymium Iron Boron (NdFeB)
Permanent Magnets
This standard is issued under the fixed designation A1101; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers technically important, commercially available, magnetically hard sintered and fully dense
neodymium iron boron (Nd Fe B, NdFeB, or “Neo”) permanent magnets. These materials are available in a wide range of
2 14
compositions with a commensurately large range of magnetic properties. The numbers in the Nd Fe B name indicate the
2 14
approximate atomic ratio of the key elements.
1.2 Neodymium Anisotropic (aligned) sintered and fully dense neodymium iron boron magnets have approximate magnetic
properties of residual magnetic induction, B , from 1.08 T1.08 T
r
(10 800 G) 800 G) up to 1.5 T (15 000 G) 1.5 T (15 000 G) and intrinsic coercive field strength, H , of 875875 kA kA/m (11 000
cJ
Oe) to above 2785⁄m (11 000 Oe) to above 2785 kA kA/m (35 000 Oe). ⁄m (35 000 Oe). Fully dense but not sintered magnets
include hot-deformed magnets using a plastic deformation technique, such as upsetting or extrusion, at elevated temperatures for
the crystallographic alignment, as opposed to magnetic field alignment in sintered magnets. Special grades and isotropic
(un-aligned) magnets can have properties outside these ranges (see Appendix X4). Specific magnetic hysteresis behavior
(demagnetization curve) can be characterized using Test Method A977/A977M.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to
customary (cgs-emu and inch-pound) units which are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs
This specification is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on Material
Specifications.
Current edition approved Nov. 1, 2016Dec. 1, 2023. Published November 2016January 2024. Originally approved in 2016. Last previous edition was approved in 2016
as A1101 – 16. DOI: 10.1520/A1101–1610.1520/A1101-23
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A1101 − 23
2.2 Other Standards:
MMPA Standard No. 0100-00 Standard Specifications for Permanent Magnet Materials
IEC 60404-8-1 Magnetic Materials Part 8: Specifications for Individual Materials Section 1 – Standard Specifications for
Magnetically Hard Materials
3. Terminology
3.1 The terms and symbols used in this specification, unless otherwise noted, are defined in Terminology A340.
3.2 Terms that are not defined in Terminology A340 but are in common usage and used herein are as follows.
3.2.1 Recoil permeability, μ , is the permeability corresponding to the slope of the recoil line. For reference see incremental,
(rec)
relative, and reversible permeabilities as defined in Terminology A340. In practical use, this is the slope of the normal hysteresis
loop in the second quadrant and in proximity to the B-axis. The value of recoil permeability is dimensionless. Note that in
producers’ product literature recoil permeability is sometimes represented by the symbol μ , which is defined by Terminology A340
r
as relative permeability.
3.2.2 Magnetic characteristics change with temperature. Two key metrics of permanent magnet performance are residual
induction, B , and intrinsic coercive field strength, H . The change in these characteristics over a defined and limited temperature
r cJ
range can be reversible, that is, nondestructive. This change is represented by values called reversible temperature coefficients. The
symbol for reversible temperature coefficient of induction is α(B ) and of (intrinsic) coercivity is α(H ). They are expressed in
r cJ
percent change per degree Celsius, %/°C, or the numerically equivalent percent per Kelvin, %/K, and represent the average rate
of change of the characteristic within the specified temperature range. The change in magnetic characteristics is nonlinear, so it
is necessary to specify the temperature range over which the coefficient applies.
3.2.3 The maximum recommended working temperature of a permanent magnet, T , is a semi-arbitrary value sometimes assigned
w
by magnet manufacturers to their products. T is not normative. See Appendix X6 for a more complete discussion.
w
4. Classification
4.1 The classification of sintered neodymium iron boron permanent magnets is given in Table 1. The classification of hot-deformed
neodymium iron boron permanent magnets is given in Table 2. Cross-reference to MMPA standard No. 0100-00 and IEC
60404-8-1 is provided in Appendix X1.
5. Ordering Information
5.1 Orders for parts conforming to this specification shall include the following information:
5.1.1 Reference to this specification and year of issue/revision.
5.1.2 Reference to an applicable part drawing.
5.1.3 Magnetic property requirements, if they are more stringent than the minimum values listed in the tables.
5.1.4 Quantity required.
5.1.5 The required magnetization state of the provided material (unmagnetized, fully magnetized, magnetized and thermally
stabilized, magnetized and then partially demagnetized). This information should appear on the part drawing whenever possible.
5.1.6 Certification of magnetic property evaluation.
5.1.7 Marking and packaging requirements.
Available from the Permanent Magnet Division of the SMMA (www.smma.org). It was previously available from The International Magnetics Association (IMA). The
IMA had been the successor to the MMPA and both organizations (MMPA and IMA) no longer exist.This standard is no longer actively maintained but it is still available
from the Permanent Magnet Division of A3 (Association for Advancing Automation), http://www.automate.org.
Available from International Electrotechnical Commission (IEC), 3, rue de Varembé, 1st Floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
A1101 − 23
A
TABLE 1 Sintered Neodymium Iron Boron Permanent Magnets: Classification and Minimum Magnetic Property Requirements
Maximum Residual Coercive Field Intrinsic Coercive
Energy Product Induction Strength Field Strength
B
ASTM Designation
(BH) B H H
max r cB cJ
kJ/m (MGOe) mT (G) kA/m (Oe) kA/m (Oe)
ANISOTROPIC Nd Fe B
2 14
ND-SA-333/875 333 (41.8) 1325 (13250) 832 (10450) 875 (11000)
ND-SA-333/875 333 (41.8) 1 325 (13 250) 832 (10 450) 875 (11 000)
ND-SA-355/875 355 (44.6) 1369 (13690) 832 (10450) 875 (11000)
ND-SA-355/875 355 (44.6) 1 369 (13 690) 832 (10 450) 875 (11 000)
ND-SA-370/875 370 (46.5) 1397 (13970) 832 (10450) 875 (11000)
ND-SA-370/875 370 (46.5) 1 397 (13 970) 832 (10 450) 875 (11 000)
ND-SA-385/875 385 (48.4) 1426 (14260) 832 (10450) 875 (11000)
ND-SA-385/875 385 (48.4) 1 426 (14 260) 832 (10 450) 875 (11 000)
ND-SA-407/875 407 (51.1) 1465 (14650) 832 (10450) 875 (11000)
ND-SA-407/875 407 (51.1) 1 465 (14 650) 832 (10 450) 875 (11 000)
ND-SA-222/955 222 (27.9) 1082 (10820) 820 (10300) 955 (12000)
ND-SA-222/955 222 (27.9) 1 082 (10 820) 820 (10 300) 955 (12 000)
ND-SA-244/955 244 (30.7) 1136 (11360) 861 (10820) 955 (12000)
ND-SA-244/955 244 (30.7) 1 136 (11 360) 861 (10 820) 955 (12 000)
ND-SA-259/955 259 (32.5) 1168 (11680) 907 (11400) 955 (12000)
ND-SA-259/955 259 (32.5) 1 168 (11 680) 907 (11 400) 955 (12 000)
ND-SA-281/955 281 (35.3) 1218 (12180) 907 (11400) 955 (12000)
ND-SA-281/955 281 (35.3) 1 218 (12 180) 907 (11 400) 955 (12 000)
ND-SA-296/955 296 (37.2) 1250 (12500) 907 (11400) 955 (12000)
ND-SA-296/955 296 (37.2) 1 250 (12 500) 907 (11 400) 955 (12 000)
ND-SA-311/955 311 (39.1) 1281 (12810) 907 (11400) 955 (12000)
ND-SA-311/955 311 (39.1) 1 281 (12 810) 907 (11 400) 955 (12 000)
ND-SA-333/955 333 (41.8) 1325 (13250) 907 (11400) 955 (12000)
ND-SA-333/955 333 (41.8) 1 325 (13 250) 907 (11 400) 955 (12 000)
ND-SA-355/955 355 (44.6) 1369 (13690) 907 (11400) 955 (12000)
ND-SA-355/955 355 (44.6) 1 369 (13 690) 907 (11 400) 955 (12 000)
ND-SA-370/955 370 (46.5) 1397 (13970) 907 (11400) 955 (12000)
ND-SA-370/955 370 (46.5) 1 397 (13 970) 907 (11 400) 955 (12 000)
ND-SA-385/955 385 (48.4) 1426 (14260) 907 (11400) 955 (12000)
ND-SA-385/955 385 (48.4) 1 426 (14 260) 907 (11 400) 955 (12 000)
ND-SA-222/1114 222 (27.9) 1082 (10820) 820 (10300) 1114 (14000)
ND-SA-222/1114 222 (27.9) 1 082 (10 820) 820 (10 300) 1 114 (14 000)
ND-SA-244/1114 244 (30.7) 1136 (11360) 861 (10820) 1114 (14000)
ND-SA-244/1114 244 (30.7) 1 136 (11 360) 861 (10 820) 1 114 (14 000)
ND-SA-259/1114 259 (32.5) 1168 (11680) 885 (11120) 1114 (14000)
ND-SA-259/1114 259 (32.5) 1 168 (11 680) 885 (11 120) 1 114 (14 000)
ND-SA-281/1114 281 (35.3) 1218 (12180) 923 (11600) 1114 (14000)
ND-SA-281/1114 281 (35.3) 1 218 (12 180) 923 (11 600) 1 114 (14 000)
ND-SA-296/1114 296 (37.2) 1250 (12500) 947 (11900) 1114 (14000)
ND-SA-296/1114 296 (37.2) 1 250 (12 500) 947 (11 900) 1 114 (14 000)
ND-SA-311/1114 311 (39.1) 1281 (12810) 971 (12200) 1114 (14000)
ND-SA-311/1114 311 (39.1) 1 281 (12 810) 971 (12 200) 1 114 (14 000)
ND-SA-333/1114 333 (41.8) 1325 (13250) 1004 (12620) 1114 (14000)
ND-SA-333/1114 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 114 (14 000)
ND-SA-355/1114 355 (44.6) 1369 (13690) 1058 (13300) 1114 (14000)
ND-SA-355/1114 355 (44.6) 1 369 (13 690) 1 058 (13 300) 1 114 (14 000)
ND-SA-370/1114 370 (46.5) 1397 (13970) 1058 (13300) 1114 (14000)
ND-SA-370/1114 370 (46.5) 1 397 (13 970) 1 058 (13 300) 1 114 (14 000)
ND-SA-385/1114 385 (48.4) 1426 (14260) 1058 (13300) 1114 (14000)
ND-SA-385/1114 385 (48.4) 1 426 (14 260) 1 058 (13 300) 1 114 (14 000)
ND-SA-207/1353 207 (26.0) 1045 (10450) 792 (9950) 1353 (17000)
ND-SA-207/1353 207 (26.0) 1 045 (10 450) 792 (9 950) 1 353 (17 000)
ND-SA-222/1353 222 (27.9) 1082 (10820) 820 (10300) 1353 (17000)
ND-SA-222/1353 222 (27.9) 1 082 (10 820) 820 (10 300) 1 353 (17 000)
ND-SA-244/1353 244 (30.7) 1136 (11360) 861 (10820) 1353 (17000)
ND-SA-244/1353 244 (30.7) 1 136 (11 360) 861 (10 820) 1 353 (17 000)
ND-SA-259/1353 259 (32.5) 1168 (11680) 885 (11120) 1353 (17000)
ND-SA-259/1353 259 (32.5) 1 168 (11 680) 885 (11 120) 1 353 (17 000)
ND-SA-281/1353 281 (35.3) 1218 (12180) 923 (11600) 1353 (17000)
ND-SA-281/1353 281 (35.3) 1 218 (12 180) 923 (11 600) 1 353 (17 000)
ND-SA-296/1353 296 (37.2) 1250 (12500) 947 (11900) 1353 (17000)
ND-SA-296/1353 296 (37.2) 1 250 (12 500) 947 (11 900) 1 353 (17 000)
ND-SA-311/1353 311 (39.1) 1281 (12810) 971 (12200) 1353 (17000)
ND-SA-311/1353 311 (39.1) 1 281 (12 810) 971 (12 200) 1 353 (17 000)
ND-SA-333/1353 333 (41.8) 1325 (13250) 1004 (12620) 1353 (17000)
ND-SA-333/1353 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 353 (17 000)
ND-SA-355/1353 355 (44.6) 1369 (13690) 1038 (13040) 1353 (17000)
ND-SA-355/1353 355 (44.6) 1 369 (13 690) 1 038 (13 040) 1 353 (17 000)
ND-SA-370/1353 370 (46.5) 1397 (13970) 1058 (13300) 1353 (17000)
ND-SA-370/1353 370 (46.5) 1 397 (13 970) 1 058 (13 300) 1 353 (17 000)
ND-SA-207/1592 207 (26.0) 1045 (10450) 792 (9950) 1592 (20000)
A1101 − 23
ND-SA-207/1592 207 (26.0) 1 045 (10 450) 792 (9 950) 1 592 (20 000)
ND-SA-222/1592 222 (27.9) 1082 (10820) 820 (10300) 1592 (20000)
ND-SA-222/1592 222 (27.9) 1 082 (10 820) 820 (10 300) 1 592 (20 000)
ND-SA-244/1592 244 (30.7) 1136 (11360) 861 (10820) 1592 (20000)
ND-SA-244/1592 244 (30.7) 1 136 (11 360) 861 (10 820) 1 592 (20 000)
ND-SA-259/1592 259 (32.5) 1168 (11680) 885 (11120) 1592 (20000)
ND-SA-259/1592 259 (32.5) 1 168 (11 680) 885 (11 120) 1 592 (20 000)
ND-SA-281/1592 281 (35.3) 1218 (12180) 923 (11600) 1592 (20000)
ND-SA-281/1592 281 (35.3) 1 218 (12 180) 923 (11 600) 1 592 (20 000)
ND-SA-296/1592 296 (37.2) 1250 (12500) 947 (11900) 1592 (20000)
ND-SA-296/1592 296 (37.2) 1 250 (12 500) 947 (11 900) 1 592 (20 000)
ND-SA-311/1592 311 (39.1) 1281 (12810) 971 (12200) 1592 (20000)
ND-SA-311/1592 311 (39.1) 1 281 (12 810) 971 (12 200) 1 592 (20 000)
ND-SA-333/1592 333 (41.8) 1325 (13250) 1004 (12620) 1592 (20000)
ND-SA-333/1592 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 592 (20 000)
ND-SA-355/1592 355 (44.6) 1369 (13690) 1038 (13040) 1592 (20000)
ND-SA-355/1592 355 (44.6) 1 369 (13 690) 1 038 (13 040) 1 592 (20 000)
ND-SA-207/1989 207 (26.0) 1045 (10450) 792 (9950) 1989 (25000)
ND-SA-207/1989 207 (26.0) 1 045 (10 450) 792 (9 950) 1 989 (25 000)
ND-SA-222/1989 222 (27.9) 1082 (10820) 820 (10300) 1989 (25000)
ND-SA-222/1989 222 (27.9) 1 082 (10 820) 820 (10 300) 1 989 (25 000)
ND-SA-244/1989 244 (30.7) 1136 (11360) 861 (10820) 1989 (25000)
ND-SA-244/1989 244 (30.7) 1 136 (11 360) 861 (10 820) 1 989 (25 000)
ND-SA-259/1989 259 (32.5) 1168 (11680) 885 (11120) 1989 (25000)
ND-SA-259/1989 259 (32.5) 1 168 (11 680) 885 (11 120) 1 989 (25 000)
ND-SA-281/1989 281 (35.3) 1218 (12180) 923 (11600) 1989 (25000)
ND-SA-281/1989 281 (35.3) 1 218 (12 180) 923 (11 600) 1 989 (25 000)
ND-SA-296/1989 296 (37.2) 1250 (12500) 947 (11900) 1989 (25000)
ND-SA-296/1989 296 (37.2) 1 250 (12 500) 947 (11 900) 1 989 (25 000)
ND-SA-311/1989 311 (39.1) 1281 (12810) 971 (12200) 1989 (25000)
ND-SA-311/1989 311 (39.1) 1 281 (12 810) 971 (12 200) 1 989 (25 000)
ND-SA-333/1989 333 (41.8) 1325 (13250) 1004 (12620) 1989 (25000)
ND-SA-333/1989 333 (41.8) 1 325 (13 250) 1 004 (12 620) 1 989 (25 000)
ND-SA-207/2387 207 (26.0) 1045 (10450) 792 (9950) 2387 (30000)
ND-SA-207/2387 207 (26.0) 1 045 (10 450) 792 (9 950) 2 387 (30 000)
ND-SA-222/2387 222 (27.9) 1082 (10820) 820 (10300) 2387 (30000)
ND-SA-222/2387 222 (27.9) 1 082 (10 820) 820 (10 300) 2 387 (30 000)
ND-SA-244/2387 244 (30.7) 1136 (11360) 861 (10820) 2387 (30000)
ND-SA-244/2387 244 (30.7) 1 136 (11 360) 861 (10 820) 2 387 (30 000)
ND-SA-259/2387 259 (32.5) 1168 (11680) 885 (11120) 2387 (30000)
ND-SA-259/2387 259 (32.5) 1 168 (11 680) 885 (11 120) 2 387 (30 000)
ND-SA-281/2387 281 (35.3) 1218 (12180) 923 (11600) 2387 (30000)
ND-SA-281/2387 281 (35.3) 1 218 (12 180) 923 (11 600) 2 387 (30 000)
ND-SA-207/2785 207 (26.0) 1045 (10450) 792 (9950) 2785 (35000)
ND-SA-207/2785 207 (26.0) 1 045 (10 450) 792 (9 950) 2 785 (35 000)
ND-SA-222/2785 222 (27.9) 1082 (10820) 820 (10300) 2785 (35000)
ND-SA-222/2785 222 (27.9) 1 082 (10 820) 820 (10 300) 2 785 (35 000)
ND-SA-244/2785 244 (30.7) 1136 (11360) 861 (10820) 2785 (35000)
ND-SA-244/2785 244 (30.7) 1 136 (11 360) 861 (10 820) 2 785 (35 000)
A
Magnetic properties at 20 °C (68 °F).
B
The ASTM designation conforms to the requirements of this specification. ASTM Designations are of the form MM-TT-XX/YYMM-TT-XX/YY, where:
MM = material (ND = neodymium iron boron),
TT = type of processing and orientation (S = sintered; I = isotropic (non-oriented), A = anisotropic (oriented)),
XX = energy product in kJ/m rounded to the nearest integer, and
YY = intrinsic coercivity in kA/m rounded to the nearest integer.
A1101 − 23
A
TABLE 2 Hot-deformed Neodymium Iron Boron Permanent Magnets: Classification and Minimum Magnetic Property Requirements
Maximum Residual Coercive Field Intrinsic Coercive
Energy Product Induction Strength Field Strength
B
ASTM Designation
(BH) B H H
max r cB cJ
kJ/m (MGOe) mT (G) kA/m (Oe) kA/m (Oe)
ANISOTROPIC Nd Fe B
2 14
ND-DR-240/1110 240 (30.2) 1 140 (11 400) 830 (10 430) 1 110 (13 949)
ND-DR-230/1590 230 (28.9) 1 080 (10 800) 810 (10 179) 1 590 (19 981)
ND-DR-270/1110 270 (33.9) 1 220 (12 200) 870 (10 933) 1 110 (13 949)
ND-DR-270/1430 270 (33.9) 1 220 (12 200) 880 (11 058) 1 430 (17 970)
ND-DR-300/1110 300 (37.7) 1 280 (12 800) 920 (11 561) 1 110 (13 949)
ND-DR-320/900 320 (40.2) 1 300 (13 000) 840 (10 556) 900 (11 310)
ND-DR-290/1430 290 (36.4) 1 270 (12 700) 920 (11 561) 1 430 (17 970)
ND-DR-310/1350 310 (39.0) 1 290 (12 900) 970 (12 189) 1 350 (16 965)
ND-DR-250/1800 250 (31.4) 1 170 (11 700) 900 (11 310) 1 800 (22 619)
ND-DA-330/1590 330 (41.5) 1 320 (13 200) 1 000 (12 566) 1 590 (19 981)
ND-DA-360/1570 360 (45.2) 1 370 (13 700) 1 050 (13 195) 1 570 (19 729)
A
Magnetic properties at 20 °C (68 °F).
B
The ASTM designation conforms to the requirements of this specification. ASTM Designations are of the form MM-TT-XX/YY, where:
MM = material (ND = neodymium iron boron),
TT = type of processing and orientation (S = sintered; D = hot-deformed; I = isotropic (non-oriented), A = axial (axially oriented); R = radial (radially oriented),
XX = energy product in kJ/m rounded to the nearest integer, and
YY = intrinsic coercivity in kA/m rounded to the nearest integer.
5.1.8 Exceptions to this specification or special requirements such as plating, coating, or functional testing as mutually agreed
upon by the producer and user.
6. Chemical Composition
6.1 Neodymium iron boron magnets should be specified primarily by magnetic performance. Chemical composition can have an
influence on both magnetic and physical characteristics but should only be specified when other options are insufficient to meet
user requirements. Agreement on composition must be mutually arrived at by producer and user.
6.2 The general chemical composition of neodymium iron boron includes the elements neodymium, iron, and boron. Approximate
chemical compositions are listed in Table X3.1 and are typical but not mandatory.
6.3 There are a number of additional elements included in the alloy to adjust magnetic, chemical, or mechanical properties. See
Appendix X3 for additional information.
7. Physical and Mechanical Properties
7.1 Typical thermal and physical properties are listed in Table X2.1 in Appendix X2.
7.2 Physical density values are given for information purposes only and are not mandatory.
7.3 Neodymium iron boron magnets are used for their magnetic characteristics. The end-use application should not rely on them
for structural purposes due to low tensile and flexural strength. These materials are brittle, and can chip or break easily. Magnetic
properties may also be affected by physical stress.
7.4 Strength testing of brittle materials such as neodymium iron boron is difficult, expensive, time-consuming, and there may be
considerable scatter in the measured values. Producers typically make a complete set of measurements at the onset of production
and they are seldom repeated.
8. Magnetic Property Requirements
8.1 Magnetic properties are listedof sintered neodymium iron boron permanent magnets are given in Table 1. Magnetic properties
of hot-deformed neodymium iron boron permanent magnets are given in Table 2.
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8.2 The values of magnetic properties listed in the table are specified minimum values at 2020 °C 6 2 °C (68(68 °F 6 4 °F),
determined after magnetizing to saturation in closed magnetic circuit.
8.3 The specified values of magnetic properties are valid only for magnet test specimens with a uniform cross-section along the
axis of magnetization. Properties for anisotropic (magnetically oriented) magnets are measured along the axis of preferred
orientation. In the case of radially oriented magnets where the orientation axes vary along the curvature, care should be taken to
minimize the error arising from the misalignment between the orientation and measurement field axis, for example, to use smaller
circumferential length of the test specimen.
8.4 Because of the nature of permanent magnet production, magnetic testing of each lot is recommended, especially for
applications where the magnet performance is closely specified. Such magnetic property evaluations shall be conducted in the
manner described below. Where the magnet shape is not suitable for magnetic testing, a specimen shall be cut from the magnet
using appropriate slicing and grinding techniques, paying attention to any magnetic orientation within the magnet.
8.4.1 The magnetic properties shall be determined in accordance with Test Method A977/A977M, or by using a suitable, mutually
agreed upon magnetometric method.
8.4.2 When magnets are being purchased in the fully magnetized condition, the testing shall determine the magnetic properties
from the as-received magnetization state, followed by magnetization to saturation and testing of the magnetic properties from the
fully magnetized condition.
8.4.3 When magnets are being purchased in the unmagnetized condition or in an unknown state of magnetization, the test
laboratory shall magnetize the test specimen(s) to saturation in the same orientationdirection as the received specimen’s indicated
direction of magnetizationorientation and measure the magnetic properties from this fully magnetized condition.
8.4.4 When magnets are being purchased in a calibrated, stabilized, or “knocked-down” condition, magnets should be handled
with care to prevent exposure to externally applied fields. Refer to Appendix X6 for an explanation of these terms. During testing
using Test Method A977/A977M, the measurement should proceed in the second quadrant only, without attempting to saturate the
magnet specimen, to avoid changing the magnetization state of the material prior to test.
8.4.5 Other test methods may be utilized as agreed to between producer and user. Such tests may include the open circuit
magnetization Helmholtz test, field strength measurements in a defined magnetic circuit or adjacent to the magnet surface.
9. Workmanship, Finish, and Appearance
9.1 Dimensions and tolerances shall be as specified on the magnet drawing and must be agreed upon between the producer and
the user.
9.2 Though porosity and voids are uncommon in Neodymium sintered or hot-deformed neodymium iron boron magnets, their
appearance shall not in themselves constitute reason for rejection unless agreed upon between producer and user. Allowable
amounts of porosity and voids shall be documented in writing and included as part of the ordering or contracting process.
9.3 Magnets shall be free of adhered magnetic particles and surface residue which may interfere with assembly or proper device
function.
9.4 Chips shall be acceptable if no more than 10 % of any surface identified as a magnetic pole surface is removed.
9.5 Cracks visible to the naked eye shall not be permitted unless otherwise agreed to by producer and user.
10. Sampling
10.1 A lot shall consist of parts of the same form and dimensions, produced from a single mixed powder batch or sintering or
hot-deformation run, and from an unchanged process, without discontinuity in production, and submitted for inspection at one
time.
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10.2 The producer and user shall agree upon a representative number of specimens for testing. Typically, a suitable number of
parts, as mutually agreed upon between producer and user, shall be randomly selected from each lot. It is advisable to test a
minimum of two parts from each lot, and more if there is reason to suspect that the magnetic properties are not uniform throughout
the lot.
11. Rejection and Rehearing
11.1 Parts that fail to conform to the requirements of this specification shall be rejected. Rejection should be reported to the
producer promptly and in writing. In case of dissatisfaction with the results of the test, the producer may make a claim for a
rehearing.
11.2 The disposition of rejected parts shall be subject to agreement between the producer and user.
12. Certification
12.1 When specified in the purchase order or contract, the user shall be furnished certification that samples representing each lot
have been either tested or inspected as directed in this specification and that the requirements have been met.
12.2 When specified in the purchase order or contract, a report of the test results shall, at a minimum, include:
12.2.1 Grade of material.
12.2.2 Lot or batch number.
12.2.3 Magnetic test results.
12.2.4 Results of any other tests stipulated in the purchase order or contract.
13. Packaging and Package Marking
13.1 Packaging shall be subject to agreement between the producer and the user.
13.2 Parts f
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