ASTM A977/A977M-07
(Test Method)Standard Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs
Standard Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs
SCOPE
1.1 This test method covers how to determine the magnetic characteristics of magnetically hard materials (permanent magnets), particularly their initial magnetization, demagnetization, and recoil curves, and such quantities as the residual induction, coercive field strength, knee field, energy product, and recoil permeability. This test method is suitable for all materials processed into bulk magnets by any common fabrication technique (casting, sintering, rolling, molding, and so forth), but not for thin films or for magnets that are very small or of unusual shape. Uniformity of composition, structure, and properties throughout the magnet volume is necessary to obtain repeatable results. Particular attention is paid to the problems posed by modern materials combining very high coercivity with high saturation induction, such as the rare-earth magnets, for which older test methods (see Test Method A 341) are unsuitable. An applicable international standard is IEC Publication 60404-5.
1.2 The magnetic system (circuit) in a device or machine generally comprises flux-conducting and nonmagnetic structural members with air gaps in addition to the permanent magnet. The system behavior depends on properties and geometry of all these components and on the operating temperature. This test method describes only how to measure the properties of the permanent magnet material. The basic test method incorporates the magnetic specimen in a magnetic circuit with a closed flux path. Test methods using ring samples or frames composed entirely of the magnetic material to be characterized, as commonly used for magnetically soft materials, are not applicable to permanent magnets.
1.3 This test method shall be used in conjunction with Practice A 34/A 34M.
1.4 The values and equations stated in customary (cgs-emu or inch-pound) or SI units are to be regarded separately as standard. Within this test method, SI units are shown in brackets except for the sections concerning calculations where there are separate sections for the respective unit systems. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this test method.
1.5 The names and symbols of magnetic quantities used in this test method, summarized in Table 1, are those generally accepted by the industry.
1.6 This test method is useful for magnet materials having Hci values between about 100 Oe and 35 kOe [8 kA/m and 2.8 MA/m], and Br values in the approximate range from 500 G to 20 kG [50 mT to 2 T]. High-coercivity rare-earth magnet test specimens may require much higher magnetizing fields than iron-core electromagnets can produce. Such samples must be premagnetized externally and transferred into the measuring yoke. Typical values of the magnetizing fields, Hmag, required for saturating magnet materials are shown in Table A2.1 .
1.7 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 health practices and determine the applicability of regulatory limitations prior to use.
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Designation: A977/A977M − 07
StandardTest Method for
Magnetic Properties of High-Coercivity Permanent Magnet
1
Materials Using Hysteresigraphs
This standard is issued under the fixed designationA977/A977M; 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 brackets except for the sections concerning calculations where
there are separate sections for the respective unit systems. The
1.1 This test method covers how to determine the magnetic
values stated in each system may not be exact equivalents;
characteristics of magnetically hard materials (permanent
therefore,eachsystemshallbeusedindependentlyoftheother.
magnets), particularly their initial magnetization,
Combining values from the two systems may result in noncon-
demagnetization, and recoil curves, and such quantities as the
formance with this test method.
residual induction, coercive field strength, knee field, energy
product, and recoil permeability. This test method is suitable
1.5 The names and symbols of magnetic quantities used in
for all materials processed into bulk magnets by any common
this test method, summarized in Table 1, are those generally
fabrication technique (casting, sintering, rolling, molding, and
accepted by the industry.
so forth), but not for thin films or for magnets that are very
1.6 This test method is useful for magnet materials having
small or of unusual shape. Uniformity of composition,
H values between about 100 Oe and 35 kOe [8 kA/m and 2.8
structure, and properties throughout the magnet volume is ci
MA/m], and B values in the approximate range from 500 G to
necessary to obtain repeatable results. Particular attention is r
20 kG [50 mT to 2 T]. High-coercivity rare-earth magnet test
paid to the problems posed by modern materials combining
specimens may require much higher magnetizing fields than
very high coercivity with high saturation induction, such as the
iron-core electromagnets can produce. Such samples must be
rare-earth magnets, for which older test methods (see Test
premagnetized externally and transferred into the measuring
Method A341/A341M) are unsuitable. An applicable interna-
yoke. Typical values of the magnetizing fields, H , required
tional standard is IEC Publication 60404-5. mag
for saturating magnet materials are shown in Table A2.1.
1.2 The magnetic system (circuit) in a device or machine
1.7 This standard does not purport to address all of the
generally comprises flux-conducting and nonmagnetic struc-
tural members with air gaps in addition to the permanent safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
magnet. The system behavior depends on properties and
geometry of all these components and on the operating priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
temperature. This test method describes only how to measure
the properties of the permanent magnet material.The basic test
method incorporates the magnetic specimen in a magnetic 2. Referenced Documents
circuitwithaclosedfluxpath.Testmethodsusingringsamples
2
2.1 ASTM Standards:
or frames composed entirely of the magnetic material to be
A34/A34M Practice for Sampling and Procurement Testing
characterized, as commonly used for magnetically soft
of Magnetic Materials
materials, are not applicable to permanent magnets.
A340 Terminology of Symbols and Definitions Relating to
1.3 This test method shall be used in conjunction with
Magnetic Testing
Practice A34/A34M.
A341/A341M Test Method for Direct Current Magnetic
Properties of Materials Using D-C Permeameters and the
1.4 The values and equations stated in customary (cgs-emu
Ballistic Test Methods
or inch-pound) or SI units are to be regarded separately as
E177 Practice for Use of the Terms Precision and Bias in
standard. Within this test method, SI units are shown in
ASTM Test Methods
1
This test method is under the jurisdiction of ASTM Committee A06 on
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
2
Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2007. Published December 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1997. Last previous edition approved in 2002 as A977/A977M–02. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/A0977_A0977M-07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unite
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:A977/A977M–02 Designation: A 977/A 977M – 07
Standard Test Method for
Magnetic Properties of High-Coercivity Permanent Magnet
1
Materials Using Hysteresigraphs
This standard is issued under the fixed designationA 977/A 977M; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method describescovers how to determine the magnetic characteristics of magnetically hard materials (permanent
magnets), particularly their initial magnetization, demagnetization, and recoil curves, and such quantities as the residual induction,
coercive field strength, knee field, energy products,product, and recoil permeability. This test method is suitable for all materials
processed into bulk magnets by any common fabrication technique (casting, sintering, rolling, molding, and so forth), but not for
thin films or for magnets that are very small or of unusual shape. Uniformity of composition, structure, and properties throughout
the magnet volume is necessary to obtain repeatable results. Particular attention is paid to the problems posed by modern materials
combining very high coercivity with high saturation induction, such as the rare-earth magnets, for which older test methods (see
Test Method A 341) are unsuitable. An applicable international standard is IEC Publication 60404-5.
1.2 The magnetic system (circuit) in a device or machine generally comprises flux-conducting and nonmagnetic structural
members with air gaps in addition to the permanent magnet. The system behavior depends on properties and geometry of all these
components and on the operating temperature. The tests described here measure This test method describes only how to measure
the properties of the permanent magnet material. The basic test method incorporates the magnetic specimen in a magnetic circuit
with a closed flux path.Test methods using ring samples or frames composed entirely of the magnetic material to be characterized,
as commonly used for magnetically soft materials, are not applicable to permanent magnets.
1.3 This test method shall be used in conjunction with Practice A 34/A 34M.
1.4 The values and equations stated in customary (cgs-emu or inch-pound) or SI units are to be regarded separately as standard.
Within this test method, SI units are shown in brackets except for the sections concerning calculations where there are separate
sectionsfortherespectiveunitsystems.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshall
be used independently of the other. Combining values from the two systems may result in nonconformance with this test method.
1.5 The names and symbols of magnetic quantities used in this test method, summarized in Table 1, are those currently
preferredgenerally accepted by U.S.the industry.
1.6 This test method is useful for magnet materials having H values between about 100 Oe and 35 kOe [8 kA/m and 2.8
ci
MA/m], and B values in the approximate range from 500 G to 20 kG [50 mT to 2 T]. High-coercivity rare-earth magnet test
r
specimens may require much higher magnetizing fields than iron-core electromagnets can produce. Such samples must be
premagnetized externally and transferred into the measuring yoke. Typical values of the magnetizing fields, H , required for
mag
saturating magnet materials are shown in Table A2.1.
1.7 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 health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
A 34/A 34M Practice for Procurement Testing Sampling and Sampling Procurement Testing of Magnetic Materials
A 340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A 341/A 341M Test Method for Direct Current Magnetic Properties of Materials Using dcD-C Permeameters and the Ballistic
Test Methods
E 177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
1
This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.
Current edition approved Oct. 10, 2002. Published November 2002. Originally published as A977–97. Last previous editi
...
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