ASTM A1054-16(2022)

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:A1054 −16 (Reapproved 2022)
Standard Specification for
Sintered Ferrite Permanent Magnets
This standard is issued under the fixed designation A1054; 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 2.2 Other Standards:
MMPA Standard No. 0100-00 Standard Specifications for
1.1 This specification covers technically important, com-
Permanent Magnet Materials
mercially available, magnetically hard sintered ferrite perma-
IEC 60404-8-1 Magnetic Materials Part 8: Specifications for
nent magnets.
individual materials Section 1 – Standard specifications
1.2 Ferrite permanent magnets have residual induction B
r
for magnetically hard materials
from 0.2 T (2000 G) up to about 0.5 T (5000 G) and intrinsic
coercive field strength H from 160 kA⁄m (2000 Oe) up to
cJ
3. Terminology
about 400 kA/m (5000 Oe). Their specific magnetic hysteresis
3.1 The terms and symbols used in this specification are
behavior (demagnetization curve) can be characterized using
defined in Terminology A340.
Test Method 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.
standard. The values given in parentheses are mathematical
3.2.1 Recoil permeability, µ , is the permeability corre-
REC
conversions to customary (cgs-emu and inch-pound) units
sponding to the slope of the recoil line. For reference, see
whichareprovidedforinformationonlyandarenotconsidered
incremental, relative, and reversible permeabilities as defined
standard.
in Terminology A340. In practical use, this is the slope of the
1.4 This standard does not purport to address all of the
normal hysteresis loop in the second quadrant and in proximity
safety concerns, if any, associated with its use. It is the
to the B-axis. The value of recoil permeability is dimension-
responsibility of the user of this standard to establish appro-
less. Note that in producers’ product literature, recoil perme-
priate safety, health, and environmental practices and deter-
ability is sometimes represented by the symbol µ , which is
r
mine the applicability of regulatory limitations prior to use.
defined by Terminology A340 as relative permeability.
1.5 This international standard was developed in accor-
3.2.2 Magnetic characteristics change with temperature.
dance with internationally recognized principles on standard-
Two key metrics of permanent magnet performance are re-
ization established in the Decision on Principles for the
sidual induction, B , and intrinsic coercive field strength, H .
r cJ
Development of International Standards, Guides and Recom-
The change in these characteristics over a defined and limited
mendations issued by the World Trade Organization Technical
temperature range can be reversible, that is, non-destructive.
Barriers to Trade (TBT) Committee.
Thischangeisrepresentedbyvaluescalledreversibletempera-
ture coefficients. The symbol for reversible temperature coef-
2. Referenced Documents
ficient of induction is α(B ) and of (intrinsic) coercivity is
r
2.1 ASTM Standards:
α(H ). They are expressed in percent change per degree
cJ
A340 Terminology of Symbols and Definitions Relating to
Celsius, %/°C, or the numerically equivalent percent per
Magnetic Testing
Kelvin, %/K. The change in magnetic characteristics is non-
A977/A977M Test Method for Magnetic Properties of High-
linear so it is necessary to specify the temperature range over
Coercivity Permanent Magnet Materials Using Hyster-
which the coefficient applies.
esigraphs
3.2.3 The maximum recommended working temperature of
a permanent magnet, T , is a semi-arbitrary value sometimes
w
This specification is under the jurisdiction of ASTM Committee A06 on
assigned by magnet manufacturers to their products. T is not
w
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
normative. See Appendix X3 for a more complete discussion.
Material Specifications.
Current edition approved Oct. 1, 2022. Published November 2022. Originally
approved in 2007. Last previous addition approved in 2016 as A1054 – 16. DOI:
10.1520/A1054-16R22.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from The International Magnetics Association (IMA), 8 South
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Michigan Avenue, Suite 1000, Chicago, IL 60603.
Standards volume information, refer to the standard’s Document Summary page on Available from IEC (International Electrotechnical Commission) Central Office
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A1054−16 (2022)
4. Classification 8. Magnetic Property Requirements
4.1 The classification of ferrite permanent magnets is given
8.1 Magnetic properties are listed in Tables 1 and 2.
in Tables 1 and 2, with cross-reference to MMPAStandard No.
8.2 The values of essential magnetic properties listed in the
0100-00 and IEC 60404-8-1 standards.
table are specified minimum values at +20 °C 6 2 °C (+68 °F
6 4 °F), determined after magnetizing to saturation.
5. Ordering Information
5.1 Orders for parts conforming to this specification shall
8.3 The specified values of magnetic properties are valid
include the following information: only for magnet test specimens with a uniform cross-section
5.1.1 Reference to this standard and year of issue/revision.
along the axis of magnetization. Properties for anisotropic
5.1.2 Reference to an applicable part drawing. (magneticallyoriented)magnetsaremeasuredalongtheaxisof
5.1.3 Magnetic property requirements if they are more
preferred orientation.
stringent than the minimum values listed in the tables.
8.4 Because of the nature of permanent magnet production,
5.1.4 Quantity required.
magnetic testing of each lot is strongly recommended, espe-
5.1.5 The required magnetization state of the provided
ciallyforapplicationswherethemagnetperformanceisclosely
material (unmagnetized, fully magnetized, magnetized and
specified. Such magnetic property evaluations shall be con-
thermally stabilized, magnetized and partially demagnetized or
ductedinthemannerdescribedbelow.Wherethemagnetshape
“calibrated”). This information should appear on the part
is not suitable for magnetic testing, a specimen shall be cut
drawing whenever possible.
from the magnet using appropriate slicing and grinding
5.1.6 Certification of magnetic property evaluation.
techniques, paying attention to any magnetic orientation within
5.1.7 Marking and packaging requirements.
the magnet.
5.1.8 Exceptions to this specification or special require-
8.4.1 The magnetic properties shall be determined in accor-
mentssuchasplating,coating,orfunctionaltestingasmutually
dance with Test Method A977/A977M, or by using a suitable,
agreed upon by the producer and user.
mutually agreed upon magnetometric method.
6. Chemical Composition
8.4.2 When magnets are being purchased in the fully
magnetized condition, the testing shall determine the magnetic
6.1 The general chemical composition of ferrite magnets is
properties from the as-received magnetization state, followed
MO · 6Fe O with M being barium, strontium (strontium
2 3
by magnetization to saturation and testing of the magnetic
preferredduetoenvironmentalissues),orsomecombinationof
properties from the fully magnetized condition.
the two. New ferrite grades may also include some rare earth
8.4.3 When magnets are being purchased in the unmagne-
elementsandcobalt.Chemicalcompositionslistedinthetables
tized condition or in an unknown state of magnetization, the
are typical and are not guaranteed.
test laboratory shall magnetize the test specimen(s) to satura-
7. Physical and Mechanical Properties
tion and measure the magnetic properties from the fully
magnetized condition.
7.1 Typical thermal properties are listed in Appendix X1.
8.4.4 When magnets are being purchased in a calibrated,
7.2 Typical physical properties are listed in Appendix X2.
stabilized, or “knocked-down” condition, magnets should be
7.3 Physical density values in Appendix X2 are given for
handled with care to prevent exposure to externally applied
information purposes only and are not guaranteed.
fields. Refer to Appendix X3 for an explanation of these terms.
7.4 Strength testing of brittle materials such as ferrite 8.4.5 Other test methods may be utilized as agreed to
permanent magnets is difficult, expensive, and time- between producer and user. Such tests may include the open
consuming. Results can be widely distributed. Producers typi- circuit magnetic field strength Helmholtz test, field strength
cally make these measurements at the onset of production and measurements in a defined magnetic circuit, or magnetic flux
they are seldom repeated. density measurements adjacent to the magnet surface.
TABLE 1 Classification and Minimum Magnetic Property Requirements for Isotropic Sintered Ferrite Permanent Magnets
Material Magnetic Properties
ASTM MMPA Original IEC IEC Maximum Remanent Normal Intrinsic Relative
Desig- Brief MMPA Brief Code Energy Induction Coercive Coercive Recoil
A
nation Desig- Class Desig- Refer- Product, B, Field Strength, Field Strength, Permeability,
r
nation nation ence (BH) mT (gauss) H H µ
max cB cJ REC
kJ/m kA/m (oersted) kA/m (oersted)
(MGOe)
CE-I-01 1.03/3 Ceramic . S1-0-1 8.4 (1.05) 230 (2300) 148 (1860) 259 (3250) 1.2
A
Designations are XX-Y-ZZZ where:
XX = material type (CE = ceramic ferrite),
Y = processing and orientation (I = isotropic (non-oriented), A = anisotropic (oriented)), and
ZZZ = numeric grade designation.
A1054−16 (2022)
TABLE 2 Classification and Minimum Magnetic Property Requirements for Anisotropic Sintered Ferrite Permanent Magnets
Material Magnetic Properties
ASTM MMPA Original IEC IEC Maximum Remanent Normal Intrinsic Relative
Desig- Brief MMPA Brief Code Energy Induction Coercive Coercive Recoil
A
nation Desig- Class Desig- Refer- Product, B, Field Strength, Field Strength, Permeability
r
nation nation ence (BH) mT (gauss) H H µ
max cB cJ REC
kJ/m kA/m (oersted) kA/m (oersted)
(MGOe)
CE-A-02 . Ceramic . . 14.3 (1.8) 290 (2900) 191 (2400) 239 (3000) 1.1
CE-A-05 3.4/2.5 Ceramic Hard fer- S1-1-6 27.1 (3.40) 380 (3800) 191 (2400) 199 (2500) 1.1
5 rite 26/18
CE-A-06 . Ceramic . . 19.5 (2.45) 320 (3200) 225 (2820) 263 (3300) 1.1
CE-A-07 2.7/4.0 Ceramic Hard fer- S1-1-2 21.9 (2.75) 340 (3400) 259 (3250) 318 (4000) 1.1
7 rite 20/28
CE-A-08A 3.5/3.1 Ceramic Hard fer- S1-1-5 27.9 (3.50) 385 (3850) 235 (2950) 243 (30
...