ASTM A1070-16

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:A1070 −16
Standard Specification for
1
Cast and Sintered Alnico Permanent Magnets
This standard is issued under the fixed designation A1070; 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 IEC 60404-8-1 Magnetic Materials Part 8: Specifications for
Individual Materials Section 1 – Standard Specifications
1.1 This specification covers technically important, com-
4
for Magnetically Hard Materials
mercially available, magnetically hard, cast and sintered per-
manent magnets known commonly as Alnico.
3. Terminology
1.2 Alnico magnets have approximate magnetic properties
3.1 The terms and symbols used in this specification are
of residual magnetic induction, B , from 0.52 T (5200 G) to
r
defined in Terminology A340, except as noted in 3.2.
1.35 T (13500 G) and coercivity, H , from 38 kA/m (475 Oe)
cB
3.2 Terms that are not defined in Terminology A340 but are
to 175 kA/m (2200 Oe). Their specific magnetic hysteresis
in common usage and used herein are as follows.
behavior (demagnetization curves) can be characterized using
3.2.1 Recoil permeability, µ , is the permeability corre-
(rec)
Test Method A977/A977M.
sponding to the slope of the recoil line. For reference see
1.3 The values stated in SI units are to be regarded as
incremental, relative, and reversible permeabilities as defined
standard. The values given in parentheses are mathematical
in Terminology A340. In practical use, this is the slope of the
conversions to customary (cgs-emu and inch-pound) units
normal hysteresis loop in the second quadrant and in proximity
whichareprovidedforinformationonlyandarenotconsidered
to the B-axis. The value of recoil permeability is dimension-
standard.
less. Note that in producers’ product literature recoil perme-
1.4 This standard does not purport to address all of the
ability is sometimes represented by the symbol µ , which is
r
safety concerns, if any, associated with its use. It is the
defined by Terminology A340 as relative permeability.
responsibility of the user of this standard to establish appro-
3.2.2 Magnetic characteristics change with temperature.
priate safety and health practices and determine the applica-
Two key metrics of permanent magnet performance are re-
bility of regulatory limitations prior to use.
sidual induction, B , and intrinsic coercive field strength, H .
r cJ
The change in characteristic over a defined and limited
2. Referenced Documents
temperature range can be reversible, that is, non-destructive.
2
2.1 ASTM Standards: Thischangeisrepresentedbyvaluescalledreversibletempera-
A340 Terminology of Symbols and Definitions Relating to ture coefficients. The symbol for reversible temperature coef-
Magnetic Testing ficient of induction is α(B ) and for (intrinsic) coercivity is
r
A977/A977M Test Method for Magnetic Properties of High- α(H ). They are expressed in percent change per degree
cJ
Coercivity Permanent Magnet Materials Using Hyster- Celsius, %/°C, or the numerically equivalent percent per
esigraphs Kelvin, %/K. The changes in magnetic characteristics are
non-linear so it is necessary to specify the temperature range
2.2 Other Standards:
MMPA Standard No. 0100-00 Standard Specifications for over which the coefficient applies.
3
3.2.3 The maximum recommended working temperature,
Permanent Magnet Materials
T , of a permanent magnet is a semi-arbitrary value sometimes
w
assigned by magnet manufacturers to their products. T is not
w
1
This specification is under the jurisdiction of ASTM Committee A06 on
normative. See Appendix X3 for a more complete discussion.
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
Material Specifications.
4. Classification
Current edition approved Nov. 1, 2016. Published November 2016. DOI:
10.1520/A1070-16.
4.1 The classification ofAlnico permanent magnets is given
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
in Table 1, and Appendix X1, Table X1.1, with cross-reference
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
to MMPA Standard No. 0100-00 and IEC 60404-8-1.
the ASTM website.
3
MMPA Standard No. 0100-00 is now available from the Permanent Magnet
4
Division of the SMAA (www.smma.org). It was previously available from The Available from International Electrotechnical Commission (IEC), 3, rue de
International MagneticsAssociation (IMA). The IMAhad been the successor to the Varembé, 1st Floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, http://
MMPA and both organizations no longer
...