ASTM_A_1070_-_16.pdf

Designation:A107016Standard Specification forCast and Sintered Alnico Permanent Magnets1This standard is issued under the fixed designation A1070;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers technically important,com-mercially available,magnetically hard,cast and sintered per-manent magnets known commonly as Alnico.1.2 Alnico magnets have approximate magnetic propertiesof residual magnetic induction,Br,from 0.52 T(5200 G)to1.35 T(13500 G)and coercivity,HcB,from 38 kA/m(475 Oe)to 175 kA/m(2200 Oe).Their specific magnetic hysteresisbehavior(demagnetization curves)can be characterized usingTest Method A977/A977M.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to customary(cgs-emu and inch-pound)unitswhich are provided for information only and are not consideredstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A340 Terminology of Symbols and Definitions Relating toMagnetic TestingA977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hyster-esigraphs2.2 Other Standards:MMPA Standard No.0100-00 Standard Specifications forPermanent Magnet Materials3IEC 60404-8-1 Magnetic Materials Part 8:Specifications forIndividual Materials Section 1 Standard Specificationsfor Magnetically Hard Materials43.Terminology3.1 The terms and symbols used in this specification aredefined in Terminology A340,except as noted in 3.2.3.2 Terms that are not defined in Terminology A340 but arein common usage and used herein are as follows.3.2.1 Recoil permeability,(rec),is the permeability corre-sponding to the slope of the recoil line.For reference seeincremental,relative,and reversible permeabilities as definedin Terminology A340.In practical use,this is the slope of thenormal hysteresis loop in the second quadrant and in proximityto the B-axis.The value of recoil permeability is dimension-less.Note that in producers product literature recoil perme-ability is sometimes represented by the symbol r,which isdefined by Terminology A340 as relative permeability.3.2.2 Magnetic characteristics change with temperature.Two key metrics of permanent magnet performance are re-sidual induction,Br,and intrinsic coercive field strength,HcJ.The change in characteristic over a defined and limitedtemperature range can be reversible,that is,non-destructive.This change is represented by values called reversible tempera-ture coefficients.The symbol for reversible temperature coef-ficient of induction is(Br)and for(intrinsic)coercivity is(HcJ).They are expressed in percent change per degreeCelsius,%/C,or the numerically equivalent percent perKelvin,%/K.The changes in magnetic characteristics arenon-linear so it is necessary to specify the temperature rangeover which the coefficient applies.3.2.3 The maximum recommended working temperature,Tw,of a permanent magnet is a semi-arbitrary value sometimesassigned by magnet manufacturers to their products.Twis notnormative.See Appendix X3 for a more complete discussion.4.Classification4.1 The classification of Alnico permanent magnets is givenin Table 1,and Appendix X1,Table X1.1,with cross-referenceto MMPA Standard No.0100-00 and IEC 60404-8-1.1This specification is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.02 onMaterial Specifications.Current edition approved Nov.1,2016.Published November 2016.DOI:10.1520/A1070-16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3MMPA Standard No.0100-00 is now available from the Permanent MagnetDivision of the SMAA(www.smma.org).It was previously available from TheInternational Magnetics Association(IMA).The IMA had been the successor to theMMPA and both organizations no longer exist.4Available from International Electrotechnical Commission(IEC),3,rue deVaremb,1st Floor,P.O.Box 131,CH-1211,Geneva 20,Switzerland,http:/www.iec.ch.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Ordering Information5.1 Orders for parts conforming to this specification shallinclude the following information:5.1.1 Reference to this specification and year of issue/revision.5.1.2 Reference to an applicable part