ASTM_A_977_-_A_977M_-_07_2013.pdf

Designation:A977/A977M07(Reapproved 2013)Standard Test Method forMagnetic Properties of High-Coercivity Permanent MagnetMaterials Using Hysteresigraphs1This standard is issued under the fixed designation A977/A977M;the number immediately following the designation indicates the yearof 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.Scope1.1 This test method covers how to determine the magneticcharacteristics of magnetically hard materials(permanentmagnets),particularlytheirinitialmagnetization,demagnetization,and recoil curves,and such quantities as theresidual induction,coercive field strength,knee field,energyproduct,and recoil permeability.This test method is suitablefor all materials processed into bulk magnets by any commonfabrication technique(casting,sintering,rolling,molding,andso forth),but not for thin films or for magnets that are verysmall or of unusual shape.Uniformity of composition,structure,and properties throughout the magnet volume isnecessary to obtain repeatable results.Particular attention ispaid to the problems posed by modern materials combiningvery high coercivity with high saturation induction,such as therare-earth magnets,for which older test methods(see TestMethod A341/A341M)are unsuitable.An applicable interna-tional standard is IEC Publication 60404-5.1.2 The magnetic system(circuit)in a device or machinegenerally comprises flux-conducting and nonmagnetic struc-tural members with air gaps in addition to the permanentmagnet.The system behavior depends on properties andgeometry of all these components and on the operatingtemperature.This test method describes only how to measurethe properties of the permanent magnet material.The basic testmethod incorporates the magnetic specimen in a magneticcircuit with a closed flux path.Test methods using ring samplesor frames composed entirely of the magnetic material to becharacterized,as commonly used for magnetically softmaterials,are not applicable to permanent magnets.1.3 This test method shall be used in conjunction withPractice A34/A34M.1.4 The values and equations stated in customary(cgs-emuor inch-pound)or SI units are to be regarded separately asstandard.Within this test method,SI units are shown inbrackets except for the sections concerning calculations wherethere are separate sections for the respective unit systems.Thevalues 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 noncon-formance with this test method.1.5 The names and symbols of magnetic quantities used inthis test method,summarized in Table 1,are those generallyaccepted by the industry.1.6 This test method is useful for magnet materials havingHcivalues between about 100 Oe and 35 kOe 8 kA/m and 2.8MA/m,and Brvalues in the approximate range from 500 G to20 kG 50 mT to 2 T.High-coercivity rare-earth magnet testspecimens may require much higher magnetizing fields thaniron-core electromagnets can produce.Such samples must bepremagnetized externally and transferred into the measuringyoke.Typical values of the magnetizing fields,Hmag,requiredfor saturating magnet materials are shown in Table A2.1.1.7 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:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA340 Terminology of Symbols and Definitions Relating toMagnetic TestingA341/A341M Test Method for Direct Current MagneticProperties of Materials Using D-C Permeameters and theBallistic Test MethodsE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved May 1,2013.Published July 2013.Originally approvedin 1997.Last previous edition approved in 2007 as A977/A977M07.DOI:10.1520/A0977_A0977M-07R13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.2 Magnetic Materials Procedure Association Standard:3MMPANo.010000 Standard Specifications for PermanentMagnet Materials2.3 International Electrotechnical Commission Document:4Publication 60404-5 Magnetic Materials Part 5:PermanentMagnet(Magnetically Hard)Materials Methods ofMe