1、Designation: E566 09E566 14Standard Practice forElectromagnetic (Eddy-Current) (Eddy Current) Sorting ofFerrous Metals1This standard is issued under the fixed designation E566; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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. Scope Scope*1.1 This practice covers the procedure for sorting ferrous metals using the electromagnetic (eddy-current) (e
3、ddy current)method. The procedure relates to instruments using absolute or comparator-type coils for distinguishing variations in mass, shape,conductivity, permeability, and other variables such as hardness and alloy that affect the electromagnetic or magnetic propertiesof the material. The selectio
4、n of specimens reference standards to determine sorting feasibility and to establish standards is alsoincluded.21.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate saf
5、ety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E105 Practice for Probability Sampling of MaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characterist
6、ic of a Lot orProcessE543 Specification for Agencies Performing Nondestructive TestingE1316 Terminology for Nondestructive Examinations2.2 ASNT Documents:4SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive TestingANSI/ASNT-CP-189 Standard for Qualification
7、 and Certification of Nondestructive Testing Personnel2.3 AIA Standard:5NAS-410 Qualification and Certification of Nondestructive Testing Personnel3. Terminology3.1 Standard terminology relating to electromagnetic examination may be found in Terminology E1316, Section C:Electromagnetic Testing.4. Su
8、mmary of Practice4.1 The two techniques that are primarily used in electromagnetic sorting employ the absolute (single-) and comparative (two-)coil methods. The decision of whether to use single-coil or two-coil operation is usually determined by empirical data. In theabsolute-coil method, the equip
9、ment is standardized by placing standards of known properties in the test coil. The value of the1 This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on ElectromagneticMethod.Current edition approved June 1,
10、2009June 1, 2014. Published June 2009July 2014. Originally approved in 1976. Last previous edition approved in 20042009 asE566 - 99E566 - 09.(2004)1. DOI: 10.1520/E0566-09.10.1520/E0566-14.2 General information can be found in the Nondestructive Testing Handbook, (Second Edition), Vol IV: Electromag
11、netic Testing, Society for Nondestructive Testing, 1986.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Ava
12、ilable from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.
13、Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previou
14、s version. Becauseit 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 versionof the standard as published by ASTM is to be considered the official document.*A Summary of Change
15、s section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1tested parameter (for instance, hardness, alloy, or heat treatment) is read on the scale of an indicator. In the comparative-coilmethod, the
16、test specimen is compared with a reference specimenstandard and the indication tells whether the test specimen iswithin or outside of the required limits.4.1.1 Absolute Coil MethodA specimen of known classification (standard) reference standard is inserted in the test coil, andthe controls of the in
17、strument are adjusted to obtain an indication. The method is then continued by inserting the test specimensto be sorted into the test coil, and observing the instrument indication.4.1.2 Comparative Coil MethodKnown reference specimens (standards) Reference standards representing the minimum ormaximu
18、m limits of acceptance, or both, are inserted in the reference coil and test coil. The instrument controls are adjusted forappropriate indications. The method is then continued by inserting the test specimens to be sorted in the test coil, leaving a knownreference standard in the reference coil, and
19、 observing the instrument indication.4.2 The range of instrument indication must be so adjusted in the initial step that the anticipated deviations will be recognizedwithin the range of readout according to whether two- or three-way sorts are to be accomplished.4.3 Both absolute and comparative meth
20、ods require comparing the test specimens with the reference specimen(s).standards.Two or more specimens reference standards representing the limits of acceptance may be required. In the absolute method theelectrical reference is generated by a test specimen.reference standard. In the comparative met
21、hod any electromagnetic conditionthat is not common to the test specimen and the reference specimenstandard will produce an imbalance in the system. Thecomparative method usually is more stable, as it normally suppresses noise.4.4 The testing process may consist of manual insertion of one specimen a
22、fter another into the test coil, or an automated feedingand classifying mechanism may be employed. In automated setups, it is sometimes necessary to stop each specimen momentarilyin the test coil while the reading is being taken, especially if low test frequencies are employed.5. Significance and Us
23、e5.1 Absolute and comparative methods provide a means for sorting large quantities of ferrous parts of stock with regard tocomposition, condition, structure, or processing, or a combination thereof.5.2 The comparative or two-coil method is used when high-sensitivity testing is required. The advantag
24、e of this method is thatit almost completely suppresses all internal or external disturbances such as temperature variations or stray magnetic fields. Thetwo-coil method is normally used when harmonic evaluation is employed for sorting.5.3 The ability to accomplish satisfactorily these types of sepa
25、rations is dependent upon the relation of the magneticcharacteristics of the ferromagnetic parts to their physical condition.5.4 These methods may be used for high-speed sorting in a fully automated setup where the speed of testing may approach tenspecimens per second depending on their size and sha
26、pe.5.5 The success of sorting ferromagnetic material depends mainly on the proper selection of magnetic field strength andfrequency of signal in the test coil, fill factor, and variables present in the sample.5.6 The degree of accuracy of a sort will be affected greatly by the coupling between the t
27、est coil field and the test specimenand the accuracy with which the specimen is held in the test coil field during the measuring period.5.7 When high currents are used in the test coil, a means should be provided to maintain a constant temperature of the referencespecimenstandard in order to minimiz
28、e measurement drift.6. Basis of Application6.1 Personnel QualificationIf specified in the contractual agreement, personnel performing examinations to this practice shallbe qualified in accordance with a nationally recognized nondestructive testing (NDT) personnel qualification practice or standard,s
29、uch asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712, or a similar document and certified by the employer or certifyingagency, as applicable. The practice or standard used and its applicable revision shall be identified in the contractual agreementbetween the using parties.6.2 Qualification of Nonde
30、structive Testing AgenciesIf specified in the contractual agreement, NDTagencies shall be qualifiedand evaluated as described in Practice E543. The applicable edition of Practice E543 shall be specified in the contractualagreement.6.3 Acceptance CriteriaSince acceptance criteria are not specified in
31、 this practice, they shall be specified in the contractualagreement.7. Interferences7.1 The specific influence of the following variables must be considered for proper interpretation of the results obtained:7.1.1 The correlation shall be established so that magnetic or electrical properties, or both
32、, of various groups do not overlap andare well defined in the standardization procedure used.E566 1427.1.2 In sorting magnetic materials, a magnetic field strength and testexamination frequency must be used that will result in awell-defined separation of variables being tested.examined.7.1.3 When ex
33、amining magnetic materials at low field strength, any influence from the previous magnetic history of the testspecimen (residual magnetism) shall be negated by demagnetization of the specimen if it restricts the electromagnetic sort.7.1.4 The temperature of the reference specimenstandard and test sp
34、ecimen shall be controlled within limits that will permit awell-defined range of conductivity or permeability, or both, for which the correlation of the group or groups is valid. Cooling ofthe reference specimensstandards when high field strengths are used or allowing test specimens to cool or heat
35、to an establishedambient range, or both, may be required.7.1.5 The geometry and mass of the reference standard and test specimen shall be controlled within limits that will permitsorting.7.1.6 Speed EffectsSee 4.4.8. Apparatus8.1 Electronic ApparatusThe electronic apparatus shall be capable of energ
36、izing the test coils with alternating currents ofsuitable frequencies and power levels and shall be capable of sensing the changes in the electromagnetic response of the test coils.Equipment may include any suitable signal-processing devices (phase discriminator, filter circuits, etc.) and the outpu
37、t may bedisplayed by meter, scope, recorder, signaling devices or any suitable combination required for the particular application.8.2 Test Coils may be of the encircling or probe-coil type and shall be capable of inducing an electromagnetic field in the testspecimen and reference specimenstandard a
38、nd sensing changes in the electric and magnetic characteristics of the test specimen.8.2.1 When selecting the test coil, the objective should be to obtain a coil fill factor as large as possible. This means that theinside of the test coil should be filled by the test specimen as much as possible. Th
39、is is of primary importance for testsexaminationsrequiring high sensitivity.8.2.2 For complicated test specimen shapes, a corresponding insert shall be provided to ensure that each specimen can be placedin the same position within the test coil. These inserts, as well as any other accessories, shoul
40、d consist of nonferromagnetic,electrically nonconductive material.8.3 Mechanical Handling ApparatusAmechanical device for feeding and sorting the test specimens may be used to automatethe particular application.9. Sampling9.1 Sampling (see Practices E105 and E122) is a method to obtain assurance tha
41、t materials are of satisfactory quality. Insteadof 100 % inspection, a portion of the material is examined to show evidence of the quality of the whole. There are two importantneeds for this approach: first, in the final inspection or examinations made to ensure that products delivered are in confor
42、mancewith specification requirements; second, to control parts and assemblies while they are being processed. Statistical acceptancesampling tables and statistical process-control sampling tables have been developed to meet these needs.9.2 Acceptance sampling may be conducted on an accept/reject (or
43、 attributes) basis, that is, determining whether or not the unitsof the sample meet the specification. Examination of the samples may also be conducted on a measurements (or variables) basis,that is, determining actual readings on the units in the sample. The majority of acceptance sampling is carri
44、ed out on a samplingby the attributes basis and the usual acceptance sampling table is designed for accept/reject criteria.9.3 Process control sampling may be conducted on material during the course of production to prevent large quantities ofdefective parts being found in the acceptance tests. Many
45、 parts and materials are subjected to several successive machining orprocessing operations before they become finished units. Parts can be most effectively controlled during production by examiningsmall samples of these parts at regularly scheduled intervals. The object of this process check is to p
46、rovide a continuous pictureof the quality of parts being produced. This helps prevent production of defective parts by stopping and correcting the problemas soon as it begins to appear in the manufacturing process and thereby keeping the process in control. Sampling may be byattributes or by variabl
47、e and process control sampling tables. The measurements (variables) control chart is by far the mosteffective process control technique.9.4 Statistical sampling tables have four definite features: (1) specifications of sampling data, that is, the size of the samples tobe selected, the conditions und
48、er which the samples are to be selected, and the conditions under which the lot will be accepted orrejected; (2) protection afforded, that is, the element of risk that the sampling schedules in a given table will reject good lots oraccept bad ones; (3) disposal procedure, that is, a set of rules tha
49、t state what is to be done with lots after sampling has beencompleted; and (4) cost required, that is, average inspection cost required to accept or reject a lot.10. Test Specimen or Sample (Standards) Reference Standards10.1 Aknown acceptable specimen reference standard and known unacceptable specimen reference standard of the precise sizeand configuration of the product to be testedexamined shall be used to set up for sorting by the absolute coil (see 11.2) orcomparative coil (see 11.3) method.E566 14310.2 Three known specimens reference standards are required for a
