1、Designation: E703 09E703 14Standard Practice forElectromagnetic (Eddy-Current) (Eddy Current) Sorting ofNonferrous Metals1This standard is issued under the fixed designation E703; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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. Scope Scope*1.1 This practice describes a procedure for sorting nonferrous metals using the electromagnetic (eddy-curr
3、ent) (eddy current)method. The procedure is intended for use with instruments using absolute or comparator-type coils for distinguishing variationsin mass, shape, conductivity, and other variables such as alloy, heat treatment, or hardness that may be closely correlated with theelectrical properties
4、 of the material. Selection of samples to evaluate sorting feasibility and to establish standards is also described.1.2 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
5、 safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E105 Practice for Probability Sampling of MaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characte
6、ristic of a Lot orProcessE543 Specification for Agencies Performing Nondestructive TestingE1316 Terminology for Nondestructive Examinations2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive TestingANSI/ASNT CP-189 Standard for Qualifica
7、tion and Certification of Nondestructive Testing Personnel2.3 AIA Standard:4NAS-410 Qualification and Certification of Nondestructive Testing Personnel3. Definitions Terminology3.1 Standard terminology relating to electromagnetic examination may be found in Terminology E1316, Section C:Electromagnet
8、ic Testing.4. Summary of Practice4.1 The techniques that are primarily used in electromagnetic sorting employ the absolute (single-) and comparative (two-) coilmethods using either encircling or probe coils. The decision of whether to use single-coil or two-coil operation is usually basedon empirica
9、l data. In the absolute-coil method (encircling or probe), the equipment is standardized by placing standards of knownproperties in the test coil. The value of the examined electrical parameter, which may be correlated with alloy, heat treatmenttemper, or hardness, is read on the display of an indic
10、ator. In the comparative coil method (encircling or probe coils), the testspecimen in one coil is compared with a reference piecestandard in a second coil to determine whether the test specimen is withinor outside of the required limits.4.1.1 Absolute Coil Method:1 This practice is under the jurisdi
11、ction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on ElectromagneticMethod.Current edition approved June 1, 2009June 1, 2014. Published June 2009 July 2014. Originally approved in 1979. Last previous edition approved in 20042009 asE703 - 98
12、E703 - 09.(2004)1. DOI: 10.1520/E0703-09.10.1520/E0703-14.2 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.3 A
13、vailable from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4 Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace
14、.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 previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prio
15、r 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 Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
16、8-2959. United States14.1.1.1 Encircling CoilSamples of known classification (standards) Various reference standards are inserted consecutively inthe test coil, and the controls of the instrument are adjusted to obtain an appropriate response. Typically, three samples would beused representing the u
17、pper, lower, and mid-range for which standardization is required. The examination is then conducted byinserting the specimens to be sorted into the test coil, and observing the instrument response.4.1.1.2 Probe CoilThe probe coil is placed consecutively on the standards of known properties reference
18、 standards and thecontrols of the instrument are adjusted for appropriate response (see 4.1.1.1). The examination is then conducted by placing theprobe on the specimens to be sorted and observing the instrument response.4.1.2 Comparative Coil Method:4.1.2.1 Encircling CoilKnown reference pieces (sta
19、ndards) Reference standards representing the minimum or maximumlimits, or both, of acceptance or sorting category are inserted in the reference and test coil. The instrument controls are adjustedfor appropriate responses.The examination is then conducted by inserting specimens to be sorted in the te
20、st coil, leaving the knownreference in the reference coil and observing the instrument response.4.1.2.2 Probe CoilBoth probe coils are placed on the reference pieces (standard) standard representing the minimum ormaximum limits, or both, of acceptance or sorting category. The instrument controls are
21、 adjusted for appropriate responses. Theexamination is then conducted by placing the test probe on the specimens to be sorted (the other probe is left on the referencestandard) and observing the instrument response.4.2 The range of instrument response must be so adjusted in the initial step that the
22、 anticipated deviations will be within therange of readout.4.3 Both absolute and comparative methods using encircling coil(s) require comparing the specimens to be examined with thereference piece(s).standards. Two or more samples representing the limits of acceptance may be required. In the absolut
23、e method,the electrical reference signal from the instrument is adjusted with the reference standard in the coil. In the comparative method,any electromagnetic condition, that is not common to the test specimen and the reference standard, will produce an imbalance inthe system. The comparative metho
24、d is usually more stable since it suppresses most of the interferences.4.4 The examination process may consist of manual insertion of one specimen after another into the test coil or an automatedfeeding and classifying mechanism may be employed. In automated setups, it is sometimes necessary to esta
25、blish empirically thetime required for the test specimen to remain in the test coil while the reading is being taken, especially if low frequencies areemployed.5. Significance and Use5.1 Absolute and comparative methods provide a measure for sorting large quantities of nonferrous parts or stock with
26、 regardto composition or condition, or both.5.2 The comparative or two-coil method is used when high-sensitivity examination is required. The advantage of this methodis that it almost completely suppresses interferences.5.3 The ability to accomplish these types of separations satisfactorily is depen
27、dent upon the relation of the electriccharacteristics of the nonferrous 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 examination may approachmany specimens per second depending on their size and shape.5.5 Success
28、ful sorting of nonferrous material depends mainly on the variables present in the sample and the proper selectionof frequency and fill factor.5.6 The accuracy of a sort will be affected greatly by the coupling between the test coil field and the examined part during themeasuring period.6. Basis of A
29、pplication6.1 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,such asANSI/ASNT-CP-189, SNT-TC-1A
30、, 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 Nondestructive Testing AgenciesIf spec
31、ified 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 this practice, they shall be spe
32、cified in the contractualagreement.E703 1427. Interferences7.1 The influence of the following variables must be considered for proper interpretation of the results:7.1.1 The correlation shall be established so that electrical properties of various groups do not overlap and are well defined inthe sta
33、ndardization procedure used.7.1.2 The examination frequency must be selected to provide a well-defined separation of variables.7.1.3 The temperature of the reference standard and test specimen shall be controlled within limits that will permit awell-defined range of conductivity or permeability, or
34、both, for which the correlation of the group or groups is valid. Cooling ofthe reference standard when high field strengths are used or allowing test specimens to cool or heat to an established ambient range,or both, may be required.7.1.4 The geometry, mass, and thickness of the reference standard a
35、nd test specimen shall be controlled within limits that willpermit sorting.7.1.5 Magnetic permeability variations can interfere when sorting paramagnetic materials.7.1.6 Signal response can result from a change in relative motion between the test specimen and the test coil, such as the lengthof time
36、 the specimen is in a test coil (see 4.4).7.1.7 Conductivity has an unambiguous relationship to hardness for certain alloys. However, when alloys are mixed, identicalconductivity does not necessarily indicate the same hardness.7.1.8 Care must also be exercised in using conductivity to sort overheate
37、d parts quenched at a high temperature as theconductivity reading for acceptable parts may repeat at a large increase in temperature.7.1.9 Lift-off can result in a change in the test system output with probe coils. This effect is a change in the magnetic couplingbetween the test specimen and probe c
38、oil. Care must be exercised to prevent this effect from interfering with examination results;either mechanical or electronic compensation must be used.7.1.10 For certain heat-treatable (aluminum) alloys, conductivity values can also repeat themselves during the aging cycle at aconstant temperature.
39、Thus, for such alloys, conductivity is not unique as a monitor of temper, etc.8. Apparatus8.1 Electronic ApparatusThe electronic apparatus shall be capable of energizing the test coils with alternating currents ofsuitable frequencies and power levels and shall be capable of sensing changes in the el
40、ectromagnetic response of the coils.Equipment may include any suitable signal-processing devices (phase discriminator, filter circuits, etc.) and the output may bedisplayed by meter, oscilloscope, recorder, signaling devices, or any suitable combination required for the particular application.8.2 Te
41、st coils may be of the encircling or probe-coil type and shall be capable of inducing an electromagnetic field in the testspecimen and reference standard, and sensing changes in the electric or magnetic characteristics of the test specimen.8.2.1 When selecting the test coil, the objective should be
42、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. This is of primary importance for examinationsrequiring high sensitivity.8.2.2 For complicated test specimen shapes, a corresponding insert shall b
43、e provided to ensure that each test specimen can beplaced in the same position within the test coil.These inserts, as well as any other accessories, should consist of non-ferromagnetic,electrically nonconductive material.8.3 Mechanical Handling ApparatusAmechanical device for feeding and sorting the
44、 test specimens may be used to automatea particular application.9. Sampling9.1 Sampling (see Practices E105 and E122) is a method to obtain assurance that materials are of satisfactory quality. Insteadof 100 % inspection, a portion of the material is examined to show evidence of the quality of the w
45、hole. There are two importantneeds for this approach: first, the final inspection or examination is made to assure that products delivered are in conformance withspecification requirements; second, to control parts and assemblies while they are being processed. Statistical acceptance samplingtables
46、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 attributes) basis; that is, determining whether or not the unitsof the sample meet the specification. Examination of the samples may also be conduc
47、ted on a measurements (or variables) basis;that is, determining actual readings on the units in the sample. The majority of acceptance sampling is carried out on a samplingby attributes basis and the usual acceptance sampling table is designed for accept/reject.9.3 Process control sampling may be co
48、nducted on material during the course of production to prevent large quantities ofdefective parts being found in the acceptance examinations. Many parts and materials are subjected to several successivemachining or processing operations before they become finished units. Parts can be most effectivel
49、y controlled during productionby examining small samples of these parts at frequent regularly scheduled intervals. The object of this process check is to providea continuous picture of the quality of parts being produced. This helps prevent production of defective parts by stopping andcorrecting the problem as soon as it begins to appear in the manufacturing process and thereby keeping the process in control.E703 143Sampling may be by attributes or by variables and process control sampling tables are used. The measurements (variables) controlchart is by far the most ef
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