ASTM E1606-20

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. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: E1606 − 15 E1606 − 20
Standard Practice for
Electromagnetic (Eddy Current) Examination of Copper and
Aluminum Redraw Rod for Electrical Purposes
This standard is issued under the fixed designation E1606; 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*
1.1 This practice covers the procedures that shall be followed in electromagnetic (eddy current) examination of copper and
aluminum redraw rods for detecting discontinuities or imperfections of a severity likely to cause failure or markedly impair surface
1 3
quality of the rod. These procedures are applicable for continuous lengths of redraw rod in diameters from ⁄4 to 1 ⁄8 in. (6.4 to
35 mm) suitable for further fabrication into electrical conductors.
1.2 This practice covers redraw rod made from tough-pitch or oxygen-free coppers. It can also be used for other types of copper,
such as fire-refined high conductivity rod. It is also appropriate for aluminum and other nonferrous alloys used for electrical
purposes.
1.3 The procedures described in this practice are based on methods for making use of differential or absolute stationary
encircling annular test coil systems.
1.4 This practice does not establish acceptance criteria. Acceptance criteria must be established by the using parties.
1.5 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are
mathematical conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E543 Specification for Agencies Performing Nondestructive Testing
E1316 Terminology for Nondestructive Examinations
E1033 Practice for Electromagnetic (Eddy Current) Examination of Type F-Continuously Welded (CW) Ferromagnetic Pipe and
Tubing Above the Curie Temperature (Withdrawn 2019)
E2884 Guide for Eddy Current Testing of Electrically Conducting Materials Using Conformable Sensor Arrays
2.2 ASNT Documents:
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing
ANSI/ASNT-CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
2.3 AIA Standard:
NAS 410 Certification and Qualification of Nondestructive Testing Personnel
This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on Electromagnetic
Method.
Current edition approved Dec. 1, 2015June 1, 2020. Published January 2016June 2020. Originally approved in 1994. Last previous edition approved in 20092015 as
E1606 - 09.E1606 – 15. DOI: 10.1520/E1606-15.10.1520/E1606-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 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 the ASTM website.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1606 − 20
2.4 ISO Standard:
ISO 9712 Non-Destructive Testing—Qualification and Certification of NDT Personnel
3. Terminology
3.1 Standard terminology relating to electromagnetic testing may be found in Terminology E1316, Section C: Electromagnetic
Testing.
4. Summary of Practice
4.1 The examination is performed by passing the rod lengthwise through a differential or absolute coil, or both, energized with
alternating current at a fixed frequency. The electrical impedance of the test coil is affected by rod vibrations, rod dimensions,
electrical conductivity of the rod material, and metallurgical or mechanical discontinuities in the rod surface. During passage of
the rod, the changes in impedance caused by these variables in the rod produce electrical signals that are processed so as to actuate
an audio, visual, or electrical signaling device. These electrical signals can also be displayed and stored digitally or used to actuate
mechanical markers to produce a record of indications.
4.2 The relative severity and type of imperfections may be indicated by eddy current signal amplitude, phase, or both, with
automatic display and recording. Alarm levels can be set to provide data for counting and recording of event totals in various
categories, as well as for providing outputs for actuating other devices. Because the responses from natural discontinuities may
vary significantly from those of artificial discontinuities, care must be exercised in establishing sensitivity and acceptance criteria
for the examination.
5. Significance and Use
5.1 Eddy current instrumentation provides timely and useful information regarding the acceptability of copper and aluminum
rod for quality control purposes, as well as providing for early warning that unacceptable rod is being produced. Eddy current
testing is a nondestructive method of locating surface discontinuities in a product. Signals can be produced by discontinuities
located on the surface of the rod. Since the density of eddy currents decreases nearly exponentially as the distance from the surface
increases, deep-seated defects may be undetected.
5.1.1 An exception is the detection of subsurface ferromagnetic inclusions with an additional, or shared, winding enveloped in
a DC magnetic field and the addition of appropriate instrumentation. The coil winding, acting as a transducer, generates a voltage
as the magnetized inclusion passes through, providing an electrical signal separate from the eddy current response to surface
imperfections. The rod is transparent to the DC effect allowing high sensitivity to ferromagnetic inclusions, in the absence of eddy
current noise. The method is inherently speed sensitive but is enhanced by high throughput speeds enabling the detection of small
subsurface ferromagnetic inclusions which are particularly detrimental to rod quality.
5.2 Some indications obtained by this practice may not be relevant to product quality. For example, a signal may be caused by
minute flaws or irregularities, by anomalies in the material, or a combination thereof, that are not detrimental to the end use of the
product. Nonrelevant indications, referred to as “noise,” can mask unacceptable discontinuities. On the other hand, relevant
indications are those that may result from unacceptable discontinuities and should be determined by agreement between the user
and the supplier. Any indication that is believed to be irrelevant shall be regarded as unacceptable until it is demonstrated by
reexamination or other means to be nonrelevant.
6. Basis of Application
6.1 Personnel Qualification—If specified in the contractual agreement, personnel performing examinations to this practice shall
be qualified in accordance with a nationally recognized nondestructive testing (NDT) personnel qualification practice or standard,
such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410,NAS 410, ISO 9712, or a similar document and certified by the employer
or certifying agency, as applicable. The practice or standard used and its applicable revision shall be identified in the contractual
agreement between the using parties.
6.2 Qualification of Nondestructive Testing Agencies—If specified in the contractual agreement, NDT agencies shall be qualified
and evaluated as described in PracticeSpecification E543. The applicable edition of PracticeSpecification E543 shall be specified
in the contractual agreement.
7. Apparatus
7.1 Electronic Apparatus, differential or absolute systems (or both) capable of energizing the test coil with alternating currents
of suitable frequencies (for example, in the range from 1 kHz to 1 MHz), and capable of sensing the changes in the electrical
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
E1606 − 20
impedance of the coils. Electrical signals that are processed so as to actuate an audio, visual, or electrical signaling device. These
electrical signals can also be displayed and stored digitally or used to actuate mechanical markers to produce a record of
indications.
7.1.1 The electronic apparatus should also be able to provide an electrical signal, either internally or externally, that can be used
to test the apparatus without having a test coil connected. This electrical signal is used to verify sensitivity levels and alarm
threshold for the apparatus.
7.1.2 The electronic apparatus should have an adjustable filter that includes in its bandwidth the anticipated flaw signal
frequencies.
7.1.3 The electronic apparatus may have a “filter out” configuration that allows the adjustable filter to be bypassed during
system standardization.
7.2 Test Coils, capable of inducing currents in the rod and sensing changes in the electrical characteristics of the rod. The test
coil diameter should be selected to yield the largest practical fill factor. The coil assembly, whether differential or absolute coils,
consists of one or more electrical coils, cooling apparatus that is adequate to maintain the proper coil-operating temperature and
prevent thermal damage, if needed, and positioning mechanisms for adjusting and maintaining a constant spacing between the coil
and the rod surface. Some assemblies may include mechanical guides to prevent physical damage to the coils by contact with the
product.
7.3 Driving Mechanism—An optional mechanical means may be used for passing the reference standard through the test coil
with minimum vibration of the test coil or rod. If used, the mechanical device shall maintain the rod substantially concentric with
the electrical center of the test coil. When using an apparatus that is sensitive to speed variations, a constant speed (up to 65.0
% of the actual rod speed) shall be maintained. When using an apparatus that can be configured to be insensitive to speed variations
for the purposes of calibration or standardization, the reference standard can be moved through the test coil manually with the
mechanical centering maintained by removable, closely fitted bushings. This technique should be utilized by the apparatus supplier
as well as the user.
8. Reference Standards
8.1 Reference standards containing one or more artificial discontinuity may be used to establish sensitivity and alarm threshold
settings to be used during eddy current examination. Sensitivity and alarm thresholds can be established using a reference standard
with a single artificial discontinuity if the instrument is configured to respond only to signal amplitude, without regard to phase
differences. If phase differences are detected and processed, additional artificial notches can be included in the reference standard
to create and display phase responses.
8.2 Artificial discontinuities are not intended to be representative of natural discontinuities or produce a direct relationship
between instrument response and discontinuity severity; they are intended only for establishing consistent sensitivity levels as
outlined in Section 9. The relationship between instrument response and discontinuity size, shape, and location is important and
should be established separately, particularly as related to the excitation frequency.
8.3 A suggested material reference standard is shown in Fig. 1. Artificial discontinuities of any other dimension or contour may
be used in a reference standard by mutual agreement between the supplier and purchaser.
8.4 When using a reference standard with multiple artificial discontinuities, they shall be spaced to provide signal resolution
adequate for interpretation. A sample of this type might be prepared with a hole drilled radially into the rod i
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