ASTM B279-13

Standard Test Method for Stiffness of Bare Soft Square and Rectangular Copper and Aluminum Wire for Magnet Wire Fabrication

SIGNIFICANCE AND USE
3.1 This test method is designed as an inspection or acceptance test of new bare soft square and rectangular wire intended for subsequent fabrication into magnet wire.Note 1—Since the applied unit stress and the time of application are constant for all wire sizes, the test enables comparisons of stiffness to be made between wires of the same or different size on the basis of the permanent elongation resulting from the application of a low unit stress.
SCOPE
1.1 This test method, known as the low-stress elongation (LSE) test, covers the procedure for determining the stiffness of bare soft square and rectangular copper and aluminum wire in terms of the permanent elongation resulting from the application of a tensile stress.  
1.2 The SI values for the mass of the specimen are regarded as the standard. For all other properties, the inch-pound values are to be regarded as standard and the SI units may be approximate.

General Information

• Status: Historical
• Publication Date: 31-Aug-2013
• ICS: 29.060.10 - Wires
• Technical Committee: B01 - Electrical Conductors
• Drafting Committee: B01.02 - Methods of Test and Sampling Procedure

Relations

• Replaces: ASTM B279-04 - Standard Test Method for Stiffness of Bare Soft Square and Rectangular Copper and Aluminum Wire for Magnet Wire Fabrication (Withdrawn 2004)
• Effective Date: 01-Sep-2013
• Replaced By: ASTM B279-13(2019) - Standard Test Method for Stiffness of Bare Soft Square and Rectangular Copper and Aluminum Wire for Magnet Wire Fabrication
• Effective Date: 01-Oct-2019
• Referred By: ASTM B48-00(2021)e1 - Standard Specification for Soft Rectangular and Square Bare Copper Wire for Electrical Conductors
• Effective Date: 01-Sep-2013
• Referred By: ASTM B324-01(2021) - Standard Specification for Aluminum Rectangular and Square Wire for Electrical Purposes
• Effective Date: 01-Sep-2013
• Referred By: ASTM D1676-17 - Standard Test Methods for Film-Insulated Magnet Wire
• Effective Date: 01-Sep-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B279 − 13
Standard Test Method for
Stiffness of Bare Soft Square and Rectangular Copper and
1
Aluminum Wire for Magnet Wire Fabrication
This standard is issued under the fixed designation B279; 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 5. Test Specimens
5.1 The test specimens shall be taken from the finished reel
1.1 This test method, known as the low-stress elongation
or coil with a minimum amount of handling and distortion,
(LSE) test, covers the procedure for determining the stiffness
retaining the original curvature of the package to the greatest
of bare soft square and rectangular copper and aluminum wire
extent possible. Test specimens having the full cross-sectional
in terms of the permanent elongation resulting from the
area of the wire shall be used. The standard gage length for the
application of a tensile stress.
measurement of elongation of wire shall be 10 in. (254 mm).
1.2 The SI values for the mass of the specimen are regarded
The total length of the specimens shall be at least equal to the
as the standard. For all other properties, the inch-pound values
gage length plus the length of wire required for the full use of
are to be regarded as standard and the SI units may be
the grips employed.
approximate.
6. Procedure
2. Referenced Documents
6.1 Straighten the test specimens carefully by hand with a
2.1 The following document forms a part of this test method
minimum amount of distortion or cold work. Improperly
to the extent referenced herein:
prepared test specimens often cause unsatisfactory test results.
2
2.2 ASTM Standards:
6.2 Cut off a test specimen of sufficient length as described
E4 Practices for Force Verification of Testing Machines
in 5.1. Measure the length to the nearest 0.01 in. (0.25 mm)
with any measuring device accurate to 0.1 % (Note 2). Mea-
3. Significance and Use
sure the mass of this specimen to the nearest 0.01 g on a
balance accurate to 0.1 %. The load required to apply a stress
3.1 This test method is designed as an inspection or accep-
to the specimen equal to 15 000 psi (103 MPa) for copper, and
tancetestofnewbaresoftsquareandrectangularwireintended
8 000 psi (55 MPa) for aluminum shall be obtained from the
for subsequent fabrication into magnet wire.
following:
NOTE 1—Since the applied unit stress and the time of application are
KW
constant for all wire sizes, the test enables comparisons of stiffness to be
P 5
made between wires of the same or different size on the basis of the L
permanent elongation resulting from the application of a low unit stress.
where:
P = Required load, lbs (N),
4. Apparatus
W = mass of specimen, g,
4.1 Tensile testing machines used for the low-stress elonga-
L = length of specimen, in., and
tion test shall conform to the requirements of Practices E4.
K = 102.74 for copper specimens, length in in., required
load in lb, or
K = 11 612.7 for copper specimens, length in mm, required
load in N, or
1
This test method is under the jurisdiction of ASTM Committee B01 on
K = 180.5 for aluminum specimens, length in in., required
Electrical Conductors and is the direct responsibility of Subcommittee B01.02 on
Methods of Test and Sampling Procedure.
load in lb, or
Current edition approved Sept. 1, 2013. Published September 2013. Originally
K = 20 401.9 for aluminum specimens, length in mm,
approved in 1953. Last previous edition approved in 2004 as B279 – 04 which was
required load in N.
withdrawninJanuary2013andreinstatedinSeptember2013.DOI:10.1520/B0279-
NOTE 2—Where a large number of specimens are to be tested, the
13.
2
calculation of the required load (P) can be simplified by careful cutting of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
all test specimens to equal lengths. The use of a jig or a pair of vices with
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on jaws set at a predetermined length apart can facilitate the cutting of equal
the ASTM website. length specimens. With all specimens having an equal length, the
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B279 − 13
specimen mass becomes the only variable and the required load (P) will
7. Low-Stress Elongation
vary proportionately specimen to specimen with the specimen mass.
Where the mass of the test specimen exceeds the capacity of the 7.1 The low-stress elongation shall be recorded as the
availa
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