ASTM D3353-98

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
An American National Standard
Designation: D 3353 – 98
Standard Test Methods for
Fibrous-Insulated Magnet Wire
This standard is issued under the fixed designation D 3353; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 149 Test Method for Dielectric Breakdown Voltage and
Dielectric Strength of Solid Electrical Insulating Materials
1.1 These test methods cover the testing of fibrous-insulated
at Commercial Power Frequencies
electrical conductors, commonly referred to as magnet wire,
D 1676 Test Method for Film-Insulated Magnet Wire
which are used in electrical apparatus. The test methods are
D 5423 Specification for Forced–Convection Laboratory
intended primarily for evaluation of the electrical insulating
Ovens for Evaluating Electrical Insulation
materials used. It is intended that these test methods be used,
E 8 Test Methods for Tension Testing of Metallic Materials
except where modified by individual specifications for particu-
2.2 IEC Standard:
lar applications.
IEC 851 Methods of Test for Winding Wires
1.1.1 These test methods apply to those magnet wires that
are fiber-covered and in which the conductor may or may not
3. Terminology
be coated with an underlying insulating film as covered by Test
3.1 Definitions of Terms Specific to This Standard:
Methods D 1676. Fiber-covered wires are produced by serving
3.1.1 serving, n—a uniform wrapping of fibrous insulation
helically or wrapping fibers or fibrous-tape insulation uni-
around a magnet wire or bare conductor.
formly around the wire in single and multiple layers. The
served or wrapped materials may be bonded to the underlying
4. Elongation
wire.
4.1 Scope—This test method covers the determination of
1.2 The values stated in inch-pound units are the standard.
the elongation of fibrous insulated magnet wire that results in
The SI equivalents of inch-pound units may be approximate.
a fracture of the conductor.
1.3 The test methods appear in the following sections:
4.2 Significance and Use—The elongation determined by
Procedure Section
this test method provides a general measure of the ductility of
Adhesion and Flexibility 8
Dielectric Breakdown Voltage 9
the conductor and the effect of the processing to which it has
Electrical Resistance of Conductors 5
been subjected during the insulating operation.
Elongation 4
4.3 Apparatus—The equipment shall have a minimum sepa-
Fibrous Coverage 6
Measurement of Dimensions 7
ration of 10 in. (254 mm) between grips, and be capable of
elongating the specimen to its breaking point, at a constant rate
1.4 This standard does not purport to address all of the
of 12 6 1 in./min (305 6 25 mm/min). The equipment shall be
safety concerns, if any, associated with its use. It is the
such that the error of the length measurement will be 1 % or
responsibility of the user of this standard to establish appro-
less. Suitable, non-slip grips are required that will not damage
priate safety and health practices and determine the applica-
the specimen in the region of elongation. Drum or capstan type
bility of regulatory limitations prior to use.See 8.4.1 and 9.5.1
grips have been found to be unsatisfactory.
for specific caution statements.
1.5 This standard and IEC 851 are similar if not equivalent
NOTE 1—See Test Methods E 8 for a discussion of machines, gripping
in technical content.
devices, and rates of stressing.
4.4 Procedure:
2. Referenced Documents
4.4.1 Remove the fibrous insulation without distorting the
2.1 ASTM Standards:
conductor for wire sizes 0.0253 in. (0.6426 mm) (AWG 22)
B 193 Test Method for Resistivity of Electrical Conductor
and finer. The insulation need not be removed from sizes larger
Materials
than 0.0253 in.
These test methods are under the jurisdiction of ASTM Committee D-9 on
Electrical and Electronic Insulating Materials and are the direct responsibility of Annual Book of ASTM Standards, Vol 10.01.
Subcommittee D09.10 on Magnet Wire Insulation. Annual Book of ASTM Standards, Vol 10.02.
Current edition approved May 10, 1998. Published March 1999. Originally Annual Book of ASTM Standards, Vol 03.01.
e1 6
published as D 3353 – 74. Last previous edition D 3353 – 92 (1995) . Available from International Engineering Consortium, 549 West Randolph
Annual Book of ASTM Standards, Vol 02.03. Street, Suite 600, Chicago IL 60661–2208.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3353
4.4.2 Standard Method: Insert the test specimen into the 5.3 Apparatus—The types of apparatus utilized for measur-
grips resulting in an original length of 10 6 0.1 in. (254 6 2.5 ing resistance and length are specified in Test Method B 193.
mm) being stretched. Elongate the wire at a constant rate of 12 5.4 Procedure—Remove the insulation on both ends of the
6 1 in./min (305 6 25 mm/min) until the conductor breaks. test specimen for electrical contact. The cleaning operation
Determine the length at break by measuring the final distance must not affect the conductor dimensions. Determine the
between the grips. Discard the results for any specimens that electrical resistance of the test specimen.
break within ⁄4 in. (6 mm) of the grips. When breaks occur
NOTE 2—For the fine magnet wires electrical contact of the test
frequently in this manner, a need for modification of the
specimen may be obtained by soldering to prepared terminals on the
equipment or technique is indicated.
measuring apparatus.
4.4.3 Bench Mark Method: Rectangular, square, and round
NOTE 3—While balancing the bridge, care must be taken to prevent
wire larger than 0.0651 in. (1.654 mm) in diameter can be
excessive heating of the specimen as a result of prolonged current flow,
and to avoid changes in temperature due to air drafts or to variations in
tested using bench marks. Measure the original length between
ambient conditions.
bench marks to ensure the distance between the bench marks is
10 6 0.1 inches (254 6 2.5 mm). Insert the wire specimen into
5.5 Report the following information:
the grips and locate the bench marks centrally and not more
5.5.1 Bare conductor dimensions,
than 1 inch (25.4 mm) from either grip. Elongate the wire
5.5.2 Bare conductor material,
specimen at a constant rate of 12 6 1 inch/min (305 6 25
5.5.3 Type and build of film insulation,
mm/min) until the conductor breaks. Match the broken ends of
5.5.4 Type of fibrous-insulation,
the specimen, place together, and measure the final length at
5.5.5 Number of servings,
break between the bench marks. In order to minimize the effect
5.5.6 Direction of servings,
of local variations in the wire under test, test three specimens
5.5.7 Type of varnish,
of the sample. Discard the results for any specimens that break
5.5.8 Test temperature,
within ⁄4 in. (6 mm) of the grips or the bench marks. When
5.5.9 Specimen length,
breaks occur frequently in this manner, a need for modification
5.5.10 Apparatus used,
of the equipment or technique is indicated.
5.5.11 Resistance reading, and
4.5 Calculation—Calculate the elongation as follows:
5.5.12 Resistance ohms per unit length corrected to 20°C
Elongation, % 5 @~A 2 B!/B# 3 100 (1)
(68°F).
5.6 Precision and Bias—
where:
5.6.1 This test method has been in use for many years, but
A 5 length at break, and
no statement of precision has been made and no activity is
B 5 original length
planned to develop such a statement.
4.6 Report the following information:
5.6.2 No information can be presented on the bias of this
4.6.1 Bare conductor dimensions,
procedure in Section 5, for measuring the electrical resistance
4.6.2 Bare conductor material,
of the conductor, as no material having an accepted reference
4.6.3 Type and build of film insulation,
value is available.
4.6.4 Type of fibrous-insulation,
4.6.5 Number of servings,
6. Fibrous Coverage
4.6.6 Direction of servings,
6.1 Scope—This test method covers the determination of
4.6.7 Type of varnish,
the quality of fibrous servings on round magnet wire or bare
4.6.8 Whether or not bench marks are used, and
conductor.
4.6.9 Individual and average elongation.
6.2 Definition of Term Specific to This Standard:
4.7 Precision and Bias:
6.2.1 fibrous coverage, n—of served-magnet wire, that char-
4.7.1 This test method has been in use for many years, but
acteristic which allows a fibrous served magnet wire to be
no statement of precision has been made and no activity is
wound around mandrels in a prescribed manner without
planned to develop such a statement.
causing observable openings in the fibrous coverage.
4.7.2 No information can be presented on the bias of this
procedure in Section 4, for measuring the percent elongation, 6.3 Significance and Use—The results of this test are
indicative of the quality of the fibrous servings applied to the
as no material having an accepted reference value is available.
wire. High quality serving is required since it will permit the
5. Electrical Resistance of Conductors
wire to be stressed by bending without exposing the conductor
or underlying film.
5.1 Scope—This test method covers the determination of
6.4 Apparatus:
the electrical resistance of fibrous insulated magnet wire
conductors. 6.4.1 Means for chucking and rotating mandrels while
maintaining suitable wire tension.
5.2 Significance and Use—Accurate control of resistance is
necessary to meet apparatus design parameters. Resistance is 6.4.2 Mandrels, to be specified.
expressed in terms of ohms per unit length corrected to 20°C
NOTE 4—Commercially, it is normally specified that the bare conductor
(68°F) and is a function of conductor dimensions, resistivity,
or underlying film shall not be exposed when the specimen is wound
and temperature. Resistance may be affected by the processing
around a mandrel having a diameter ten times the diameter of the bare
operation. conductor.
D 3353
6.5 Procedure: 7.3 Apparatus:
6.5.1 Wind the wire, with only sufficient tension to form it 7.3.1 Micrometer, apparatus for measuring the dimensions
around a mandrel of a diameter to be specified, without of bare conductor and fibrous–insulated wire shall consist of
twisting or stretching and at a speed not to exceed 40 rpm. Ten accurate hand or bench micrometers. The micrometer spindle
turns closely spaced along the mandrel shall constitute a test loading shall not be greater than 8 oz/ ⁄4-in. diameter anvil (225
specimen. g/6.36-mm diameter anvil) for 0.0651 in. (1.654 mm) (AWG
6.5.2 Examine the test specimen for exposed bare conductor 14) and finer. For all round wire sizes larger than 0.0651 in.
or underlying film with normal vision under a minimum light (1.654 mm) and for all rectangular and square wire sizes, the
level of 100 fc(1klx). micrometer spindle loading shall be 3 lb 6 1 oz/ ⁄4-in. diameter
6.6 Report the following information: anvil (1360 6 28 g/6.36-mm diameter anvil).
6.6.1 Bare conductor dimensions,
NOTE 5—Other instruments such as electronic micrometers or light
6.6.2 Bare conductor material,
wave micrometers may be used for measuring bare conductor diameter.
6.6.3 Type and build of film insulation,
NOTE 6—Spindle pressures specified above have been established
6.6.4 Type of fibrous-insulation,
based on experience with copper. Reduced pressures may be required for
6.6.5 Number of servings,
other metals.
6.6.6 Direction of servings, and
7.3.2 Mandrel, tapered (Fig. 1).
6.6.7 List the smallest mandrel diameter that does not
7.3.3 Weights, suitable (Table 1).
expose the bare conductor or underlying film.
7.3.4 Calipers, precision, with vernier reading to 0.001 in.
6.7 Precision and Bias—
(0.025 mm).
6.7.1 No information is presented about either the precision
7.4 Specimens:
or bias of Section 6 for evaluating fibrous coverage since the
7.4.1 When using the micrometer technique, the test speci-
test result is nonquantitative.
mens shall consist of at least 3 in. (76 mm) straight lengths of
7. Measurement of Dimensions
wire free of kinks or obvious defects. Carefully remove the
specimens from the spool or container at 1 ft (0.3 m) intervals
7.1 Scope:
without more than 1 % stretch for straightening.
7.1.1 These test methods determine the dimensions of the
7.4.2 When measuring the diameter using the tapered man-
bare conductor and the fibrous–insulated magnet wire.
drel technique, the specimen shall be of sufficient length to
7.1.1.1 The micrometer technique is applicable to wires
wind a minimum of 25 turns on the tapered mandrel and shall
where compressibility of the conductor or insulation is not a
be free of kinks or other obvious defects. Carefully remove the
factor.
specimens from the spool to avoid damaging or stretching.
7.1.1.2 The tapered mandrel technique is suitable for mea-
7.5 Procedure:
suring the diameter of wires where compressibility is a factor
as in stranded or litz wire, or where the insulating material may 7.5.1 For round wire, using a micrometer, measure the
overall diameter at four places approximately 45° apart around
be readily distorted as in the case of some organic fibers.
7.2 Significance and Use—Knowledge of the dimensions of the specimen. The average of the high and low values shall be
the overall or specimen diameter.
the bare conductor, overall dimensions of fibrous–insulated
magnet wire, and average insulation addition to the dimensions 7.5.2 For round wire, using the tapered mandrel technique,
attach one end of the specimen to the small end of the mandrel,
are necessary for specification and use purposes. Bare conduc-
tor dimensions are one of the basic parameters used in the pass the wire over a pulley as indicated in Fig. 2 and attach the
free end of the wire to the load specified in Table 1. Closely
design of electrical machinery and the breakdown voltage is
related to the thickness of the insulation. wind a minimum of 25 turns onto the tapered mandrel at the
FIG. 1 Tapered Mandrel
D 3353
A
TABLE 1 Copper Wire Tension
Nominal Bare Diameter Tension to Produce 7500 psi (52 MPa)
AWG Size in. mm lb kg
22 0.0253 0.6426 3.8 1.75
23 0.0226 0.5740 3.0 1.50
24 0.0201 0.5105 2.4 1.10
25 0.0179 0.4547 1.9 0.85
26 0.0159 0.4039 1.5 0.70
27 0.0142 0.3607 1.2 0.55
B
28 0.0126 0.3200 0.45
B
29 0.0113 0.2870 0.35
B
30 0.0100 0.2540 0.27
B
31 0.0089 0.2261 0.21
B
32 0.0080 0.2032 0.17
B
33 0.0071 0.1803 0.14
B
34 0.0063 0.1600 0.11
B
35 0.0056 0.1422 0.085
B
36 0.0050 0.1270 0.065
B
37 0.0045 0.1143 0.055
B
38 0.0040 0.1016 0.045
B
39 0.0035 0.0889 0.035
B
40 0.0031 0.0787 0.025
B
41 0.0
...