ASTM A719-97

Designation: A 719 – 97 An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
1
Lamination Factor of Magnetic Materials
This standard is issued under the fixed designation A 719; 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 5. Apparatus
1.1 This test method covers measurement of the lamination 5.1 Testing Machine—A compression testing machine or
factor (Note 1) of a specimen composed of strips cut from other compression device capable of exerting the specified
magnetic material. pressure.
1.2 This method shall be used in conjunction with Practice 5.2 Metal Plates—Two flat, smooth, rigid metal plates with
A 34. square edges and ends are required. They shall be of sufficient
1.3 The values stated in either customary units or SI units stiffness to distribute the pressure uniformly over the surface of
are to be regarded separately as standard. Within this test the sample. Each plate shall be 8.46 in. [215 mm] long and
method, the SI units are shown in brackets except for the have a minimum width of 1.97 in. [50 mm] so that the area of
sections concerning calculations which are separate. strips under pressure when testing 1.18-in. [30-mm] wide
2 2
1.4 This standard does not purport to address the safety specimens will be 10 in. [6450 mm ].
problems associated with its use. It is the responsibility of the 5.2.1 Extensions can be added to the plates to allow the use
user of this standard to establish appropriate safety and health of micrometers or outside calipers instead of inside calipers for
practices and determine the applicability of regulatory limita- determining plate separation. Precautions must be taken to
tions prior to use. ensure that, within the limits of accuracy of the measurements,
no significant deflection of these extensions result from the test
NOTE 1—Lamination factor is also termed space factor or stacking
pressure.
factor.
5.3 Length-Measuring Tools—Calipers or other devices of
2. Referenced Documents
adequate accuracy for measurement of plate separation.
2.1 ASTM Standards:
6. Sampling
A 34 Practice for Sample and Procurement Testing of Mag-
2
6.1 Test strips shall be selected as representative of the
netic Materials
surface condition. Core loss test specimens (Epstein test
3. Summary of Test Method
specimens) are normally used for this purpose.
6.2 In routine testing, where the core loss specimens are too
3.1 The laminated test specimen is subjected to pressure in
small to conform to the number of strips requirement of Table
a compression device and the resulting volume is then deter-
1, sufficient specimens may be combined to provide an
mined from the measured specimen height, width, and length.
adequate test specimen. The combined specimens must be of
An equivalent solid volume is calculated from the specimen
the same thickness and material, have similar surfaces, and be
mass and the true density of the specimen material. The ratio of
representative of the surface condition of the test lot.
the calculated (equivalent solid) volume to the measured
6.3 When a referee test becomes necessary, the test speci-
volume is the lamination factor.
men must be composed of strips taken from one lot of steel. It
4. Significance and Use
must be representative of the surface condition, thickness, and
other variables. The shearing burrs should be removed and the
4.1 Lamination factor, S, indicates the deficiency of effec-
strips wiped free of loose particles.
tive steel volume which is due to the presence of oxides,
roughness, insulating coatings, and other conditions affecting
7. Test Specimen
the steel surface.
7.1 The test specimens shall consist of the number of strips
prescribed in Table 1.
1
This test method is under the jurisdiction of ASTM Committee A-6 on
7.2 Each strip shall have a minimum length of 9.84 in. [250
Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test
Methods.
mm] and a width of 1.18 in. [30 mm]. Refer to Practice A 34.
Current edition approved April 10, 1997. Published December 1997. Originally
7.3 Length and width dimensions should be known to at
published as A 719–75. Last previous edition A 719–90.
2 least 0.25 % and preferably to 0.1 %.
Annual Book of ASTM Standards, Vol 03.04.
1

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A 719
TABLE 1 Number of Strips in Lamination Factor Test Specimens
on the longitudinal axis of the strips at each end of the plates,
Number of are required.
Thickness
Electrical Sheet
Strips per
A
Gage Number
in. [mm]
Test Specimen
9. Calculation
16 0.0625 1.59 24
9.1 Customary Units:
17 0.0560 1.42 24
...