ASTM A719/A719M-14(2019)

Standard Test Method for Lamination Factor of Magnetic Materials

SIGNIFICANCE AND USE
4.1 Lamination factor, S, indicates the deficiency of effective steel volume which is due to the presence of oxides, roughness, insulating coatings, and other conditions affecting the steel surface.  
4.2 The term Lamination Factor, S, pertains strictly to the determination of the proportion of material as defined by precise sampling and procedures of this test method. Alternative usage of the term Lamination Factor has evolved to include sampling and procedures outside of the context of this test method. Consideration of alternative sampling and procedures should not be included within the scope of this test method.
SCOPE
1.1 This test method covers measurement of the lamination factor (Note 1) of a specimen composed of strips cut from magnetic material.
Note 1: Lamination factor is also termed space factor or stacking factor.  
1.2 This test method shall be used in conjunction with Practice A34/A34M.  
1.3 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this test method, SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this test method.  
1.4 This standard does not purport to address the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2019
• ICS: 29.030 - Magnetic materials
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.01 - Test Methods

Relations

• Replaces: ASTM A719/A719M-14 - Standard Test Method for Lamination Factor of Magnetic Materials
• Effective Date: 01-Oct-2019
• Refers: ASTM A34/A34M-06(2012) - Standard Practice for Sampling and Procurement Testing of Magnetic Materials
• Effective Date: 01-Nov-2012
• Refers: ASTM A34/A34M-06 - Standard Practice for Sampling and Procurement Testing of Magnetic Materials
• Effective Date: 01-Nov-2006
• Refers: ASTM A34/A34M-96 - Standard Practice for Sampling and Procurement Testing of Magnetic Materials
• Effective Date: 10-Oct-2001
• Refers: ASTM A34/A34M-01 - Standard Practice for Sampling and Procurement Testing of Magnetic Materials
• Effective Date: 10-Oct-2001
• Referred By: ASTM A876-17e1 - Standard Specification for Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully Processed Types
• Effective Date: 01-Oct-2019
• Referred By: ASTM A677-16 - Standard Specification for Nonoriented Electrical Steel Fully Processed Types
• Effective Date: 01-Oct-2019
• Referred By: ASTM A683-16 - Standard Specification for Nonoriented Electrical Steel, Semiprocessed Types
• Effective Date: 01-Oct-2019
• Referred By: ASTM A345-19 - Standard Specification for Flat-Rolled Electrical Steels for Magnetic Applications
• Effective Date: 01-Oct-2019
• Referred By: ASTM A1086-20 - Standard Specification for Thin-Gauge Nonoriented Electrical Steel Fully Processed Types
• Effective Date: 01-Oct-2019

Overview

ASTM A719/A719M-14(2019) sets out the standard test method for determining the lamination factor of magnetic materials. Developed by ASTM International, this method is crucial for measuring how much of a magnetic material's volume is effectively steel, versus how much is lost to surface oxides, roughness, or insulating coatings. The standard supports accurate and consistent evaluation of lamination factor-also known as space factor or stacking factor-in specimens composed of strips cut from magnetic materials. This measurement plays a key role in the quality control of materials used in electrical and magnetic applications.

Key Topics

• Lamination Factor (Space Factor, Stacking Factor): The proportion of effective steel volume within a laminated stack as compared to the total volume, accounting for voids, coatings, and other surface effects.
• Significance: Identifies deficiencies in effective steel caused by oxides, surface roughness, or coatings-factors that directly impact magnetic performance.
• Test Method Essentials:
  • Uses a compression device and two rigid metal plates to compress test specimens of cut strips.
  • Mass, dimensions, and measured height under pressure are used to calculate the lamination factor.
  • Requires accurate, representative sampling following ASTM A34/A34M for credible results.
• Separate Units: Values may be calculated using either SI or customary (inch-pound, cgs-emu) units; methods must not be mixed within a test.

Applications

ASTM A719/A719M is adopted by manufacturers and quality assurance professionals in industries using magnetic steel, such as:

• Electrical Engineering: Ensures efficiency in transformers, electric motors, and generator cores by maximizing magnetic material performance.
• Material Procurement: Provides a standardized method for buyers and suppliers to evaluate batch-to-batch consistency in steel materials.
• Research and Development: Helps in the development and validation of new magnetic alloys and coatings by assessing their impact on stacking factor.
• Routine Quality Control: Aids in the acceptance or rejection of lots based on measured lamination factors, supporting efficient operation of plants and compliance with specified standards.

Related Standards

ASTM A719/A719M is typically used alongside several other standards to provide a comprehensive approach to testing and sampling of magnetic materials:

• ASTM A34/A34M - Practice for Sampling and Procurement Testing of Magnetic Materials: Outlines procedures for obtaining representative samples for physical property testing.
• ASTM Standards for Electrical Steel: For core loss and permeability testing, to fully characterize electrical steel’s performance.

For full compliance and accurate interpretation, users should always refer to the latest versions of these and any referenced standards.

---

Keywords: lamination factor, magnetic materials, ASTM A719, space factor, stacking factor, steel lamination testing, electrical steel standards, quality control, magnetic core materials, standard test method

Standards Content (Sample)

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.
Designation: A719/A719M − 14 (Reapproved 2019)
Standard Test Method for
Lamination Factor of Magnetic Materials
This standard is issued under the fixed designationA719/A719M; 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 3. Summary of Test Method
3.1 The laminated test specimen is subjected to pressure in
1.1 This test method covers measurement of the lamination
a compression device and the resulting volume is then deter-
factor (Note 1) of a specimen composed of strips cut from
mined from the measured specimen height, width, and length.
magnetic material.
An equivalent solid volume is calculated from the specimen
NOTE 1—Lamination factor is also termed space factor or stacking
mass and the true density of the specimen material.The ratio of
factor.
the calculated (equivalent solid) volume to the measured
1.2 This test method shall be used in conjunction with
volume is the lamination factor.
Practice A34/A34M.
4. Significance and Use
1.3 The values and equations stated in customary (cgs-emu
and inch-pound) or SI units are to be regarded separately as 4.1 Lamination factor, S, indicates the deficiency of effec-
tive steel volume which is due to the presence of oxides,
standard. Within this test method, SI units are shown in
brackets. The values stated in each system may not be exact roughness, insulating coatings, and other conditions affecting
equivalents; therefore each system shall be used independently the steel surface.
of the other. Combining values from the two systems may
4.2 The term Lamination Factor, S, pertains strictly to the
result in nonconformance with this test method.
determination of the proportion of material as defined by
precise sampling and procedures of this test method. Alterna-
1.4 This standard does not purport to address the safety
tive usage of the term Lamination Factor has evolved to
concerns associated with its use. It is the responsibility of the
include sampling and procedures outside of the context of this
user of this standard to establish appropriate safety, health,
test method. Consideration of alternative sampling and proce-
andenvironmentalpracticesanddeterminetheapplicabilityof
regulatory limitations prior to use. dures should not be included within the scope of this test
method.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Apparatus
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.1 Testing Machine—A compression testing machine or
mendations issued by the World Trade Organization Technical
other compression device capable of exerting the specified
Barriers to Trade (TBT) Committee.
pressure.
5.2 Metal Plates—Two flat, smooth, rigid metal plates with
2. Referenced Documents
square edges and ends are required. They shall be of sufficient
2.1 ASTM Standards: stiffness to distribute the pressure uniformly over the surface of
A34/A34M Practice for Sampling and Procurement Testing the sample. Each plate shall be 8.46 in. [215 mm] long and
of Magnetic Materials have a minimum width of 1.97 in. [50 mm] so that the area of
strips under pressure when testing 1.18-in. [30-mm] wide
2 2
specimens will be 10 in. [6450 mm ].
5.2.1 Extensions can be added to the plates to allow the use
This test method is under the jurisdiction of ASTM Committee A06 on
of micrometers or outside calipers instead of inside calipers for
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods.
determining plate separation. Precautions must be taken to
Current edition approved Oct. 1, 2019. Published October 2019. Originally
ensure that, within the limits of accuracy of the measurements,
approved in 1975. Last previous edition approved in 2014 as A719/A719M – 14.
no significant deflection of these extensions result from the test
DOI: 10.1520/A0719_A0719M-14R19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or pressure.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.3 Length-Measuring Tools—Calipers or other devices of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. adequate accuracy for measurement of plate separation.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A719/A719M − 14 (2019)
6. Sampling 8.4 The recommended standard minimum test pressure shall
be 50 psi [345 kPa]. Other pressures, depending on the
6.
...