Standard Historical Last Updated: Nov 03, 2022
ASTM A971/A971M-17

Standard Test Method for Measuring Edge Taper and Crown of Flat-Rolled Electrical Steel Coils

Significance and Use

5.1 Flat-rolled electrical steel master coils are usually slit into narrower coils. Usually these slit coils are punched or sheared into laminations of various shapes. The laminations are then uniformly stacked to become the cores of magnetic devices such as motors and transformers. Stacking of many laminations exhibiting excessive taper causes assembly problems and poor appearance. Nonuniform stack lengths in motors cause imbalance and noise. When the laminations are interleaved in transformers, taper causes air spaces within the core resulting in increased noise, increased exciting current, and higher core loss.


1.1 This test method provides a procedure for measuring edge taper and crown of flat-rolled electrical steel coils as produced at the steel mill.

1.2 The values and equations stated in customary (cgs-emu and inch-pound) units or SI units are to be regarded separately as standard. Within this standard, the 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 standard.

1.3 The following material specifications include requirements for edge taper or crown: A677, A683, A726, A876, and A1086. Specification A840 also includes requirements for edge taper or crown, but it has been withdrawn and reference to it is included for historical purposes.

1.4 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, 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.

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Book of Standards Volume: 03.07
Developed by Subcommittee: A06.01
Pages: 4
DOI: 10.1520/A0971_A0971M-17
ICS Code: 77.140.50