ASTM A971/A971M-17(2022)
(Test Method)Standard Test Method for Measuring Edge Taper and Crown of Flat-Rolled Electrical Steel Coils
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.
SCOPE
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 Specification A840 also includes requirements for edge taper or crown, but it has been withdrawn and reference to it is included for historical purposes.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.
General Information
- Status
- Published
- Publication Date
- 30-Sep-2022
- Technical Committee
- A06 - Magnetic Properties
- Drafting Committee
- A06.01 - Test Methods
Relations
- Refers
ASTM A683-16(2023) - Standard Specification for Nonoriented Electrical Steel, Semiprocessed Types - Effective Date
- 01-Dec-2023
- Effective Date
- 01-Dec-2023
- Refers
ASTM A677-16(2023) - Standard Specification for Nonoriented Electrical Steel Fully Processed Types - Effective Date
- 01-Dec-2023
- Effective Date
- 15-Oct-2019
- Effective Date
- 15-Jun-2019
- Effective Date
- 15-Feb-2019
- Effective Date
- 01-Jun-2018
- Effective Date
- 15-Oct-2017
- Effective Date
- 01-Jul-2017
- Effective Date
- 01-Apr-2017
- Effective Date
- 01-May-2016
- Effective Date
- 01-May-2016
- Effective Date
- 01-Oct-2015
- Effective Date
- 01-Oct-2014
- Effective Date
- 01-Aug-2013
Overview
ASTM A971/A971M-17(2022) - Standard Test Method for Measuring Edge Taper and Crown of Flat-Rolled Electrical Steel Coils - provides a standardized procedure for assessing the quality of electrical steel coils produced at steel mills. Monitoring edge taper and crown is essential, as these characteristics significantly influence the performance of cores used in magnetic devices such as motors and transformers. Excessive taper or crown can lead to assembly issues, nonuniform stack lengths, imbalances, noise, and increased energy losses in final products.
Key Topics
Edge Taper and Crown Measurements
- Edge Taper: Refers to the variation in thickness from the edge to approximately 4 inches (100 mm) inward from the edge of the coil, measured perpendicular to the rolling direction.
- Crown: The variation in thickness from the edge to the center of the coil, also perpendicular to the rolling direction.
- These measurements are distinct from general thickness variation, which is typically assessed parallel to the rolling direction.
Purpose and Importance
- Accurately measuring edge taper and crown ensures quality control in flat-rolled electrical steel production.
- Uniform thickness prevents assembly challenges, ensures better stack appearance, minimizes vibration and noise in motors, and reduces core losses in transformers.
- Edge trimming can be used as a corrective measure when edge taper exceeds specified limits.
Test Procedure
- Use a gamma strip cut from the master coil to determine thickness at defined points across the width.
- Thickness measurements are taken using a micrometer with high repeatability (100 µin. / 2.54 µm).
- Data from these points are used to calculate both edge taper and crown, informing whether the material meets specification before further processing.
Unit Systems and Compliance
- Both inch-pound and SI (metric) units are included; users should not interchange values between systems to avoid nonconformance.
- The standard highlights the importance of following appropriate safety and environmental practices during testing.
Applications
Electrical Steel Manufacturing
- Enables steel mills to provide coils with verified, uniform thickness across the width, enhancing producer and customer confidence.
- Supports the production of slitted coils that meet strict magnetic and mechanical requirements essential in electrical applications.
Lamination Production
- Ensures laminations, when stacked, yield consistent, high-performing magnetic cores for motors and transformers.
- Reduces issues such as uneven stacking, increased noise, higher exciting current, and core losses in magnetic device operation.
Quality Assurance and Compliance
- Facilitates compliance with material specifications such as ASTM A677, A683, A726, A876, and A1086, which specify requirements for edge taper and crown.
- Supports international trade and product reliability by conforming to recognized standards and WTO principles.
Related Standards
- ASTM A677: Specification for Nonoriented Electrical Steel, Fully Processed Types
- ASTM A683: Specification for Nonoriented Electrical Steel, Semiprocessed Types
- ASTM A726: Specification for Cold-Rolled Magnetic Lamination Quality Steel, Semiprocessed Types
- ASTM A876: Specification for Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully Processed Types
- ASTM A1086: Specification for Thin-Gauge Nonoriented Electrical Steel, Fully Processed Types
- Historical reference: ASTM A840 (withdrawn)
By strictly adhering to ASTM A971/A971M-17(2022), manufacturers, processors, and users of flat-rolled electrical steel coils can improve product quality, performance consistency, and compliance with international standards - supporting efficient, reliable manufacturing in the electrical and power sectors.
Get Certified
Connect with accredited certification bodies for this standard
Element Materials Technology
Materials testing and product certification.
Inštitut za kovinske materiale in tehnologije
Institute of Metals and Technology. Materials testing, metallurgical analysis, NDT.
Sponsored listings
Frequently Asked Questions
ASTM A971/A971M-17(2022) is a standard published by ASTM International. Its full title is "Standard Test Method for Measuring Edge Taper and Crown of Flat-Rolled Electrical Steel Coils". This standard covers: 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. SCOPE 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.
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. SCOPE 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.
ASTM A971/A971M-17(2022) is classified under the following ICS (International Classification for Standards) categories: 77.140.50 - Flat steel products and semi-products. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM A971/A971M-17(2022) has the following relationships with other standards: It is inter standard links to ASTM A683-16(2023), ASTM A340-23a, ASTM A677-16(2023), ASTM A340-19b, ASTM A340-19a, ASTM A340-19, ASTM A340-18, ASTM A340-17a, ASTM A340-17, ASTM A876-17, ASTM A340-16e1, ASTM A340-16, ASTM A340-15, ASTM A340-14, ASTM A1086-13. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM A971/A971M-17(2022) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: A971/A971M −17 (Reapproved 2022)
Standard Test Method for
Measuring Edge Taper and Crown of Flat-Rolled Electrical
Steel Coils
This standard is issued under the fixed designationA971/A971M; 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 A677 Specification for Nonoriented Electrical Steel Fully
Processed Types
1.1 This test method provides a procedure for measuring
A683 Specification for Nonoriented Electrical Steel, Semi-
edge taper and crown of flat-rolled electrical steel coils as
processed Types
produced at the steel mill.
A726 Specification for Cold-Rolled Magnetic Lamination
1.2 The values and equations stated in customary (cgs-emu
Quality Steel, Semiprocessed Types
and inch-pound) units or SI units are to be regarded separately
A840 Specification for Fully Processed Magnetic Lamina-
as standard. Within this standard, the SI units are shown in
tion Steel (Withdrawn 2011)
brackets. The values stated in each system may not be exact
A876 Specification for Flat-Rolled, Grain-Oriented, Silicon-
equivalents;therefore,eachsystemshallbeusedindependently
Iron, Electrical Steel, Fully Processed Types
of the other. Combining values from the two systems may
A1086 Specification for Thin-Gauge Nonoriented Electrical
result in nonconformance with this standard.
Steel Fully Processed Types
1.3 The following material specifications include require-
3. Terminology
ments for edge taper or crown: A677, A683, A726, A876, and
A1086.SpecificationA840alsoincludesrequirementsforedge
3.1 Definitions: Except as defined as follows, the symbols
taper or crown, but it has been withdrawn and reference to it is and terminology used in this test method are defined in
included for historical purposes.
Terminology A340.
3.1.1 edge taper and crown—the variations of thickness
1.4 This standard does not purport to address all of the
across the widths of cold-rolled steel coils, that is, perpendicu-
safety concerns, if any, associated with its use. It is the
lar to the rolling direction. Edge taper and crown are not the
responsibility of the user of this standard to establish appro-
same as thickness variation. Thickness variation is measured
priate safety, health, and environmental practices and deter-
paralleltotherollingdirection(althoughitislooselydefinedas
mine the applicability of regulatory limitations prior to use.
variation in any direction). See Fig. 1.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1.1.1 crown—the variation of thickness from the edge to
ization established in the Decision on Principles for the the center, perpendicular to the rolling direction.
Development of International Standards, Guides and Recom-
3.1.1.2 edge taper—the variation of thickness from the edge
mendations issued by the World Trade Organization Technical
to approximately 4 in. [100 mm] from the edge of the coil.
Barriers to Trade (TBT) Committee.
3.1.1.3 edge taper gamma (γ)—theslopeoftheedgetaper(a
dimensionless number) expressed in ten thousandths of a unit
2. Referenced Documents
per unit.
2.1 ASTM Standards:
3.1.2 edge trimming—the slitting of a narrow strip from
A340 Terminology of Symbols and Definitions Relating to
each edge of the master coil for discard. This reduces the edge
Magnetic Testing
taper gamma on the remainder of the coil.
3.1.3 gamma strip—a 1 in. to 4 in. [25 mm to 102 mm] strip
This test method is under the jurisdiction of ASTM Committee A06 on
cut across the full width of the master coil (or master coil
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods. coupon), for the purpose of measuring edge taper and crown.
Current edition approved Oct. 1, 2022. Published November 2022. Originally
3.1.4 master coils—full-width coils as produced by cold-
approved in 1997. Last previous edition approved in 2017 as A971/A971M – 17.
rolling mills. Slit coils are narrower width coils slit from a
DOI: 10.1520/A0971_A0971M-17R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A971/A971M − 17 (2022)
FIG. 1 Typical Steel Mill Coil Thickness Profile across Width of Coil
master coil. A master coil coupon is a full-width piece of the 6. Interference
master coil, usually manually cut off for test purposes.
6.1 This test method assumes that edge taper and crown are
consistent through each individual coil. If different coils are
4. Summary of Test Method
welded together to make up a finished coil, this may not be the
case. Nevertheless, edge trim can be used to correct for
4.1 In determining the edge taper and crown, a gamma strip
is taken from the coil head and tail. Thickness readings are inconsistencies.
taken using a micrometer or other measuring device along a
7. Description of Gamma Strip and Equipment Required
singlelineperpendiculartotherollingdirectionatpoints ⁄8 in.,
3 3 3 7.1 A coupon is cut from head and tail ends of the master
1 ⁄8 in., 2 ⁄8 in., and 4 ⁄8 in. [10 mm, 35 mm, 60 mm, and
coil.Ashearingoodworkingconditionwithsufficientcapacity
111 mm] from each edge to determine edge taper and in the
is used to cut a gamma strip from the coupon.The shear can be
center to determine crown. The readings are recorded, and
fitted with an edge gu
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...