IEC 60404-9:2018

Overview

IEC 60404-9:2018 is an international standard published by the International Electrotechnical Commission (IEC) that specifies precise methods for measuring the geometrical characteristics of electrical steel strip and sheet. These metals are critical in manufacturing magnetic circuits used in electrical devices such as transformers, motors, and generators. The standard focuses on testing procedures for key physical traits affecting performance and quality, ensuring consistency and reliability across suppliers and manufacturers.

This part 9 of the IEC 60404 series addresses the evaluation of:

• Edge wave (wave factor)
• Residual curvature
• Edge camber
• Deviation from the shearing line (internal stress)
• Burr height

It is applicable to electrical steel strips and sheets within Classes B2, C21, C22, and C23 as classified in IEC 60404-1.

Key Topics

Edge Wave (Wave Factor)

• Definition: Variation of flatness near the edge of the steel strip or sheet in the form of waves.
• Measurement: The wave factor represents the ratio of wave height to wave length, expressed as a percentage.
• Specimen Size: Standard length is 1 meter if not otherwise specified.
• Importance: Controls flatness quality, which impacts assembly and performance in electrical steel applications.

Residual Curvature

• Definition: Permanent curvature remaining along the rolling direction of the strip or sheet.
• Test Methods:
  • Horizontal method: Preferred for safety; involves placing the specimen horizontally and measuring curvature.
  • Vertical method: Traditional approach with noted safety concerns described in the standard.
• Effect: Residual curvature can influence stacking and lamination, affecting magnetic properties.

Edge Camber

• Definition: The greatest distance of an edge from a straight line connecting the two edge endpoints.
• Test Procedure: Uses specified specimen lengths and precise measurement tools to determine camber.
• Relevance: Ensures edges are within tolerance, vital for material feeding and manufacturing processes.

Deviation from Shearing Line (Internal Stress)

• Definition: Measures the maximum distance difference between the two sheared edges of a specimen centered on its width.
• Purpose: Quantifies internal stresses induced by shearing, which can affect the mechanical and magnetic performance.
• Measurement: Requires sheared test specimens and accurate dimensional assessment methods.

Burr Height

• Definition: Difference in thickness measured at the slit edge compared to a point 10 mm away.
• Measurement Methods:
  • Includes the use of a hand-held micrometer and other linear measuring devices.
  • The burr height is characterized by the maximum value observed.
• Importance: Burrs can cause assembly difficulties and lead to increased wear or insulation damage.

Applications

IEC 60404-9:2018 standard is crucial for:

• Manufacturers of electrical steel strips and sheets who aim to certify material geometry for quality assurance.
• Electrical device producers who require stringent material specifications for optimal magnetic circuit construction.
• Quality control laboratories performing acceptance tests and routine evaluation of steel materials.
• Research and development teams studying effects of geometrical defects on electromagnetic performance.
• Supply chain management to align specifications and compliance between steel producers and consumers.

By following the specified test methods, stakeholders can identify and minimize defects that reduce efficiency, cause mechanical failures, or complicate downstream processing.

Related Standards

• IEC 60404-1: Magnetic Materials – Classification
  Defines classes B2, C21, C22, and C23 of electrical steel sheet and strip, referenced for selecting appropriate materials.

• IEC 60050-121 & IEC 60050-221: International Electrotechnical Vocabulary (IEV)
  Provides terminology related to electromagnetism and magnetic materials used within this standard.

• Other parts of IEC 60404 series
  Cover different magnetic properties and material testing methods crucial for the comprehensive assessment of magnetic materials.

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Keywords: IEC 60404-9, electrical steel strip, electrical steel sheet, magnetic materials, edge wave, residual curvature, edge camber, shearing line deviation, burr height, magnetic circuits, geometric characteristics, standards for electrical steel, IEC standards.