IEC 60404-8-8:2017

Overview

IEC 60404-8-8:2017 - "Magnetic materials - Part 8-8: Specifications for individual materials - Thin electrical steel strip and sheet for use at medium frequencies" - defines grades, requirements and inspection rules for thin electrical steel intended for magnetic circuits operating predominantly in the 100 Hz to 10 kHz range. The standard covers both non‑oriented (NO) and grain‑oriented (GO) thin electrical steel supplied in the finally annealed condition as coils or sheets, and it extends the family of materials to include improved grades.

Key product ranges:

• Non‑oriented electrical steel nominal thicknesses: 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 mm (additional thicknesses may be agreed).
• Grain‑oriented electrical steel nominal thicknesses: 0.05, 0.10, 0.15, 0.18 mm.

An example designation format defined by the standard: NO 20‑13 = non‑oriented, 0.20 mm, maximum specific total loss 13 W/kg at 1.0 T.

Key Topics and Technical Requirements

The standard specifies practical and testable attributes including:

• Magnetic properties: classification by maximum specific total loss at 1.0 T (W/kg) and magnetic polarization characteristics for medium‑frequency applications.
• Geometric characteristics and tolerances: thickness, width, edge camber, residual curvature and burr height tolerances for strip and sheet.
• Technological characteristics: density, stacking factor, number of bends (ductility indicator), and insulation coating resistance.
• Production and delivery requirements: production process, form of supply (coils/sheets), final annealed condition, and surface requirements.
• Inspection and testing procedures: sample selection, specimen preparation and referenced test methods for magnetic, geometric and technological tests (see related IEC measurement parts).

Practical Applications and Users

IEC 60404-8-8 is intended for stakeholders involved in design, manufacture and procurement of magnetic components used at medium frequencies:

• Motor and generator designers specifying thin electrical steel for rotors/stators.
• Transformer and inductor manufacturers for medium‑frequency magnetic circuits.
• Steel producers and suppliers who classify and mark thin NO/GO electrical steel grades.
• Quality, testing and inspection laboratories performing magnetic loss, thickness and stacking factor measurements.
• Purchasing engineers negotiating thicknesses, tolerances and coating/stacking requirements.

Using this standard ensures consistent material performance, traceable acceptance tests and compatibility between purchaser requirements and supplier delivery for medium‑frequency magnetic applications.

Related Standards

IEC 60404-8-8 references measurement and test methods in the IEC 60404 series and relevant ISO/IEC delivery and test documents, including standards for:

• Magnetic property measurement at medium frequencies
• Geometrical characteristics and stacking factor tests
• General technical delivery requirements for steel

Keywords: IEC 60404-8-8, thin electrical steel, non‑oriented electrical steel, grain‑oriented electrical steel, medium frequencies, magnetic properties, specific total loss, thickness tolerances, stacking factor, inspection procedures.