IEC 60404-8-4:2022

Overview

IEC 60404-8-4:2022 specifies grades and delivery requirements for cold-rolled non-oriented electrical steel strip and sheet supplied in the fully-processed (final annealed) state. The standard covers nominal thicknesses of 0.35 mm, 0.47 mm, 0.50 mm, 0.65 mm and 1.00 mm (the 0.47 mm grade is specified for use at 60 Hz only). It defines general requirements, magnetic properties, geometric characteristics, tolerances, technological characteristics and inspection procedures for materials intended for magnetic circuits. This part applies to coils or sheets in the fully-processed state and does not cover semi-processed materials (see IEC 60404-8-3).

Key topics and technical requirements

• Magnetic properties: Defined grades and measured using standardized methods (Epstein method referenced to IEC 60404-2). Tables provide magnetic polarization, specific total loss and anisotropy of loss where applicable.
• Geometrical characteristics & tolerances: Nominal thickness tolerances (Table 3), width and length tolerances, edge wave (wave factor), residual curvature, edge camber and related measurement methods. Test specimen length for geometric testing revised to 1 m (was 2 m).
• Technological characteristics: Density, stacking factor, number of bends, deviation from shearing line (internal stress) and other manufacturability criteria relevant to assembly and lamination.
• Inspection & testing procedures: Sampling, specimen preparation, test methods, retests, plus marking, labelling, packaging and complaint handling requirements.
• Classification: Grades correspond to Class C.21 of IEC 60404-1.
• Consistency updates: Terminology and geometric requirements aligned with IEC 60404-9:2018.

Practical applications and who uses this standard

IEC 60404-8-4 is essential for:

• Motor and generator designers selecting lamination steel for magnetic circuits.
• Transformer and electrical equipment manufacturers specifying sheet or strip for core construction.
• Material suppliers and steel producers setting product grades and certificates.
• Quality assurance and testing laboratories performing magnetic and geometric tests.
• Procurement and purchasing teams creating compliant specifications and contracts.

Practical value:

• Ensures consistent magnetic performance and mechanical tolerances across suppliers.
• Reduces risk in core assembly (stacking factor, flatness, edge condition).
• Facilitates compliance with international testing methods (Epstein test) and interoperability with related IEC 60404 parts.

Related standards

• IEC 60404-1 (classification)
• IEC 60404-2 (Epstein method for magnetic loss and properties)
• IEC 60404-8-3 (semi-processed cold-rolled non-oriented steel)
• IEC 60404-9:2018 (geometrical characteristics terminology)

Keywords: IEC 60404-8-4, cold-rolled non-oriented electrical steel, non-oriented electrical steel strip and sheet, magnetic materials, fully-processed state, Epstein method, Class C.21, tolerances, annealed.