Overview
IEC 63182-6:2025 - "Magnetic powder cores - Guidelines on dimensions and the limits of surface irregularities - Part 6: EQ-cores" - is an IEC international standard that defines the mechanical and surface-quality requirements for a preferred range of EQ-cores made from metallic magnetic powder. The standard specifies the essential dimensions for mechanical interchangeability, the effective parameters used in electromagnetic calculations, the required dimensions of compatible coil formers, and practical limits on surface irregularities. It is intended to support clear agreements between magnetic powder core manufacturers and customers.
Key topics and technical requirements
- Scope and purpose
- Defines primary dimensions that ensure mechanical interchangeability of complete assemblies and coil formers.
- Supports negotiation and specification of allowable surface defects between suppliers and users.
- Dimensional data
- Main core dimensions for a preferred range of EQ-cores are presented (see Table 1 and Figure 1 in the standard). Size designations (for example, EQ 21/8/14, EQ 27/10/19) identify core length, height and width.
- Recommended tolerance ranges for new core designs are described (percent ranges for dimensions A, B, C, F).
- Effective parameters
- Effective parameter and A-values for use in inductance and magnetic calculations are given (Table 2), calculated per IEC 60205.
- Notes address magnetic leakage effects and practical measurement considerations (e.g., influence of coil geometry and low turn counts).
- Coil former dimensions
- Essential dimensional limits for coil formers compatible with EQ-cores are provided (Figure 2 and Table 3) to ensure interchangeability.
- Surface irregularities
- Definitions and examples of defects (chips, ragged edges, cracks, flash, rust, discoloration) and their allowable limits.
- Specific rules: minimum distinguishable chip area 0.5 mm²; maximum cumulative chip area on a surface is 50 mm²; chips on mating surfaces limited to less than 6% of the centre-leg mating surface and ragged edges less than 25% of the mating-surface perimeter; other surfaces allow double the chip area limit.
Applications and who uses it
- Used by magnetic component designers, transformer and inductor manufacturers, procurement/specification engineers, and quality assurance teams.
- Applies to product design (mechanical fits and inductance calculations), production specifications, incoming inspection criteria, and commercial contracts between core manufacturers and customers.
- Useful in ensuring interchangeability of parts and consistent electromagnetic performance across suppliers.
Related standards
- IEC 60205 - Calculation of the effective parameters of magnetic piece parts (normative for parameter calculations).
- IEC 63182-1 - Part 1: General specification (terms, definitions and common rules referenced).
- Annex A of IEC 63182-6 discusses the use of "derived" standards for more detailed component specifications while remaining compliant.
Keywords: IEC 63182-6, EQ-cores, magnetic powder cores, surface irregularities, coil formers, effective parameters, mechanical interchangeability, IEC 60205.