IEC 63182-8:2025

Magnetic powder cores - Guidelines on dimensions and the limits of surface irregularities - Part 8: U-cores

IEC 63182-8:2025 specifies the dimensions that are of importance for mechanical interchangeability for a preferred range of U-cores made of metallic magnetic powder and gives guidelines on allowable limits of surface irregularities applicable to U-cores.
This document is a specification that is useful in the negotiations between magnetic powder core manufacturers and customers about surface irregularities.
The use of "derived" standards which give more detailed specifications of component parts while still permitting conformance with this document is discussed in Annex A.

General Information

• Status: Published
• Publication Date: 27-Aug-2025
• ICS: 29.100.10 - Magnetic components
• Technical Committee: TC 51 - Magnetic components, ferrite and magnetic powder materials
• Drafting Committee: WG 1 - TC 51/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 28-Aug-2025
• Completion Date: 26-Sep-2025

Overview

IEC 63182-8:2025 - "Magnetic powder cores - Guidelines on dimensions and the limits of surface irregularities - Part 8: U-cores" specifies the key geometric dimensions and acceptable surface irregularities for a preferred range of U-cores made from metallic magnetic powder. The standard focuses on ensuring mechanical interchangeability of cores and provides guidance for negotiations between magnetic powder core manufacturers and their customers. It also references calculation of effective magnetic parameters (per IEC 60205) and discusses the use of more detailed, “derived” standards (Annex A).

Key topics and requirements

• Primary dimensions and tolerances: Main dimensions (A, B, C, D, E, L) and a preferred size range for many common U-core types are defined. Typical tolerance guidance is provided (e.g., dimensions A and B ≈ 3.0% of center value; C ≈ 3.5%; E and L ≈ 4.0%).
• Effective parameters: Effective magnetic parameters (Ae, le, Ve, etc.) are specified for U-cores that meet the dimension table; calculations follow IEC 60205. Suppliers may list more precise values in catalogues.
• Surface irregularities: Clear visual acceptance limits are defined for defects such as chips, ragged edges, cracks, flash, rust and discoloration. Examples and locations are illustrated in figures.
  • Chips: Minimum observable chip area = 0.5 mm²; maximum cumulative chip area on a surface = 50 mm². For mating surfaces, cumulative chip area < 6% of the mating surface; ragged-edge length < 25% of the mating-surface perimeter. Non-mating surfaces allow doubled chip area but the same ragged-edge rule.
  • Cracks: For mating surfaces, individual cracks < 25% of a reference dimension and total crack length per surface ≤ 50% of the reference. For non-mating surfaces, cracks ≤ 50% of the reference and ≤ 3 cracks per surface.
• Inspection references: Visual inspection criteria and reference areas are given in IEC 63182-1.

Applications

• Core manufacturers use this standard to design U-core dimensions, set production tolerances, and define catalog data.
• Transformer and inductor designers ensure mechanical interchangeability and predict inductance using the provided effective parameters.
• Purchasing and quality engineers use the surface-irregularity limits during supplier negotiations, incoming inspection and acceptance testing.
• Test labs and certification bodies apply the defined limits when assessing conformity to IEC 63182 series requirements.

Related standards

• IEC 63182-1 - General specification and visual inspection references for magnetic powder cores.
• IEC 60205 - Calculation of effective parameters of magnetic piece parts.
• Other parts of the IEC 63182 series and any “derived” standards (Annex A) that provide more detailed component specifications while maintaining conformance.

Keywords: IEC 63182-8:2025, magnetic powder cores, U-cores, surface irregularities, dimensions, mechanical interchangeability, effective parameter, IEC 60205.

Standards Content (Sample)

IEC 63182-8 ®
Edition 1.0 2025-08
INTERNATIONAL
STANDARD
Magnetic powder cores - Guidelines on dimensions and the limits of surface
irregularities -
Part 8: U-cores
ICS 29.100.10  ISBN 978-2-8327-0668-8

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CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Primary dimensions . 4
4.1 General . 4
4.2 Dimensions of U-cores . 4
4.2.1 Main dimensions . 4
4.2.2 Effective parameter . 6
5 Limits of surface irregularities . 6
5.1 General . 6
5.2 Examples of surface irregularities . 6
5.3 Chips and ragged edges . 7
5.3.1 General. 7
5.3.2 Chips and ragged edges of mating surfaces. 7
5.3.3 Chips and ragged edges on the other surfaces. 7
5.4 Cracks . 8
5.5 Flash . 8
5.6 Rust . 9
5.7 Discoloration . 9
Annex A (informative) Derived standards . 10

Figure 1 – Main dimensions of U-cores . 5
Figure 2 – Examples of surface irregularities . 7
Figure 3 – Locations of chips and ragged edges for U-cores . 7
Figure 4 – Locations of cracks for U-cores . 8
Figure 5 – Locations of flashes for U-cores . 8
Figure 6 – Locations of rust for U-cores . 9

Table 1 – Main dimensions of U-cores . 5
Table 2 – Effective parameter . 6

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Magnetic powder cores -
Guidelines on dimensions and the limits of surface irregularities -
Part 8: U-cores
FOREWORD
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IEC 63182-8 has been prepared by IEC technical committee 51: Magnetic components, ferrite
and magnetic powder materials. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
51/1562/FDIS 51/1578/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 63182 series, published under the general title Magnetic powder
cores – Guidelines on dimensions and the limits of surface irregularities, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to t
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