IEC 63093-15:2025

IEC 63093-15 ®
Edition 1.0 2025-08
INTERNATIONAL
STANDARD
Ferrite cores - Guidelines on dimensions and the limits of surface irregularities -
Part 15: U-cores
ICS 29.100.10  ISBN 978-2-8327-0619-0

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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 . 5
4.2.1 Main dimensions. 5
4.2.2 Effective parameter and A values . 6
min
4.3 Dimensional limits for coil formers . 7
5 Limits of surface irregularities . 8
5.1 General . 8
5.2 Examples of surface irregularities . 8
5.3 Chips and ragged edges . 9
5.3.1 General . 9
5.3.2 Chips and ragged edges on the mating surfaces . 9
5.3.3 Chips and ragged edges on the other surfaces . 9
5.4 Cracks . 10
5.5 Pull-out . 11
5.6 Crystallites . 11
5.7 Pores . 12
Annex A (informative) Derived standards . 13
Annex B (informative) Limits for allowable chipping areas . 14

Figure 1 – Main dimensions of U-cores . 5
Figure 2 – Main dimensions of coil formers . 7
Figure 3 – Examples of surface irregularities . 9
Figure 4 – Chip and ragged edge locations for U-cores . 10
Figure 5 – Locations of cracks for U-cores . 10
Figure 6 – Pull-out location for U-cores . 11
Figure 7 – Crystallite location for U-cores . 11
Figure 8 – Pore location for U-cores . 12

Table 1 – Main dimensions of U-cores . 5
Table 2 – Effective parameter and A values . 6
min
Table 3 – Main dimensions of Type 1 coil formers. 8
Table 4 – Main dimensions of Type 2 coil formers. 8
Table B.1 – Limits for allowable chipping areas . 14

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Ferrite cores - Guidelines on dimensions
and the limits of surface irregularities -
Part 15: U-cores
FOREWORD
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IEC 63093-15 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
51/1559/FDIS 51/1574/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 63093 series, published under the general title Ferrite 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 the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
1 Scope
This part of IEC 63093 specifies the dimensions that are of importance for mechanical
interchangeability for a preferred range of U-cores made of ferrite, the essential dimensions of
coil formers to be used with them, as well as the effective parameter values to be used in
calculations involving them and gives guidelines on allowable limits of surface irregularities
applicable to U-cores.
The selection of core sizes for this document is based on the philosophy of including those
sizes which are industrial standards, either by inclusion in national standards, or by broad-
based use in industry.
This document is a specification useful in the negotiations between ferrite 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.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60205, Calculation of the effective parameters of magnetic piece parts
IEC 60401-1, Terms and nomenclature for cores made of magnetically soft ferrites - Part 1:
Terms used for physical irregularities and reference of dimensions
IEC 63093-1, Ferrite cores - Guidelines on dimensions and the limits of surface irregularities -
Part 1: General specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60401-1 and
IEC 63093-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Primary dimensions
4.1 General
Compliance with the following requirements ensures mechanical interchangeability of complete
assemblies and coil formers.
4.2 Dimensions of U-cores
4.2.1 Main dimensions
The main dimensions of U-cores sh
...