Magnetic Powder Core Classification: IEC 63299 Guide

Magnetic powder cores come in several material families with very different properties, and the same permeability is available from multiple suppliers. IEC 63299:2022 defines a uniform classification so engineers can compare cores across manufacturers. This guide explains the classification system and how to read a powder core designation.

1. The classification code

Each powder core is designated by a material family letter plus a three-digit permeability code. For example, H060 means iron-nickel (Fe-Ni) powder with an effective initial permeability of 60. The families defined by IEC 63299 are:

2. Permeability code and grades

The subclassification is based on effective initial permeability, written as a three-digit code — 010, 026, 035, 040, 055, 060, 075, 090, 125, 147, 160, 173. Typical published grades include iron powder I060/I075, iron-silicon K060/K090, Sendust S060/S090, high flux H060/H125/H160, MPP M060/M125/M160/M173, amorphous A060/A090 and nanocrystalline N060.

3. Properties that define a powder core

• Initial permeability — the classification basis and the inductance-per-turn driver
• Saturation magnetic flux density (Bs) — measured at 50 Hz and 20 kA/m
• DC-bias characteristic — how much inductance holds at a given DC field
• Power loss density — quoted in kW/m³ at defined frequency and flux (e.g., 100 kHz / 100 mT)
• Temperature coefficient of permeability — stability over temperature
• Plus density, mechanical strength and thermal conductivity for mechanical design

4. Core shapes covered

Powder cores are produced as rings (toroids), blocks, cylinders, ellipses, E types, EQ types, EER types, U types and pot types. The shape and dimensions are agreed in the detailed specification, while the material class and permeability code define the magnetic performance.

5. Where each family fits

• High-current power inductors (AI GPU VRM, server POL, EV) → Fe-Ni high flux (Bs ≥1.5 T, stable bias)
• Lowest-loss powder-core filtering → Fe-Ni-Mo (MPP)
• PFC and EMI filter roles → Sendust (Fe-Si-Al)
• Cost-sensitive benign applications → iron powder
• High-frequency / high-permeability niches → amorphous and nanocrystalline powder cores

Ferrite is a different material family (ceramic, not powder); the Ferrite Core Guide and High Flux Cores Guide compare the two sides of the decision. Test methods for these properties are defined in IEC 63300, and the Core Selection Tool applies the classification to real design inputs. Full property tables for every subclass (I010–I075, K026–K090, S026–S125, H026–H160, M026–M200, A060–A090, N060) are on the Technical Data page.

YUTE Magnetics manufactures Fe-Ni powder cores and inductors (YTFN series) with full-process testing. Send your inductance, current and frequency targets through the engineering RFQ for a free technical evaluation.