Iron-Based Dust Core Powder Composition for High Green Density

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for producing dust cores with high magnetic flux density and low iron loss are limited by the need to classify and mix powders of different particle sizes, which can lead to coagulation and inconsistent apparent density, thereby affecting the green density and magnetic properties.

Innovation Solution

The use of an iron-based powder for dust cores with a maximum particle size of 1 mm or less, where the median circularity of particles is 0.40 or more and the uniformity number in the Rosin-Rammler equation is 0.30 or more and 90.0 or less, allows for improved apparent density and green density without the need for classification and specific mixing ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If powders of different particle sizes are classified and mixed at specific ratios to control apparent density, then the apparent density can be controlled, but coarse particles or fine particles coagulate depending on mixing conditions, making it impossible to achieve desired apparent density

Engineering Contradiction:
Improveapparent densityVSAvoidpowder mixture uniformity
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent changes the particle size distribution parameters by controlling the D10, D50, and D90 values to specific ranges, and by controlling the uniformity number n to 0.30 or more. This parameter optimization allows the powder to achieve high apparent density (3.5 g/cm³ or more) without requiring classification and mixing operations, preventing coagulation while achieving the desired density.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the particle size distribution into specific ranges (D10: 1-10 μm, D50: 50-200 μm, D90: 200-500 μm) with controlled distribution width, creating a optimized size distribution that prevents coagulation of coarse or fine particles while achieving high apparent density without mixing operations.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If only the particle shape of fine powder is controlled to enhance compressibility, then the compressibility of fine powder is improved, but the particle shape of coarse powder is not considered, and the friction between coarse particles and fine particles is not optimized

Engineering Contradiction:
ImprovecompressibilityVSAvoidapparent density
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent optimizes the circularity parameter for the entire particle size distribution, not just fine powder. By controlling the D10, D50, and D90 particle sizes along with their circularity, the patent achieves both high compressibility and high apparent density, resolving the issue of insufficient consideration of coarse particle shape effects on friction and packing.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12272491B2Iron-based powder for dust cores and dust core
Publication Date: 2025.04.08 JFE STEEL CORP

AI summary

Provided is an iron-based powder for dust cores that has high apparent density and enables producing dust cores having high green density. An iron-based powder for dust cores comprises a maximum particle size of 1 mm or less, wherein a median circularity of particles constituting the iron-based powder for dust cores is 0.40 or more, and a uniformity number in Rosin-Rammler equation is 0.30 or more and 90.0 or less.