Rare-Earth Bonded Magnet Compound with Tuned Powder Size Distribution
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Solution Overview
Problem
Existing rare-earth bonded magnet compounds often exhibit low flowability, especially when a coupling agent is not present or is ineffective, which can result in incomplete filling of molds during injection molding, preventing the production of magnets with predetermined shapes.
Innovation Solution
A rare-earth bonded magnet compound is developed by kneading a mixture of coarse and fine rare-earth magnet powders, where the coarse powder has a D50 of 240 µm or more and less than 380 µm, and the fine powder has a D50 of 35 µm or less, with a D90/D10 ratio of 28 or more and 37 or less, enhancing the compound's flowability regardless of the presence of a coupling agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a coupling agent is added to improve flowability, then the compound can flow better in some cases, but the flowability may decrease in other cases despite adding the coupling agent
Solution Approach 1:
The invention changes the physical parameters of the magnet powder by controlling particle size distribution (D50 of coarse powder at 240-380 μm, D50 of fine powder at 35 μm or less, and D90/D10 ratio at 28-37). This parameter optimization enables high flowability without relying on coupling agents, resolving the inconsistency in flowability that occurs with coupling agent addition.
Solution Approach 2:
The invention extracts the dependency on coupling agents for achieving flowability. By optimizing the particle size distribution of the magnet powder itself, the compound achieves high flowability independently of coupling agents, eliminating the unreliable situation where coupling agents may fail to improve or even worsen flowability.
2Manufacturing precision
If the compound has low flowability, then the compound does not spread over the entire mold, but increasing flowability requires adding coupling agents which may not always work
Solution Approach 1:
The invention optimizes the particle size distribution parameters (D50 of coarse powder: 240-380 μm, D50 of fine powder: 35 μm or less, D90/D10 ratio: 28-37) to achieve high flowability. This ensures complete mold filling without requiring additional coupling agents, thus improving manufacturing precision while avoiding increased composition complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The enhanced flowability of the rare-earth bonded magnet compound allows for more reliable filling of molds during injection molding, ensuring the production of magnets with complex shapes and improved manufacturing efficiency.
Implementation Method 1
the rare-earth magnet powder is obtained by mixing a coarse powder having a D50 of 240 μm or more and less than 380 μm and a fine powder having a D50 of 35 μm or less, and D90/D10, which is a ratio of D90 to D10 in a particle size distribution of the entire rare-earth magnet powder, is 28 or more and 37 or less
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2~3
AI summary
The present invention relates to a rare-earth bonded magnet compound (10), the compound including: a rare-earth magnet powder (11) that includes a coarse powder (111) and a fine powder (112); and a resin binder (12), in which the rare-earth bonded magnet compound (10) is obtained by kneading the rare-earth magnet powder (11) and the resin binder (12), the rare-earth magnet powder (11)is obtained by mixing the coarse powder (111) and the fine powder (112), the coarse powder (111) has a D50 of 240 µm or more and less than 380 µm, the fine powder (112) has a D50 of 35 µm or less, and the rare-earth magnet powder (11) has a D90/D10, which is a ratio of D90 to D10 in a particle size distribution of the entire rare-earth magnet powder, of 28 or more and 37 or less.