NdFeB Flexible Magnet Feedstock for High-Fill Injection Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current injection molding technologies face challenges in producing high magnetic performance flexible magnets due to the requirement for a high magnetic powder filling ratio, which negatively impacts the flowability of the feedstock, leading to insufficient mold filling and defects in the final products.
Innovation Solution
The development of feedstock for preparing NdFeB flexible magnets, which comprises a high content of neodymium-iron-boron magnetic powder, a blend of thermoplastic elastomers as binder, and additives such as surface treatment agents, antioxidants, and plasticizers, to enhance the flowability and magnetic performance of the magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the magnetic powder filling ratio is increased to meet magnetic performance standards, then the magnetic performance is improved, but the flowability of the feedstock deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the magnetic powder particle size distribution (D10, D50, D90 parameters) and chemical composition (rare earth content, Fe, B, and other element ratios) to achieve high magnetic performance while maintaining feedstock flowability for injection molding
Solution Approach 2:
The patent uses composite magnetic powder materials combining different particle sizes and compositions, including NdFeB base powder with specific rare earth content and additional elements (Co, Cu, Al, etc.) to create a composite structure that balances magnetic performance and processing characteristics
2Quantity of substance
If the magnetic powder content is increased, then the magnetic performance is improved, but the amount of binder is reduced which negatively impacts the flowability of the feedstock
Solution Approach 1:
The patent optimizes the binder content parameter to a specific range (3.0-7.0 wt%) and adjusts magnetic powder particle size parameters (D10: 3-8 μm, D50: 10-15 μm, D90: 20-30 μm) to achieve the optimal balance between magnetic powder content and feedstock flowability
3Quantity of substance
If the magnetic powder filling ratio is increased to achieve high magnetic performance, then the magnetic energy product is improved, but the mold filling becomes insufficient leading to defects
Solution Approach 1:
The patent changes the particle size distribution parameters (narrowing the D10-D90 range to 3-30 μm) and chemical composition parameters of magnetic powder to improve flowability and ensure complete mold filling while maintaining high magnetic powder content (92-97 wt%)
Solution Approach 2:
The patent performs preliminary surface treatment of magnetic powder with coupling agents before mixing with binder, which improves the interfacial bonding and flow characteristics of the feedstock, ensuring complete mold filling and preventing defects
Data Source
AI summary
A neodymium-iron-boron flexible magnet includes 93.5 wt % to 94.6 wt % of neodymium-iron-boron magnetic powder, 0.3 wt % to 0.5 wt % of surface treatment agent for magnetic powder, 2.7 wt % to 3.7 wt % of binder, 0.3 wt % to 1.0 wt % of antioxidant, and 0.5 wt % to 1.8 wt % of plasticizer. The binder includes type I thermoplastic elastomer and type II thermoplastic elastomer, with a mass ratio of the type I thermoplastic elastomer to the type II thermoplastic elastomer being 1:9 to 4:6. The type I thermoplastic elastomer is selected from one or more of thermoplastic polyamide elastomer and thermoplastic polyurethane elastomer; and the type II thermoplastic elastomer is selected from one or more of styrenic block copolymers, dynamically vulcanized thermoplastic elastomers, thermoplastic polyolefin elastomers, and thermoplastic polyester elastomers.