Ferrite Sintered Magnet Injection Molding Surface Roughness
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Solution Overview
Problem
Ferrite sintered magnets generate dust and tarnish during transport and assembly, leading to increased production and packing costs, and when used in motors, they cause dirt due to friction with other components, necessitating additional processes and materials to mitigate these issues.
Innovation Solution
A method involving mixing magnetic powders with a binder resin and applying a magnetic field during injection molding to produce a ferrite sintered magnet with a surface roughness of 3.5 μm or less, reducing dust emission and tarnish, and eliminating the need for grinding or additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a glass glaze is applied to the surface of a ferrite sintered magnet and baked, then dust emission and surface tarnish are suppressed, but the number of processes is increased and material cost is increased
Solution Approach 1:
The invention extracts and eliminates the unnecessary glass glaze application and baking processes from the conventional manufacturing flow. By using injection molding with a controlled surface roughness mold (Rz ≤ 3.5 μm), the patent directly produces ferrite sintered magnets with dust-resistant surfaces, removing the separate surface treatment steps entirely.
Solution Approach 2:
The mold surface roughness is designed to self-generate the desired surface quality on the ferrite sintered magnet during injection molding. The mold's controlled roughness (Rz ≤ 2.0 μm) directly transfers to the magnet surface, creating a dust-resistant finish without requiring additional surface treatment processes.
2Object-affected harmful factors
If a glass glaze is applied to the surface of a ferrite sintered magnet and baked, then dust emission and surface tarnish are suppressed, but material cost is increased
Solution Approach 1:
The invention removes the glass glaze material requirement entirely by using injection molding to directly form the ferrite sintered magnet with an optimized surface roughness. This eliminates the need to purchase, store, and apply glass glaze materials, reducing material costs while achieving the same dust suppression effect.
Solution Approach 2:
The invention changes the critical parameter from surface coating composition (glass glaze) to surface roughness control (Rz ≤ 3.5 μm). By controlling the mold surface roughness (Rz ≤ 2.0 μm) and injection molding parameters, the patent achieves dust-resistant surfaces through physical surface characteristics rather than chemical coatings, reducing material requirements.
3Object-affected harmful factors
If ferrite sintered magnets are individually packed before transport, then dust generation and surface tarnish are suppressed, but packing cost is increased
Solution Approach 1:
The invention performs preliminary surface protection by creating a dust-resistant surface finish (Rz ≤ 3.5 μm) during the injection molding process itself. This preliminary surface treatment eliminates the need for subsequent individual packing operations, as the magnets are inherently protected against dust generation and surface tarnish during transport and handling.
Solution Approach 2:
The ferrite sintered magnets possess self-protective surface characteristics due to the controlled roughness (Rz ≤ 3.5 μm) achieved through injection molding. This self-service property allows the magnets to resist dust generation and surface tarnish without requiring external protective packaging, eliminating packing operations and associated costs.
4Reliability
If ferrite sintered magnets are rubbed with fastening tools during assembly, then magnets are secured to the motor case, but dust is generated and the motor gets dirty
Solution Approach 1:
The invention changes the surface roughness parameter to Rz ≤ 3.5 μm through controlled injection molding (mold Rz ≤ 2.0 μm). This optimized surface parameter reduces dust generation during assembly operations while maintaining sufficient surface area for reliable fixation with fastening tools, resolving the contradiction between assembly reliability and dust control.
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 method effectively decreases dust emission, tarnish, and dirt when ferrite sintered magnets are assembled, improving productivity and reducing costs by eliminating the need for extra processing steps and materials, while maintaining high magnetic characteristics.
Implementation Method 1
injection molding the magnetic powder mixture inside of a mold having a surface roughness of a surface in contact with the magnetic powder mixture of 2.0 μm or less with a magnetic field applied to the mold
Implementation Method 2
sintering the molded body
Data Source
AI summary
A ferrite sintered magnet has a surface roughness Rz of 3.5 μm or less. A method for producing a ferrite sintered magnet includes: mixing magnetic powders with at least a binder resin to obtain a magnetic powder mixture; injection molding the magnetic powder mixture inside of a mold having a surface roughness of a surface in contact with the magnetic powder mixture of 2.0 μm or less with a magnetic field applied to the mold, to obtain a molded body; and sintering the molded body.