The Fixation of magnets and iron cores is a key process in the manufacturing of permanent magnet synchronous motors. This article mainly introduces several common methods for fixing magnets and iron cores.
Adhesive Fixation of Magnets
Adhesive fixation of magnets is an earlier solution that offers high flexibility, making it suitable for small batch prototypes. However, it is not generally used in mass production due to the following disadvantages:
| Poor Cleanliness: After curing, excess adhesive tends to seep onto the iron core’s surface, requiring cleaning, which adds complexity.
| High Cost: Heat-resistant adhesive for magnets is usually epoxy-based, which is relatively expensive, costing around 500 RMB/kg.
Due to these costs and cleanliness issues, this fixing method has largely been eliminated. However, its flexibility makes it a viable option for small batch prototypes.
Injection Molding (Thermosetting) Fixation of Magnets
To address the disadvantages of adhesive fixation, injection molding (thermosetting) technology has become popular, characterized by its significant advantages in both cost and cleanliness compared to adhesive methods.
Mainstream injection molding materials available on the market include PA66 and Sumitomo M500A. While PA66 is lower in cost, it has poor flow characteristics, typically allowing only single-layer iron core injection molding. In contrast, M500A, with its good flow properties, enables whole rotor iron core injection, resulting in better rotor balance performance and enhanced product performance.
Iron Core Leaf Spring Fixation of Magnets
The leaf spring design is an innovative solution characterized by the absence of binding materials between the magnets and the iron core, thereby reducing raw material costs. However, this design faces certain challenges: the book is
The magnets are relatively brittle, so ensuring they do not fracture during mass production becomes a critical process issue.
At high speeds, the silicon steel sheets in the iron core undergo deformation, affecting the interference fit between the magnets and the iron core, complicating the selection of interference amounts. The current practice is to first subject the iron core to high-speed processing to induce deformation before inserting the magnets, stabilizing the interference fit significantly.
Rivet Fixation of Magnets
Rivet point fixing of magnets and iron cores is another method that involves inserting the iron core into the gaps between magnets and then riveting them to achieve fixation.
The advantage of this method is its ability to address the disadvantages of the leaf spring design. However, it also presents certain risks, particularly concerning the axial movement of the magnets, which is more pronounced compared to other solutions. The rivet point fixation method has clear advantages, though it entails greater design and validation challenges than the aforementioned methods.
Magnets Manufacturer
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Image Source: Hvhindustrial & Eurekamagazine & Lammotor
