Within non-sintered permanent magnet materials, “bonded magnets” represent a broad category, primarily encompassing two mainstream processes: compression-bonded and injection-molded. Although both involve combining magnetic powder with a polymer binder, they differ in material properties, manufacturing procedures, and suitable applications.

      Compression-bonded NdFeB magnets are typically made by mixing magnetic powder with a small amount of thermoset or thermoplastic binder, then pressing and curing the mixture in a mold under high pressure. This process achieves a relatively high magnetic powder loading, resulting in stronger magnetic performance. These magnets can also undergo limited mechanical machining, making them suitable for components with simpler geometries but higher requirements for magnetic flux density—such as sensor cores or small motor segments.

      In contrast, injection-molded magnets are formed by compounding magnetic powder with thermoplastic resins (e.g., PPS or PA) and injecting the mixture into a mold via an injection molding machine. This method enables the production of more complex three-dimensional structures—such as rotors with shaft bores, snap-fit features, or asymmetric poles—and offers better surface finish and tighter dimensional tolerances. However, due to the higher resin content, their magnetic performance is generally lower than that of compression-bonded types, making them more appropriate for applications where structural integration is critical and absolute magnetic strength is moderately required.

      Each process has its own application boundaries. For instance, compression-bonded magnets are better suited when post-machining such as cutting or tapping is needed, whereas injection-molded solutions show advantages in small rotating parts that benefit from assembly-free design and high consistency. Selection should be based on a comprehensive evaluation of motor topology, assembly method, and environmental conditions.

      Ningbo Buer Magnetic & Electric Technology Co., Ltd. has development capabilities for both compression-bonded and injection-molded magnets. The company can provide technical explanations of different process routes upon request, helping engineers understand the relationship between material characteristics and design constraints.