What advantages does bonded NdFeB possess in complex shape forming that sintered NdFeB cannot achieve?
Publish Time: 2026-02-24
In modern high-end manufacturing and precision electronics, permanent magnet materials are increasingly widely used, with NdFeB becoming the mainstream choice due to its superior magnetic properties. Based on different manufacturing processes, NdFeB is mainly divided into two categories: sintered and bonded. While sintered NdFeB possesses high energy product and excellent temperature stability, it has significant limitations in forming complex geometries. Bonded NdFeB, with its unique manufacturing process, exhibits advantages that sintered products cannot match in achieving irregular, miniaturized, and integrated structures, becoming a key support for the development of precision magnetic devices.1. Flexible forming methods, overcoming geometric limitationsSintered NdFeB relies on compression molding and high-temperature sintering. During sintering, the material undergoes approximately 15%-20% linear shrinkage, and the shrinkage rate in each direction is difficult to be completely uniform, leading to deformation, cracking, or uneven density in complex-shaped parts. Therefore, typical NdFeB products are mostly regular square, circular, or ring-shaped structures, making it difficult to achieve complex configurations such as curved surfaces, concave surfaces, and thin-walled cantilever structures. Bonded NdFeB, however, uses a binder to inject, compress, or extrude rapidly quenched magnetic powder, resulting in no significant volume shrinkage during the molding process. Furthermore, the material has good flowability, allowing for precise filling of complex mold cavities and enabling highly flexible three-dimensional structural designs, such as multi-pole magnetic rings, asymmetric magnets, and structures with inserts, greatly expanding the design boundaries of magnets.2. Support for Miniaturization and High-Precision MoldingWith the development of smart devices, micromotors, and wearable technology, the demand for micromagnets has surged. Bonded NdFeB can be manufactured using precision injection molding technology, resulting in a high surface finish suitable for automated assembly. For example, in mobile phone vibration motors, TWS earphone driver units, and micro stepper motors, multi-pole magnetized micromagnetic rings are often required. The bonding process can complete molding and polarity layout in one step, while sintered NdFeB requires subsequent cutting and grinding, which is difficult to process and has a low yield, making it difficult to meet the needs of large-scale miniaturization.3. Enables Multi-Material Composites and Functional IntegrationA major advantage of bonding technology is its strong material compatibility. Magnetic powder can be combined with insulating fillers, thermally conductive materials, or reinforcing fibers to create composite magnets that possess both magnetic properties and specific physical functions. Furthermore, through insert molding or two-color injection molding technology, magnets can be integrated with metal shafts, plastic shells, or circuit supports to form "ready-to-use" functional modules. This integrated design not only reduces assembly steps but also improves product reliability and space utilization. In contrast, sintered NdFeB is a brittle material, difficult to directly composite with other materials, resulting in high integration costs and complex processes.4. High Production Efficiency, Suitable for Customization and Rapid IterationBonded NdFeB has a short molding cycle, with each injection molding taking only tens of seconds, making it suitable for automated mass production. Simultaneously, flexible mold changes are suitable for multi-variety, small-batch, or rapid prototyping development. For design verification stages requiring frequent structural adjustments, bonding technology can respond quickly, shortening the product development cycle. Sintered NdFeB, from pressing to sintering, processing, and surface treatment, involves a long process and a long cycle. Each step can affect the final size and performance, making it difficult to meet highly flexible customization needs.5. High Material Utilization and Environmentally FriendlyBonded NdFeB has almost no waste, with a material utilization rate close to 100%. In contrast, sintered NdFeB suffers material loss of over 30% during post-processing such as cutting and grinding, especially when manufacturing irregularly shaped parts. Furthermore, the bonding process eliminates the need for high-temperature sintering, significantly reducing energy consumption and aligning better with green manufacturing principles.In summary, bonded NdFeB, with its high flexibility in complex shape forming, miniaturization capabilities, functional integration, and production adaptability, compensates for the shortcomings of sintered NdFeB in precision structure manufacturing. Although its magnetic properties are slightly lower, bonding technology has become an irreplaceable solution in applications requiring extremely high structural complexity, integration, and production efficiency, driving the continuous evolution of magnetic devices towards greater intelligence, compactness, and efficiency.
