Thermoset-bonded injection-molded magnets with defined structure of magnetization

聚合物键合永磁体是由嵌入硬磁填料颗粒的聚合物基体组成的复合材料。在传统的聚合物工艺中，如压制或注射成型，这些化合物可以加工成具有足够机械强度和刚度的磁铁。到目前为止，热固性粘结磁体的加工都是采用压制的方法，这严重限制了加工过程中的几何自由度和其他功能的集成。通过注射成型制造热固性粘结磁体，可以实现具有更高功能集成度的复杂部件和磁化结构。此外，由于粘度较低，与热塑性粘结磁铁相比，热固性粘结磁铁具有更高的温度和化学物质抗性。该项目的目的是系统地研究材料组成、工艺影响和组件几何形状以及浇注系统对填料方向的功能关系，从而对多极热固性粘结磁体的磁性能产生影响。该工艺使磁体具有明确的磁化结构，复杂的薄壁几何形状，同时通过使用注射成型工艺的可能性，具有高功率密度。与热塑性基质体系相比，热固性体系只有在注入腔内后才能达到最低的粘度，因此在填料取向方面可以预期显著的优势。在这种情况下，颗粒的方向发生在存在最低阻力（腔内粘度低）的时刻，从而能够精确表示磁场，特别是直接在工具接触表面，这是需要的，例如在高精度传感器系统中。特别是，这种改进的填料方向将有利于具有小极宽和对极宽精度要求高的组件，但也适用于具有高峰值通量密度要求的组件。此外，由于热固性系统的高温和耐介质性，聚合物粘结磁体在泵系统和高精度传感器系统中的应用可能性将得到扩大。热塑性粘结磁体很难提供这种电阻效应，只有当应用PPS作为基体材料时。在这个项目的范围内，最终的指导方针的化合物组成，以及热固性粘结永磁体的加工和设计是推导出来的。此外，考虑到热固性系统的时间和固化行为，应通过系统地改变化合物组成、工艺参数和组件几何形状来检查影响硬磁填料颗粒取向性的变量。

Polymer-bonded permanent magnets are composite materials consisting of a polymer matrix with em-bedded hard-magnetic filler particles. In conventional polymer processes, such as pressing or injec-tion molding, these compounds can be processed into magnets with sufficient mechanical strength and stiffness. So far, thermoset-bonded magnets are only processed by pressing which severely restricts the geometrical freedom and the integration of other functions within the process. By fabricating thermoset-bonded magnets via injection molding, complex components and magnetization structures with an increased functional integration could be ena-bled. Furthermore thermoset-bonded magnets allow for higher resistance to temperature and chemical substances compared to thermoplastic-bonded magnets due to lower viscosity.The aim of this project is the systematic investigation of the functional relationship of material com-position, process influences and component geometry as well as gating system on the filler orientation and thus, on the magnetic properties of multipolar thermoset-bonded magnets. This process enables the production of magnets with a defined structure of magnetization, complex and thin-walled geometry and, at the same time, high power density by using the possibilities of the injection molding process. In contrast to thermoplastic matrix systems, thermoset systems achieve their lowest viscosity only after the injection into the cavity, so that significant advantages can be expected with respect to filler orientation. In this case, the orientation of the particles takes place at the moment at which the lowest resistance forces (low viscosity in the cavity) are present, enabling a precise representation of the magnetic field especially directly at the tool contact surfaces, as is required, for example in highly accurate sensor systems. In particular, this improved filler orientation would be advantageous for components with a small pole width and high demands for accuracy of the pole width, but also for components with requirements for a high peak flux density. Furthermore, the application possibilities of polymer-bonded magnets in pump systems and highly accurate sensor systems shall be expanded due to high temperature and media resistance of thermoset systems. Thermoplastic-bonded magnets hardly offer this resistance effect, and only when applying PPS as matrix material. Within the scope of this project, final guidelines for the compound composition, as well as for the processing and design of thermoset-bonded permanent magnets are to be derived. Additionally, influencing variables on the orientability of the hard-magnetic filler particles shall be examined by systematically varying the compound composition, process parameters and component geometry, taking into account the time and curing behaviour of thermoset systems.