Influences on the Magnetic Properties of Injection Molded Multipolar Rings

Abstract

Abstract Polymer bonded magnets with a multipolar structure can be economically produced using the injection molding process for applications such as electric drives or sensor modules. Depending on the specific application, certain requirements of the multipolar bonded magnets, such as a high peak flux density or accurate pole length of each pole, must be assured. The multipolar magnetic structure of the parts can be applied during the injection molding process by incorporating a magnetic field inside the mold. Thus, the hard magnetic particles are oriented and magnetized directly in the injection molding process. The final properties of the multipolar molded magnets are affected by different parameters, such as the magnetic compound, the mold design and the processing parameters. This paper addresses the effects processing parameters have during the injection molding process. Additionally, the role the filler volume content plays with the properties of pole-oriented molded multipolar rings is also investigated. In particular, the magnetic characteristics, such as the maximum radial flux density, the pole length and the rate of the course of the flux density, were investigated. Further, the orientation of the particles and the influence of the varied parameters on the geometry of the rings were analyzed. It was found that the varied parameters do not significantly influence the accuracy of the pole length. The slope of the flux density curve is influenced by the peak maxima and varies slightly due to the high peak flux densities.