Variation of the Pole Length in Pole-Oriented Bonded Rings due to the Location and Number of Injection Points

2023

To expand the range of applications of multipolar bonded magnets based on a thermoplastic matrix, the chemical and thermal resistance has to be increased and the reduced orientation in the rapid solidified surface layer has to be overcome. To meet these requirements, the matrix of multipolar bonded magnets can be based on thermosets. This paper investigates in the magnetic properties, especially in the orientation of hard magnetic fillers, the pole accuracy and the mechanical properties of multipolar bonded ring magnets based on the hard magnetic filler strontium-ferrite-oxide and compares the possibilities of thermoplastic (polyamide)- and thermoset (epoxy resin, phenolic resin)-based matrices. It was shown that the magnetic potential of the thermoset-based material can only be fully used with further magnetization. However, the magnetic properties can be increased using thermoset-based compounds compared to thermoplastics in multipolar bonded ring magnets. Further, a model of the orientation and pole accuracy is found in terms of thermoset-based multipolar magnets. In addition, the change of the mechanical properties due to the different matrix systems was shown, with an increase in E-Modulus, Et, and a reduction in tensile strength, σm, and elongation at break, εm, in terms of thermosets compared to thermoplastics.

Section: Injection Mouldingmentioning

confidence: 99%

Extension of the Application Range of Multipolar Bonded Ring Magnets by Thermosets in Comparison to Thermoplastics

2023

“…Thermoplastics need a high temperature for plastification and are injected into the cavity with a low temperature leading to a rapid and premature cooling in the edge zone of the cavity along with a fast increase of the viscosity [18]. The temperature profile reveals a relatively high viscosity in the cavity, which impedes the orientation of the magnetic fillers [19]. Thermosets undergo a change of their chemical structure within the injection-molding process and under high temperatures, which are applied and lead to cross-linking of polymer chains.…”

Section: Injection Moldingmentioning

confidence: 99%

Understanding the Effect of Material Parameters on the Processability of Injection-Molded Thermoset-Based Bonded Magnets

2022

Self Cite

The applications of bonded magnets in the field of injection-molded samples can be expanded by thermoset-based polymer-bonded magnets, as thermosets provide the opportunity to comply with the demands of, for example, the chemical industry or pump systems in drive applications through to their improved chemical and thermal resistance, viscosity and creep behaviour, especially compared to thermoplastic-based magnets. This paper investigates the influence of the matrix material (epoxy resin, phenolic resin), the filler type (strontium-ferrite-oxide, neodymium-iron-boron) and the filler grade on the reaction kinetics and the viscosity. Based on the determination of the impact, the theory of the network structure is founded. The network and the cross-linked structure are essential to know, as they significantly define not only the material but also the sample behaviour. The correlation between the material system and the mechanical as well as the magnetic properties is portrayed based on the general understanding of the behaviour in terms of the reaction kinetics and the viscosity as well as the theory of the network structure. With that, a basic understanding of the correlation within the material system (matrix, filler, filler grade) and between the reaction kinetics, the network and the cross-linked structure was determined, which gives the opportunity to change the mechanical and the magnetic properties based on the analyzed impact factors and to expand the applications of bonded magnets in the field of thermoset-based ones.

“…Thus, rapid cooling takes place in the edge zone where the viscosity increases fast and prematurely. This temperature profile leads to a relatively high viscosity in the cavity, which impedes the orientation of the magnetic filler particles [24]. Thermosets undergo a change of the chemical structure within the injection molding process as the polymer chains are cross-linked due to high temperatures.…”

Section: Injection Moldingmentioning

confidence: 99%

Correlation between the Flow and Curing Behavior of Hard Magnetic Fillers in Thermosets and the Magnetic Properties

2021

Self Cite

Polymer bonded magnets based on thermoplastics are economically produced by the injection molding process for applications in sensor and drive technology. Especially the lack of orientation in the edge layer, as well as the chemical resistance and the creep behavior limit the possible implementations of thermoplastic based polymer bonded magnets. However, thermoset based polymer bonded magnets have the opportunity to expand the applications by complying with the demands of the chemical industry or pump systems through to improved chemical and thermal resistance, viscosity and creep behavior of thermosets. This paper investigates the influence of hard magnetic particles on the flow and curing behavior of highly filled thermoset compounds based on an epoxy resin. The basic understanding of the behavior of those highly filled hard magnetic thermoset systems is essential for the fabrication of polymer bonded magnets based on thermosets in the injection molding process. It is shown that several factors like the crystal structure, the particle shape and size, as well as the thermal conductivity and the adherence between filler and matrix influence the flow and curing behavior of highly filled thermoset compounds based on epoxy resin. However, these influencing factors can be applied to any filler system with respect to a high filler amount in a thermoset compound, as they are based on the material behavior of particles. Further, the impact of the flow and curing behavior on the magnetic properties of polymer bonded magnets based on thermosets is shown. With that, the correlation between material based factors and magnetic properties within thermosets are portrayed.