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The layer-wise deposition intrinsic to extrusion-based additive manufacturing induces mesostructural features that behave as distributed air gaps and can modify the effective magnetic response of printed cores, an aspect that remains insufficiently documented for soft ferrites. In this work, the inherent impact of Fused Deposition Modeling (FDM) printing paths on the magnetic properties of additively manufactured MnZn ferrite cores is investigated experimentally. Toroidal cores were fabricated using a PIM-like FDM process from a polymer-based pellet feedstock loaded with 50 vol% MnZn ferrite powder. Two deposition routes were compared: concentric and rectilinear patterns. Magnetic characterization reveals a clear influence of the deposition path on the effective magnetic permeability. While moderate differences are observed under low-signal excitation, significant deviations appear at higher excitation levels. These variations are attributed to the oriented inter-bead porosities induced by the FDM process, which behave as distributed air gaps within the magnetic circuit. Additional investigations based on under-extrusion highlight a marked difference in sensitivity between the two deposition strategies, with concentric patterns exhibiting a higher robustness to local variations in material deposition. In contrast, magnetic losses remain only slightly affected by the deposition strategy. These results highlight the deposition path as an additional design parameter for tailoring the magnetic behavior of additively manufactured ferrite components.

Additive manufacturing provides flexibility in terms of the shapes that can be produced. This work investigates the impact of Fused Deposition Modeling (FDM) printing paths on the magnetic properties of additively manufactured MnZn ferrite cores. Cores with concentric and straight deposition paths were manufactured using a 50%vol MnZn-filled filament. Magnetic characterization has revealed a significant difference in their static permeability. The process induced small air gaps in-between each deposition line, which influences significantly the permeability. This finding can be relevant for power electronics applications for distributed air gaps components.