Binder Jetting of Fe-50Ni Complex Cores for Enhanced Soft Magnetic Performance

Additive manufacturing offers efficient material usage and enables customized shape designs that are difficult to achieve with conventional methods. This study investigates the binder jetting of Fe-50Ni soft magnetic alloys, which are widely used in transformers, inductors, and motors due to their high flux saturation. The process evaluation focuses on the final densities and magnetic properties of both bulk and complex toroidal designs. Two Fe-50Ni powders with different particle size distributions were processed and sintered under both atmospheric and vacuum conditions. Sintering temperatures near 1360 °C enabled near-full densification, whereas 1335 °C produced geometrically stable parts for complex designs with ~ 80% density, suitable for toroidal inductors. Magnetic characterization showed that binder-jetted bulk toroid samples reached saturation flux densities comparable to a commercial reference at 50 Hz but exhibited broader hysteresis loops due to eddy current loss. In contrast, complex geometries incorporating cavities and segmented designs provided clear benefits, with concentric square-ring designs achieving the highest permeability and highest inductance up to ~ 7 kHz. These results confirm the feasibility of binder jetting for producing Fe-50Ni soft magnetic cores and highlight the potential of geometry-based design strategies to mitigate core losses and enable advanced electrical and electronic applications.