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Material extrusion additive manufacturing can process a wide variety of functional materials including electrically conductive, magnetic, and mechanically compliant polymer composites. While filaments developed for 3D printing often exhibit limited functionality, highly loaded functional composites originally formulated for specialised manufacturing processes can be processed via material extrusion. In this work, a commercial multi-material extrusion 3D printer was modified to process conductive inks, soft and hard magnetic composite pellets, and rigid and compliant polymeric filaments. Using this system, solenoids, hard magnets, and springs were fabricated. These components were combined through straightforward assembly to demonstrate the first fully 3D-printed electric motor — a linear actuator composed of five distinct functional materials: dielectric, electrically conductive, soft magnetic, hard magnetic, and flexible. The solenoids produced up to 2.03 mT magnetic fields, the magnets generated up to 71 mT magnetic fields, and the linear actuator attained a maximum displacement of 318 μm at its resonant frequency (41.6 Hz). This study demonstrates the capability of multi-modal, multi-material extrusion 3D printing to fabricate all critical components of electrical machines, with magnetisation of the hard magnets being the only post-printing step. This milestone advances multi-material, multi-functional 3D printing towards implementing in-situ, customised, low-waste, and low-cost functional hardware.
Cañada et al. (Mon,) studied this question.