Field-Assisted 3D Printing Creates Programmable Bonded Magnets With Custom Magnetic Properties

Researchers at Auckland University of Technology's Additive Manufacturing Research Centre have achieved a breakthrough in 3D printed magnets using a field-assisted selective laser sintering (SLS) approach that allows for locally programmable magnetic properties.

The Innovation

Traditional 3D printed magnets are limited to uniform magnetic properties throughout the entire piece. But this new technique combines magnetic particle alignment with precise laser sintering to create magnets with controlled magnetic heterogeneity—meaning different regions of the same magnet can have different magnetic strengths or orientations.

The research team hypothesised that controlled dispersion of multiple powder materials and localised external magnetic fields in specific orientations during sintering can lead to bonded magnets with controlled magnetic heterogeneity.

How It Works

The process mixes NdFeB (neodymium-iron-boron) magnetic particles with polymer powders and uses selective laser sintering to consolidate them into bonded magnets. During the sintering process, external magnetic fields are applied to align the magnetic particles.

The key innovation is that the magnetic field orientation can be changed at different points during the printing process, allowing each section of the magnet to be programmed with different magnetic properties. The team experimented with different material combinations including NdFeB/FeSi and NdFeB/FeCo composites.

Results

While the as-printed samples show relatively weak polarisation (approximately 1.5-2 mT flux), applying external fields during use significantly amplifies the magnetic properties. Under 1.5-1.9 Tesla external fields, flux values reach up to 6 mT North / 3 mT South for NdFeB/FeSi samples and an impressive 14 mT North / 6 mT South for NdFeB/FeCo samples.

Both sample types demonstrated 80% retention of their magnetised state, showing practical stability for real-world applications.

Applications

This technology opens up possibilities for motors and generators with magnets having varying field strengths, sensors with spatially varying magnetic fields, medical devices with custom magnets for implants, and RFID applications with complex magnetic patterns.

The research was published in Nature Scientific Reports and represents a significant step forward in functional 3D printing.