The technique, developed at the Technical University of Vienna, allows magnets to be produced in complex forms and precisely customised magnetic fields using combinations of magnetics materials for power supplies or magnetic sensors.
“The strength of a magnetic field is not the only factor,” says Dieter Süss, dead of the Christian-Doppler Advanced Magnetic Sensing and Materials laboratory at TU Wien. “We often require special magnetic fields, with field lines arranged in a very specific way – such as a magnetic field that is relatively constant in one direction, but which varies in strength in another direction.”
In order to achieve such requirements, magnets must be produced with a sophisticated geometric form. “A magnet can be designed on a computer, adjusting its shape until all requirements for its magnetic field are met,” said Christian Huber, a doctoral student in Dieter Süss’ team.
Rather than injection moulding, the new technqiue uses magnetic particles in a polymer matrix. The magnet 3D printer uses specially produced filaments of magnetic micro granulate, which is held together by a polymer binding material. The printer heats the material and applies it point by point in the desired locations using a nozzle. The result is a three-dimensional object composed of roughly 90% magnetic material and 10% plastic.
The end product is not yet magnetic as the granulate is deployed in an unmagnetised state. At the very end of the process, the finished article is exposed to a strong external magnetic field, converting it into a permanent magnet.
“This method allows us to process various magnetic materials, such as neodymium iron boron magnets,” said Süss. “Magnet designs created using a computer can now be quickly and precisely implemented – at a size ranging from just a few centimetres through to decimetres, with an accuracy of well under a single millimetre.”
The fast and cost-effective process also opens up new possibilities in magnetics design. Different materials can be used in a single magnet to create a smooth transition between strong and weak magnetism, for instance. “Now we will test the limits of how far we can go – but for now it is certain that 3D printing brings something to magnet design which we could previously only dream of,” said Süss.