Oct 25, 2016 | By Benedict

Researchers at TU Wien in Austria have devised a method of fabricating permanent magnets using a 3D printer. The method allows for the 3D printing of complex forms with precisely customized magnetic fields, useful for magnetic sensors and other devices.

3D printing a magnetic object

If you’re visiting this website, chance are you have something of a magnetic attraction to 3D printing. Until now, however, 3D printers have had a hard time creating real, accurate, 3D printed magnets. In order to control the magnetic field of a magnet, the magnet must be given a sophisticated geometric shape. This kind of shape can be designed on a computer using CAD software, but fabricating the actual object has proven difficult.

“The strength of a magnetic field is not the only factor,” said Dieter Süss, Head 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.”

Magnetic 3D printing filament

One way to create such magnets is by using injection molding, the process of injecting a material into a mold shaped like the inverse of the desired object. However, creating the mold itself is a time-consuming process, and is often not worth the large monetary expenditure when only a few copies of the object are required.

Over time, 3D printing has come to replace injection molding in many applications, and magnet production can now count itself as one of those applications. TU Wien researchers have now successfully 3D printed magnetic objects using a Builder 3D printer and a specially formulated filament consisting of a magnetic micro-granulate combined with polymer binding material.

The first stage of the magnetic 3D printing process is to print the object in the specified geometric shape using a digital 3D model. As with normal 3D printing processes, this shape is printed layer by layer, but is composed of roughly 90% magnetic material and 10% plastic. Printing the shape is, however, just the start. Since the 3D printed object is made from a granulate in an unmagnetized state, the object itself is not yet magnetic.

Once the object has been 3D printed, it then needs to be exposed to a strong external magnetic field. This magnetic field turns the 3D printed object into a permanent magnet. “This method allows us to process various magnetic materials, such as the exceptionally strong neodymium iron boron magnets," Süss explained. “Magnet designs created using a computer can now be quickly and precisely implemented at a size ranging from just a few centimeters through to decimeters, with an accuracy of well under a single millimeter.”

Researchers Christian Huber (l) and Dieter Süss (r)

The rapid and cost-effective new magnet 3D printing process could open up several new possibilities for scientists, including the use of different materials within a single magnet to create a smooth transition between strong and weak magnetism. “Now we will test the limits of how far we can go,” Süss concluded. “But for now it is certain that 3D printing brings something to magnet design which we could previously only dream of.”

The researchers’ paper, titled “3D print of polymer bonded rare-earth magnets, and 3D magnetic field scanning with an end-user 3D printer,” has been published in Applied Physics Letters.

Posted in 3D Printing Application

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