Magnets are typically made via an injection molding process, which is fine if you're manufacturing enough of them to make it worthwhile building a mold. Scientists, however, often just need a few in specific shapes for research projects or specialized sensors. Thankfully for them, a team at the Vienna University of Technology has developed a method of 3D printing magnets in any form desired.

First of all, though, why would anyone want an unusually-shaped magnet?

"The strength of a magnetic field is not the only factor," says project leader Dr. Dieter Süss. "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."

To make such a magnet using the new technology, you start by creating a digital model of it on a computer. That model is then fed into a 3D printer, which starts building the actual magnet up layer by layer.

Instead of using straight-up polymer, however, the printer heats and extrudes a mixture of 90 percent magnetic micro granulate filaments, and 10 percent polymer binder. Because the granulate is applied in an unmagnetized state, the resulting object has to finally be exposed to a strong magnetic field, turning it into a permanent magnet.

Not only can the process be used to produce magnets in different shapes, but it also allows for different types of magnetic material to be included in one magnet – this means that a single magnet could have areas of both weak and strong magnetism.

A paper on the research was recently published in the journal Applied Physics Letters.

Source: Vienna University of Technology