Learn the Secrets of Electro-Permanent Magnets and How You Can Use Them
To shed some light on EPMs, Hackaday has a nice writeup explaining more about the technology seen in a 2024 EEVblog episode.
You know about magnets and you know about electromagnets. You may even know about switchable permanent magnets, which are common in some industries. But I bet you don’t know about electro-permanent magnets (EPMs) and that’s a shame, because they’re really cool. To shed some light on EPMs, Hackaday has a nice writeup explaining more about the technology seen in a 2024 EEVblog episode.
EPMs are useful because you can turn them on and off. If you want magnetism, turn on the EPM. If you no longer require magnetism, turn off the EPM. But unlike switchable permanent magnets, which physically move magnets to align or cancel out magnetic fields, EPMs do that without moving parts, but rather by using electricity. And unlike electromagnets, EPMs remain in the state they’re set to — even if you lose power.
The two most common applications are machine workholding and lifting. In fact, I have an EPM chuck made by Tecnomagnete on my manual mill. It can hold steel securely while the 5hp spindle motor plows an end mill through. Tecnomagnete also sells lifting units that can handle as much as 50 tons of weight. EPM tech is expensive, but ideal for those applications because there is no danger of losing grip in the event of power loss.
The Zubax FluxGrip FG40 is similar to Tecnomagnete’s lifter, though much more affordable and tailored to robot and drone grippers. But, how does it work?
Similar to a switchable permanent magnet, an EPM works by aligning or canceling out magnetic fields. However, it does so with one permanent magnet and one semi-hard magnet paired with an electromagnetic coil. By pulsing current through the coil, it can “charge” the semi-hard magnet. And it can do that in either polarity. In one direction, the semi-hard magnet works with the permanent magnet. In the other, it cancels out the permanent magnet.
The result is on-demand magnetism that you can control electronically, which is ideal for robots and drones.
If you like that idea and want to experiment with EPM technology, Zubax’s FluxGrip FG40 is by far the most accessible option I’ve ever seen — it is orders of magnitude less expensive than anything sold by Tecnomagnete. The FG401M costs just €139.00 and is controllable through a CAN bus, which is a very nice touch.