Transformers are one of the basic, common, and important electrical components in use today. Transformers are tailored to a variety of applications, but all of them transmit electricity without a physical metallic connection between two coils that share a ferrous core. When the first coil is energized with alternating current, it creates a varying magnetic flux that energizes the second coil. By giving the second coil a different number of windings than the first, you can change the voltage. YouTuber GreatScott! wanted to find out if it’s possible to 3D print the core of a mains transformer, and made a video with his findings.
All transformer cores are made of ferrous material that responds to magnetic fields, but those cores come in different shapes. “Core form” cores are surrounded by windings, while “shell form” cores surround the windings. Either style can be laminated, where the core is made up of multiple sheets that are isolated in order to avoid eddy currents that can cause noise. In this experiment, GreatScott! chose a laminated shell form core. He first tested it using manufactured electrical steel sheets, and then with 3D-printed sheets.
Those sheets were 3D-printed using Proto-Pasta magnetic iron PLA, and have the same dimensions as the manufactured electrical steel sheets. The 3D-printed versions are thicker, but the overall thickness of the core was identical. Both cores were tested with hand-wound coils. The conclusion that GreatScott! came to is that it isn’t possible—or at least practical—to 3D print a mains transformer. That’s because the density of the magnetic material (the iron) in the 3D-printed coil was too low. Essentially, it’s 90 times weaker. It could potentially be used for other types of transformers, but they would never be anywhere close to as efficient as a commercial transformer.