this post was submitted on 22 May 2025
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So, found out the hard way that you can't apply heat to neodymium magnets. Had 16 magnets to press into a print (tool holder). Thought since the soldering pen I use for inserting threaded nuts into prints works so well, I would use it for this too. And it did work well, but now all the magnets are not magnets any more. Yup, heat will demagnetize them. Part is useless, so had to trash it. Found out something new, but wish I had heard about this beforehand.

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[–] [email protected] 9 points 1 month ago (11 children)

Lesson learned, I guess 🙂 here’s some more:

At what temperature a material loses its permanent magnetic properties is called the Curie temperature. For Neodymium magnets this temperature is around 310–400°C (ca. 590–752°F). So if the heat is below that, you’re mostly safe.

Maybe look into how to design/modify a part and how you can pause your print a at a specific layer height so you can just drop in the magnets (use a drop of super glue to they won’t attach to the hot-end or make a test print with various diameters to find out the perfect width for press-fitting the magnets in) and then continue the print.

This also results in nicer looking prints because the magnets are invisible. Depending on thickness above the magnets and strength of the magnets the result might be less strong, so ideally there are only very few layers of material covering the magnets.

This is a very straightforward and in-depth video on how to do this in a good way:

https://www.youtube.com/watch?v=wJgoH2Or03s

[–] [email protected] 6 points 1 month ago (9 children)

Commenter above you said 60*C.

Not saying you're wrong but one of you is and I don't think OP heated their magnets to 310*C+

[–] [email protected] 5 points 1 month ago (1 children)
[–] [email protected] 5 points 1 month ago

This should be higher up. OP clearly learned a lesson here but one larger lesson most everyone can learn is that neodymium magnets aren't the only kind of magnets. Especially when high temperature performance is needed. Samarium Cobalt magnets are much better suited for high temperature and corrosive applications. Plus if I remember correctly they've been around longer.

Most neodymium loses it's magnetism at 200-230C. Some Samarium Cobalt can retain their magnetic properties all the way up to 350C or higher grades up to 500C (1022F)

I nerded out on this a few years ago when I made a magnetic thermal blanket for my pellet smoker and experienced the same thing. Samarium Cobalt did the trick in my application.

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