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In designing a switch, I made it such that it "springs" back via two neodymium magnets (one in button repelling one in switch). I've found the magnets are too weak and don't spring back. I've resorted to putting a spring in the prototype for now and it works fine.

I have to produce 1000s of these. It's cheaper to use springs, but I'd much prefer use magnets. I can get more magnets (double my order) to hopefully see a stronger repulsive force, but I'm not sure if magnetic fields work like this.

Do two magnets together repel more than just one? Here's some text to illustrate:

S = switch magnet, B = button magnet

[-S+] [+B-] (repulsion is too weak)

[-S+-S+] [+B-+B-] (proposed change)

Does the repulsion stack? Is it a linear increase? I need to know because I can either use springs (guaranteed to work), or more magnets (what I want to do but unsure if it works).

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When you stack two identical permanent magnets, you get roughly the strength of one twice the size. However, a magnet twice the size has to spread its magnetic energy over twice the volume, so the surface strength of the magnet is rarely significantly increased. Smaller neodymium magnets that have the same rating typically have roughly the same surface strength as larger ones. What increases is the holding power, because they have larger surface area.

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protected by AccidentalFourierTransform Sep 12 '18 at 0:06

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