If you’ve ever held two NdFeB magnets in your hand and felt them snap together with a sharp, almost visceral force, or push apart so aggressively you have to squint to keep your fingers clear, you already have a front-row seat to one of the most dramatic interactions in permanent magnet science. As someone who’s worked with these materials for over a decade—running shipments, troubleshooting field applications, and talking through design challenges with engineers across industries—I’ve seen firsthand how NdFeB magnets don’t just “attract” or “repel” like basic bar magnets. Their interactions with other magnetic materials are nuanced, often counterintuitive, and critical to getting everything from wind turbine generators to electric vehicle motors to medical imaging equipment to work as intended. NdFeB Magnet
To start, let’s ground this in what NdFeB actually is. Short for neodymium iron boron, these are rare-earth permanent magnets, developed in the 1980s as a more powerful alternative to samarium cobalt (SmCo) and ferrite (ceramic) magnets. Their secret is a unique crystalline structure that lets them retain magnetization at much higher flux densities than almost any other permanent magnet. But that strength isn’t just a constant—its behavior changes drastically depending on what other magnetic material they’re paired with, and even how they’re oriented relative to that material. Let’s break down the most common interactions, starting with the materials I see our customers ask about most often: ferrite magnets, samarium cobalt, alnico, soft magnetic materials, and other NdFeB grades.
First up: ferrite (ceramic) magnets. These are the workhorses of consumer goods, used in fridge magnets, small speaker drivers, and low-torque power tools. At first glance, pairing NdFeB and ferrite seems like a no-brainer—their opposite poles should attract, right? And they do, strongly. But here’s a detail most people don’t realize: ferrite magnets are low-coercivity, meaning they lose their magnetization easily if exposed to a strong external magnetic field. NdFeB’s coercivity is among the highest of any permanent magnet, so when you bring a NdFeB magnet near a ferrite one, the NdFeB’s field doesn’t just pull the ferrite—it actually magnetizes it further, amplifying the overall combined force. I once had a customer who was designing a small magnetic latch for a smart door lock, and they thought pairing a NdFeB disc with a standard ferrite block would give them enough holding force. When they tested it, the combined assembly pulled 20% more force than their calculations predicted, which actually solved a problem they were having with the latch failing during vibration tests. It’s a quirk we now point out to any customer working on latch or holding applications: if you’re using a mix of hard magnetic materials, don’t just use basic attraction equations—account for the mutual magnetization between NdFeB and lower-coercivity magnets.
Next, samarium cobalt (SmCo). These are the other common rare-earth magnet, prized for their ability to perform at extreme temperatures (up to 300°C, compared to most NdFeB’s 80–150°C maximum, depending on grade). When paired, their interactions are both predictable and delicate. Like NdFeB, SmCo is a high-coercivity hard magnet, so the basic attraction/repulsion rule applies: north to south pulls, north to north pushes. But because both are made of rare-earth metals, their magnetic fields can interfere with each other in ways that don’t happen with ferrite. The big risk here is demagnetization. If you bring two SmCo magnets too close, their opposing fields can weaken each other, but that risk is amplified when you pair them with NdFeB. I’ve had a aerospace engineer reach out to me a few years back, working on a satellite sensor that needed a small magnetic assembly. They originally planned to use only SmCo, but when they tested a prototype with NdFeB to boost strength, the SmCo magnets lost 12% of their magnetization within a week. The issue was the NdFeB’s stronger residual field—its remanence (the amount of magnetic flux it retains) is around 1.2–1.4 T, compared to SmCo’s 0.8–1.1 T. When the two were placed side by side, the NdFeB’s field exerted enough reverse force on the SmCo’s domains to flip a portion of them, leading to permanent demagnetization. We fixed the issue by offsetting the magnets 90 degrees, so their fields didn’t run parallel to each other, cutting the demagnetizing effect to almost zero. It’s a small adjustment, but it’s the kind of interaction that trips up even experienced design teams.
Then there’s alnico magnets, the oldest of the common permanent magnets, dating back to the 1930s. Made of aluminum, nickel, and cobalt, alnico is low-coercivity, similar to ferrite, but far more temperature-stable than ferrite. Alnico’s big quirk is that it’s highly susceptible to “temperature-induced demagnetization,” and pairing it with NdFeB can be a big win or a big loss, depending on how you set up the assembly. For example, if you have a sensor that needs to hold its position at 200°C, a NdFeB magnet alone would lose half its strength at that temperature, but pairing it with an alnico magnet can boost the overall temperature stability. Wait, you might be thinking—NdFeB is stronger, why add alnico? Because while NdFeB’s field drops off sharply at high temps, alnico’s actually holds steady until much higher thresholds. When you pair the two, the NdFeB’s strong field magnetizes the alnico, locking its domains in place, and the alnico acts as a stabilizer, preventing the NdFeB from demagnetizing as quickly as it would alone. That said, if you put them in the wrong orientation, it can go wrong fast. If the NdFeB is placed so its field is opposing the alnico’s, the alnico will actually demagnetize completely at temperatures where it would have stayed stable on its own. I saw this play out with a customer making industrial flow meters a couple of years ago—they tested a prototype with NdFeB and alnico, got way lower signal than expected, and it turned out the alnico had demagnetized because the poles were reversed. A simple pole flip fixed it, and their meter’s temperature range went from 50°C to 250°C, a huge upgrade.
Now, one of the most important interactions for industrial and automotive applications: NdFeB with soft magnetic materials. Unlike hard magnets (which retain magnetization), soft magnetic materials (like iron, nickel-iron alloys, and silicon steel) are designed to easily magnetize and demagnetize, making them perfect for cores in motors, transformers, and magnetic circuits. How do they interact with NdFeB? Well, soft magnets act as magnetic shunts and conductors for NdFeB’s field. Let’s take an electric vehicle traction motor as an example. The motor’s stator core is made of soft silicon steel, and the rotor uses NdFeB magnets. The NdFeB’s field flows through the air gap between rotor and stator, but if there was no soft material, most of that field would leak out uselessly into the surrounding space. Instead, the soft steel’s high permeability (ability to conduct magnetic flux) pulls the NdFeB’s field into the stator core, concentrating it where it needs to be to generate torque. But this isn’t a one-way street—the soft material can also affect how the NdFeB performs. If the soft core is too small, or has gaps in its lamination, it can create “magnetic resistance” that reduces the overall flux output from the NdFeB. Or, if the core has sharp corners, it can cause the NdFeB’s field to focus too much in one spot, leading to local overheating in the core, which can in turn demagnetize the NdFeB over time. This is a huge part of what we work on with motor and generator manufacturers. We don’t just sell magnets—we’ll suggest not just the right grade of NdFeB, but also how to design the soft magnetic components around it, because even a small mistake there can cut a motor’s efficiency by 5–10%, or cause premature failure.
I’d be remiss if I didn’t talk about interactions between two NdFeB magnets, because that’s the most common question our clients ask us. When you put two NdFeB magnets together, the forces are dramatically stronger than other magnet pairs—we’re talking 500–2,000 N per square centimeter of contact, depending on grade. But their interaction depends entirely on grade and orientation. For example, if you take a high-grade N52 NdFeB (our strongest off-the-shelf grade) and a lower-grade N35, pairing them with opposite poles will give you almost the same holding force as two N52s, because the N52’s stronger field will fully magnetize the lower-grade one. But if you orient them with opposite poles but shift them so only a portion of their surfaces overlap, the force drops off sharply—this is called “edge effect,” and it’s something we see all the time in assembly processes. We’ve had customers tell us they can’t get their NdFeB magnets to snap together without chipping, and when we looked at their setup, it turned out they were placing the two magnets at a 15-degree angle, so only 20% of their surfaces were touching. The uneven force from that edge contact led to chipped corners, which ruin the magnet’s overall strength. We now include a quick guideline with every shipment advising clients to align flat faces parallel when assembling two NdFeB magnets, and to use spacers if they need to separate them, to avoid damage.
Another key point about NdFeB’s interactions: temperature and demagnetization risk with other materials. A lot of customers don’t realize that a magnet’s maximum operating temperature isn’t a hard limit—it’s a threshold where it starts losing 1–2% of its strength over time. But that loss can be accelerated if the NdFeB is exposed to a reverse magnetic field from another material. For example, if you have a NdFeB magnet paired with a soft magnetic core that has residual magnetization from a previous process, that residual field can act as a reverse demagnetizing force, cutting the NdFeB’s lifespan by half or more. We recently helped a customer in the robotics industry resolve this: their grippers were using NdFeB magnets and iron cores, and after 6 months of use, the magnets were losing holding force. Testing showed the iron cores had residual magnetization from the manufacturing process, which was exerting a reverse field on the NdFeB. We suggested demagnetizing the cores before assembly, and switching to a higher-temperature NdFeB grade, and the force loss dropped to almost zero.
So why does all this matter for you, if you’re a designer, engineer, or procurement manager working with magnetic assemblies? The days of just ordering a magnet and pairing it with whatever metal you have lying around are long gone. NdFeB’s strength makes it indispensable for most high-performance applications, but its interactions with other materials aren’t intuitive—they’re dependent on grade, orientation, temperature, and even surface finish. A pairing that works for a consumer speaker might fail in a wind turbine, a setup that works at room temperature might fall apart at 150°C, and a small edge misalignment that’s irrelevant for ferrite magnets can destroy a NdFeB assembly.
At our company, we don’t just sell NdFeB magnets. We work with clients through every step of their project, from initial material selection to prototype testing, to make sure their magnet interactions are optimized for performance, durability, and cost. Whether you’re designing a medical MRI machine that needs precise, stable magnetic fields, an electric bus motor that needs to last 10 years, or a small consumer gadget that needs a strong, compact latch, we have the expertise to help you avoid the common pitfalls of NdFeB interactions with other magnetic materials.
If you’re working on a project that involves permanent magnets, and you’re not sure how NdFeB will work with the other materials in your assembly, reach out to our team to discuss your requirements. We can help you select the right NdFeB grade, design your magnetic circuit to minimize demagnetization and maximize efficiency, and even provide custom prototypes to test before you commit to full production runs.
NdFeB Magnet References
- McCaig, M. (1977). Permanent Magnets in Theory and Practice. John Wiley & Sons.
- Croat, J. J. (1980). New material for permanent magnets on a base of Nd and Fe. Journal of Applied Physics, 51(11), 5948–5951.
- Cullity, B. D., & Graham, C. D. (2009). Introduction to Magnetic Materials (2nd ed.). John Wiley & Sons.
- Bolling, D., & Tuma, R. (2015). NdFeB Magnet Applications: Design Considerations for Magnetic Circuits. IEEE Transactions on Industry Applications, 51(3), 2478–2485.
- Parker, R. J., & Studders, R. J. (1962). Permanent Magnets and Their Applications. John Wiley & Sons.
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