NdFeB vs Ferrite in a Magnetic Window Cleaner: Which Magnet Should You Spec?

Neodymium is not the upgrade and ferrite is not the downgrade — in a magnetic window cleaner the two materials fail in opposite directions. Standard NdFeB is roughly ten times stronger per unit volume, but it is rated to only 80 °C and corrodes unless plated. Ferrite is far weaker, yet runs to 250 °C, ignores water entirely, and instead gets weaker as it gets cold. Glass thickness picks the material; destination climate decides whether that pick survives.

This is a spec guide for distributors and importers who are comparing quotes where one factory says “neodymium” and another says “ferrite” as though one answer is simply better. Below is what each material actually gives you on glass, where each one breaks, and how to write the requirement into your order.

What is the real difference between NdFeB and ferrite magnets?

NdFeB (neodymium-iron-boron) is a sintered rare-earth magnet; ferrite (also sold as ceramic) is a sintered iron-oxide magnet with strontium or barium. The gap in raw magnetic output is large and not in dispute — a common Y30 ferrite grade stores roughly a tenth of the energy of a common N35 neodymium grade, at about a third of the remanence. What is usually left out of a sales pitch is that ferrite wins outright on temperature and corrosion.

Figures are standard material ranges at room temperature. Ferrite grade data from e-Magnets UK and Stanford Magnets; ferrite temperature ceiling per supermagnete; low-temperature coercivity behaviour per Arnold Magnetic Technologies.

Which magnet holds better through thick glass?

NdFeB, and it is not close — but only because hold falls off with the air gap, and the glass is the air gap. Every millimetre of pane between the two halves of a double-sided cleaner costs pull force. On a 3–8 mm single pane the gap is small enough that a properly sized ferrite assembly holds safely. On a 24 mm double-glazed unit, matching that same hold with ferrite would need an assembly so large and heavy that the tool stops being usable in one hand.

This is why the material split in a real product range is a thickness split, not a price split. It is also why “we use neodymium” on its own tells you nothing: magnet volume and magnetic-circuit design (steel yoke and pole layout) move hold far more than the material label. We covered that trap in detail in N35 vs N52: why a higher grade is not a firmer grip.

Where does neodymium fail in a window cleaner?

Heat and water — the two things a window cleaner is guaranteed to meet. A no-suffix NdFeB grade is rated to 80 °C. A dark-framed pane in direct summer sun can approach that, and once exceeded the loss is partly irreversible: the tool comes back weaker than it went out. Heat tolerance comes from the temperature suffix (M, H, SH and up), not from the N-number, so a buyer specifying for Australia, the Gulf or southern Europe should be asking about the suffix.

Corrosion is the second one. Bare NdFeB rusts, and this product is used wet, with detergent, often on bathroom and shower glass. Production magnets are plated and sealed inside the housing, but plating quality is a real variable between factories and it is invisible in a photograph. Ask for the plating spec in writing.

Where does ferrite fail in a window cleaner?

Cold, which is the failure mode almost no buyer asks about. Ferrite behaves the opposite way to neodymium with temperature: its intrinsic coercivity has a positive temperature coefficient of roughly +0.2 to +0.4 %/°C, so resistance to demagnetisation drops as the magnet cools. By around −60 °C a ceramic magnet has lost approximately one third of its room-temperature Hci, and part of that loss does not come back.

For an importer this is a market question, not a physics question. A ferrite entry SKU that performs perfectly in Spain or Malaysia is the wrong specification for winter exterior cleaning in Canada, the Nordics or an Alpine market. If your catalogue ships to both, the material split has to follow the climate, not just the price point.

How should a distributor write this into an order?

Specify the glass range and the destination climate, and let the factory answer with a material. A factory that only quotes a grade is answering a different question than the one that decides whether your units get returned. Four lines are usually enough:

• Glass thickness range the SKU must cover, in mm, including whether double glazing is in scope.
• Destination climate — peak summer glass temperature and winter exterior use, if any.
• Wet-use expectation — bathroom and shower glass, coastal humidity, and the plating spec that follows from it.
• Release behaviour — how the two halves are separated safely, which is a circuit and geometry question, not a material one.

How Fonoran splits the two materials

Fonoran manufactures magnetic window cleaners only, and the range is built on exactly the split described above: NdFeB across the range, with ferrite used on the FN-Classic 3–8 mm entry SKU, where thin single glazing makes it the correct and cheaper answer rather than a compromise. Above that the models run on neodymium with six-stage adjustable force, covering 3–45 mm of glass across the FN-Ultra, FN-Hydra, FN-Vista, FN-Square and FN-Guard families.

Because the range covers both materials, a distributor does not have to pick a factory by material and then live with it — the SKU mix can follow the markets you actually sell into. See the full product range, or the private-label programme if you are specifying an own-brand line.

Fonoran is the export brand of Taizhou Mingyou Intelligent Technology Co., Ltd., a factory-direct manufacturer of magnetic window cleaners in Taizhou, China — ISO 9001 certified, CE / RoHS compliant, exporting to 60+ countries. OEM and private-label MOQ from 100 units. Browse products · Request a quote.