UMT 11x17 colorless / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent power, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after 10 years, the performance loss is only ~1% (according to literature),
• They show strong resistance to demagnetization from external magnetic fields,
• Thanks to the polished finish and gold coating, they have an aesthetic appearance,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Wide application in new technology industries – they are used in hard drives, electric drives, healthcare devices and technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time enhances its overall strength,
• They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to humidity can oxidize. Therefore, for outdoor applications, it's best to use waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Potential hazard due to small fragments may arise, in case of ingestion, which is crucial in the protection of children. Additionally, tiny components from these products have the potential to interfere with diagnostics after being swallowed,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given strength of the magnet corresponds to the optimal strength, measured in the best circumstances, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• in normal thermal conditions

Lifting capacity in real conditions – factors

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.