MW 40x15 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their superior magnetism, neodymium magnets have these key benefits:

• Their power is maintained, and after approximately 10 years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by ambient electromagnetic environments effectively,
• Thanks to the glossy finish and silver coating, they have an aesthetic appearance,
• They possess strong magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and precise design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Key role in modern technologies – they serve a purpose in HDDs, electric drives, clinical machines or even technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them ideal in compact constructions

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall robustness,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on form). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing holes directly in the magnet,
• Possible threat from tiny pieces may arise, when consumed by mistake, which is significant in the protection of children. Additionally, tiny components from these products have the potential to hinder health screening if inside the body,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum lifting capacity of the magnet – what contributes to it?

The given holding capacity of the magnet means the highest holding force, calculated in ideal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• at room temperature

Lifting capacity in practice – influencing factors

The lifting capacity of a magnet depends on in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause 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 was measured with the use of a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.