MPL 25x2x6 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their immense pulling force, neodymium magnets offer the following advantages:

• They retain their full power for almost 10 years – the drop is just ~1% (according to analyses),
• They remain magnetized despite exposure to strong external fields,
• The use of a polished silver surface provides a eye-catching finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• With the option for tailored forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Significant impact in new technology industries – they are utilized in data storage devices, electromechanical systems, healthcare devices as well as sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage and strengthens its overall robustness,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening 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 damp air can corrode. Therefore, for outdoor applications, we advise waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is risky,
• Health risk linked to microscopic shards may arise, if ingested accidentally, which is crucial in the health of young users. Moreover, miniature parts from these assemblies have the potential to hinder health screening if inside the body,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Maximum lifting force for a neodymium magnet – what affects it?

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

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• in normal thermal conditions

Practical lifting capacity: 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, 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 was determined using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.