MPL 12x10x4 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their immense magnetic power, neodymium magnets offer the following advantages:

• They have unchanged lifting capacity, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• The use of a decorative gold surface provides a smooth finish,
• They possess intense magnetic force measurable at the magnet’s surface,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• The ability for custom shaping and adaptation to specific needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which extends the scope of their use cases,
• Important function in advanced technical fields – they serve a purpose in data storage devices, electric drives, healthcare devices and high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them ideal in compact constructions

Disadvantages of rare earth magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to shocks, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage while also enhances its overall robustness,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline 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,
• They rust in a damp environment, especially when used outside, we recommend using sealed magnets, such as those made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing fine shapes directly in the magnet,
• Safety concern from tiny pieces may arise, in case of ingestion, which is significant in the family environments. Furthermore, miniature parts from these assemblies might complicate medical imaging once in the system,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Highest magnetic holding force – what contributes to it?

The given lifting capacity of the magnet means the maximum lifting force, calculated in ideal conditions, specifically:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

Key elements affecting lifting force

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

• Air gap between the magnet and the plate, as 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.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.