MW 6x2 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during around 10 years – the reduction of strength is only ~1% (theoretically),
• They are very resistant to demagnetization caused by external magnetic sources,
• By applying a shiny layer of silver, the element gains a sleek look,
• They possess strong magnetic force measurable at the magnet’s surface,
• 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 magnetic form),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their usage potential,
• Significant impact in cutting-edge sectors – they find application in HDDs, electric drives, diagnostic apparatus or even technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them ideal in small systems

Disadvantages of neodymium magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and strengthens its overall durability,
• They lose power at high temperatures. Most neodymium magnets experience permanent degradation 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,
• 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 limitations in manufacturing holes directly in the magnet,
• Possible threat linked to microscopic shards may arise, especially if swallowed, which is crucial in the health of young users. Furthermore, tiny components from these devices have the potential to interfere with diagnostics when ingested,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

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

The given holding capacity of the magnet represents the highest holding force, measured in ideal conditions, namely:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• in normal thermal conditions

What influences lifting capacity in practice

Practical lifting force is determined by elements, by priority:

• 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 testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.