MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They have unchanged lifting capacity, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• They show exceptional resistance to demagnetization from external field exposure,
• By applying a shiny layer of gold, the element gains a sleek look,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which increases their application range,
• Key role in advanced technical fields – they are used in data storage devices, electromechanical systems, clinical machines along with high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to mechanical hits, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and additionally enhances its overall resistance,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on height). 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 humidity can corrode. Therefore, for outdoor applications, we recommend waterproof types made of plastic,
• Limited ability to create threads in the magnet – the use of a mechanical support is recommended,
• Potential hazard due to small fragments may arise, in case of ingestion, which is notable in the family environments. It should also be noted that minuscule fragments from these magnets have the potential to complicate medical imaging when ingested,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Highest magnetic holding force – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, calculated under optimal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• with no separation
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key factors

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

• 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 optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.