MW 25x5 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their magnetic field remains stable, and after around 10 years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by ambient electromagnetic environments very well,
• The use of a decorative silver surface provides a refined finish,
• They possess significant 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 shape),
• The ability for custom shaping and customization to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Important function in modern technologies – they are used in HDDs, electromechanical systems, clinical machines and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which allows for use in compact constructions

Disadvantages of neodymium magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to external force, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage while also enhances its overall strength,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent decline 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,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Health risk related to magnet particles may arise, if ingested accidentally, which is crucial in the protection of children. It should also be noted that miniature parts from these products may complicate medical imaging when ingested,
• In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

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

The given holding capacity of the magnet corresponds to the highest holding force, assessed in ideal conditions, specifically:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• at room temperature

Key elements affecting lifting force

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, 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 tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.