UMH 48x11x65 [M6] / N38 - magnetic holder with hook

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (according to literature),
• Their ability to resist magnetic interference from external fields is impressive,
• The use of a polished silver surface provides a refined finish,
• Magnetic induction on the surface of these magnets is very strong,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for accurate shaping as well as adaptation to individual needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Wide application in new technology industries – they serve a purpose in hard drives, electric motors, diagnostic apparatus or even high-tech tools,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to shocks, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time enhances its overall robustness,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on size). 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 moist environment. For outdoor use, we recommend using encapsulated magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing fine shapes directly in the magnet,
• Health risk related to magnet particles may arise, especially if swallowed, which is notable in the context of child safety. It should also be noted that small elements from these assemblies may complicate medical imaging once in the system,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Highest magnetic holding force – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, assessed in a perfect environment, specifically:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• with vertical force applied
• in normal thermal conditions

Determinants of practical lifting force of a magnet

Practical lifting force is determined by factors, by priority:

• Air gap between the magnet and the plate, since 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 the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.