UMC 16x5/2x5 / N38 - cylindrical magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their magnetic properties for almost 10 years – the drop is just ~1% (in theory),
• They are very resistant to demagnetization caused by external field interference,
• In other words, due to the glossy nickel coating, the magnet obtains an professional appearance,
• They possess intense 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),
• With the option for fine forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
• Wide application in modern technologies – they are utilized in hard drives, electric motors, medical equipment or even other advanced devices,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to shocks, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall robustness,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent deterioration 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,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of rubber for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Health risk due to small fragments may arise, in case of ingestion, which is notable in the protection of children. Additionally, minuscule fragments from these assemblies may complicate medical imaging after being swallowed,
• Due to expensive raw materials, their cost is relatively high,

Optimal lifting capacity of a neodymium magnet – what affects it?

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

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• in normal thermal conditions

Key elements affecting lifting force

The lifting capacity of a magnet is determined by in practice key elements, ordered from most important to least significant:

• 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 testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, however under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.