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

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They do not lose their power around 10 years – the decrease of power is only ~1% (according to tests),
• They are very resistant to demagnetization caused by external magnetic sources,
• Because of the brilliant layer of nickel, the component looks aesthetically refined,
• They possess intense magnetic force measurable at the magnet’s surface,
• With the right combination of materials, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the form),
• The ability for accurate shaping as well as customization to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Significant impact in new technology industries – they are utilized in hard drives, electric motors, medical equipment as well as high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and reinforces its overall durability,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent loss 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 plastic for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing holes directly in the magnet,
• Possible threat from tiny pieces may arise, especially if swallowed, which is crucial in the family environments. It should also be noted that miniature parts from these devices have the potential to complicate medical imaging after being swallowed,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Maximum magnetic pulling force – what affects it?

The given holding capacity of the magnet represents the highest holding force, assessed in the best circumstances, that is:

• with mild steel, used as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Lifting capacity in real conditions – factors

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• 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.

* Lifting capacity was assessed with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under vertically applied force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.