UMT 20x25 black / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their strong magnetism, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• They are highly resistant to demagnetization caused by external field interference,
• By applying a reflective layer of silver, the element gains a sleek look,
• They possess intense magnetic force measurable at the magnet’s surface,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which expands their functional possibilities,
• Important function in new technology industries – they serve a purpose in data storage devices, electric drives, healthcare devices as well as other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a powerful 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 additionally strengthens its overall strength,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to wet conditions can oxidize. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• Limited ability to create precision features in the magnet – the use of a external casing is recommended,
• Potential hazard due to small fragments may arise, in case of ingestion, which is crucial in the protection of children. Moreover, miniature parts from these magnets have the potential to interfere with diagnostics once in the system,
• Due to a complex production process, their cost is considerably higher,

Maximum magnetic pulling force – what it depends on?

The given strength of the magnet means the optimal strength, assessed in ideal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Magnet lifting force in use – key 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, because even a very small distance (e.g. 0.5 mm) can cause 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 conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under shearing force the holding force is lower. Moreover, even a small distance {between} the magnet and the plate reduces the load capacity.