UMT 12x20 blue / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain their attractive force for around 10 years – the drop is just ~1% (based on simulations),
• They are extremely resistant to demagnetization caused by external field interference,
• Thanks to the glossy finish and gold coating, they have an visually attractive appearance,
• They have extremely strong magnetic induction on the surface of the magnet,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• The ability for precise shaping or adjustment to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Key role in cutting-edge sectors – they are utilized in data storage devices, electromechanical systems, clinical machines along with other advanced devices,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to mechanical hits, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time reinforces its overall durability,
• High temperatures may significantly reduce the magnetic power 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,
• They rust in a wet environment – during outdoor use, we recommend using sealed magnets, such as those made of rubber,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Health risk from tiny pieces may arise, especially if swallowed, which is crucial in the protection of children. It should also be noted that small elements from these magnets might disrupt scanning if inside the body,
• In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

Magnetic strength at its maximum – what contributes to it?

The given strength of the magnet means the optimal strength, measured in the best circumstances, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Determinants of practical lifting force of a magnet

In practice, the holding capacity of a magnet is affected 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) 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 carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.