SM 32x375 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (based on calculations),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• By applying a bright layer of silver, the element gains a sleek look,
• They possess significant magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• The ability for accurate shaping and adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Important function in cutting-edge sectors – they find application in hard drives, electric drives, medical equipment and technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which allows for use in miniature devices

Disadvantages of neodymium magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage and strengthens its overall resistance,
• They lose power at extreme temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can oxidize. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Limited ability to create threads in the magnet – the use of a mechanical support is recommended,
• Possible threat from tiny pieces may arise, when consumed by mistake, which is notable in the health of young users. It should also be noted that small elements from these products might complicate medical imaging if inside the body,
• In cases of mass production, neodymium magnet cost may be a barrier,

Maximum lifting capacity of the magnet – what contributes to it?

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

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet depends on in practice key elements, according to their importance:

• 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 determined by applying a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.