SM 25x200 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They have stable power, and over nearly 10 years their performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic surroundings,
• By applying a shiny layer of silver, the element gains a sleek look,
• They have extremely strong magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which broadens their functional possibilities,
• Significant impact in new technology industries – they are utilized in data storage devices, electric drives, diagnostic apparatus along with high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to external force, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and strengthens its overall resistance,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on shape). 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 damp environment. For outdoor use, we recommend using waterproof magnets, such as those made of polymer,
• Limited ability to create complex details in the magnet – the use of a external casing is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is notable in the protection of children. Moreover, small elements from these assemblies might complicate medical imaging after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Highest magnetic holding force – what it depends on?

The given holding capacity of the magnet means the highest holding force, calculated in ideal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Determinants of practical lifting force of a magnet

The lifting capacity of a magnet depends on in practice the following factors, 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 testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.