SM 32x300 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (according to literature),
• They show exceptional resistance to demagnetization from external magnetic fields,
• Because of the reflective layer of gold, the component looks high-end,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• Thanks to their high temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• With the option for fine forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Important function in cutting-edge sectors – they are used in computer drives, rotating machines, diagnostic apparatus along with high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks while also strengthens its overall durability,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on height). 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,
• Magnets exposed to humidity can degrade. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing threads directly in the magnet,
• Potential hazard linked to microscopic shards may arise, especially if swallowed, which is notable in the family environments. Additionally, minuscule fragments from these devices have the potential to complicate medical imaging once in the system,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Maximum holding power of the magnet – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, measured in the best circumstances, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Determinants of lifting force in real conditions

The lifting capacity of a magnet depends on in practice the following factors, ordered from most important to least significant:

• 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 was assessed with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.