SM 32x150 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their exceptional strength, neodymium magnets offer the following advantages:

• They do not lose their magnetism, even after nearly ten years – the loss of lifting capacity is only ~1% (theoretically),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• The use of a mirror-like gold surface provides a smooth finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• The ability for custom shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Important function in modern technologies – they are utilized in data storage devices, electric drives, medical equipment and other advanced devices,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. 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 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,
• Magnets exposed to wet conditions can oxidize. Therefore, for outdoor applications, we advise waterproof types made of coated materials,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is crucial in the family environments. Additionally, small elements from these magnets might interfere with diagnostics once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, measured under optimal conditions, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Practical aspects of lifting capacity – factors

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

• Air gap between the magnet and the plate, because 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 performed on a smooth plate of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.