SM 25x200 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable magnetic power, neodymium magnets offer the following advantages:

• They retain their magnetic properties for nearly 10 years – the drop is just ~1% (based on simulations),
• They protect against demagnetization induced by ambient magnetic influence remarkably well,
• Because of the reflective layer of silver, the component looks aesthetically refined,
• They possess strong magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• With the option for customized forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Important function in new technology industries – they are utilized in HDDs, rotating machines, clinical machines along with sophisticated instruments,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage while also increases its overall durability,
• High temperatures may significantly reduce the holding force 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,
• They rust in a wet environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Health risk linked to microscopic shards may arise, if ingested accidentally, which is significant in the protection of children. It should also be noted that minuscule fragments from these products can hinder health screening once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given holding capacity of the magnet means the highest holding force, measured in the best circumstances, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• in a perpendicular direction of force
• at room temperature

Practical aspects of lifting capacity – factors

Practical lifting force is determined by elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, as 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.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as 5 times. Moreover, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.