SM 32x450 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (according to literature),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the shiny finish and gold coating, they have an visually attractive appearance,
• 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 customized forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
• Key role in advanced technical fields – they are utilized in HDDs, electromechanical systems, clinical machines and technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of magnetic elements:

• They can break when subjected to a strong impact. If the magnets are exposed to physical collisions, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time reinforces its overall strength,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on size). 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of synthetic coating for outdoor use,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Possible threat due to small fragments may arise, when consumed by mistake, which is important in the health of young users. Moreover, miniature parts from these devices may complicate medical imaging after being swallowed,
• In cases of mass production, neodymium magnet cost may not be economically viable,

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

The given pulling force of the magnet means the maximum force, determined in ideal conditions, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• with vertical force applied
• at room temperature

What influences lifting capacity in practice

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

• Air gap between the magnet and the plate, because 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 measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under parallel forces the lifting capacity is smaller. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.