SM 32x150 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during approximately ten years – the reduction of lifting capacity is only ~1% (based on measurements),
• They are extremely resistant to demagnetization caused by external field interference,
• In other words, due to the glossy gold coating, the magnet obtains an aesthetic appearance,
• They possess significant magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• With the option for fine forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Wide application in advanced technical fields – they find application in computer drives, rotating machines, medical equipment as well as technologically developed systems,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time reinforces its overall durability,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent loss 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,
• They rust in a humid environment – during outdoor use, we recommend using waterproof magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Potential hazard due to small fragments may arise, in case of ingestion, which is crucial in the health of young users. Furthermore, tiny components from these magnets have the potential to complicate medical imaging if inside the body,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Magnetic strength at its maximum – what it depends on?

The given pulling force of the magnet means the maximum force, determined in a perfect environment, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is influenced by in practice the following factors, according to their importance:

• 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 measured by applying a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.