SM 25x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They do not lose their power around ten years – the loss of lifting capacity is only ~1% (theoretically),
• They are highly resistant to demagnetization caused by external magnetic fields,
• In other words, due to the metallic gold coating, the magnet obtains an professional appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• With the right combination of magnetic alloys, they reach significant thermal stability, enabling operation at or above 230°C (depending on the design),
• With the option for tailored 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 serve a purpose in computer drives, electromechanical systems, clinical machines along with technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and additionally increases its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can degrade. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is risky,
• Safety concern linked to microscopic shards may arise, especially if swallowed, which is notable in the health of young users. It should also be noted that tiny components from these products have the potential to interfere with diagnostics after being swallowed,
• In cases of mass production, neodymium magnet cost is a challenge,

Maximum magnetic pulling force – what contributes to it?

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

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, from crucial to less important:

• 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 steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.