SM 32x225 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their superior magnetic energy, neodymium magnets have these key benefits:

• Their strength is durable, and after approximately 10 years, it drops only by ~1% (theoretically),
• They remain magnetized despite exposure to strong external fields,
• Because of the brilliant layer of silver, the component looks high-end,
• They possess significant magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for tailored forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Wide application in new technology industries – they serve a purpose in computer drives, electric motors, healthcare devices as well as technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them useful in compact constructions

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to physical collisions, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall durability,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on form). 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 humidity can rust. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing fine shapes directly in the magnet,
• Potential hazard linked to microscopic shards may arise, when consumed by mistake, which is significant in the context of child safety. Additionally, small elements from these devices have the potential to disrupt scanning after being swallowed,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The given strength of the magnet corresponds to the optimal strength, determined in the best circumstances, that is:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Practical lifting capacity: influencing factors

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, since 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 was measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet and the plate reduces the holding force.