SM 25x350 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They have constant strength, and over around ten years their performance decreases symbolically – ~1% (in testing),
• They are highly resistant to demagnetization caused by external magnetic sources,
• By applying a shiny layer of nickel, the element gains a modern look,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their usage potential,
• Key role in cutting-edge sectors – they serve a purpose in hard drives, electric motors, medical equipment and other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are fragile 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 cracks , and at the same time enhances its overall durability,
• They lose magnetic force at extreme temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a humid environment – during outdoor use, we recommend using encapsulated magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing threads directly in the magnet,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is crucial in the family environments. It should also be noted that tiny components from these devices can interfere with diagnostics when ingested,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Magnetic strength at its maximum – what it depends on?

The given strength of the magnet corresponds to the optimal strength, determined under optimal conditions, namely:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

What influences lifting capacity in practice

The lifting capacity of a magnet depends on in practice the following factors, from primary to secondary:

• 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 determined with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.