SMZR 32x175 / N52 - magnetic separator with handle

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They remain magnetized despite exposure to magnetic surroundings,
• In other words, due to the metallic nickel coating, the magnet obtains an aesthetic appearance,
• 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 individual requirements, neodymium magnets can be created in different geometries, which broadens their application range,
• Significant impact in modern technologies – they are used in data storage devices, electromechanical systems, healthcare devices or even high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time enhances its overall robustness,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent loss 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,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of rubber for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a magnetic holder is recommended,
• Health risk due to small fragments may arise, when consumed by mistake, which is important in the family environments. It should also be noted that tiny components from these assemblies have the potential to hinder health screening once in the system,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Magnetic strength at its maximum – what affects it?

The given holding capacity of the magnet means the highest holding force, determined in ideal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Key elements affecting lifting force

Practical lifting force is dependent on elements, by priority:

• 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 testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, however under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.