SMZR 25x175 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous field intensity, neodymium magnets offer the following advantages:

• Their magnetic field remains stable, and after approximately 10 years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic fields effectively,
• Because of the lustrous layer of silver, the component looks aesthetically refined,
• They exhibit extremely high 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,
• With the option for tailored forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Significant impact in cutting-edge sectors – they are utilized in HDDs, rotating machines, medical equipment as well as high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to mechanical hits, 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 at the same time enhances its overall robustness,
• They lose field intensity at high temperatures. Most neodymium magnets experience permanent degradation 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,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of plastic for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing fine shapes directly in the magnet,
• Possible threat related to magnet particles may arise, especially if swallowed, which is crucial in the protection of children. Additionally, small elements from these assemblies may disrupt scanning when ingested,
• In cases of tight budgets, neodymium magnet cost is a challenge,

Magnetic strength at its maximum – what contributes to it?

The given lifting capacity of the magnet means the maximum lifting force, calculated under optimal conditions, specifically:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• Air gap between the magnet and the plate, because 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 carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.