UMT 20x25 white / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (based on calculations),
• They are extremely resistant to demagnetization caused by external magnetic fields,
• Thanks to the glossy finish and gold coating, they have an visually attractive 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,
• With the option for fine forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Significant impact in new technology industries – they are utilized in HDDs, electric drives, clinical machines as well as high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, it is suggested to place them 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 strength,
• They lose power at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry 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 recommended to use sealed magnets made of rubber for outdoor use,
• Limited ability to create complex details in the magnet – the use of a housing is recommended,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is important in the health of young users. Furthermore, small elements from these assemblies have the potential to disrupt scanning after being swallowed,
• Due to a complex production process, their cost is relatively high,

Maximum lifting capacity of the magnet – what affects it?

The given pulling force of the magnet represents the maximum force, determined in ideal conditions, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• at room temperature

Key elements affecting lifting force

The lifting capacity of a magnet is influenced by in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, since 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.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.