MP 5x2.7/1.2x5 C / N38 - ring magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (based on calculations),
• They show strong resistance to demagnetization from outside magnetic sources,
• Because of the reflective layer of gold, the component looks aesthetically refined,
• Magnetic induction on the surface of these magnets is notably high,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• The ability for custom shaping and adjustment to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Key role in cutting-edge sectors – they are used in data storage devices, electric motors, healthcare devices or even technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which allows for use in compact constructions

Disadvantages of neodymium magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage and additionally increases its overall resistance,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of synthetic coating for outdoor use,
• Limited ability to create threads in the magnet – the use of a magnetic holder is recommended,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is important in the health of young users. Additionally, small elements from these assemblies might complicate medical imaging if inside the body,
• In cases of tight budgets, neodymium magnet cost is a challenge,

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The given lifting capacity of the magnet means the maximum lifting force, assessed in the best circumstances, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• at room temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by the following aspects, arranged from the most important to the least relevant:

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

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate reduces the load capacity.