MPL 80x40x15 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their power nearly ten years – the decrease of power is only ~1% (according to tests),
• Their ability to resist magnetic interference from external fields is among the best,
• By applying a shiny layer of nickel, the element gains a clean look,
• They possess intense magnetic force measurable at the magnet’s surface,
• 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),
• With the option for customized forming and precise design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Wide application in cutting-edge sectors – they find application in HDDs, electric motors, diagnostic apparatus as well as sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which makes them ideal in small systems

Disadvantages of neodymium magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to external force, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks and enhances its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s dimensions). 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 rubber for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing complex structures directly in the magnet,
• Potential hazard related to magnet particles may arise, in case of ingestion, which is notable in the context of child safety. Furthermore, tiny components from these assemblies have the potential to hinder health screening once in the system,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Highest magnetic holding force – what it depends on?

The given pulling force of the magnet means the maximum force, determined in ideal conditions, namely:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• in normal thermal conditions

Impact of factors on magnetic holding capacity in practice

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, 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.

* Lifting capacity was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the lifting capacity.