MPL 15x3x6 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable pulling force, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (in laboratory conditions),
• They remain magnetized despite exposure to strong external fields,
• Thanks to the glossy finish and silver coating, they have an visually attractive appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• 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),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their application range,
• Key role in modern technologies – they find application in hard drives, electric motors, clinical machines and other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to mechanical hits, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage while also increases its overall strength,
• 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,
• They rust in a moist environment. If exposed to rain, we recommend using sealed magnets, such as those made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing complex structures directly in the magnet,
• Safety concern from tiny pieces may arise, if ingested accidentally, which is notable in the family environments. It should also be noted that miniature parts from these magnets have the potential to hinder health screening if inside the body,
• Due to the price of neodymium, their cost is considerably higher,

Maximum holding power of the magnet – what it depends on?

The given strength of the magnet corresponds to the optimal strength, assessed in the best circumstances, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

Key elements affecting lifting force

The lifting capacity of a magnet is influenced by in practice the following factors, according to their importance:

• 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 tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.