MPL 5x5x1.5 / N38 - lamellar magnet

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 10 years, the decline in efficiency is only ~1% (based on calculations),
• They remain magnetized despite exposure to magnetic noise,
• Because of the reflective layer of silver, the component looks high-end,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• The ability for precise shaping as well as adjustment to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Significant impact in advanced technical fields – they are utilized in data storage devices, electromechanical systems, healthcare devices and sophisticated instruments,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to physical collisions, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks and additionally reinforces its overall resistance,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on height). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Magnets exposed to wet conditions can corrode. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Safety concern linked to microscopic shards may arise, if ingested accidentally, which is crucial in the family environments. Furthermore, small elements from these magnets have the potential to hinder health screening when ingested,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Magnetic strength at its maximum – what contributes to it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, calculated in a perfect environment, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Practical lifting capacity: influencing factors

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, since 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 performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate decreases the holding force.