MPL 25x12.5x5 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their immense magnetic power, neodymium magnets offer the following advantages:

• They do not lose their even during approximately ten years – the loss of lifting capacity is only ~1% (based on measurements),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• The use of a decorative nickel surface provides a refined finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• The ability for precise shaping or adaptation to specific needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Key role in modern technologies – they are utilized in HDDs, electromechanical systems, medical equipment and technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to physical collisions, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and increases its overall robustness,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a damp environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing fine shapes directly in the magnet,
• Safety concern linked to microscopic shards may arise, in case of ingestion, which is important in the family environments. It should also be noted that tiny components from these assemblies might disrupt scanning if inside the body,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Detachment force of the magnet in optimal conditions – what it depends on?

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

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Key elements affecting lifting force

In practice, the holding capacity of a magnet is conditioned by these factors, in descending order of importance:

• Air gap between the magnet and the plate, because 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 measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.