MPL 25x15x2 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetism, neodymium magnets have these key benefits:

• They do not lose their power around ten years – the reduction of strength is only ~1% (based on measurements),
• They remain magnetized despite exposure to strong external fields,
• Because of the lustrous layer of silver, the component looks aesthetically refined,
• They exhibit extremely high 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 accurate shaping as well as adjustment to individual needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which amplifies their functionality across industries,
• Key role in advanced technical fields – they serve a purpose in computer drives, electric motors, diagnostic apparatus or even technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall robustness,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent deterioration 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of rubber for outdoor use,
• Limited ability to create threads in the magnet – the use of a housing is recommended,
• Health risk from tiny pieces may arise, in case of ingestion, which is significant in the context of child safety. Moreover, miniature parts from these products have the potential to hinder health screening if inside the body,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, measured in ideal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

Lifting capacity in real conditions – factors

Practical lifting force is dependent on elements, by priority:

• Air gap between the magnet and the plate, as 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 checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.