MPL 40x18x10 SH / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after 10 years, the decline in efficiency is only ~1% (based on calculations),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the reflective layer of nickel, the component looks aesthetically refined,
• They have exceptional magnetic induction on the surface of the magnet,
• Thanks to their enhanced temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• With the option for customized forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Wide application in cutting-edge sectors – they are used in hard drives, rotating machines, clinical machines as well as sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

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 protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time reinforces its overall robustness,
• High temperatures may significantly reduce the strength 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 recommended to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is difficult,
• Health risk due to small fragments may arise, especially if swallowed, which is significant in the family environments. Moreover, tiny components from these assemblies may hinder health screening after being swallowed,
• Due to expensive raw materials, their cost is relatively high,

Maximum lifting force for a neodymium magnet – what affects it?

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

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• at room temperature

Lifting capacity in real conditions – factors

The lifting capacity of a magnet is influenced by in practice key elements, ordered from most important to least significant:

• 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.

* Lifting capacity was determined using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate lowers the load capacity.