MPL 25x25x10 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their stability, neodymium magnets are valued for these benefits:

• They do not lose their even during around ten years – the decrease of strength is only ~1% (theoretically),
• Their ability to resist magnetic interference from external fields is among the best,
• Because of the reflective layer of nickel, the component looks aesthetically refined,
• They have exceptional magnetic induction on the surface of the magnet,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Wide application in advanced technical fields – they are used in computer drives, rotating machines, diagnostic apparatus and sophisticated instruments,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to external force, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall strength,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we recommend waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is risky,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is important in the protection of children. Furthermore, miniature parts from these assemblies have the potential to disrupt scanning after being swallowed,
• In cases of tight budgets, neodymium magnet cost is a challenge,

Maximum magnetic pulling force – what contributes to it?

The given pulling force of the magnet means the maximum force, measured in the best circumstances, namely:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• in normal thermal conditions

Magnet lifting force in use – key factors

The lifting capacity of a magnet is determined by in practice the following factors, 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) 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 tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet and the plate reduces the holding force.