MPL 25x10x3 / N38 - lamellar magnet

Strengths and weaknesses of rare earth magnets.

Besides their tremendous pulling force, neodymium magnets offer the following advantages:

• Their magnetic field is durable, and after approximately ten years it drops only by ~1% (theoretically),
• They do not lose their magnetic properties even under strong external field,
• In other words, due to the metallic layer of silver, the element gains a professional look,
• The surface of neodymium magnets generates a maximum magnetic field – this is a distinguishing feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can function (depending on the shape) even at a temperature of 230°C or more...
• Thanks to the possibility of free shaping and adaptation to unique projects, neodymium magnets can be produced in a broad palette of shapes and sizes, which amplifies use scope,
• Versatile presence in advanced technology sectors – they find application in HDD drives, motor assemblies, medical devices, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which allows their use in miniature devices

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited possibility of making nuts in the magnet and complicated forms - preferred is casing - magnet mounting.
• Possible danger related to microscopic parts of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, small components of these magnets are able to disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling force – what contributes to it?

The lifting capacity listed is a theoretical maximum value performed under the following configuration:

• with the contact of a yoke made of special test steel, guaranteeing maximum field concentration
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• with direct contact (without impurities)
• under vertical force direction (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Magnet lifting force in use – key factors

Real force is influenced by specific conditions, such as (from most important):

• Clearance – the presence of any layer (paint, tape, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Material type – ideal substrate is pure iron steel. Hardened steels may generate lower lifting capacity.
• Surface condition – ground elements ensure maximum contact, which increases field saturation. Rough surfaces weaken the grip.
• Temperature – temperature increase causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the holding force.