ZM XMAG2 210 elementów - magnetic toy

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their strength is durable, and after around ten years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic influence very well,
• Because of the lustrous layer of nickel, the component looks visually appealing,
• They have extremely strong magnetic induction on the surface of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• The ability for precise shaping and adaptation to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in advanced technical fields – they serve a purpose in computer drives, electromechanical systems, healthcare devices as well as sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which makes them ideal in compact constructions

Disadvantages of neodymium magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage and additionally strengthens its overall robustness,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on shape). 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,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• Limited ability to create precision features in the magnet – the use of a external casing is recommended,
• Possible threat linked to microscopic shards may arise, especially if swallowed, which is notable in the context of child safety. It should also be noted that minuscule fragments from these devices may complicate medical imaging after being swallowed,
• Due to the price of neodymium, their cost is considerably higher,

Maximum lifting capacity of the magnet – what contributes to it?

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

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet depends on in practice the following factors, according to their importance:

• 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.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, however under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate reduces the load capacity.