MW 8x15 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent magnetic energy, neodymium magnets have these key benefits:

• Their strength is maintained, and after around ten years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by external magnetic influence very well,
• By applying a shiny layer of silver, the element gains a sleek look,
• They possess strong magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their usage potential,
• Key role in cutting-edge sectors – they are utilized in computer drives, electric drives, medical equipment and technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and enhances its overall durability,
• High temperatures may significantly reduce the strength 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,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of rubber for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing threads directly in the magnet,
• Potential hazard from tiny pieces may arise, when consumed by mistake, which is notable in the health of young users. It should also be noted that minuscule fragments from these devices have the potential to interfere with diagnostics after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Maximum holding power of the magnet – what it depends on?

The given pulling force of the magnet means the maximum force, calculated under optimal conditions, that is:

• using a steel plate with low carbon content, serving 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
• at room temperature

Lifting capacity in practice – influencing factors

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

• Air gap between the magnet and the plate, as 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 optimal thickness, under perpendicular forces, in contrast under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.