MW 5x7 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their power approximately ten years – the loss of strength is only ~1% (according to tests),
• They protect against demagnetization induced by ambient magnetic influence effectively,
• By applying a shiny layer of silver, the element gains a clean look,
• They have exceptional magnetic induction on the surface of the magnet,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• With the option for fine forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Key role in cutting-edge sectors – they are used in computer drives, rotating machines, healthcare devices as well as technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which allows for use in small systems

Disadvantages of magnetic elements:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage and increases its overall resistance,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a damp environment – during outdoor use, we recommend using sealed magnets, such as those made of non-metallic materials,
• Limited ability to create complex details in the magnet – the use of a housing is recommended,
• Health risk from tiny pieces may arise, if ingested accidentally, which is significant in the family environments. It should also be noted that miniature parts from these assemblies may interfere with diagnostics when ingested,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured under optimal conditions, specifically:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Lifting capacity in practice – influencing factors

The lifting capacity of a magnet depends on in practice key elements, according to their importance:

• Air gap between the magnet and the plate, because 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.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.