MW 25x12 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They retain their magnetic properties for around 10 years – the drop is just ~1% (according to analyses),
• They protect against demagnetization induced by ambient magnetic fields remarkably well,
• In other words, due to the shiny nickel coating, the magnet obtains an stylish appearance,
• Magnetic induction on the surface of these magnets is impressively powerful,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• The ability for custom shaping or customization to specific needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which amplifies their functionality across industries,
• Significant impact in cutting-edge sectors – they find application in computer drives, electric drives, clinical machines or even technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to shocks, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time strengthens its overall durability,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent loss 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,
• Magnets exposed to humidity can degrade. Therefore, for outdoor applications, we recommend waterproof types made of rubber,
• Limited ability to create complex details in the magnet – the use of a external casing is recommended,
• Health risk from tiny pieces may arise, in case of ingestion, which is important in the family environments. Additionally, tiny components from these devices may complicate medical imaging when ingested,
• In cases of tight budgets, neodymium magnet cost is a challenge,

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

The given holding capacity of the magnet corresponds to the highest holding force, assessed 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
• under perpendicular detachment force
• in normal thermal conditions

Lifting capacity in practice – influencing factors

In practice, the holding capacity of a magnet is conditioned by these factors, arranged from the most important to the least relevant:

• 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.