MW 35x5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their superior power, neodymium magnets have these key benefits:

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (based on calculations),
• They are highly resistant to demagnetization caused by external field interference,
• By applying a bright layer of nickel, the element gains a modern look,
• The outer field strength of the magnet shows advanced magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Important function in modern technologies – they are used in computer drives, electric drives, medical equipment or even high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which makes them ideal in compact constructions

Disadvantages of rare earth magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to external force, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture while also reinforces its overall resistance,
• They lose strength at high temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of protective material for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a magnetic holder is recommended,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is significant in the context of child safety. Additionally, minuscule fragments from these magnets have the potential to disrupt scanning once in the system,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Optimal lifting capacity of a neodymium magnet – what affects it?

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

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• at room temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• Air gap between the magnet and the plate, because 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 was determined with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.