MW 4x8 / N38 - cylindrical magnet

Advantages as well as disadvantages of NdFeB magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• Magnets very well defend themselves against loss of magnetization caused by foreign field sources,
• The use of an shiny coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in designing and the ability to modify to individual projects,
• Huge importance in future technologies – they are utilized in computer drives, drive modules, medical devices, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which allows their use in compact constructions

What to avoid - cons of neodymium magnets: weaknesses and usage proposals

• At strong impacts they can crack, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• We recommend casing - magnetic holder, due to difficulties in creating nuts inside the magnet and complex shapes.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which is particularly important in the context of child safety. It is also worth noting that small components of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• Due to complex production process, their price exceeds standard values,

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

The load parameter shown represents the limit force, recorded under optimal environment, specifically:

• on a plate made of structural steel, effectively closing the magnetic flux
• whose thickness equals approx. 10 mm
• with an polished contact surface
• with total lack of distance (no coatings)
• during pulling in a direction vertical to the plane
• at standard ambient temperature

What influences lifting capacity in practice

It is worth knowing that the magnet holding will differ influenced by the following factors, starting with the most relevant:

• Distance (betwixt the magnet and the plate), as even a tiny distance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to paint, corrosion or debris).
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet exhibits significantly lower power (typically approx. 20-30% of maximum force).
• Plate thickness – insufficiently thick steel causes magnetic saturation, causing part of the power to be wasted to the other side.
• Material type – ideal substrate is pure iron steel. Hardened steels may attract less.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Rough surfaces reduce efficiency.
• Temperature influence – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was assessed by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the holding force is lower. Moreover, even a small distance {between} the magnet and the plate decreases the load capacity.