SM 25x275 [2xM8] / N52 - magnetic separator

Pros and cons of NdFeB magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They do not lose magnetism, even over nearly 10 years – the drop in power is only ~1% (based on measurements),
• They do not lose their magnetic properties even under close interference source,
• By applying a lustrous layer of nickel, the element acquires an aesthetic look,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of custom machining as well as optimizing to specific applications,
• Universal use in future technologies – they are used in computer drives, drive modules, advanced medical instruments, as well as industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in miniature devices

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited ability of making nuts in the magnet and complex forms - recommended is a housing - magnetic holder.
• Possible danger resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the aspect of protecting the youngest. Furthermore, small elements of these products are able to complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets can be a barrier,

Magnetic strength at its maximum – what it depends on?

The lifting capacity listed is a measurement result performed under specific, ideal conditions:

• on a plate made of structural steel, effectively closing the magnetic flux
• whose thickness is min. 10 mm
• with an polished touching surface
• with direct contact (without paint)
• under axial application of breakaway force (90-degree angle)
• in stable room temperature

Lifting capacity in practice – influencing factors

Bear in mind that the magnet holding will differ influenced by the following factors, in order of importance:

• Gap (betwixt the magnet and the metal), as even a very small distance (e.g. 0.5 mm) results in a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – insufficiently thick steel does not accept the full field, causing part of the flux to be escaped to the other side.
• Chemical composition of the base – low-carbon steel gives the best results. Higher carbon content decrease magnetic permeability and holding force.
• Smoothness – ideal contact is obtained only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the load capacity.