SM 18x125 [2xM5] / N42 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

Apart from their notable holding force, neodymium magnets have these key benefits:

• They retain full power for around ten years – the drop is just ~1% (based on simulations),
• They maintain their magnetic properties even under close interference source,
• The use of an elegant finish of noble metals (nickel, gold, silver) causes the element to look better,
• Magnets have extremely high magnetic induction on the outer layer,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to modularity in shaping and the ability to adapt to specific needs,
• Universal use in modern industrial fields – they serve a role in mass storage devices, drive modules, diagnostic systems, and complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• At very strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power 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 start to 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.
• Due to limitations in creating nuts and complicated shapes in magnets, we propose using a housing - magnetic holder.
• Possible danger resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small components of these devices can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The lifting capacity listed is a theoretical maximum value executed under specific, ideal conditions:

• with the application of a yoke made of low-carbon steel, ensuring maximum field concentration
• with a thickness minimum 10 mm
• characterized by even structure
• without any clearance between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• in stable room temperature

Impact of factors on magnetic holding capacity in practice

Real force is affected by working environment parameters, mainly (from priority):

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Material composition – not every steel reacts the same. High carbon content weaken the attraction effect.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.