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

Pros and cons of rare earth magnets.

Besides their tremendous magnetic power, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• Magnets very well protect themselves against loss of magnetization caused by ambient magnetic noise,
• By applying a reflective coating of silver, the element acquires an elegant look,
• Magnets are characterized by maximum 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 form) even at a temperature of 230°C or more...
• In view of the possibility of precise molding and customization to custom solutions, neodymium magnets can be produced in a variety of geometric configurations, which amplifies use scope,
• Significant place in modern technologies – they are used in data components, drive modules, medical equipment, as well as complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which makes them useful in compact constructions

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a steel housing, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in realizing nuts and complex shapes in magnets, we recommend using cover - magnetic holder.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which becomes key in the context of child health protection. Additionally, small elements of these magnets can be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting force for a neodymium magnet – what it depends on?

The declared magnet strength concerns the limit force, obtained under laboratory conditions, namely:

• with the contact of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• with a thickness no less than 10 mm
• with a surface perfectly flat
• with zero gap (no paint)
• under vertical force vector (90-degree angle)
• at room temperature

What influences lifting capacity in practice

In real-world applications, the real power depends on many variables, ranked from crucial:

• Gap (betwixt the magnet and the plate), since even a tiny distance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Load vector – maximum parameter is available only during pulling at a 90° angle. The force required to slide of the magnet along the surface is usually many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Plate material – low-carbon steel attracts best. Alloy steels reduce magnetic permeability and holding force.
• Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, reducing force.
• Temperature influence – high temperature reduces magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.