SM 32x150 [2xM8] / N52 - magnetic separator

Pros as well as cons of NdFeB magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (according to literature),
• Magnets perfectly protect themselves against demagnetization caused by ambient magnetic noise,
• In other words, due to the shiny layer of nickel, the element becomes visually attractive,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to freedom in forming and the capacity to adapt to individual projects,
• Fundamental importance in advanced technology sectors – they are used in mass storage devices, electric motors, medical equipment, also modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend 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 strength 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
• 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 secure oxidation and corrosion.
• We suggest a housing - magnetic holder, due to difficulties in producing nuts inside the magnet and complex shapes.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets can be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Detachment force of the magnet in optimal conditions – what affects it?

The declared magnet strength represents the maximum value, obtained under laboratory conditions, meaning:

• on a base made of structural steel, perfectly concentrating the magnetic field
• with a thickness minimum 10 mm
• with a surface cleaned and smooth
• without any clearance between the magnet and steel
• during pulling in a direction perpendicular to the plane
• at standard ambient temperature

Impact of factors on magnetic holding capacity in practice

During everyday use, the actual holding force is determined by a number of factors, listed from crucial:

• Gap (between the magnet and the plate), since even a very small clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to paint, rust or dirt).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Base massiveness – too thin steel causes magnetic saturation, causing part of the power to be lost to the other side.
• Material type – ideal substrate is high-permeability steel. Stainless steels may generate lower lifting capacity.
• Surface condition – ground elements guarantee perfect abutment, which increases field saturation. Rough surfaces weaken the grip.
• Heat – 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 checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate lowers the load capacity.