SM 32x225 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They have stable power, and over around ten years their attraction force decreases symbolically – ~1% (according to theory),
• Magnets perfectly defend themselves against demagnetization caused by external fields,
• In other words, due to the shiny surface of gold, the element gains a professional look,
• The surface of neodymium magnets generates a concentrated magnetic field – this is a key feature,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling functioning at temperatures approaching 230°C and above...
• Possibility of accurate machining as well as modifying to specific applications,
• Significant place in high-tech industry – they serve a role in data components, motor assemblies, medical devices, and technologically advanced constructions.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Cons of neodymium magnets and proposals for their use:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures 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.
• Limited possibility of creating threads in the magnet and complicated forms - recommended is cover - mounting mechanism.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these devices are able to disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling force – what contributes to it?

Magnet power was determined for the most favorable conditions, taking into account:

• on a base made of structural steel, perfectly concentrating the magnetic field
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• without the slightest insulating layer between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• in temp. approx. 20°C

What influences lifting capacity in practice

It is worth knowing that the application force will differ depending on elements below, in order of importance:

• Space between surfaces – every millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to detachment vertically. When slipping, the magnet exhibits significantly lower power (typically approx. 20-30% of nominal force).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Steel type – low-carbon steel attracts best. Higher carbon content lower magnetic permeability and lifting capacity.
• Base smoothness – the more even the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Heat – NdFeB sinters have a sensitivity to temperature. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.