SM 25x325 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of neodymium magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• They show high resistance to demagnetization induced by external magnetic fields,
• By using a decorative layer of silver, the element gains an nice look,
• Neodymium magnets deliver maximum magnetic induction on a their surface, which increases force concentration,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Possibility of precise modeling as well as modifying to atypical requirements,
• Huge importance in future technologies – they serve a role in data components, motor assemblies, medical equipment, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in small systems

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complicated forms.
• Health risk to health – tiny shards of magnets are risky, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these products can be problematic in diagnostics medical in case of swallowing.
• With mass production the cost of neodymium magnets is economically unviable,

Magnetic strength at its maximum – what affects it?

The declared magnet strength concerns the peak performance, obtained under ideal test conditions, namely:

• using a sheet made of high-permeability steel, serving as a ideal flux conductor
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• characterized by even structure
• without any insulating layer between the magnet and steel
• under vertical force vector (90-degree angle)
• in temp. approx. 20°C

Determinants of lifting force in real conditions

In practice, the real power depends on several key aspects, listed from crucial:

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Angle of force application – maximum parameter is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of generating force.
• Material type – the best choice is high-permeability steel. Cast iron may attract less.
• Surface condition – smooth surfaces ensure maximum contact, which improves force. Uneven metal reduce efficiency.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the load capacity.