SM 32x350 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

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

• They have unchanged lifting capacity, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
• They are resistant to demagnetization induced by presence of other magnetic fields,
• Thanks to the glossy finish, the layer of nickel, gold-plated, or silver gives an professional appearance,
• Neodymium magnets ensure maximum magnetic induction on a small area, which allows for strong attraction,
• Thanks to resistance to high temperature, they are able to function (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of exact machining as well as modifying to defined applications,
• Fundamental importance in advanced technology sectors – they are commonly used in data components, electromotive mechanisms, diagnostic systems, and technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• When exposed to humidity, magnets usually rust. To use them in conditions 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 forms in magnets, we recommend using a housing - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these devices can be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets is a challenge,

Maximum holding power of the magnet – what it depends on?

The lifting capacity listed is a theoretical maximum value executed under the following configuration:

• on a block made of structural steel, effectively closing the magnetic flux
• whose transverse dimension is min. 10 mm
• characterized by smoothness
• under conditions of gap-free contact (metal-to-metal)
• for force acting at a right angle (pull-off, not shear)
• at conditions approx. 20°C

What influences lifting capacity in practice

Real force impacted by specific conditions, including (from priority):

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Load vector – highest force is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Steel grade – ideal substrate is high-permeability steel. Hardened steels may attract less.
• Surface structure – the more even the surface, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity was determined with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.