SM 32x275 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

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

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (according to literature),
• They do not lose their magnetic properties even under strong external field,
• The use of an metallic layer of noble metals (nickel, gold, silver) causes the element to present itself better,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to flexibility in designing and the ability to modify to complex applications,
• Significant place in advanced technology sectors – they find application in magnetic memories, electric drive systems, medical equipment, also multitasking production systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we advise using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of producing nuts in the magnet and complicated shapes - preferred is casing - magnet mounting.
• Potential hazard resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these devices are able to disrupt the diagnostic process medical after entering the body.
• With large orders the cost of neodymium magnets is economically unviable,

Maximum lifting capacity of the magnet – what affects it?

The force parameter is a theoretical maximum value performed under standard conditions:

• on a plate made of structural steel, effectively closing the magnetic flux
• with a cross-section minimum 10 mm
• with a surface free of scratches
• under conditions of gap-free contact (surface-to-surface)
• during detachment in a direction vertical to the plane
• at ambient temperature room level

Practical lifting capacity: influencing factors

In practice, the real power results from several key aspects, listed from the most important:

• Clearance – the presence of any layer (rust, dirt, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is reached only during perpendicular pulling. The shear force of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel attracts best. Alloy steels lower magnetic permeability and lifting capacity.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature influence – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.