SM 32x425 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of rare earth magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They retain attractive force for nearly ten years – the loss is just ~1% (in theory),
• They have excellent resistance to weakening of magnetic properties when exposed to external fields,
• The use of an metallic layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Neodymium magnets achieve maximum magnetic induction on a contact point, which allows for strong attraction,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of precise machining and adapting to individual requirements,
• Universal use in innovative solutions – they are utilized in mass storage devices, motor assemblies, medical devices, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which enables their usage in compact constructions

Disadvantages of neodymium magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets decrease their strength 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
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Due to limitations in producing nuts and complicated shapes in magnets, we recommend using a housing - magnetic holder.
• Health risk related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. Furthermore, tiny parts of these devices can complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum magnetic pulling force – what contributes to it?

The load parameter shown represents the limit force, recorded under laboratory conditions, namely:

• on a plate made of mild steel, effectively closing the magnetic flux
• whose thickness equals approx. 10 mm
• with an ideally smooth contact surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Please note that the working load will differ depending on the following factors, starting with the most relevant:

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
• Angle of force application – highest force is reached only during perpendicular pulling. The force required to slide of the magnet along the plate is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Material composition – different alloys reacts the same. Alloy additives worsen the attraction effect.
• Plate texture – smooth surfaces guarantee perfect abutment, which increases force. Uneven metal weaken the grip.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.