SM 32x125 [2xM8] / N52 - magnetic separator

Pros as well as cons of NdFeB magnets.

Besides their immense pulling force, neodymium magnets offer the following advantages:

• They do not lose magnetism, even during nearly 10 years – the decrease in lifting capacity is only ~1% (theoretically),
• Magnets perfectly protect themselves against loss of magnetization caused by foreign field sources,
• Thanks to the shiny finish, the coating of Ni-Cu-Ni, gold-plated, or silver gives an aesthetic appearance,
• They show high magnetic induction at the operating surface, making them more effective,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of precise forming and adapting to atypical applications,
• Key role in electronics industry – they are utilized in hard drives, electric drive systems, precision medical tools, also complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a strong case, which not only secures them against impacts but also raises their durability
• Neodymium magnets lose 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• We suggest cover - magnetic mechanism, due to difficulties in producing threads inside the magnet and complicated forms.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. Furthermore, tiny parts of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is relatively high,

Maximum lifting capacity of the magnet – what affects it?

Magnet power was defined for optimal configuration, assuming:

• on a base made of mild steel, effectively closing the magnetic flux
• with a cross-section no less than 10 mm
• with a plane cleaned and smooth
• without any air gap between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• in stable room temperature

What influences lifting capacity in practice

Effective lifting capacity is affected by working environment parameters, including (from most important):

• Clearance – existence of foreign body (rust, tape, gap) acts as an insulator, which lowers capacity steeply (even by 50% at 0.5 mm).
• Load vector – highest force is reached only during perpendicular pulling. The resistance to sliding of the magnet along the plate is standardly several times lower (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Steel grade – the best choice is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface structure – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness acts like micro-gaps.
• Temperature influence – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.