SMZR 25x200 / N52 - magnetic separator with handle

Strengths and weaknesses of rare earth magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even over nearly 10 years – the drop in lifting capacity is only ~1% (according to tests),
• Magnets very well protect themselves against loss of magnetization caused by foreign field sources,
• Thanks to the shiny finish, the surface of nickel, gold-plated, or silver-plated gives an professional appearance,
• Magnets are distinguished by maximum magnetic induction on the outer layer,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• In view of the potential of free molding and customization to custom needs, magnetic components can be produced in a variety of shapes and sizes, which increases their versatility,
• Significant place in future technologies – they are utilized in magnetic memories, drive modules, medical devices, and complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop 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 very resistant to heat
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those 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 holder.
• Possible danger resulting from small fragments of magnets are risky, in case of ingestion, which is particularly important in the context of child health protection. Additionally, small components of these magnets can be problematic in diagnostics medical after entering the body.
• Due to expensive raw materials, their price is relatively high,

Best holding force of the magnet in ideal parameters – what contributes to it?

The declared magnet strength refers to the limit force, obtained under laboratory conditions, meaning:

• on a base made of mild steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• with a plane cleaned and smooth
• under conditions of ideal adhesion (metal-to-metal)
• during detachment in a direction perpendicular to the plane
• in neutral thermal conditions

Key elements affecting lifting force

In practice, the actual holding force results from many variables, presented from most significant:

• Clearance – existence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet exhibits much less (often approx. 20-30% of nominal force).
• Plate thickness – insufficiently thick steel does not close the flux, causing part of the flux to be lost into the air.
• Steel grade – ideal substrate is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface quality – the smoother and more polished the surface, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet and the plate lowers the holding force.