SMZR 25x225 / N52 - magnetic separator with handle

Pros as well as cons of NdFeB magnets.

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

• They have unchanged lifting capacity, and over around ten years their attraction force decreases symbolically – ~1% (according to theory),
• They show high resistance to demagnetization induced by external field influence,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• The surface of neodymium magnets generates a strong magnetic field – this is a distinguishing feature,
• 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 accurate forming and optimizing to individual requirements,
• Versatile presence in modern industrial fields – they are utilized in mass storage devices, electric drive systems, medical devices, as well as modern systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Cons of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• We recommend a housing - magnetic holder, due to difficulties in realizing nuts inside the magnet and complex shapes.
• Potential hazard resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that tiny parts of these magnets are able to be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

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

The load parameter shown represents the peak performance, recorded under optimal environment, namely:

• with the application of a sheet made of low-carbon steel, ensuring maximum field concentration
• possessing a massiveness of min. 10 mm to avoid saturation
• with a surface perfectly flat
• under conditions of gap-free contact (surface-to-surface)
• during detachment in a direction vertical to the mounting surface
• at ambient temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

Please note that the application force may be lower depending on elements below, in order of importance:

• Gap (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) can cause a reduction in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Plate material – mild steel attracts best. Higher carbon content decrease magnetic permeability and lifting capacity.
• Surface quality – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet and the plate reduces the holding force.