SM 32x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

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

• They do not lose strength, even over around ten years – the drop in power is only ~1% (according to tests),
• Neodymium magnets are distinguished by highly resistant to loss of magnetic properties caused by external field sources,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• Magnetic induction on the surface of the magnet turns out to be extremely intense,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Considering the ability of flexible shaping and adaptation to individualized needs, magnetic components can be manufactured in a wide range of shapes and sizes, which makes them more universal,
• Versatile presence in innovative solutions – they are used in hard drives, drive modules, diagnostic systems, also other advanced devices.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We recommend cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complex forms.
• Possible danger resulting from small fragments of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. It is also worth noting that small elements of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Best holding force of the magnet in ideal parameters – what it depends on?

The lifting capacity listed is a theoretical maximum value executed under standard conditions:

• with the application of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• under conditions of ideal adhesion (surface-to-surface)
• during pulling in a direction vertical to the plane
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

In practice, the real power results from many variables, listed from crucial:

• Gap (betwixt the magnet and the plate), since even a very small clearance (e.g. 0.5 mm) results in a decrease in force by up to 50% (this also applies to varnish, rust or debris).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Element thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Material type – the best choice is pure iron steel. Hardened steels may attract less.
• Smoothness – full contact is possible only on smooth steel. Any scratches and bumps create air cushions, weakening the magnet.
• Heat – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.