SM 25x250 [2xM8] / N42 - magnetic separator

Pros and cons of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• They are noted for resistance to demagnetization induced by external field influence,
• In other words, due to the aesthetic finish of nickel, the element becomes visually attractive,
• Magnetic induction on the working layer of the magnet remains impressive,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Due to the ability of flexible shaping and customization to unique projects, neodymium magnets can be manufactured in a variety of shapes and sizes, which makes them more universal,
• Significant place in modern industrial fields – they are commonly used in mass storage devices, brushless drives, precision medical tools, as well as modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only shields the magnet but also improves 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 force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We suggest cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complicated forms.
• Possible danger resulting from small fragments of magnets are risky, if swallowed, which gains importance in the context of child health protection. It is also worth noting that small components of these devices are able to disrupt the diagnostic process 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 holding power of the magnet – what affects it?

Magnet power was defined for the most favorable conditions, assuming:

• with the application of a yoke made of special test steel, guaranteeing full magnetic saturation
• possessing a massiveness of at least 10 mm to avoid saturation
• characterized by even structure
• with zero gap (without impurities)
• under axial force direction (90-degree angle)
• at temperature room level

What influences lifting capacity in practice

During everyday use, the actual lifting capacity depends on many variables, presented from most significant:

• Air gap (betwixt the magnet and the metal), as even a microscopic distance (e.g. 0.5 mm) leads to a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet holds much less (often approx. 20-30% of nominal force).
• Plate thickness – insufficiently thick plate does not accept the full field, causing part of the power to be escaped into the air.
• Steel type – low-carbon steel attracts best. Alloy steels reduce magnetic properties and lifting capacity.
• Base smoothness – the smoother and more polished the plate, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Heat – neodymium magnets have a sensitivity to temperature. When it is hot they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.