SM 18x300 [2xM5] / N42 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

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

• They retain magnetic properties for nearly 10 years – the loss is just ~1% (according to analyses),
• They maintain their magnetic properties even under close interference source,
• Thanks to the shiny finish, the layer of nickel, gold-plated, or silver gives an modern appearance,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, enabling functioning at temperatures reaching 230°C and above...
• Considering the ability of precise forming and customization to custom needs, NdFeB magnets can be modeled in a wide range of forms and dimensions, which makes them more universal,
• Universal use in high-tech industry – they are commonly used in data components, drive modules, precision medical tools, and complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can break, therefore we advise placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their force 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
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• We suggest cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complicated shapes.
• Possible danger resulting from small fragments of magnets pose a threat, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small components of these products can 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 increases costs of application in large quantities

Maximum lifting force for a neodymium magnet – what contributes to it?

Information about lifting capacity was defined for optimal configuration, including:

• on a plate made of structural steel, effectively closing the magnetic flux
• whose thickness reaches at least 10 mm
• with an ideally smooth touching surface
• without any air gap between the magnet and steel
• under vertical application of breakaway force (90-degree angle)
• at temperature approx. 20 degrees Celsius

Key elements affecting lifting force

In real-world applications, the real power results from several key aspects, ranked from most significant:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Base massiveness – too thin sheet causes magnetic saturation, causing part of the power to be escaped to the other side.
• Steel type – low-carbon steel attracts best. Higher carbon content lower magnetic properties and holding force.
• Surface finish – full contact is possible only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. At higher temperatures they lose power, and at low temperatures gain strength (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. Moreover, even a minimal clearance {between} the magnet and the plate decreases the holding force.