SM 25x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of rare earth magnets.

Apart from their superior power, neodymium magnets have these key benefits:

• They do not lose power, even after nearly 10 years – the decrease in strength is only ~1% (according to tests),
• Neodymium magnets are distinguished by remarkably resistant to magnetic field loss caused by magnetic disturbances,
• The use of an refined coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• The surface of neodymium magnets generates a intense magnetic field – this is a key feature,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in constructing and the capacity to adapt to unusual requirements,
• Fundamental importance in modern technologies – they are utilized in mass storage devices, electric drive systems, medical devices, and other advanced devices.
• Thanks to concentrated force, small magnets offer high operating force, occupying minimum space,

Disadvantages of neodymium 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
• Neodymium magnets decrease 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Limited ability of making nuts in the magnet and complex shapes - preferred is a housing - magnetic holder.
• Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. Additionally, small elements of these magnets can disrupt the diagnostic process medical in case of swallowing.
• Due to expensive raw materials, their price is higher than average,

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The load parameter shown refers to the maximum value, recorded under ideal test conditions, namely:

• using a plate made of mild steel, functioning as a magnetic yoke
• with a cross-section of at least 10 mm
• characterized by even structure
• with total lack of distance (no coatings)
• under vertical application of breakaway force (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

Holding efficiency is influenced by specific conditions, mainly (from priority):

• Distance (betwixt the magnet and the plate), because even a tiny clearance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to varnish, corrosion or debris).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the holding force 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 attraction force (the magnet "punches through" it).
• Steel grade – ideal substrate is high-permeability steel. Cast iron may have worse magnetic properties.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Thermal environment – temperature increase causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate decreases the load capacity.