SM 25x250 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

Apart from their strong holding force, neodymium magnets have these key benefits:

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (based on calculations),
• They possess excellent resistance to magnetism drop due to external fields,
• By applying a reflective coating of nickel, the element gains an nice look,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to the potential of accurate forming and customization to specialized requirements, neodymium magnets can be modeled in a variety of forms and dimensions, which amplifies use scope,
• Significant place in modern industrial fields – they are utilized in HDD drives, brushless drives, precision medical tools, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Disadvantages of neodymium magnets:

• At very strong impacts they can crack, therefore we advise placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of creating threads in the magnet and complicated shapes - preferred is a housing - magnetic holder.
• Potential hazard to health – tiny shards of magnets pose a threat, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these devices can be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum lifting force for a neodymium magnet – what it depends on?

Holding force of 0 kg is a result of laboratory testing executed under specific, ideal conditions:

• on a block made of structural steel, optimally conducting the magnetic field
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• with total lack of distance (without paint)
• during detachment in a direction vertical to the mounting surface
• in neutral thermal conditions

Key elements affecting lifting force

In real-world applications, the real power depends on a number of factors, presented from the most important:

• Clearance – existence of foreign body (rust, dirt, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Chemical composition of the base – mild steel attracts best. Alloy admixtures decrease magnetic properties and holding force.
• Base smoothness – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Temperature – heating the magnet causes a temporary drop of force. Check the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.