SM 18x200 [2xM5] / N42 - magnetic separator

Advantages and disadvantages of rare earth magnets.

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

• They do not lose strength, even after around ten years – the reduction in lifting capacity is only ~1% (based on measurements),
• They possess excellent resistance to magnetic field loss as a result of opposing magnetic fields,
• By applying a lustrous coating of gold, the element presents an aesthetic look,
• They are known for high magnetic induction at the operating surface, which improves attraction properties,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of precise creating and optimizing to concrete applications,
• Fundamental importance in high-tech industry – they are utilized in mass storage devices, brushless drives, medical devices, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in compact constructions

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously increases its durability.
• NdFeB magnets demagnetize 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 extremely resistant to heat
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Due to limitations in realizing threads and complicated forms in magnets, we propose using a housing - magnetic mount.
• Potential hazard related to microscopic parts of magnets can be dangerous, if swallowed, which becomes key in the context of child safety. Additionally, small components of these products can disrupt the diagnostic process medical when they are in the body.
• Due to expensive raw materials, their price is higher than average,

Optimal lifting capacity of a neodymium magnet – what it depends on?

Breakaway force is the result of a measurement for the most favorable conditions, taking into account:

• using a plate made of low-carbon steel, functioning as a magnetic yoke
• with a cross-section no less than 10 mm
• with a surface perfectly flat
• without any air gap between the magnet and steel
• during detachment in a direction vertical to the plane
• at ambient temperature approx. 20 degrees Celsius

Magnet lifting force in use – key factors

Holding efficiency is affected by working environment parameters, such as (from priority):

• Clearance – the presence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material composition – not every steel attracts identically. High carbon content worsen the attraction effect.
• Surface structure – the more even the plate, the larger the contact zone and higher the lifting capacity. Roughness creates an air distance.
• Temperature influence – hot environment weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under vertically applied force, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet and the plate lowers the load capacity.