SM 25x300 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• Neodymium magnets remain extremely resistant to loss of magnetic properties caused by magnetic disturbances,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnetic induction on the top side of the magnet turns out to be extremely intense,
• Thanks to resistance to high temperature, they are able to function (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of detailed creating and adapting to specific needs,
• Versatile presence in modern technologies – they are utilized in hard drives, electric drive systems, diagnostic systems, as well as multitasking production systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously improves its 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 usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• We recommend casing - magnetic mount, due to difficulties in creating threads inside the magnet and complex shapes.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child safety. Additionally, tiny parts of these products are able to complicate diagnosis medical after entering the body.
• Due to complex production process, their price is relatively high,

Maximum holding power of the magnet – what contributes to it?

The lifting capacity listed is a measurement result executed under standard conditions:

• with the application of a yoke made of low-carbon steel, ensuring maximum field concentration
• whose thickness equals approx. 10 mm
• with an ideally smooth contact surface
• without any insulating layer between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at standard ambient temperature

Impact of factors on magnetic holding capacity in practice

Real force is affected by working environment parameters, such as (from most important):

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Plate thickness – too thin steel does not close the flux, causing part of the power to be escaped to the other side.
• Steel type – low-carbon steel gives the best results. Alloy steels lower magnetic permeability and holding force.
• Surface condition – ground elements guarantee perfect abutment, which increases field saturation. Rough surfaces reduce efficiency.
• Temperature – heating the magnet results in weakening of force. Check the thermal limit for a given model.

* 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 holding force is lower. Moreover, even a slight gap {between} the magnet and the plate lowers the holding force.