SM 25x100 [2xM8] / N42 - magnetic separator

Pros and cons of neodymium magnets.

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

• They have stable power, and over nearly 10 years their performance decreases symbolically – ~1% (according to theory),
• They retain their magnetic properties even under strong external field,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to look better,
• The surface of neodymium magnets generates a strong magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• In view of the possibility of flexible forming and customization to specialized solutions, neodymium magnets can be modeled in a wide range of forms and dimensions, which amplifies use scope,
• Key role in electronics industry – they are utilized in magnetic memories, drive modules, medical equipment, also modern systems.
• Compactness – despite small sizes they generate large force, 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 increases its durability.
• NdFeB magnets lose power 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 those in rubber or plastics, which prevent oxidation as well as corrosion.
• We suggest casing - magnetic mechanism, due to difficulties in creating threads inside the magnet and complex shapes.
• Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. Furthermore, small components of these devices are able to complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Best holding force of the magnet in ideal parameters – what contributes to it?

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

• on a base made of structural steel, effectively closing the magnetic flux
• with a cross-section no less than 10 mm
• with a plane free of scratches
• without any clearance between the magnet and steel
• under vertical application of breakaway force (90-degree angle)
• in temp. approx. 20°C

Magnet lifting force in use – key factors

Holding efficiency impacted by working environment parameters, mainly (from priority):

• Clearance – the presence of foreign body (rust, tape, gap) acts as an insulator, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick plate causes magnetic saturation, causing part of the power to be lost to the other side.
• Material type – ideal substrate is pure iron steel. Cast iron may attract less.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures gain strength (up to a certain limit).

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the load capacity.