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

Strengths as well as weaknesses of rare earth magnets.

Besides their tremendous strength, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (in laboratory conditions),
• Neodymium magnets are characterized by exceptionally resistant to magnetic field loss caused by external interference,
• A magnet with a shiny gold surface has better aesthetics,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to modularity in constructing and the ability to modify to specific needs,
• Significant place in future technologies – they are commonly used in hard drives, motor assemblies, diagnostic systems, and industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which allows their use in miniature devices

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of producing threads in the magnet and complex shapes - preferred is cover - magnet mounting.
• Possible danger resulting from small fragments of magnets can be dangerous, in case of ingestion, which gains importance in the context of child safety. It is also worth noting that small elements of these devices are able to be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets can be a barrier,

Best holding force of the magnet in ideal parameters – what it depends on?

Information about lifting capacity is the result of a measurement for optimal configuration, including:

• on a block made of mild steel, optimally conducting the magnetic flux
• whose thickness equals approx. 10 mm
• characterized by lack of roughness
• under conditions of no distance (surface-to-surface)
• for force applied at a right angle (in the magnet axis)
• in temp. approx. 20°C

Practical aspects of lifting capacity – factors

Real force impacted by specific conditions, such as (from priority):

• Space between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice is high-permeability steel. Cast iron may generate lower lifting capacity.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Uneven metal reduce efficiency.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate lowers the load capacity.