SM 25x350 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (according to theory),
• They have excellent resistance to magnetic field loss due to external magnetic sources,
• Thanks to the metallic finish, the plating of Ni-Cu-Ni, gold, or silver-plated gives an elegant appearance,
• Magnetic induction on the working part of the magnet remains strong,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to the possibility of flexible shaping and customization to custom requirements, NdFeB magnets can be created in a wide range of geometric configurations, which increases their versatility,
• Huge importance in electronics industry – they are used in data components, drive modules, advanced medical instruments, and other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which enables their usage in small systems

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets decrease their strength 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 durability even at temperatures up to 230°C
• When exposed to humidity, magnets start to 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.
• Due to limitations in realizing nuts and complex forms in magnets, we propose using casing - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the aspect of protecting the youngest. It is also worth noting that tiny parts of these devices are able to be problematic in diagnostics medical in case of swallowing.
• Due to expensive raw materials, their price exceeds standard values,

Breakaway strength of the magnet in ideal conditions – what affects it?

Information about lifting capacity was defined for ideal contact conditions, taking into account:

• using a sheet made of high-permeability steel, acting as a circuit closing element
• possessing a thickness of min. 10 mm to avoid saturation
• characterized by smoothness
• without any air gap between the magnet and steel
• under perpendicular force direction (90-degree angle)
• at standard ambient temperature

Determinants of lifting force in real conditions

Real force is influenced by working environment parameters, such as (from priority):

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin steel does not close the flux, causing part of the flux to be lost into the air.
• Steel type – low-carbon steel gives the best results. Higher carbon content decrease magnetic permeability and lifting capacity.
• Surface quality – the smoother and more polished the plate, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was assessed with the use of a smooth steel plate of suitable thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet and the plate decreases the holding force.