SM 32x125 [2xM8] / N42 - magnetic separator

Pros as well as cons of rare earth magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• They show high resistance to demagnetization induced by external magnetic fields,
• A magnet with a shiny silver surface has an effective appearance,
• Magnetic induction on the surface of the magnet turns out to be extremely intense,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in shaping and the ability to customize to specific needs,
• Versatile presence in modern technologies – they serve a role in HDD drives, electric drive systems, medical equipment, and other advanced devices.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously increases its durability.
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening 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 secure oxidation and corrosion.
• Limited ability of making threads in the magnet and complex forms - preferred is a housing - mounting mechanism.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these products can disrupt the diagnostic process medical in case of swallowing.
• With large orders the cost of neodymium magnets is economically unviable,

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

Information about lifting capacity is the result of a measurement for ideal contact conditions, taking into account:

• using a base made of low-carbon steel, functioning as a magnetic yoke
• with a cross-section no less than 10 mm
• with an polished contact surface
• without the slightest insulating layer between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• in neutral thermal conditions

Practical lifting capacity: influencing factors

Please note that the magnet holding may be lower influenced by the following factors, starting with the most relevant:

• Space between surfaces – every millimeter of separation (caused e.g. by veneer or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Direction of force – highest force is reached only during pulling at a 90° angle. The force required to slide of the magnet along the plate is standardly several times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material type – ideal substrate is high-permeability steel. Stainless steels may attract less.
• Plate texture – ground elements ensure maximum contact, which improves field saturation. Uneven metal reduce efficiency.
• Temperature influence – high temperature weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity was assessed with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.