SM 32x325 [2xM8] / N42 - magnetic separator

Pros as well as cons of NdFeB magnets.

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

• They have stable power, and over nearly ten years their performance decreases symbolically – ~1% (according to theory),
• They retain their magnetic properties even under external field action,
• Thanks to the shiny finish, the coating of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• The surface of neodymium magnets generates a strong magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of detailed forming and modifying to concrete conditions,
• Universal use in future technologies – they serve a role in data components, drive modules, diagnostic systems, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Disadvantages of neodymium magnets:

• At very strong impacts they can break, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of producing threads in the magnet and complex shapes - preferred is casing - magnet mounting.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these devices are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Magnetic strength at its maximum – what contributes to it?

The declared magnet strength refers to the peak performance, measured under laboratory conditions, meaning:

• on a plate made of mild steel, effectively closing the magnetic field
• whose transverse dimension is min. 10 mm
• characterized by lack of roughness
• under conditions of gap-free contact (metal-to-metal)
• during detachment in a direction perpendicular to the plane
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

In practice, the actual holding force results from many variables, listed from crucial:

• Clearance – existence of foreign body (rust, tape, air) acts as an insulator, which reduces capacity steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is available only during perpendicular pulling. The force required to slide of the magnet along the plate is standardly many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel attracts identically. Alloy additives weaken the interaction with the magnet.
• Surface condition – ground elements ensure maximum contact, which improves field saturation. Rough surfaces weaken the grip.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was determined by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.