SM 32x150 [2xM8] / N42 - magnetic separator

Pros and cons of rare earth magnets.

Besides their tremendous magnetic power, neodymium magnets offer the following advantages:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
• Magnets perfectly protect themselves against loss of magnetization caused by external fields,
• By covering with a decorative coating of gold, the element has an aesthetic look,
• Neodymium magnets generate maximum magnetic induction on a small area, which allows for strong attraction,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of precise forming as well as adjusting to individual conditions,
• Significant place in future technologies – they are utilized in computer drives, motor assemblies, diagnostic systems, also modern systems.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Problematic aspects of neodymium magnets and ways of using them

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously increases 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Limited ability of making nuts in the magnet and complicated shapes - preferred is casing - magnet mounting.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which becomes key in the context of child safety. Furthermore, tiny parts of these magnets are able to disrupt the diagnostic process medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Optimal lifting capacity of a neodymium magnet – what contributes to it?

Magnet power was defined for ideal contact conditions, assuming:

• on a base made of mild steel, effectively closing the magnetic field
• whose transverse dimension is min. 10 mm
• with a surface free of scratches
• with total lack of distance (without impurities)
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

Effective lifting capacity is affected by working environment parameters, mainly (from priority):

• Distance (betwixt the magnet and the metal), as even a microscopic clearance (e.g. 0.5 mm) can cause a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Load vector – highest force is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – insufficiently thick plate does not accept the full field, causing part of the flux to be wasted to the other side.
• Plate material – mild steel gives the best results. Alloy admixtures decrease magnetic properties and holding force.
• Smoothness – full contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Thermal environment – heating the magnet results in weakening of induction. Check the maximum operating temperature for a given model.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the lifting capacity is smaller. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the load capacity.