SM 18x250 [2xM5] / N42 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain magnetic properties for nearly 10 years – the drop is just ~1% (based on simulations),
• Neodymium magnets remain highly resistant to loss of magnetic properties caused by external field sources,
• By applying a decorative layer of silver, the element presents an aesthetic look,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to the ability of precise forming and customization to unique projects, NdFeB magnets can be created in a variety of shapes and sizes, which amplifies use scope,
• Key role in innovative solutions – they are utilized in HDD drives, brushless drives, diagnostic systems, as well as other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which allows their use in small systems

Cons of neodymium magnets: tips and applications.

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• 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 prevent oxidation as well as corrosion.
• We suggest cover - magnetic mechanism, due to difficulties in producing threads inside the magnet and complicated shapes.
• Health risk resulting from small fragments of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. Additionally, small elements of these products are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Detachment force of the magnet in optimal conditions – what contributes to it?

Holding force of 0 kg is a theoretical maximum value conducted under standard conditions:

• using a plate made of mild steel, serving as a ideal flux conductor
• with a cross-section no less than 10 mm
• with a surface free of scratches
• under conditions of no distance (surface-to-surface)
• for force applied at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

In real-world applications, the actual lifting capacity depends on a number of factors, listed from crucial:

• Clearance – the presence of foreign body (paint, tape, gap) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is obtained 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).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Steel grade – ideal substrate is high-permeability steel. Hardened steels may have worse magnetic properties.
• Plate texture – ground elements guarantee perfect abutment, which increases field saturation. Uneven metal reduce efficiency.
• Temperature – temperature increase results in weakening of force. Check the thermal limit for a given model.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.