SM 32x125 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

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

• They retain attractive force for nearly ten years – the loss is just ~1% (based on simulations),
• They are resistant to demagnetization induced by external disturbances,
• In other words, due to the aesthetic layer of nickel, the element gains visual value,
• Magnetic induction on the surface of the magnet remains strong,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to versatility in forming and the capacity to modify to individual projects,
• Significant place in advanced technology sectors – they are used in HDD drives, brushless drives, medical devices, as well as other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a special holder, which not only secures them against impacts but also raises their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 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 prevent oxidation as well as corrosion.
• Limited ability of creating threads in the magnet and complicated forms - preferred is casing - magnet mounting.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these devices are able to be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum magnetic pulling force – what it depends on?

The specified lifting capacity represents the peak performance, recorded under optimal environment, namely:

• with the application of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• possessing a thickness of at least 10 mm to avoid saturation
• with an polished touching surface
• under conditions of no distance (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Key elements affecting lifting force

Holding efficiency is influenced by specific conditions, such as (from most important):

• Space between magnet and steel – every millimeter of distance (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Chemical composition of the base – mild steel gives the best results. Alloy steels decrease magnetic permeability and holding force.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Rough surfaces reduce efficiency.
• Operating temperature – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under perpendicular forces, however under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.