SM 25x200 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

Apart from their notable magnetism, neodymium magnets have these key benefits:

• They have constant strength, and over nearly ten years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets are characterized by highly resistant to magnetic field loss caused by external field sources,
• A magnet with a shiny nickel surface looks better,
• Neodymium magnets generate maximum magnetic induction on a small surface, which increases force concentration,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to the potential of accurate forming and customization to individualized requirements, magnetic components can be modeled in a wide range of geometric configurations, which increases their versatility,
• Wide application in modern industrial fields – they serve a role in HDD drives, motor assemblies, medical equipment, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• We recommend casing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complicated forms.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. It is also worth noting that tiny parts of these devices are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

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

Breakaway force is the result of a measurement for the most favorable conditions, including:

• on a block made of structural steel, optimally conducting the magnetic flux
• possessing a massiveness of minimum 10 mm to avoid saturation
• with a plane free of scratches
• without any insulating layer between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

During everyday use, the actual holding force results from several key aspects, presented from the most important:

• Air gap (between the magnet and the metal), because even a tiny distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Steel thickness – too thin steel does not close the flux, causing part of the power to be escaped into the air.
• Material type – the best choice is pure iron steel. Hardened steels may attract less.
• Surface condition – smooth surfaces ensure maximum contact, which increases force. Uneven metal reduce efficiency.
• Temperature – temperature increase results in weakening of induction. Check the thermal limit for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate reduces the load capacity.