SM 25x325 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

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

• They retain full power for around 10 years – the loss is just ~1% (in theory),
• They possess excellent resistance to magnetic field loss as a result of external magnetic sources,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• The surface of neodymium magnets generates a intense magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to flexibility in constructing and the ability to customize to individual projects,
• Versatile presence in modern technologies – they serve a role in hard drives, electromotive mechanisms, medical equipment, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in compact constructions

What to avoid - cons of neodymium magnets and proposals for their use:

• To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its 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.
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of making nuts in the magnet and complex forms - preferred is casing - magnet mounting.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these products can be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is higher than average,

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

Breakaway force was determined for ideal contact conditions, assuming:

• on a block made of mild steel, effectively closing the magnetic field
• whose thickness is min. 10 mm
• characterized by even structure
• without any air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

Bear in mind that the magnet holding will differ depending on the following factors, starting with the most relevant:

• Clearance – existence of foreign body (paint, tape, gap) acts as an insulator, which reduces capacity steeply (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Material composition – different alloys reacts the same. Alloy additives weaken the attraction effect.
• Surface condition – smooth surfaces ensure maximum contact, which improves field saturation. Rough surfaces reduce efficiency.
• Temperature influence – high temperature reduces magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, whereas under shearing force the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.