SM 25x275 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

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

• They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• They feature excellent resistance to weakening of magnetic properties when exposed to external magnetic sources,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• The surface of neodymium magnets generates a maximum magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to freedom in designing and the ability to modify to unusual requirements,
• Huge importance in high-tech industry – they find application in mass storage devices, electric drive systems, diagnostic systems, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets and ways of using them

• At very strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. 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
• 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 protecting against moisture
• Due to limitations in producing nuts and complex forms in magnets, we propose using casing - magnetic mechanism.
• Health risk to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, small components of these products are able to be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what affects it?

Holding force of 0 kg is a result of laboratory testing conducted under standard conditions:

• with the use of a yoke made of special test steel, guaranteeing full magnetic saturation
• with a thickness no less than 10 mm
• with a surface perfectly flat
• without the slightest clearance between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

In practice, the actual holding force results from several key aspects, listed from crucial:

• Gap (between the magnet and the plate), as even a very small distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Base massiveness – insufficiently thick plate does not accept the full field, causing part of the flux to be lost to the other side.
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Plate texture – ground elements ensure maximum contact, which increases field saturation. Rough surfaces weaken the grip.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet and the plate decreases the holding force.