SM 18x150 [2xM5] / N42 - magnetic separator

Pros and cons of rare earth magnets.

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

• Their power is maintained, and after around 10 years it decreases only by ~1% (according to research),
• Magnets effectively defend themselves against demagnetization caused by ambient magnetic noise,
• Thanks to the reflective finish, the coating of nickel, gold-plated, or silver gives an elegant appearance,
• Magnetic induction on the top side of the magnet remains exceptional,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to versatility in shaping and the capacity to modify to unusual requirements,
• Versatile presence in high-tech industry – they serve a role in magnetic memories, electric drive systems, advanced medical instruments, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which allows their use in small systems

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures 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 magnets in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of creating threads in the magnet and complex shapes - preferred is casing - magnet mounting.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which becomes key in the context of child health protection. It is also worth noting that small elements of these devices can complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum magnetic pulling force – what affects it?

The lifting capacity listed is a theoretical maximum value conducted under specific, ideal conditions:

• on a plate made of mild steel, optimally conducting the magnetic field
• whose thickness reaches at least 10 mm
• characterized by even structure
• with zero gap (without coatings)
• for force acting at a right angle (in the magnet axis)
• at room temperature

Lifting capacity in practice – influencing factors

In real-world applications, the actual holding force results from several key aspects, presented from most significant:

• Air gap (betwixt the magnet and the metal), since even a very small distance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Angle of force application – highest force is reached only during perpendicular pulling. The resistance to sliding of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Steel thickness – insufficiently thick sheet does not accept the full field, causing part of the flux to be lost to the other side.
• Steel type – low-carbon steel gives the best results. Alloy steels decrease magnetic properties and holding force.
• Surface finish – full contact is obtained only on polished steel. Rough texture create air cushions, weakening the magnet.
• Temperature influence – hot environment weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate decreases the load capacity.