SM 32x400 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

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

• They retain magnetic properties for nearly ten years – the loss is just ~1% (according to analyses),
• They are extremely resistant to demagnetization induced by external magnetic fields,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnetic induction on the working layer of the magnet remains maximum,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, allowing for operation at temperatures approaching 230°C and above...
• Thanks to versatility in shaping and the ability to modify to complex applications,
• Wide application in innovative solutions – they are commonly used in data components, electromotive mechanisms, medical equipment, as well as complex engineering applications.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• At strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• Due to limitations in creating nuts and complicated forms in magnets, we propose using cover - magnetic holder.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these devices are able to disrupt the diagnostic process medical when they are in the body.
• Due to neodymium price, their price exceeds standard values,

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

The declared magnet strength refers to the peak performance, obtained under optimal environment, meaning:

• using a plate made of high-permeability steel, serving as a ideal flux conductor
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a plane free of scratches
• with direct contact (without impurities)
• for force applied at a right angle (pull-off, not shear)
• at temperature room level

Lifting capacity in practice – influencing factors

Real force impacted by specific conditions, mainly (from priority):

• Space between surfaces – every millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of maximum force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Material type – the best choice is pure iron steel. Cast iron may generate lower lifting capacity.
• Base smoothness – the smoother and more polished the plate, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Temperature influence – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate lowers the holding force.