SM 32x225 [2xM8] / N42 - magnetic separator

Pros as well as cons of rare earth magnets.

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

• Their strength is durable, and after around ten years it drops only by ~1% (theoretically),
• Magnets effectively defend themselves against loss of magnetization caused by foreign field sources,
• In other words, due to the metallic layer of gold, the element is aesthetically pleasing,
• They feature high magnetic induction at the operating surface, which increases their power,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for functioning at temperatures reaching 230°C and above...
• Thanks to the potential of free molding and adaptation to unique needs, magnetic components can be manufactured in a variety of geometric configurations, which makes them more universal,
• Fundamental importance in electronics industry – they are utilized in mass storage devices, drive modules, medical equipment, as well as other advanced devices.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a special holder, which not only protects them against impacts but also increases their durability
• Neodymium magnets decrease their force 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
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of producing threads in the magnet and complex shapes - preferred is cover - mounting mechanism.
• Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, tiny parts of these devices can disrupt the diagnostic process medical in case of swallowing.
• Due to neodymium price, their price is higher than average,

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

Holding force of 0 kg is a measurement result executed under specific, ideal conditions:

• with the application of a sheet made of special test steel, guaranteeing maximum field concentration
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a surface free of scratches
• with total lack of distance (without impurities)
• for force acting at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Practical aspects of lifting capacity – factors

Real force is influenced by working environment parameters, including (from most important):

• Clearance – the presence of any layer (rust, dirt, air) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Loading method – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of nominal force).
• Steel thickness – too thin plate does not close the flux, causing part of the flux to be escaped into the air.
• Material composition – different alloys reacts the same. High carbon content worsen the attraction effect.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Temperature influence – hot environment reduces pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate reduces the holding force.