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

Advantages and disadvantages of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They do not lose strength, even over approximately ten years – the drop in power is only ~1% (according to tests),
• They maintain their magnetic properties even under external field action,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Neodymium magnets generate maximum magnetic induction on a small surface, which allows for strong attraction,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to modularity in constructing and the capacity to adapt to complex applications,
• Versatile presence in advanced technology sectors – they serve a role in HDD drives, drive modules, advanced medical instruments, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in miniature devices

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

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in strength. 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
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• We recommend a housing - magnetic mount, due to difficulties in creating threads inside the magnet and complex forms.
• Potential hazard to health – tiny shards of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small elements of these products are able to disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what it depends on?

Breakaway force was determined for the most favorable conditions, including:

• with the application of a yoke made of low-carbon steel, ensuring full magnetic saturation
• whose thickness reaches at least 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• at conditions approx. 20°C

Magnet lifting force in use – key factors

Real force is affected by working environment parameters, such as (from most important):

• Clearance – the presence of foreign body (paint, tape, air) interrupts the magnetic circuit, which reduces power rapidly (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Plate thickness – insufficiently thick plate causes magnetic saturation, causing part of the power to be lost into the air.
• Steel type – mild steel gives the best results. Alloy admixtures decrease magnetic properties and lifting capacity.
• Smoothness – full contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Temperature influence – high temperature reduces magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, however under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the holding force.