SM 18x300 [2xM5] / N42 - magnetic separator

Strengths as well as weaknesses of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They show high resistance to demagnetization induced by external field influence,
• Thanks to the shimmering finish, the surface of nickel, gold-plated, or silver gives an modern appearance,
• Magnetic induction on the working layer of the magnet is strong,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Considering the option of accurate molding and customization to custom requirements, neodymium magnets can be created in a broad palette of shapes and sizes, which makes them more universal,
• Fundamental importance in future technologies – they are utilized in data components, motor assemblies, advanced medical instruments, also technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

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

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• Limited ability of producing nuts in the magnet and complicated forms - preferred is cover - mounting mechanism.
• Possible danger to health – tiny shards of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. It is also worth noting that small components of these devices are able to disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what contributes to it?

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

• using a plate made of mild steel, serving as a ideal flux conductor
• whose thickness is min. 10 mm
• with a surface free of scratches
• without the slightest air gap between the magnet and steel
• under vertical application of breakaway force (90-degree angle)
• at standard ambient temperature

Practical aspects of lifting capacity – factors

Real force is influenced by specific conditions, such as (from priority):

• Clearance – existence of foreign body (rust, tape, gap) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Plate material – low-carbon steel attracts best. Alloy admixtures decrease magnetic properties and holding force.
• Surface structure – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal factor – high temperature weakens pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.