SM 32x375 [2xM8] / N42 - magnetic separator

Pros as well as cons of NdFeB magnets.

Besides their tremendous pulling force, neodymium magnets offer the following advantages:

• They retain attractive force for almost 10 years – the loss is just ~1% (in theory),
• They feature excellent resistance to magnetic field loss as a result of opposing magnetic fields,
• By covering with a decorative layer of silver, the element has an proper look,
• Neodymium magnets create maximum magnetic induction on a their surface, which allows for strong attraction,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Considering the potential of flexible forming and customization to specialized needs, magnetic components can be modeled in a wide range of shapes and sizes, which increases their versatility,
• Fundamental importance in high-tech industry – they are commonly used in HDD drives, electric motors, advanced medical instruments, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of creating nuts in the magnet and complicated forms - recommended is casing - mounting mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that small components of these magnets can be problematic in diagnostics medical when they are in the body.
• With mass production the cost of neodymium magnets is economically unviable,

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

The lifting capacity listed is a result of laboratory testing conducted under the following configuration:

• using a base made of high-permeability steel, acting as a circuit closing element
• whose thickness equals approx. 10 mm
• with an ground touching surface
• under conditions of ideal adhesion (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

Real force impacted by working environment parameters, including (from priority):

• Gap (betwixt the magnet and the metal), since even a tiny clearance (e.g. 0.5 mm) results in a drastic drop in force by up to 50% (this also applies to varnish, rust or debris).
• Angle of force application – highest force is reached only during perpendicular pulling. The shear force of the magnet along the plate is usually many times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Metal type – not every steel attracts identically. Alloy additives weaken the attraction effect.
• Surface structure – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Temperature influence – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the lifting capacity is smaller. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.