MW 35x5 / N38 - cylindrical magnet

Pros and cons of NdFeB magnets.

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

• They do not lose strength, even over around ten years – the decrease in lifting capacity is only ~1% (theoretically),
• They possess excellent resistance to magnetic field loss as a result of external magnetic sources,
• The use of an shiny layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets possess extremely high magnetic induction on the outer side,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in constructing and the capacity to customize to complex applications,
• Versatile presence in innovative solutions – they are utilized in HDD drives, motor assemblies, precision medical tools, and modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks under impact, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in creating nuts and complex shapes in magnets, we recommend using cover - magnetic mount.
• Potential hazard resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. It is also worth noting that small components of these devices are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum lifting force for a neodymium magnet – what it depends on?

Information about lifting capacity is the result of a measurement for ideal contact conditions, taking into account:

• using a plate made of mild steel, serving as a circuit closing element
• with a cross-section minimum 10 mm
• with an ground contact surface
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in neutral thermal conditions

What influences lifting capacity in practice

Holding efficiency is influenced by working environment parameters, such as (from priority):

• Clearance – the presence of any layer (rust, dirt, air) acts as an insulator, which reduces capacity steeply (even by 50% at 0.5 mm).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the flux to be wasted to the other side.
• Material composition – different alloys reacts the same. High carbon content worsen the attraction effect.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.