MW 8x20 / N38 - cylindrical magnet

Advantages as well as disadvantages of NdFeB magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• Their strength remains stable, and after approximately ten years it decreases only by ~1% (according to research),
• They are noted for resistance to demagnetization induced by presence of other magnetic fields,
• In other words, due to the reflective surface of gold, the element becomes visually attractive,
• Magnets are characterized by very high magnetic induction on the outer side,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of exact shaping and adjusting to complex applications,
• Huge importance in electronics industry – they are utilized in data components, brushless drives, medical devices, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a special holder, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• We suggest cover - magnetic mechanism, due to difficulties in realizing threads inside the magnet and complex forms.
• Health risk to health – tiny shards of magnets pose a threat, if swallowed, which is particularly important in the context of child health protection. Furthermore, small components of these devices are able to complicate diagnosis medical after entering the body.
• With large orders the cost of neodymium magnets is a challenge,

Maximum magnetic pulling force – what affects it?

The declared magnet strength concerns the limit force, measured under laboratory conditions, meaning:

• on a base made of mild steel, perfectly concentrating the magnetic flux
• with a cross-section minimum 10 mm
• with a surface free of scratches
• with total lack of distance (without paint)
• under vertical force vector (90-degree angle)
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

In real-world applications, the actual lifting capacity results from a number of factors, listed from crucial:

• Gap between surfaces – even a fraction of a millimeter of distance (caused e.g. by veneer or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is available only during perpendicular pulling. The resistance to sliding of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Steel thickness – insufficiently thick plate does not close the flux, causing part of the power to be wasted into the air.
• Metal type – not every steel attracts identically. High carbon content weaken the interaction with the magnet.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness acts like micro-gaps.
• Thermal factor – high temperature reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate reduces the load capacity.