MW 20x35 / N38 - cylindrical magnet

Strengths as well as weaknesses of neodymium magnets.

Apart from their notable power, neodymium magnets have these key benefits:

• Their power is maintained, and after approximately 10 years it decreases only by ~1% (according to research),
• Neodymium magnets are exceptionally resistant to loss of magnetic properties caused by external magnetic fields,
• A magnet with a smooth nickel surface is more attractive,
• Neodymium magnets achieve maximum magnetic induction on a their surface, which allows for strong attraction,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate machining as well as modifying to precise applications,
• Versatile presence in modern industrial fields – they are utilized in computer drives, brushless drives, diagnostic systems, also modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• We recommend cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complicated shapes.
• Potential hazard resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the context of child health protection. It is also worth noting that small components of these devices can complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is economically unviable,

Highest magnetic holding force – what affects it?

The declared magnet strength represents the limit force, measured under optimal environment, namely:

• on a plate made of mild steel, effectively closing the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by lack of roughness
• without the slightest air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Real force is influenced by working environment parameters, including (from most important):

• Distance – existence of foreign body (paint, tape, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is reached only during perpendicular pulling. The force required to slide of the magnet along the plate is standardly many times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Smoothness – ideal contact is obtained only on smooth steel. Rough texture create air cushions, weakening the magnet.
• Thermal factor – hot environment weakens pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, however under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet and the plate reduces the lifting capacity.