MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (according to literature),
• They show high resistance to demagnetization induced by presence of other magnetic fields,
• The use of an refined coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnetic induction on the working part of the magnet is extremely intense,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to modularity in shaping and the ability to customize to unusual requirements,
• Fundamental importance in high-tech industry – they are used in hard drives, drive modules, medical equipment, as well as industrial machines.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their power 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
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of producing threads in the magnet and complicated shapes - preferred is casing - magnet mounting.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the context of child health protection. Furthermore, small components of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Breakaway strength of the magnet in ideal conditions – what contributes to it?

Magnet power was defined for optimal configuration, assuming:

• on a block made of mild steel, perfectly concentrating the magnetic flux
• possessing a massiveness of minimum 10 mm to avoid saturation
• characterized by smoothness
• with direct contact (no paint)
• under axial force direction (90-degree angle)
• at temperature room level

Magnet lifting force in use – key factors

Holding efficiency is affected by specific conditions, such as (from most important):

• Distance – existence of foreign body (rust, dirt, air) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of maximum force).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Material composition – different alloys attracts identically. High carbon content worsen the attraction effect.
• Plate texture – ground elements guarantee perfect abutment, which improves force. Rough surfaces weaken the grip.
• Thermal factor – hot environment reduces 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 the force acted perpendicularly, 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 holding force.