MW 8x15 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• Magnets perfectly resist against loss of magnetization caused by foreign field sources,
• Thanks to the reflective finish, the coating of Ni-Cu-Ni, gold, or silver gives an elegant appearance,
• Magnets are distinguished by extremely high magnetic induction on the outer layer,
• 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 exact creating and adapting to defined applications,
• Versatile presence in innovative solutions – they are commonly used in data components, electric motors, medical devices, as well as other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• At very strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (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 rust. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• We suggest a housing - magnetic holder, due to difficulties in producing nuts inside the magnet and complex shapes.
• Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. Additionally, small elements of these devices are able to complicate diagnosis 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 magnetic pulling force – what contributes to it?

The lifting capacity listed is a theoretical maximum value executed under standard conditions:

• on a block made of mild steel, effectively closing the magnetic flux
• with a cross-section minimum 10 mm
• with a plane perfectly flat
• with total lack of distance (no paint)
• under axial application of breakaway force (90-degree angle)
• at standard ambient temperature

Lifting capacity in practice – influencing factors

It is worth knowing that the working load may be lower subject to elements below, in order of importance:

• Gap between magnet and steel – every millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds much less (often approx. 20-30% of maximum force).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Metal type – not every steel attracts identically. High carbon content worsen the attraction effect.
• Surface condition – smooth surfaces ensure maximum contact, which improves force. Uneven metal weaken the grip.
• Temperature influence – hot environment weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.