MW 20x5 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain full power for almost ten years – the loss is just ~1% (based on simulations),
• Neodymium magnets are distinguished by highly resistant to magnetic field loss caused by magnetic disturbances,
• A magnet with a metallic silver surface has an effective appearance,
• Magnetic induction on the working part of the magnet turns out to be extremely intense,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Possibility of detailed shaping and adapting to specific needs,
• Key role in electronics industry – they are commonly used in HDD drives, motor assemblies, medical devices, also complex engineering applications.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Problematic aspects of neodymium magnets: tips and applications.

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in realizing threads and complex forms in magnets, we propose using a housing - magnetic mechanism.
• Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets 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 hinders application in large quantities

Maximum lifting capacity of the magnet – what affects it?

The lifting capacity listed is a measurement result conducted under the following configuration:

• on a plate made of mild steel, effectively closing the magnetic field
• possessing a massiveness of at least 10 mm to avoid saturation
• with an ground contact surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (in the magnet axis)
• at standard ambient temperature

Practical lifting capacity: influencing factors

Real force is influenced by working environment parameters, such as (from priority):

• Distance – the presence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Loading method – catalog parameter refers to detachment vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of converting into lifting capacity.
• Metal type – not every steel attracts identically. High carbon content worsen the interaction with the magnet.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under shearing force the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.