MW 8x15 / N38 - cylindrical magnet

Strengths and weaknesses of NdFeB magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over around 10 years their attraction force decreases symbolically – ~1% (in testing),
• Neodymium magnets are exceptionally resistant to demagnetization caused by external magnetic fields,
• Thanks to the glossy finish, the layer of Ni-Cu-Ni, gold, or silver gives an clean appearance,
• Neodymium magnets ensure maximum magnetic induction on a small surface, which increases force concentration,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to modularity in forming and the capacity to adapt to client solutions,
• Versatile presence in future technologies – they are used in hard drives, drive modules, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which makes them useful in miniature devices

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, 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 strength. 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
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• We suggest a housing - magnetic mount, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Potential hazard to health – tiny shards of magnets are risky, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small components of these devices can complicate diagnosis medical in case of swallowing.
• Due to neodymium price, their price is higher than average,

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

The load parameter shown represents the peak performance, measured under optimal environment, meaning:

• using a sheet made of low-carbon steel, functioning as a ideal flux conductor
• with a thickness of at least 10 mm
• with an ideally smooth touching surface
• without the slightest air gap between the magnet and steel
• under vertical application of breakaway force (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

During everyday use, the actual lifting capacity is determined by many variables, ranked from most significant:

• Distance – existence of foreign body (paint, tape, air) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Steel thickness – too thin sheet does not close the flux, causing part of the flux to be wasted into the air.
• Chemical composition of the base – low-carbon steel attracts best. Higher carbon content decrease magnetic properties and holding force.
• Surface quality – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal factor – hot environment reduces pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet and the plate decreases the load capacity.