MW 20x5 / N38 - cylindrical magnet

Strengths and weaknesses of NdFeB magnets.

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

• They virtually do not lose power, because even after 10 years the performance loss is only ~1% (in laboratory conditions),
• They maintain their magnetic properties even under external field action,
• Thanks to the shimmering finish, the surface of Ni-Cu-Ni, gold, or silver gives an visually attractive appearance,
• Magnets exhibit huge magnetic induction on the outer layer,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in forming and the capacity to modify to individual projects,
• Universal use in high-tech industry – they are used in HDD drives, drive modules, advanced medical instruments, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which makes them useful in miniature devices

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest casing - magnetic holder, due to difficulties in producing threads inside the magnet and complicated forms.
• Possible danger related to microscopic parts of magnets pose a threat, in case of ingestion, which becomes key in the context of child safety. It is also worth noting that small elements of these devices are able to complicate diagnosis medical after entering the body.
• With budget limitations the cost of neodymium magnets is economically unviable,

Maximum magnetic pulling force – what it depends on?

Holding force of 5.53 kg is a result of laboratory testing conducted under standard conditions:

• on a base made of mild steel, optimally conducting the magnetic field
• whose thickness equals approx. 10 mm
• with an ground touching surface
• with total lack of distance (without impurities)
• during detachment in a direction perpendicular to the plane
• at temperature room level

Determinants of practical lifting force of a magnet

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

• Space between magnet and steel – every millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to pulling vertically. When applying parallel force, the magnet exhibits much less (typically approx. 20-30% of maximum force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel gives the best results. Alloy admixtures lower magnetic permeability and lifting capacity.
• Surface condition – ground elements guarantee perfect abutment, which improves force. Uneven metal weaken the grip.
• Temperature – heating the magnet causes a temporary drop of force. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity was assessed using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.