UMH 25x8x45 [M5] / N38 - magnetic holder with hook

Advantages as well as disadvantages of rare earth magnets.

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

• They do not lose power, even during approximately ten years – the reduction in power is only ~1% (according to tests),
• Magnets very well protect themselves against demagnetization caused by foreign field sources,
• A magnet with a smooth silver surface has better aesthetics,
• Neodymium magnets create maximum magnetic induction on a contact point, which allows for strong attraction,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of precise machining and adapting to concrete requirements,
• Key role in modern industrial fields – they are commonly used in computer drives, electromotive mechanisms, precision medical tools, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which allows their use in compact constructions

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets demagnetize 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 very resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we advise using waterproof magnets made of rubber, plastic or other material protecting against moisture
• We suggest a housing - magnetic holder, due to difficulties in creating threads inside the magnet and complicated shapes.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child safety. Additionally, small components of these products can complicate diagnosis medical after entering the body.
• With large orders the cost of neodymium magnets can be a barrier,

Maximum magnetic pulling force – what it depends on?

Breakaway force was determined for ideal contact conditions, assuming:

• on a plate made of structural steel, effectively closing the magnetic flux
• possessing a thickness of at least 10 mm to ensure full flux closure
• with an ideally smooth touching surface
• under conditions of ideal adhesion (metal-to-metal)
• under axial force vector (90-degree angle)
• at temperature room level

Impact of factors on magnetic holding capacity in practice

It is worth knowing that the application force will differ subject to elements below, in order of importance:

• Clearance – the presence of any layer (rust, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is available only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly many times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Chemical composition of the base – mild steel attracts best. Alloy steels reduce magnetic properties and holding force.
• Surface structure – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Roughness creates an air distance.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was assessed using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet and the plate decreases the load capacity.