MW 29x10 / N38 - cylindrical magnet

Advantages and disadvantages of rare earth magnets.

Besides their tremendous strength, neodymium magnets offer the following advantages:

• They have stable power, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
• They possess excellent resistance to weakening of magnetic properties when exposed to external fields,
• By using a shiny coating of gold, the element presents an nice look,
• Neodymium magnets generate maximum magnetic induction on a their surface, which increases force concentration,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to modularity in designing and the capacity to modify to specific needs,
• Key role in advanced technology sectors – they find application in data components, drive modules, medical equipment, also technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in power. 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.
• Due to limitations in producing threads and complex shapes in magnets, we propose using casing - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these products are able to disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what it depends on?

The specified lifting capacity represents the maximum value, measured under ideal test conditions, namely:

• using a plate made of mild steel, functioning as a ideal flux conductor
• possessing a thickness of min. 10 mm to avoid saturation
• characterized by lack of roughness
• under conditions of no distance (metal-to-metal)
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

During everyday use, the actual holding force is determined by a number of factors, listed from most significant:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds significantly lower power (typically approx. 20-30% of maximum force).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Material composition – different alloys attracts identically. High carbon content weaken the interaction with the magnet.
• Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate lowers the holding force.