MW 15x4 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

Besides their immense magnetic power, neodymium magnets offer the following advantages:

• They do not lose magnetism, even over approximately 10 years – the reduction in strength is only ~1% (theoretically),
• Magnets effectively resist against loss of magnetization caused by foreign field sources,
• In other words, due to the shiny layer of nickel, the element gains visual value,
• They are known for high magnetic induction at the operating surface, which increases their power,
• 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...
• Considering the potential of flexible shaping and adaptation to specialized solutions, neodymium magnets can be manufactured in a broad palette of geometric configurations, which increases their versatility,
• Universal use in future technologies – they are utilized in computer drives, motor assemblies, medical equipment, as well as complex engineering applications.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks under impact, we recommend using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening 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
• They oxidize in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We suggest cover - magnetic mechanism, due to difficulties in producing nuts inside the magnet and complicated forms.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child safety. Furthermore, tiny parts of these devices are able to complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what affects it?

The load parameter shown concerns the maximum value, obtained under laboratory conditions, meaning:

• on a plate made of structural steel, optimally conducting the magnetic flux
• whose thickness is min. 10 mm
• with an ideally smooth touching surface
• with zero gap (without coatings)
• during pulling in a direction perpendicular to the plane
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

It is worth knowing that the working load may be lower subject to elements below, in order of importance:

• Clearance – existence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to pulling vertically. When slipping, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Plate thickness – insufficiently thick plate causes magnetic saturation, causing part of the power to be lost to the other side.
• Plate material – mild steel gives the best results. Higher carbon content lower magnetic permeability and holding force.
• Surface condition – ground elements ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet and the plate reduces the holding force.