MP 5x2.7/1.2x5 C / N38 - ring magnet

Strengths as well as weaknesses of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over more than 10 years their performance decreases symbolically – ~1% (in testing),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• Thanks to the glossy finish, the layer of Ni-Cu-Ni, gold, or silver gives an visually attractive appearance,
• Magnetic induction on the surface of the magnet turns out to be exceptional,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the shape) even at a temperature of 230°C or more...
• Considering the option of free forming and customization to custom projects, neodymium magnets can be modeled in a variety of geometric configurations, which expands the range of possible applications,
• Huge importance in innovative solutions – they are commonly used in magnetic memories, drive modules, precision medical tools, and technologically advanced constructions.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (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
• When exposed to humidity, magnets start to 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 recommend cover - magnetic mechanism, due to difficulties in producing nuts inside the magnet and complicated shapes.
• Health risk resulting from small fragments of magnets pose a threat, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these magnets can be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The load parameter shown represents the peak performance, obtained under ideal test conditions, namely:

• on a plate made of mild steel, optimally conducting the magnetic flux
• whose thickness equals approx. 10 mm
• with a surface perfectly flat
• under conditions of ideal adhesion (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

In practice, the actual lifting capacity results from many variables, ranked from most significant:

• Gap between surfaces – every millimeter of distance (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Steel type – mild steel attracts best. Alloy admixtures decrease magnetic properties and holding force.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases field saturation. Rough surfaces weaken the grip.
• Heat – neodymium magnets have a sensitivity to temperature. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.