SM 25x250 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They have stable power, and over more than 10 years their performance decreases symbolically – ~1% (in testing),
• Magnets very well protect themselves against demagnetization caused by foreign field sources,
• By applying a decorative coating of nickel, the element acquires an nice look,
• The surface of neodymium magnets generates a intense magnetic field – this is a distinguishing feature,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to versatility in forming and the capacity to customize to unusual requirements,
• Wide application in high-tech industry – they find application in computer drives, motor assemblies, advanced medical instruments, as well as other advanced devices.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• At very strong impacts they can crack, therefore we advise placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• We suggest cover - magnetic holder, due to difficulties in producing nuts inside the magnet and complicated shapes.
• Health risk resulting from small fragments of magnets can be dangerous, if swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small elements of these magnets are able to complicate diagnosis medical in case of swallowing.
• Due to complex production process, their price is higher than average,

Maximum holding power of the magnet – what contributes to it?

Breakaway force was defined for ideal contact conditions, assuming:

• using a base made of high-permeability steel, acting as a circuit closing element
• whose thickness is min. 10 mm
• with an ground touching surface
• under conditions of ideal adhesion (metal-to-metal)
• during pulling in a direction perpendicular to the mounting surface
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

Holding efficiency is influenced by specific conditions, mainly (from priority):

• Air gap (betwixt the magnet and the metal), because even a microscopic distance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to paint, corrosion or dirt).
• Loading method – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet holds much less (often approx. 20-30% of nominal force).
• Plate thickness – insufficiently thick plate does not accept the full field, causing part of the flux to be wasted to the other side.
• Steel grade – the best choice is high-permeability steel. Cast iron may attract less.
• Base smoothness – the more even the surface, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Operating temperature – neodymium magnets 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 steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, however under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.