SM 25x325 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of neodymium magnets.

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

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• They do not lose their magnetic properties even under strong external field,
• By applying a reflective layer of silver, the element presents an elegant look,
• The surface of neodymium magnets generates a concentrated magnetic field – this is one of their assets,
• Neodymium magnets are characterized by extremely 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 individual creating as well as modifying to atypical conditions,
• Key role in advanced technology sectors – they are utilized in magnetic memories, electric drive systems, advanced medical instruments, also multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which makes them useful in small systems

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• They rust in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We suggest cover - magnetic holder, due to difficulties in realizing threads inside the magnet and complex shapes.
• Possible danger related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets are able to complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Highest magnetic holding force – what affects it?

Information about lifting capacity was determined for ideal contact conditions, assuming:

• with the use of a sheet made of low-carbon steel, ensuring full magnetic saturation
• whose thickness equals approx. 10 mm
• characterized by smoothness
• with direct contact (no coatings)
• under axial application of breakaway force (90-degree angle)
• in temp. approx. 20°C

Magnet lifting force in use – key factors

Please note that the working load may be lower depending on elements below, in order of importance:

• Distance – existence of foreign body (paint, tape, air) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Steel thickness – insufficiently thick sheet does not accept the full field, causing part of the power to be wasted to the other side.
• Material composition – different alloys attracts identically. High carbon content worsen the attraction effect.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases field saturation. Uneven metal reduce efficiency.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.