SM 32x125 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of rare earth magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• Their magnetic field is maintained, and after around 10 years it drops only by ~1% (according to research),
• Neodymium magnets remain highly resistant to magnetic field loss caused by external field sources,
• By applying a shiny coating of silver, the element presents an proper look,
• They feature high magnetic induction at the operating surface, making them more effective,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate creating and adapting to atypical conditions,
• Universal use in modern industrial fields – they find application in data components, electric motors, medical devices, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as 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 start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• Limited possibility of producing threads in the magnet and complicated forms - preferred is cover - magnet mounting.
• Possible danger resulting from small fragments of magnets can be dangerous, if swallowed, which gains importance in the context of child health protection. Additionally, small elements of these devices can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum lifting force for a neodymium magnet – what contributes to it?

The specified lifting capacity represents the maximum value, measured under laboratory conditions, meaning:

• on a block made of structural steel, effectively closing the magnetic flux
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with an ideally smooth touching surface
• under conditions of no distance (surface-to-surface)
• under perpendicular force vector (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

During everyday use, the actual holding force depends on many variables, ranked from the most important:

• Air gap (between the magnet and the plate), as even a tiny clearance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to varnish, corrosion or debris).
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet exhibits much less (typically approx. 20-30% of nominal force).
• Steel thickness – insufficiently thick plate causes magnetic saturation, causing part of the power to be escaped to the other side.
• Material type – ideal substrate is pure iron steel. Hardened steels may attract less.
• Surface finish – ideal contact is obtained only on polished steel. Rough texture create air cushions, weakening the magnet.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was measured by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.