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

Pros and cons of NdFeB magnets.

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

• Their magnetic field remains stable, and after around ten years it decreases only by ~1% (theoretically),
• Magnets effectively resist against demagnetization caused by ambient magnetic noise,
• By covering with a smooth coating of gold, the element has an nice look,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to modularity in forming and the capacity to modify to complex applications,
• Versatile presence in innovative solutions – they are commonly used in mass storage devices, motor assemblies, precision medical tools, as well as technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. Often, when the temperature exceeds 80°C, their power 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. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• Limited possibility of creating threads in the magnet and complicated forms - preferred is casing - magnet mounting.
• Possible danger resulting from small fragments of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. Additionally, small components of these magnets are able to be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Detachment force of the magnet in optimal conditions – what it depends on?

Breakaway force is the result of a measurement for ideal contact conditions, taking into account:

• with the use of a sheet made of special test steel, guaranteeing maximum field concentration
• with a cross-section no less than 10 mm
• characterized by lack of roughness
• without any insulating layer between the magnet and steel
• under perpendicular application of breakaway force (90-degree angle)
• at ambient temperature room level

Lifting capacity in practice – influencing factors

It is worth knowing that the application force will differ depending on elements below, in order of importance:

• Clearance – the presence of any layer (paint, tape, air) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Material composition – different alloys reacts the same. High carbon content weaken the attraction effect.
• Surface structure – the more even the surface, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity was determined by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.