SM 32x375 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose their magnetism, even after approximately 10 years – the reduction of strength is only ~1% (according to tests),
• Their ability to resist magnetic interference from external fields is notable,
• In other words, due to the shiny nickel coating, the magnet obtains an professional appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for fine forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Significant impact in advanced technical fields – they find application in hard drives, electromechanical systems, clinical machines or even other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in small dimensions, which makes them useful in compact constructions

Disadvantages of neodymium magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage while also strengthens its overall strength,
• They lose strength at high temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a wet environment – during outdoor use, we recommend using sealed magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing complex structures directly in the magnet,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is important in the family environments. Additionally, tiny components from these products have the potential to complicate medical imaging once in the system,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Maximum lifting force for a neodymium magnet – what affects it?

The given strength of the magnet means the optimal strength, determined under optimal conditions, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is affected by these factors, in descending order of importance:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.