SM 25x325 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They do not lose their even over around 10 years – the decrease of lifting capacity is only ~1% (theoretically),
• They show exceptional resistance to demagnetization from external field exposure,
• In other words, due to the metallic silver coating, the magnet obtains an stylish appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the possibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their application range,
• Significant impact in cutting-edge sectors – they are used in data storage devices, electric motors, healthcare devices along with other advanced devices,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to physical collisions, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens its overall resistance,
• They lose power at high temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of protective material for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing threads directly in the magnet,
• Potential hazard linked to microscopic shards may arise, especially if swallowed, which is important in the health of young users. Furthermore, miniature parts from these assemblies might hinder health screening after being swallowed,
• Due to the price of neodymium, their cost is above average,

Breakaway strength of the magnet in ideal conditions – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, calculated in the best circumstances, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet depends on in practice key elements, according to their importance:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes 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 plates with a smooth surface of optimal thickness, under a perpendicular pulling force, in contrast under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.