BM 850x180x70 [4x M8] - magnetic beam

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (in laboratory conditions),
• They remain magnetized despite exposure to magnetic noise,
• Thanks to the polished finish and gold coating, they have an visually attractive appearance,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the structure),
• The ability for accurate shaping as well as adjustment to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Important function in new technology industries – they find application in computer drives, electric motors, healthcare devices along with technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to external force, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time strengthens its overall resistance,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on height). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of synthetic coating for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing fine shapes directly in the magnet,
• Potential hazard linked to microscopic shards may arise, in case of ingestion, which is significant in the health of young users. Furthermore, minuscule fragments from these magnets can hinder health screening once in the system,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given lifting capacity of the magnet represents the maximum lifting force, calculated in a perfect environment, namely:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Magnet lifting force in use – key factors

Practical lifting force is dependent on elements, by priority:

• 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 a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.