BM 380x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their magnetic field is maintained, and after approximately ten years, it drops only by ~1% (theoretically),
• They show exceptional resistance to demagnetization from external field exposure,
• The use of a polished nickel surface provides a eye-catching finish,
• They possess intense magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• With the option for customized forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Significant impact in new technology industries – they serve a purpose in HDDs, electromechanical systems, diagnostic apparatus along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which makes them ideal in compact constructions

Disadvantages of magnetic elements:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to external force, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and additionally strengthens its overall robustness,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent weakening 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 protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is restricted,
• Possible threat due to small fragments may arise, especially if swallowed, which is notable in the protection of children. Furthermore, miniature parts from these magnets have the potential to complicate medical imaging if inside the body,
• In cases of mass production, neodymium magnet cost may be a barrier,

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

The given strength of the magnet represents the optimal strength, determined in ideal conditions, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• with vertical force applied
• at room temperature

Practical lifting capacity: influencing factors

Practical lifting force is dependent on factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, as 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.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate decreases the holding force.