BM 510x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable power, neodymium magnets have these key benefits:

• Their strength remains stable, and after around ten years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is among the best,
• Thanks to the polished finish and nickel coating, they have an aesthetic appearance,
• Magnetic induction on the surface of these magnets is very strong,
• 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 magnetic form),
• With the option for tailored forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Significant impact in modern technologies – they are utilized in HDDs, electric drives, clinical machines or even high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to mechanical hits, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture while also increases its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of synthetic coating for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is notable in the context of child safety. Furthermore, miniature parts from these magnets may complicate medical imaging if inside the body,
• Due to a complex production process, their cost is considerably higher,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, assessed under optimal conditions, namely:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• at room temperature

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, as 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 was determined by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate lowers the lifting capacity.