BM 750x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their exceptional pulling force, neodymium magnets offer the following advantages:

• They have stable power, and over more than ten years their attraction force decreases symbolically – ~1% (in testing),
• They are highly resistant to demagnetization caused by external field interference,
• The use of a polished silver surface provides a eye-catching finish,
• Magnetic induction on the surface of these magnets is notably high,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Key role in modern technologies – they are used in computer drives, electromechanical systems, medical equipment as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which allows for use in compact constructions

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall robustness,
• They lose field intensity at high temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a moist environment, especially when used outside, we recommend using sealed magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is difficult,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is important in the family environments. Additionally, minuscule fragments from these devices have the potential to interfere with diagnostics when ingested,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

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

The given lifting capacity of the magnet means the maximum lifting force, measured in ideal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Magnet lifting force in use – key factors

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• 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 performed on a smooth plate of optimal thickness, under perpendicular forces, however under parallel forces the load capacity is reduced by as much as fivefold. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the holding force.