BM 950x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• Their ability to resist magnetic interference from external fields is among the best,
• In other words, due to the glossy nickel coating, the magnet obtains an professional appearance,
• Magnetic induction on the surface of these magnets is notably high,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Important function in advanced technical fields – they find application in data storage devices, electromechanical systems, medical equipment as well as technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to mechanical hits, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (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,
• They rust in a humid environment. If exposed to rain, we recommend using waterproof magnets, such as those made of plastic,
• Limited ability to create internal holes in the magnet – the use of a mechanical support is recommended,
• Possible threat linked to microscopic shards may arise, when consumed by mistake, which is crucial in the health of young users. It should also be noted that minuscule fragments from these products have the potential to complicate medical imaging after being swallowed,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Detachment force of the magnet in optimal conditions – what contributes to it?

The given holding capacity of the magnet means the highest holding force, calculated in the best circumstances, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with zero air gap
• under perpendicular detachment force
• at room temperature

Impact of factors on magnetic holding capacity in practice

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

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

* Lifting capacity was determined using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate decreases the holding force.