BM 380x180x70 [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:

• Their power is durable, and after around 10 years, it drops only by ~1% (according to research),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• The use of a decorative gold surface provides a eye-catching finish,
• The outer field strength of the magnet shows advanced magnetic properties,
• With the right combination of compounds, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• With the option for customized 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 hard drives, electric motors, clinical machines or even sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage and additionally strengthens its overall resistance,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a moist environment, especially when used outside, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• Limited ability to create threads in the magnet – the use of a external casing is recommended,
• Safety concern linked to microscopic shards may arise, in case of ingestion, which is significant in the health of young users. It should also be noted that small elements from these magnets can interfere with diagnostics after being swallowed,
• Due to expensive raw materials, their cost is above average,

Maximum magnetic pulling force – what contributes to it?

The given holding capacity of the magnet means the highest holding force, calculated under optimal conditions, namely:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• in normal thermal conditions

What influences lifting capacity in practice

The lifting capacity of a magnet depends on in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, since 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 testing was conducted on a smooth plate of suitable thickness, under perpendicular forces, however under shearing force the load capacity is reduced by as much as 75%. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.