BM 510x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• Their magnetic field is maintained, and after around 10 years, it drops only by ~1% (according to research),
• They show superior resistance to demagnetization from external field exposure,
• By applying a shiny layer of silver, the element gains a clean look,
• The outer field strength of the magnet shows elevated magnetic properties,
• 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),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which increases their functional possibilities,
• Significant impact in new technology industries – they are utilized in HDDs, electromechanical systems, medical equipment along with technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them ideal in miniature devices

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall strength,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (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 advisable to use sealed magnets made of synthetic coating for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is crucial in the protection of children. Additionally, miniature parts from these devices can hinder health screening once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum magnetic pulling force – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, assessed in the best circumstances, that is:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• at room temperature

Key elements affecting lifting force

Practical lifting force is dependent on elements, 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.

* Lifting capacity was measured with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet and the plate reduces the lifting capacity.