BM 320x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after 10 years, the decline in efficiency is only ~1% (based on calculations),
• They protect against demagnetization induced by external magnetic fields remarkably well,
• The use of a decorative nickel surface provides a eye-catching finish,
• The outer field strength of the magnet shows advanced 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 flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in various configurations, which broadens their functional possibilities,
• Key role in modern technologies – they find application in hard drives, electric motors, medical equipment as well as technologically developed systems,
• 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 sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and enhances its overall resistance,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions 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 moisture-resistant magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is risky,
• Safety concern related to magnet particles may arise, in case of ingestion, which is notable in the health of young users. Additionally, tiny components from these devices can interfere with diagnostics when ingested,
• Due to the price of neodymium, their cost is above average,

Maximum holding power of the magnet – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, assessed in ideal conditions, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Key elements affecting lifting force

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

• 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 was determined using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.