BM 320x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their strength is maintained, and after around 10 years, it drops only by ~1% (according to research),
• They remain magnetized despite exposure to strong external fields,
• Because of the lustrous layer of nickel, the component looks visually appealing,
• Magnetic induction on the surface of these magnets is impressively powerful,
• With the right combination of compounds, they reach increased thermal stability, enabling operation at or above 230°C (depending on the structure),
• The ability for accurate shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Important function in cutting-edge sectors – they are used in hard drives, electric drives, clinical machines and other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to shocks, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time increases its overall resistance,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can degrade. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Potential hazard due to small fragments may arise, in case of ingestion, which is significant in the context of child safety. Furthermore, minuscule fragments from these products might complicate medical imaging after being swallowed,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Maximum lifting force for a neodymium magnet – what affects it?

The given strength of the magnet means the optimal strength, assessed under optimal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Determinants of lifting force in real conditions

Practical lifting force is determined by 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 testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, whereas under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate reduces the holding force.