BM 750x180x70 [4x M8] - magnetic beam

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose their even during nearly ten years – the loss of strength is only ~1% (theoretically),
• They protect against demagnetization induced by ambient magnetic influence very well,
• By applying a bright layer of nickel, the element gains a sleek look,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their usage potential,
• Important function in new technology industries – they find application in HDDs, electric drives, clinical machines along with other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to mechanical hits, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time strengthens its overall strength,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on height). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Magnets exposed to wet conditions can oxidize. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Safety concern due to small fragments may arise, when consumed by mistake, which is notable in the protection of children. Moreover, minuscule fragments from these devices may complicate medical imaging once in the system,
• Due to the price of neodymium, their cost is above average,

Maximum lifting capacity of the magnet – what contributes to it?

The given pulling force of the magnet corresponds to the maximum force, determined in a perfect environment, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Lifting capacity in practice – influencing factors

Practical lifting force is determined by factors, by priority:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) causes 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 performed on a smooth plate of suitable thickness, under perpendicular forces, whereas under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate decreases the holding force.