MPL 50x50x10 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They have unchanged lifting capacity, and over nearly ten years their attraction force decreases symbolically – ~1% (according to theory),
• Their ability to resist magnetic interference from external fields is impressive,
• The use of a mirror-like gold surface provides a smooth finish,
• They possess strong magnetic force measurable at the magnet’s surface,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the structure),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which broadens their usage potential,
• Important function in modern technologies – they are used in computer drives, electromechanical systems, medical equipment and sophisticated instruments,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks and enhances its overall strength,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent loss 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 wet conditions can degrade. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Possible threat related to magnet particles may arise, when consumed by mistake, which is notable in the family environments. It should also be noted that tiny components from these devices might complicate medical imaging if inside the body,
• Due to the price of neodymium, their cost is considerably higher,

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

The given pulling force of the magnet corresponds to the maximum force, assessed in ideal 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 smooth surface
• with zero air gap
• with vertical force applied
• under standard ambient temperature

What influences lifting capacity in practice

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) 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 assessed using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate decreases the load capacity.