AM ucho [M12] - magnetic accessories

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their exceptional field intensity, neodymium magnets offer the following advantages:

• They retain their magnetic properties for around ten years – the drop is just ~1% (according to analyses),
• They are extremely resistant to demagnetization caused by external field interference,
• Thanks to the shiny finish and gold coating, they have an elegant appearance,
• They have exceptional magnetic induction on the surface of the magnet,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the design),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which broadens their usage potential,
• Key role in advanced technical fields – they find application in hard drives, electric motors, healthcare devices and sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of magnetic elements:

• They may fracture 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 breakage and reinforces its overall robustness,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of rubber for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing threads directly in the magnet,
• Health risk related to magnet particles may arise, when consumed by mistake, which is crucial in the protection of children. Furthermore, small elements from these assemblies may disrupt scanning when ingested,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Maximum holding power of the magnet – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, determined in ideal conditions, 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 polished side
• with no separation
• under perpendicular detachment force
• at room temperature

Key elements affecting lifting force

Practical lifting force is dependent on 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 carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.