AM ucho [M8] - magnetic accessories

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their full power for nearly 10 years – the loss is just ~1% (based on simulations),
• They are highly resistant to demagnetization caused by external magnetic fields,
• Thanks to the glossy finish and gold coating, they have an aesthetic appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• The ability for custom shaping as well as adaptation to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Important function in advanced technical fields – they are utilized in data storage devices, electromechanical systems, diagnostic apparatus and sophisticated instruments,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They can break when subjected to a powerful impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from breakage and additionally increases its overall robustness,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent reduction 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 advisable to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is risky,
• Safety concern from tiny pieces may arise, especially if swallowed, which is crucial in the family environments. Furthermore, small elements from these products might interfere with diagnostics if inside the body,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given pulling force of the magnet corresponds to the maximum force, determined in ideal conditions, namely:

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

Lifting capacity in real conditions – factors

Practical lifting force is dependent on factors, by priority:

• Air gap between the magnet and the plate, because 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.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.