AM ucho [M10] - magnetic accessories

Advantages and 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 performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic noise,
• Because of the reflective layer of silver, the component looks aesthetically refined,
• The outer field strength of the magnet shows remarkable magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for precise shaping or adjustment to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in new technology industries – they serve a purpose in hard drives, electromechanical systems, clinical machines along with technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from damage while also strengthens its overall resistance,
• They lose field intensity at extreme temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we recommend waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is difficult,
• Possible threat due to small fragments may arise, if ingested accidentally, which is significant in the protection of children. Additionally, tiny components from these products may complicate medical imaging if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what it depends on?

The given pulling force of the magnet represents the maximum force, determined under optimal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

• 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, whereas under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate decreases the lifting capacity.