MW 29x10 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have stable power, and over around 10 years their performance decreases symbolically – ~1% (according to theory),
• They remain magnetized despite exposure to magnetic surroundings,
• The use of a polished gold surface provides a smooth finish,
• The outer field strength of the magnet shows elevated 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 custom shaping and adaptation to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Wide application in cutting-edge sectors – they are utilized in hard drives, electric motors, clinical machines as well as technologically developed systems,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to mechanical hits, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time strengthens its overall durability,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent decline 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,
• They rust in a damp environment. If exposed to rain, we recommend using waterproof magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is restricted,
• Safety concern related to magnet particles may arise, in case of ingestion, which is important in the protection of children. It should also be noted that minuscule fragments from these assemblies have the potential to disrupt scanning after being swallowed,
• Due to expensive raw materials, their cost is relatively high,

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given pulling force of the magnet means the maximum force, measured in the best circumstances, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• in normal thermal conditions

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, because 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 testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under shearing force the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate lowers the holding force.