MW 80x30 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain their attractive force for nearly ten years – the drop is just ~1% (in theory),
• They remain magnetized despite exposure to strong external fields,
• Thanks to the shiny finish and silver coating, they have an aesthetic appearance,
• They possess intense magnetic force measurable at the magnet’s surface,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for tailored forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Wide application in advanced technical fields – they are used in data storage devices, electromechanical systems, medical equipment and high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and strengthens its overall resistance,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on size). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• They rust in a moist environment, especially when used outside, we recommend using waterproof magnets, such as those made of plastic,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Safety concern from tiny pieces may arise, when consumed by mistake, which is crucial in the protection of children. It should also be noted that small elements from these products have the potential to hinder health screening when ingested,
• Due to a complex production process, their cost is relatively high,

Highest magnetic holding force – what contributes to it?

The given holding capacity of the magnet means the highest holding force, calculated in the best circumstances, namely:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a polished side
• with no separation
• with vertical force applied
• under standard ambient temperature

Determinants of lifting force in real conditions

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, since 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, however under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.