MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (in laboratory conditions),
• Their ability to resist magnetic interference from external fields is impressive,
• By applying a shiny layer of gold, the element gains a modern look,
• Magnetic induction on the surface of these magnets is very strong,
• Thanks to their enhanced temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• The ability for accurate shaping as well as customization to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Wide application in new technology industries – they are used in data storage devices, electric drives, clinical machines as well as high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which makes them useful in miniature devices

Disadvantages of magnetic elements:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time increases its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent deterioration 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of plastic for outdoor use,
• Limited ability to create complex details in the magnet – the use of a external casing is recommended,
• Possible threat due to small fragments may arise, if ingested accidentally, which is crucial in the health of young users. Furthermore, small elements from these devices have the potential to hinder health screening if inside the body,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Highest magnetic holding force – what contributes to it?

The given pulling force of the magnet represents the maximum force, assessed under optimal conditions, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is influenced by in practice key elements, ordered from most important to least significant:

• 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 was determined by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.