UMGZ 25x17x8 [M5] GZ / N38 - magnetic holder external thread

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their strong holding force, neodymium magnets have these key benefits:

• They do not lose their even during approximately ten years – the decrease of lifting capacity is only ~1% (according to tests),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the shiny finish and gold coating, they have an aesthetic appearance,
• They possess significant magnetic force measurable at the magnet’s surface,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to build),
• With the option for customized forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Significant impact in new technology industries – they are utilized in computer drives, electric drives, healthcare devices and high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which allows for use in miniature devices

Disadvantages of neodymium magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture while also increases its overall resistance,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we recommend waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Possible threat due to small fragments may arise, in case of ingestion, which is significant in the family environments. Moreover, minuscule fragments from these products have the potential to hinder health screening if inside the body,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum lifting force for a neodymium magnet – what it depends on?

The given pulling force of the magnet represents the maximum force, assessed in the best circumstances, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• 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, however under shearing force the holding force is lower. Additionally, even a small distance {between} the magnet and the plate lowers the lifting capacity.