WM 34.5x24.3x17 / N38 - magnetic hanger

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable strength, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after 10 years, the performance loss is only ~1% (in laboratory conditions),
• They remain magnetized despite exposure to strong external fields,
• The use of a polished nickel surface provides a smooth finish,
• They possess significant magnetic force measurable at the magnet’s surface,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for fine forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Key role in cutting-edge sectors – they find application in HDDs, rotating machines, medical equipment and sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them ideal in miniature devices

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall robustness,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on form). 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 humid environment. If exposed to rain, we recommend using sealed magnets, such as those made of plastic,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is difficult,
• Potential hazard linked to microscopic shards may arise, in case of ingestion, which is important in the context of child safety. Moreover, miniature parts from these devices might complicate medical imaging after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Highest magnetic holding force – what affects it?

The given strength of the magnet represents the optimal strength, measured under optimal conditions, that is:

• 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 refined outer layer
• with no separation
• with vertical force applied
• at room temperature

Lifting capacity in real conditions – factors

The lifting capacity of a magnet depends on in practice the following factors, ordered from most important to least significant:

• Air gap between the magnet and the plate, since 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.