UMP 107x40 [M8+M10] GW F400 Lina / N38 - search holder

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after 10 years, the performance loss is only ~1% (based on calculations),
• They remain magnetized despite exposure to magnetic noise,
• Because of the lustrous layer of silver, the component looks aesthetically refined,
• Magnetic induction on the surface of these magnets is impressively powerful,
• With the right combination of materials, they reach significant thermal stability, enabling operation at or above 230°C (depending on the structure),
• Thanks to the freedom in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Wide application in modern technologies – they find application in HDDs, rotating machines, medical equipment along with technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them useful in miniature devices

Disadvantages of magnetic elements:

• They can break when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage and additionally reinforces its overall robustness,
• They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a humid environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of plastic,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Safety concern due to small fragments may arise, especially if swallowed, which is important in the protection of children. Moreover, tiny components from these products can interfere with diagnostics when ingested,
• Due to expensive raw materials, their cost is considerably higher,

Best holding force of the magnet in ideal parameters – what it depends on?

The given strength of the magnet represents the optimal strength, assessed in the best circumstances, specifically:

• using a steel plate with low carbon content, acting 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

Determinants of lifting force in real conditions

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) 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 testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under shearing force the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.