UMP 75x25 [M10x3] GW F200 GOLD Lina / N42 - search holder

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their stability, neodymium magnets are valued for these benefits:

• They do not lose their even during approximately 10 years – the decrease of power is only ~1% (according to tests),
• They show strong resistance to demagnetization from outside magnetic sources,
• By applying a bright layer of nickel, the element gains a sleek look,
• They have exceptional magnetic induction on the surface of the magnet,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the form),
• With the option for tailored forming and precise design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Significant impact in modern technologies – they are used in data storage devices, electric motors, diagnostic apparatus as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They can break when subjected to a sudden impact. If the magnets are exposed to external force, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens its overall robustness,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on shape). 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 wet environment – during outdoor use, we recommend using waterproof magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is restricted,
• Possible threat linked to microscopic shards may arise, if ingested accidentally, which is significant in the health of young users. Moreover, miniature parts from these magnets have the potential to disrupt scanning after being swallowed,
• Due to expensive raw materials, their cost is considerably higher,

Maximum holding power of the magnet – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, determined in a perfect environment, 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
• with vertical force applied
• under standard ambient temperature

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is conditioned by these factors, in descending order of importance:

• 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 assessed using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate decreases the holding force.