MW 100x10 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their superior power, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (in laboratory conditions),
• They remain magnetized despite exposure to magnetic surroundings,
• Thanks to the shiny finish and silver coating, they have an visually attractive appearance,
• Magnetic induction on the surface of these magnets is impressively powerful,
• 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 adjustment to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Important function in advanced technical fields – they find application in data storage devices, rotating machines, healthcare devices as well as sophisticated instruments,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and increases its overall strength,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of rubber for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing holes directly in the magnet,
• Possible threat due to small fragments may arise, especially if swallowed, which is important in the protection of children. Additionally, tiny components from these magnets might complicate medical imaging when ingested,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

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

The given strength of the magnet represents the optimal strength, assessed in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet depends on in practice the following factors, from primary to secondary:

• Air gap between the magnet and the plate, as 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 measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.