SMZR 25x150 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• Their power is durable, and after around 10 years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the shiny finish and silver coating, they have an elegant appearance,
• They have very high magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for custom shaping or adjustment to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Significant impact in advanced technical fields – they are used in hard drives, electric motors, medical equipment and other advanced devices,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to external force, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from damage while also reinforces its overall resistance,
• 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 dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of rubber,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is crucial in the family environments. Additionally, miniature parts from these magnets may complicate medical imaging when ingested,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Magnetic strength at its maximum – what affects it?

The given pulling force of the magnet represents the maximum force, assessed under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

Lifting capacity in real conditions – factors

In practice, the holding capacity of a magnet is affected by these factors, 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) 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.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under a perpendicular pulling force, however under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate lowers the holding force.