SM 32x300 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They have unchanged lifting capacity, and over nearly ten years their performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic noise,
• The use of a mirror-like silver surface provides a eye-catching finish,
• They possess intense magnetic force measurable at the magnet’s surface,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• The ability for precise shaping or adjustment to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Key role in new technology industries – they find application in data storage devices, electric drives, medical equipment along with technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They can break when subjected to a strong 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 fracture and additionally increases its overall resistance,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent decline 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,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Possible threat linked to microscopic shards may arise, in case of ingestion, which is notable in the context of child safety. Furthermore, small elements from these assemblies may interfere with diagnostics when ingested,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Maximum lifting capacity of the magnet – what affects it?

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

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Lifting capacity in real conditions – factors

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• 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.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.