SM 18x150 [2xM5] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their magnetic field is maintained, and after around ten years, it drops only by ~1% (according to research),
• They remain magnetized despite exposure to strong external fields,
• By applying a shiny layer of gold, the element gains a sleek look,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Thanks to their high temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• Thanks to the possibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which increases their functional possibilities,
• Significant impact in advanced technical fields – they are utilized in computer drives, rotating machines, medical equipment and technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them ideal in compact constructions

Disadvantages of magnetic elements:

• They can break when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall durability,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of synthetic coating for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing holes directly in the magnet,
• Health risk from tiny pieces may arise, when consumed by mistake, which is important in the family environments. Additionally, tiny components from these magnets may complicate medical imaging when ingested,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

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

The given pulling force of the magnet means the maximum force, calculated in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• at room temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet depends on in practice the following factors, according to their importance:

• 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 was determined by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.