SM 25x175 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (according to literature),
• They maintain their magnetic properties even under external field action,
• A magnet with a smooth gold surface is more attractive,
• The surface of neodymium magnets generates a strong magnetic field – this is one of their assets,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• In view of the option of free molding and adaptation to unique requirements, neodymium magnets can be modeled in a variety of shapes and sizes, which expands the range of possible applications,
• Wide application in electronics industry – they are used in hard drives, drive modules, advanced medical instruments, and technologically advanced constructions.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

What to avoid - cons of neodymium magnets and proposals for their use:

• At strong impacts they can crack, therefore we advise placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We suggest cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complex forms.
• Potential hazard resulting from small fragments of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these magnets can complicate diagnosis medical when they are in the body.
• Due to expensive raw materials, their price exceeds standard values,

Maximum magnetic pulling force – what affects it?

The specified lifting capacity concerns the maximum value, obtained under ideal test conditions, specifically:

• on a base made of structural steel, effectively closing the magnetic flux
• possessing a massiveness of at least 10 mm to avoid saturation
• with an ideally smooth touching surface
• with total lack of distance (no coatings)
• during detachment in a direction perpendicular to the mounting surface
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

Bear in mind that the application force may be lower subject to the following factors, starting with the most relevant:

• Clearance – the presence of foreign body (rust, dirt, air) acts as an insulator, which lowers capacity steeply (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is obtained only during perpendicular pulling. The shear force of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Metal type – different alloys attracts identically. High carbon content weaken the interaction with the magnet.
• Plate texture – ground elements guarantee perfect abutment, which increases force. Uneven metal reduce efficiency.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost they can be stronger (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.