SM 25x125 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose power, even over approximately ten years – the decrease in strength is only ~1% (according to tests),
• They maintain their magnetic properties even under close interference source,
• A magnet with a shiny nickel surface looks better,
• Magnets are characterized by extremely high magnetic induction on the surface,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures approaching 230°C and above...
• Thanks to versatility in constructing and the capacity to adapt to complex applications,
• Key role in electronics industry – they serve a role in HDD drives, electric drive systems, medical equipment, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which makes them useful in compact constructions

Characteristics of disadvantages of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest casing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complicated shapes.
• Potential hazard resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, small components of these magnets can complicate diagnosis medical in case of swallowing.
• Due to neodymium price, their price is relatively high,

Maximum lifting force for a neodymium magnet – what contributes to it?

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

• on a base made of structural steel, perfectly concentrating the magnetic flux
• with a cross-section of at least 10 mm
• with an ideally smooth contact surface
• with total lack of distance (no paint)
• under perpendicular force direction (90-degree angle)
• at temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

Holding efficiency is influenced by specific conditions, such as (from priority):

• Clearance – the presence of foreign body (paint, tape, gap) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet holds much less (often approx. 20-30% of nominal force).
• Plate thickness – insufficiently thick steel does not close the flux, causing part of the flux to be lost to the other side.
• Material composition – not every steel reacts the same. High carbon content weaken the interaction with the magnet.
• Surface quality – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Operating temperature – neodymium magnets have a sensitivity to temperature. At higher temperatures they are weaker, and in frost gain strength (up to a certain limit).

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.