SMZR 32x200 / N52 - magnetic separator with handle

Pros as well as cons of NdFeB magnets.

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

• They virtually do not lose strength, because even after 10 years the performance loss is only ~1% (according to literature),
• Magnets effectively resist against loss of magnetization caused by foreign field sources,
• The use of an elegant finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets exhibit very high magnetic induction on the outer side,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to versatility in constructing and the ability to customize to complex applications,
• Significant place in high-tech industry – they are used in HDD drives, drive modules, advanced medical instruments, as well as other advanced devices.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a strong case, which not only secures them against impacts but also increases their durability
• NdFeB magnets lose strength 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
• They rust in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mount, due to difficulties in creating nuts inside the magnet and complicated forms.
• Potential hazard resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the context of child health protection. It is also worth noting that small elements of these magnets are able to complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what affects it?

The declared magnet strength refers to the peak performance, measured under ideal test conditions, namely:

• on a plate made of structural steel, perfectly concentrating the magnetic field
• whose transverse dimension is min. 10 mm
• with a surface perfectly flat
• under conditions of gap-free contact (surface-to-surface)
• under perpendicular force direction (90-degree angle)
• at ambient temperature room level

Determinants of practical lifting force of a magnet

Real force is influenced by specific conditions, including (from priority):

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by veneer or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Plate material – mild steel attracts best. Alloy steels reduce magnetic properties and lifting capacity.
• Surface quality – the more even the plate, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Temperature – temperature increase causes a temporary drop of induction. Check the thermal limit for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.