SMZR 32x125 / N52 - magnetic separator with handle

Strengths as well as weaknesses of rare earth magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They retain magnetic properties for nearly ten years – the loss is just ~1% (based on simulations),
• They maintain their magnetic properties even under close interference source,
• The use of an aesthetic finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• The surface of neodymium magnets generates a maximum magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to flexibility in forming and the capacity to modify to complex applications,
• Fundamental importance in advanced technology sectors – they are utilized in HDD drives, brushless drives, advanced medical instruments, as well as technologically advanced constructions.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks under impact, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in realizing nuts and complex forms in magnets, we propose using cover - magnetic holder.
• Health risk resulting from small fragments of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these products are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what contributes to it?

The force parameter is a theoretical maximum value executed under standard conditions:

• using a sheet made of mild steel, functioning as a circuit closing element
• whose transverse dimension equals approx. 10 mm
• characterized by smoothness
• with zero gap (no coatings)
• during detachment in a direction vertical to the mounting surface
• at temperature approx. 20 degrees Celsius

What influences lifting capacity in practice

Effective lifting capacity is affected by working environment parameters, including (from priority):

• Distance (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) results in a drastic drop in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Direction of force – maximum parameter is reached only during pulling at a 90° angle. The force required to slide of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material composition – different alloys reacts the same. High carbon content worsen the interaction with the magnet.
• Surface structure – the more even the surface, the better the adhesion and stronger the hold. Roughness acts like micro-gaps.
• Temperature – heating the magnet causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, however under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the holding force.