SMZR 25x175 / N52 - magnetic separator with handle

Pros as well as cons of neodymium magnets.

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

• They have stable power, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• Neodymium magnets are exceptionally resistant to demagnetization caused by external interference,
• In other words, due to the aesthetic surface of silver, the element is aesthetically pleasing,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to flexibility in designing and the ability to adapt to individual projects,
• Significant place in electronics industry – they are utilized in magnetic memories, electromotive mechanisms, medical devices, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which allows their use in miniature devices

Cons of neodymium magnets and proposals for their use:

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets lose their force 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
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing nuts and complicated forms in magnets, we propose using a housing - magnetic holder.
• Potential hazard resulting from small fragments of magnets are risky, if swallowed, which is particularly important in the context of child safety. Furthermore, small components of these products are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what contributes to it?

Magnet power was determined for ideal contact conditions, including:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• whose transverse dimension equals approx. 10 mm
• with an polished contact surface
• under conditions of no distance (surface-to-surface)
• under perpendicular application of breakaway force (90-degree angle)
• at conditions approx. 20°C

What influences lifting capacity in practice

Bear in mind that the application force will differ influenced by elements below, starting with the most relevant:

• Distance – the presence of foreign body (rust, tape, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Metal type – different alloys attracts identically. High carbon content weaken the interaction with the magnet.
• Surface condition – smooth surfaces ensure maximum contact, which increases field saturation. Uneven metal weaken the grip.
• Heat – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.