SMZR 25x150 / N52 - magnetic separator with handle

Pros and cons of neodymium magnets.

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

• They do not lose strength, even over around ten years – the drop in power is only ~1% (according to tests),
• Neodymium magnets are distinguished by highly resistant to demagnetization caused by external interference,
• In other words, due to the metallic layer of silver, the element gains a professional look,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in shaping and the capacity to adapt to complex applications,
• Fundamental importance in high-tech industry – they find application in mass storage devices, electromotive mechanisms, precision medical tools, as well as industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which makes them useful in compact constructions

Characteristics of disadvantages of neodymium magnets and proposals for their use:

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only shields the magnet but also improves its resistance to damage
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Due to limitations in creating threads and complicated forms in magnets, we propose using casing - magnetic mount.
• Health risk resulting from small fragments of magnets can be dangerous, if swallowed, which is particularly important in the context of child safety. Additionally, tiny parts of these magnets can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Highest magnetic holding force – what it depends on?

The load parameter shown refers to the limit force, recorded under ideal test conditions, namely:

• on a base made of mild steel, optimally conducting the magnetic flux
• with a thickness of at least 10 mm
• characterized by lack of roughness
• with total lack of distance (without paint)
• for force applied at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

Holding efficiency is affected by specific conditions, including (from priority):

• Distance (betwixt the magnet and the plate), as even a tiny clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to paint, rust or debris).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – mild steel gives the best results. Alloy steels reduce magnetic permeability and lifting capacity.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Rough surfaces weaken the grip.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was measured using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.