SMZR 25x175 / N52 - magnetic separator with handle

Pros and cons of rare earth magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• Magnets perfectly resist against loss of magnetization caused by ambient magnetic noise,
• The use of an aesthetic finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets achieve maximum magnetic induction on a small area, which increases force concentration,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of accurate forming and modifying to concrete needs,
• Universal use in innovative solutions – they serve a role in magnetic memories, brushless drives, advanced medical instruments, as well as complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Limited possibility of making nuts in the magnet and complex shapes - recommended is casing - mounting mechanism.
• Possible danger to health – tiny shards of magnets are risky, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these devices are able to complicate diagnosis medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what affects it?

The lifting capacity listed is a result of laboratory testing executed under the following configuration:

• on a block made of mild steel, perfectly concentrating the magnetic flux
• whose transverse dimension equals approx. 10 mm
• with an ground touching surface
• with total lack of distance (no coatings)
• during detachment in a direction vertical to the plane
• at room temperature

Determinants of lifting force in real conditions

In real-world applications, the actual lifting capacity results from a number of factors, ranked from crucial:

• Gap (between the magnet and the metal), as even a very small distance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel attracts best. Alloy admixtures reduce magnetic properties and lifting capacity.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the load capacity.