SMZR 25x100 / N52 - magnetic separator with handle

Pros as well as cons of rare earth magnets.

Apart from their notable holding force, neodymium magnets have these key benefits:

• They do not lose strength, even during around ten years – the reduction in strength is only ~1% (theoretically),
• Magnets very well defend themselves against loss of magnetization caused by foreign field sources,
• A magnet with a smooth gold surface looks better,
• They show high magnetic induction at the operating surface, making them more effective,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to modularity in forming and the ability to modify to individual projects,
• Universal use in advanced technology sectors – they find application in mass storage devices, electric drive systems, diagnostic systems, and industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 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
• Limited ability of creating nuts in the magnet and complex forms - recommended is cover - magnetic holder.
• Possible danger to health – tiny shards of magnets can be dangerous, in case of ingestion, which is particularly important in the context of child health protection. Additionally, small elements of these devices are able to complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets can be a barrier,

Maximum holding power of the magnet – what it depends on?

The lifting capacity listed is a theoretical maximum value performed under the following configuration:

• using a sheet made of low-carbon steel, serving as a magnetic yoke
• possessing a thickness of minimum 10 mm to ensure full flux closure
• characterized by smoothness
• under conditions of ideal adhesion (metal-to-metal)
• for force acting at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Lifting capacity in real conditions – factors

Bear in mind that the magnet holding will differ subject to the following factors, in order of importance:

• Distance (between the magnet and the plate), because even a tiny clearance (e.g. 0.5 mm) results in a decrease in force by up to 50% (this also applies to paint, rust or dirt).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Material composition – not every steel reacts the same. Alloy additives weaken the attraction effect.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Heat – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was measured with the use of a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the lifting capacity.