SM 25x250 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

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

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• They are resistant to demagnetization induced by external disturbances,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• They feature high magnetic induction at the operating surface, which improves attraction properties,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of custom modeling as well as optimizing to individual conditions,
• Huge importance in high-tech industry – they are used in hard drives, drive modules, medical equipment, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

What to avoid - cons of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also raises their 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 advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in creating nuts and complicated shapes in magnets, we propose using cover - magnetic mount.
• Possible danger resulting from small fragments of magnets pose a threat, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small elements of these magnets can be problematic in diagnostics medical after entering the body.
• With large orders the cost of neodymium magnets is economically unviable,

Detachment force of the magnet in optimal conditions – what affects it?

Holding force of 0 kg is a result of laboratory testing performed under standard conditions:

• on a base made of structural steel, perfectly concentrating the magnetic flux
• whose thickness is min. 10 mm
• with an ideally smooth touching surface
• with total lack of distance (without impurities)
• during detachment in a direction vertical to the plane
• at room temperature

Magnet lifting force in use – key factors

In practice, the actual holding force depends on several key aspects, ranked from most significant:

• Air gap (between the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) can cause a decrease in force by up to 50% (this also applies to varnish, corrosion or debris).
• Force direction – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Surface finish – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal environment – heating the magnet causes a temporary drop of force. Check the maximum operating temperature for a given model.

* Lifting capacity was determined by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under vertically applied force, whereas under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet and the plate decreases the holding force.