SM 25x350 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

Besides their tremendous magnetic power, neodymium magnets offer the following advantages:

• Their magnetic field is maintained, and after approximately 10 years it drops only by ~1% (according to research),
• They retain their magnetic properties even under close interference source,
• The use of an refined coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnetic induction on the surface of the magnet remains very high,
• Due to their enhanced temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• Possibility of individual creating as well as modifying to precise needs,
• Fundamental importance in future technologies – they are utilized in data components, electromotive mechanisms, precision medical tools, as well as multitasking production systems.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only protects the magnet but also improves its resistance to damage
• 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.
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• We suggest cover - magnetic mechanism, due to difficulties in producing threads inside the magnet and complicated shapes.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these magnets are able to complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Breakaway strength of the magnet in ideal conditions – what affects it?

The lifting capacity listed is a measurement result conducted under standard conditions:

• with the application of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• whose transverse dimension equals approx. 10 mm
• characterized by smoothness
• without any clearance between the magnet and steel
• under perpendicular application of breakaway force (90-degree angle)
• at ambient temperature room level

Impact of factors on magnetic holding capacity in practice

During everyday use, the actual lifting capacity depends on a number of factors, presented from the most important:

• Distance – existence of foreign body (paint, dirt, gap) interrupts the magnetic circuit, which reduces capacity steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to pulling vertically. When slipping, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Material composition – not every steel reacts the same. High carbon content worsen the attraction effect.
• Surface structure – the more even the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Operating temperature – 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 was determined by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate decreases the load capacity.