SM 25x125 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after 10 years the performance loss is only ~1% (based on calculations),
• Neodymium magnets are highly resistant to magnetic field loss caused by external field sources,
• Thanks to the shiny finish, the surface of Ni-Cu-Ni, gold, or silver-plated gives an clean appearance,
• The surface of neodymium magnets generates a intense magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of custom shaping and adjusting to defined needs,
• Key role in innovative solutions – they are utilized in mass storage devices, electromotive mechanisms, medical devices, and multitasking production systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• We warn that neodymium magnets can reduce their power 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
• Due to limitations in realizing nuts and complicated forms in magnets, we propose using casing - magnetic holder.
• Possible danger resulting from small fragments of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child safety. It is also worth noting that small elements of these magnets can complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

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

Information about lifting capacity was defined for the most favorable conditions, assuming:

• using a base made of mild steel, acting as a magnetic yoke
• with a cross-section minimum 10 mm
• with an ideally smooth contact surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• in stable room temperature

Practical aspects of lifting capacity – factors

During everyday use, the actual holding force depends on a number of factors, ranked from crucial:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to detachment vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Metal type – different alloys attracts identically. High carbon content weaken the attraction effect.
• Plate texture – ground elements guarantee perfect abutment, which increases field saturation. Uneven metal reduce efficiency.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was measured using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.