SM 25x375 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

Besides their exceptional pulling force, neodymium magnets offer the following advantages:

• Their strength is maintained, and after around 10 years it drops only by ~1% (theoretically),
• Neodymium magnets are highly resistant to magnetic field loss caused by external magnetic fields,
• By covering with a smooth coating of gold, the element acquires an proper look,
• They are known for high magnetic induction at the operating surface, which improves attraction properties,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures reaching 230°C and above...
• Possibility of detailed forming and adapting to atypical applications,
• Wide application in advanced technology sectors – they are utilized in HDD drives, electromotive mechanisms, advanced medical instruments, also industrial machines.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also improves its resistance to damage
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complicated shapes in magnets, we recommend using casing - magnetic mount.
• Potential hazard resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which gains importance in the context of child safety. Additionally, small components of these magnets can complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Maximum magnetic pulling force – what contributes to it?

Breakaway force is the result of a measurement for ideal contact conditions, taking into account:

• on a block made of mild steel, effectively closing the magnetic flux
• whose thickness equals approx. 10 mm
• with an polished contact surface
• without any air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Please note that the magnet holding may be lower subject to elements below, starting with the most relevant:

• Distance – the presence of foreign body (paint, tape, gap) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to detachment vertically. When slipping, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
• Surface finish – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, reducing force.
• Temperature – heating the magnet causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet and the plate reduces the holding force.