SM 25x300 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

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

• Their strength is maintained, and after around 10 years it decreases only by ~1% (theoretically),
• Magnets effectively defend themselves against demagnetization caused by foreign field sources,
• By using a reflective layer of silver, the element presents an modern look,
• Neodymium magnets achieve maximum magnetic induction on a contact point, which allows for strong attraction,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to flexibility in forming and the capacity to adapt to complex applications,
• Huge importance in future technologies – they are commonly used in hard drives, electric drive systems, medical equipment, as well as other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which enables their usage in small systems

Disadvantages of neodymium magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth protecting 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 reduce their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of making threads in the magnet and complex forms - recommended is cover - magnetic holder.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these products are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what affects it?

The force parameter is a measurement result executed under specific, ideal conditions:

• with the contact of a sheet made of special test steel, ensuring maximum field concentration
• whose thickness reaches at least 10 mm
• with an ideally smooth touching surface
• without any insulating layer between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in stable room temperature

Key elements affecting lifting force

Holding efficiency is influenced by specific conditions, mainly (from priority):

• Clearance – existence of any layer (rust, tape, air) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – highest force is reached only during pulling at a 90° angle. The force required to slide of the magnet along the plate is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of converting into lifting capacity.
• Steel grade – the best choice is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface finish – full contact is obtained only on polished steel. Rough texture create air cushions, reducing force.
• Temperature – temperature increase results in weakening of induction. Check the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet and the plate lowers the holding force.