SM 25x275 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

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

• They have constant strength, and over nearly 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Magnets very well defend themselves against loss of magnetization caused by ambient magnetic noise,
• In other words, due to the reflective surface of nickel, the element is aesthetically pleasing,
• They feature high magnetic induction at the operating surface, making them more effective,
• Due to their enhanced temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• Thanks to freedom in shaping and the ability to modify to unusual requirements,
• Key role in advanced technology sectors – they are commonly used in magnetic memories, electromotive mechanisms, diagnostic systems, also complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a special holder, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited possibility of producing threads in the magnet and complex shapes - preferred is cover - mounting mechanism.
• Potential hazard to health – tiny shards of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these devices can complicate diagnosis medical when they are in the body.
• With budget limitations the cost of neodymium magnets is a challenge,

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

Information about lifting capacity is the result of a measurement for optimal configuration, taking into account:

• using a plate made of mild steel, serving as a magnetic yoke
• with a thickness of at least 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• in neutral thermal conditions

Lifting capacity in real conditions – factors

Real force is influenced by specific conditions, such as (from priority):

• Air gap (betwixt the magnet and the metal), as even a tiny clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Load vector – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Thermal conditions – neodymium magnets have a sensitivity to temperature. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate reduces the load capacity.