SM 19x225 [2xM6] / N50 - magnetic separator

Pros and cons of rare earth magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (based on calculations),
• They do not lose their magnetic properties even under strong external field,
• In other words, due to the reflective finish of nickel, the element looks attractive,
• Neodymium magnets achieve maximum magnetic induction on a small area, which ensures high operational effectiveness,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to the option of free shaping and customization to unique requirements, neodymium magnets can be modeled in a variety of geometric configurations, which makes them more universal,
• Versatile presence in modern industrial fields – they serve a role in HDD drives, motor assemblies, medical devices, and multitasking production systems.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing 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 lose their power 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 advise using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mount, due to difficulties in producing nuts inside the magnet and complex forms.
• Possible danger to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these products can disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what it depends on?

Holding force of 0 kg is a measurement result executed under standard conditions:

• using a plate made of high-permeability steel, serving as a circuit closing element
• with a cross-section of at least 10 mm
• with an polished touching surface
• without any insulating layer between the magnet and steel
• during pulling in a direction vertical to the mounting surface
• in neutral thermal conditions

Lifting capacity in real conditions – factors

Holding efficiency is influenced by working environment parameters, including (from most important):

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of generating force.
• Metal type – not every steel attracts identically. Alloy additives worsen the attraction effect.
• Surface structure – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was assessed using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.