SM 32x225 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

Apart from their superior power, neodymium magnets have these key benefits:

• They have unchanged lifting capacity, and over around 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets are remarkably resistant to magnetic field loss caused by external field sources,
• In other words, due to the smooth surface of silver, the element is aesthetically pleasing,
• Magnetic induction on the working part of the magnet remains impressive,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in designing and the ability to adapt to specific needs,
• Wide application in modern industrial fields – they are utilized in HDD drives, motor assemblies, advanced medical instruments, as well as modern systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Problematic aspects of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Limited ability of producing nuts in the magnet and complicated shapes - recommended is cover - magnet mounting.
• Potential hazard related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child health protection. It is also worth noting that small elements of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

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

Holding force of 0 kg is a measurement result performed under specific, ideal conditions:

• using a plate made of high-permeability steel, acting as a circuit closing element
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with an ground touching surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (in the magnet axis)
• at temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

Effective lifting capacity impacted by specific conditions, such as (from most important):

• Clearance – existence of any layer (paint, tape, air) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically many times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Chemical composition of the base – low-carbon steel attracts best. Higher carbon content reduce magnetic permeability and holding force.
• Surface condition – ground elements guarantee perfect abutment, which improves field saturation. Rough surfaces reduce efficiency.
• Temperature – heating the magnet causes a temporary drop of induction. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate decreases the holding force.