SM 25x325 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They do not lose power, even over nearly 10 years – the drop in strength is only ~1% (theoretically),
• Neodymium magnets are characterized by extremely resistant to magnetic field loss caused by magnetic disturbances,
• A magnet with a smooth gold surface looks better,
• Neodymium magnets generate maximum magnetic induction on a small surface, which increases force concentration,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Considering the potential of precise shaping and adaptation to custom requirements, NdFeB magnets can be manufactured in a variety of shapes and sizes, which expands the range of possible applications,
• Significant place in modern technologies – they are commonly used in mass storage devices, motor assemblies, advanced medical instruments, as well as complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• We suggest casing - magnetic holder, due to difficulties in producing threads inside the magnet and complex shapes.
• Potential hazard related to microscopic parts of magnets pose a threat, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, small components of these products can be problematic in diagnostics medical in case of swallowing.
• Due to neodymium price, their price exceeds standard values,

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

Magnet power was defined for optimal configuration, taking into account:

• with the application of a yoke made of special test steel, guaranteeing maximum field concentration
• whose thickness equals approx. 10 mm
• with an ideally smooth touching surface
• with zero gap (without paint)
• during pulling in a direction perpendicular to the plane
• at room temperature

Determinants of lifting force in real conditions

In real-world applications, the actual holding force is determined by several key aspects, listed from crucial:

• Space between magnet and steel – every millimeter of separation (caused e.g. by veneer or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Material type – ideal substrate is pure iron steel. Hardened steels may attract less.
• Surface structure – the more even the plate, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Temperature – heating the magnet results in weakening of force. Check the maximum operating temperature for a given model.

* Lifting capacity was determined using a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet and the plate lowers the lifting capacity.