SM 18x300 [2xM5] / N42 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their power is durable, and after approximately ten years it decreases only by ~1% (according to research),
• They feature excellent resistance to weakening of magnetic properties when exposed to external magnetic sources,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnetic induction on the working part of the magnet is strong,
• 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...
• Possibility of exact machining and adjusting to individual conditions,
• Fundamental importance in advanced technology sectors – they are commonly used in computer drives, electric motors, medical devices, as well as multitasking production systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Cons of neodymium magnets: weaknesses and usage proposals

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited possibility of creating nuts in the magnet and complicated forms - recommended is casing - magnet mounting.
• Health risk related to microscopic parts of magnets pose a threat, in case of ingestion, which gains importance in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets can disrupt the diagnostic process medical after entering the body.
• Due to complex production process, their price is relatively high,

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

Information about lifting capacity was determined for optimal configuration, including:

• on a plate made of mild steel, optimally conducting the magnetic field
• with a cross-section of at least 10 mm
• characterized by smoothness
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction perpendicular to the plane
• in neutral thermal conditions

Magnet lifting force in use – key factors

It is worth knowing that the application force may be lower influenced by elements below, in order of importance:

• Gap between surfaces – every millimeter of separation (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of maximum force).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Steel type – mild steel attracts best. Higher carbon content lower magnetic permeability and holding force.
• Surface finish – full contact is possible only on polished steel. Rough texture create air cushions, reducing force.
• Thermal factor – high temperature weakens pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.