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

Pros and cons of NdFeB magnets.

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

• They retain magnetic properties for nearly ten years – the loss is just ~1% (according to analyses),
• They feature excellent resistance to magnetism drop due to external fields,
• Thanks to the shimmering finish, the coating of nickel, gold, or silver gives an aesthetic appearance,
• Magnets exhibit extremely high magnetic induction on the outer side,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to the possibility of accurate shaping and customization to unique needs, NdFeB magnets can be modeled in a broad palette of shapes and sizes, which expands the range of possible applications,
• Key role in modern technologies – they are used in hard drives, motor assemblies, diagnostic systems, also complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Problematic aspects of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also increases their durability
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of producing nuts in the magnet and complicated forms - recommended is casing - magnetic holder.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Additionally, tiny parts of these devices can complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what affects it?

The lifting capacity listed is a result of laboratory testing conducted under specific, ideal conditions:

• on a block made of mild steel, optimally conducting the magnetic field
• whose thickness equals approx. 10 mm
• characterized by smoothness
• with direct contact (without coatings)
• during detachment in a direction perpendicular to the mounting surface
• at ambient temperature room level

Magnet lifting force in use – key factors

Real force is influenced by working environment parameters, mainly (from priority):

• Air gap (between the magnet and the plate), as even a very small clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to varnish, rust or debris).
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds much less (typically approx. 20-30% of nominal force).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Plate texture – ground elements guarantee perfect abutment, which increases field saturation. Rough surfaces reduce efficiency.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.