SMZR 32x175 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets.

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

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (according to literature),
• They have excellent resistance to magnetism drop when exposed to opposing magnetic fields,
• A magnet with a smooth gold surface has an effective appearance,
• They are known for high magnetic induction at the operating surface, which increases their power,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Possibility of custom forming as well as optimizing to concrete needs,
• Universal use in innovative solutions – they serve a role in hard drives, motor assemblies, diagnostic systems, as well as other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which enables their usage in compact constructions

Disadvantages of NdFeB magnets:

• Brittleness 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 increases their durability
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape as well as 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• We suggest cover - magnetic mount, due to difficulties in producing nuts inside the magnet and complex shapes.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which becomes key in the context of child safety. Additionally, small elements of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The force parameter is a result of laboratory testing conducted under standard conditions:

• using a sheet made of low-carbon steel, acting as a circuit closing element
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• characterized by smoothness
• without the slightest insulating layer between the magnet and steel
• under vertical force direction (90-degree angle)
• in stable room temperature

Practical lifting capacity: influencing factors

During everyday use, the real power results from many variables, listed from the most important:

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by veneer or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Angle of force application – highest force is reached only during perpendicular pulling. The shear force of the magnet along the plate is standardly many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Material composition – not every steel attracts identically. Alloy additives worsen the attraction effect.
• Surface finish – ideal contact is obtained only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Temperature influence – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, however under attempts to slide the magnet the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.