SM 32x125 [2xM8] / N52 - magnetic separator

Pros and cons of rare earth magnets.

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

• Their strength is durable, and after approximately 10 years it decreases only by ~1% (theoretically),
• They retain their magnetic properties even under external field action,
• In other words, due to the reflective layer of gold, the element looks attractive,
• Magnets are distinguished by maximum magnetic induction on the outer layer,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of precise forming as well as modifying to atypical applications,
• Significant place in electronics industry – they are used in computer drives, electromotive mechanisms, diagnostic systems, as well as multitasking production systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Problematic aspects of neodymium magnets: application proposals

• At strong impacts they can crack, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop 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 very resistant to heat
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of making nuts in the magnet and complex shapes - recommended is cover - mounting mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which gains importance in the context of child safety. Additionally, tiny parts of these magnets can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Best holding force of the magnet in ideal parameters – what affects it?

The specified lifting capacity concerns the limit force, obtained under ideal test conditions, meaning:

• with the contact of a sheet made of special test steel, ensuring full magnetic saturation
• with a cross-section of at least 10 mm
• with an polished contact surface
• with zero gap (without impurities)
• during pulling in a direction vertical to the mounting surface
• in neutral thermal conditions

Determinants of lifting force in real conditions

During everyday use, the real power results from several key aspects, listed from most significant:

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Chemical composition of the base – low-carbon steel gives the best results. Alloy steels lower magnetic properties and lifting capacity.
• Smoothness – ideal contact is obtained only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Temperature influence – high temperature reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.