SM 25x250 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• They retain magnetic properties for almost ten years – the drop is just ~1% (according to analyses),
• They retain their magnetic properties even under external field action,
• In other words, due to the glossy layer of silver, the element becomes visually attractive,
• The surface of neodymium magnets generates a concentrated magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of individual shaping and optimizing to concrete applications,
• Fundamental importance in advanced technology sectors – they are used in magnetic memories, electromotive mechanisms, advanced medical instruments, also complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also increases its resistance to damage
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (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 very resistant to heat
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• We recommend casing - magnetic mechanism, due to difficulties in creating threads inside the magnet and complex shapes.
• Health risk related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Furthermore, small components of these products can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum lifting capacity of the magnet – what affects it?

The specified lifting capacity represents the limit force, recorded under ideal test conditions, specifically:

• using a base made of high-permeability steel, functioning as a magnetic yoke
• with a cross-section of at least 10 mm
• characterized by smoothness
• under conditions of ideal adhesion (metal-to-metal)
• during pulling in a direction vertical to the mounting surface
• in stable room temperature

Lifting capacity in real conditions – factors

Please note that the application force will differ subject to elements below, starting with the most relevant:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Material composition – different alloys reacts the same. High carbon content worsen the attraction effect.
• Surface finish – full contact is obtained only on smooth steel. Rough texture create air cushions, weakening the magnet.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.