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

Advantages and disadvantages of neodymium magnets.

Apart from their consistent magnetism, neodymium magnets have these key benefits:

• Their strength remains stable, and after around 10 years it decreases only by ~1% (theoretically),
• Magnets effectively protect themselves against demagnetization caused by external fields,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• Magnets possess extremely high magnetic induction on the working surface,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Possibility of individual modeling and adjusting to complex needs,
• Key role in future technologies – they serve a role in magnetic memories, drive modules, diagnostic systems, as well as technologically advanced constructions.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a special holder, which not only secures them against impacts but also raises their durability
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (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
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in creating nuts and complex shapes in magnets, we propose using a housing - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small elements of these products can complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

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

Breakaway force is the result of a measurement for optimal configuration, assuming:

• using a sheet made of mild steel, serving as a magnetic yoke
• whose transverse dimension equals approx. 10 mm
• with a plane free of scratches
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

In practice, the real power depends on several key aspects, listed from the most important:

• Clearance – existence of any layer (rust, tape, gap) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of nominal force).
• Plate thickness – too thin plate does not accept the full field, causing part of the flux to be lost to the other side.
• Plate material – low-carbon steel gives the best results. Higher carbon content decrease magnetic permeability and holding force.
• Surface quality – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal factor – hot environment weakens pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, however under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.