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

Advantages as well as disadvantages of rare earth magnets.

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

• Their magnetic field is maintained, and after around ten years it decreases only by ~1% (according to research),
• They possess excellent resistance to weakening of magnetic properties when exposed to external fields,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets possess excellent magnetic induction on the outer side,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to flexibility in constructing and the ability to modify to complex applications,
• Wide application in future technologies – they are used in data components, motor assemblies, precision medical tools, as well as other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Characteristics of disadvantages of neodymium magnets: application proposals

• To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we advise using waterproof magnets made of rubber, plastic or other material protecting against moisture
• We suggest casing - magnetic mechanism, due to difficulties in creating threads inside the magnet and complicated shapes.
• Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these magnets can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

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

The lifting capacity listed is a measurement result performed under specific, ideal conditions:

• on a block made of mild steel, optimally conducting the magnetic flux
• possessing a thickness of minimum 10 mm to avoid saturation
• characterized by even structure
• without the slightest clearance between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

During everyday use, the real power is determined by many variables, presented from the most important:

• Distance – the presence of any layer (rust, tape, air) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Loading method – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet exhibits much less (often approx. 20-30% of maximum force).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material composition – not every steel attracts identically. High carbon content worsen the interaction with the magnet.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Operating temperature – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was assessed using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate lowers the holding force.