SM 25x300 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of rare earth magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose magnetism, even during nearly ten years – the reduction in power is only ~1% (theoretically),
• Magnets perfectly protect themselves against loss of magnetization caused by ambient magnetic noise,
• A magnet with a metallic silver surface is more attractive,
• Magnets are distinguished by extremely high magnetic induction on the outer side,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, allowing for action at temperatures approaching 230°C and above...
• In view of the possibility of flexible forming and adaptation to custom solutions, NdFeB magnets can be manufactured in a variety of geometric configurations, which makes them more universal,
• Key role in modern technologies – they find application in magnetic memories, electric drive systems, medical devices, and other advanced devices.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Drawbacks and weaknesses of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited ability of making threads in the magnet and complicated shapes - recommended is casing - magnet mounting.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the context of child health protection. It is also worth noting that small components of these products are able to be problematic in diagnostics medical when they are in the body.
• With mass production the cost of neodymium magnets is a challenge,

Highest magnetic holding force – what affects it?

Magnet power was determined for ideal contact conditions, taking into account:

• with the application of a sheet made of low-carbon steel, ensuring maximum field concentration
• with a thickness of at least 10 mm
• with an ground touching surface
• under conditions of ideal adhesion (surface-to-surface)
• during pulling in a direction vertical to the plane
• at temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

It is worth knowing that the working load will differ subject to the following factors, in order of importance:

• Distance (between the magnet and the metal), as even a microscopic distance (e.g. 0.5 mm) can cause a decrease in force by up to 50% (this also applies to varnish, corrosion or debris).
• Loading method – catalog parameter refers to pulling vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the interaction with the magnet.
• Base smoothness – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Thermal environment – heating the magnet causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured by applying a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the holding force.