SM 18x150 [2xM5] / N42 - magnetic separator

Pros as well as cons of NdFeB magnets.

Besides their exceptional field intensity, neodymium magnets offer the following advantages:

• They do not lose magnetism, even over nearly 10 years – the decrease in lifting capacity is only ~1% (based on measurements),
• They are noted for resistance to demagnetization induced by external magnetic fields,
• By using a smooth coating of silver, the element has an proper look,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Thanks to flexibility in shaping and the ability to customize to client solutions,
• Universal use in innovative solutions – they are commonly used in computer drives, motor assemblies, medical devices, as well as 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 protecting magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of creating threads in the magnet and complicated shapes - recommended is cover - magnet mounting.
• Possible danger resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these magnets are able to disrupt the diagnostic process medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum lifting force for a neodymium magnet – what affects it?

The force parameter is a measurement result conducted under the following configuration:

• with the use of a sheet made of special test steel, guaranteeing full magnetic saturation
• whose thickness reaches at least 10 mm
• with a surface perfectly flat
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction perpendicular to the mounting surface
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

It is worth knowing that the application force may be lower subject to elements below, in order of importance:

• Clearance – existence of foreign body (rust, tape, gap) acts as an insulator, which reduces capacity steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is usually many times smaller (approx. 1/5 of the lifting capacity).
• 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.
• Metal type – not every steel attracts identically. High carbon content weaken the interaction with the magnet.
• Surface structure – the more even the plate, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.