SM 32x450 [2xM8] / N42 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

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

• They do not lose magnetism, even after nearly ten years – the reduction in strength is only ~1% (according to tests),
• They do not lose their magnetic properties even under strong external field,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnets have excellent magnetic induction on the working surface,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Possibility of individual shaping and adjusting to precise applications,
• Wide application in advanced technology sectors – they are commonly used in mass storage devices, drive modules, advanced medical instruments, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in small systems

Problematic aspects of neodymium magnets and ways of using them

• At strong impacts they can crack, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets lose their power 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 durability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Due to limitations in realizing nuts and complicated shapes in magnets, we propose using a housing - magnetic mount.
• Possible danger to health – tiny shards of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. Furthermore, small elements of these products can disrupt the diagnostic process medical in case of swallowing.
• With mass production the cost of neodymium magnets is economically unviable,

Maximum lifting force for a neodymium magnet – what contributes to it?

The force parameter is a theoretical maximum value performed under specific, ideal conditions:

• using a sheet made of high-permeability steel, functioning as a magnetic yoke
• with a thickness minimum 10 mm
• with an polished touching surface
• with total lack of distance (no impurities)
• under perpendicular force direction (90-degree angle)
• at standard ambient temperature

Lifting capacity in practice – influencing factors

It is worth knowing that the working load will differ depending on elements below, in order of importance:

• Air gap (betwixt the magnet and the metal), since even a very small clearance (e.g. 0.5 mm) can cause a reduction in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Load vector – highest force is available only during perpendicular pulling. The force required to slide of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Chemical composition of the base – mild steel attracts best. Higher carbon content reduce magnetic permeability and holding force.
• Surface finish – full contact is obtained only on smooth steel. Any scratches and bumps create air cushions, weakening the magnet.
• Thermal environment – temperature increase results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under perpendicular forces, whereas under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.