SM 25x350 [2xM8] / N52 - magnetic separator

Pros and cons of neodymium magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose strength, even during approximately 10 years – the drop in power is only ~1% (according to tests),
• They maintain their magnetic properties even under close interference source,
• Thanks to the glossy finish, the coating of Ni-Cu-Ni, gold, or silver-plated gives an visually attractive appearance,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of accurate shaping and optimizing to complex requirements,
• Versatile presence in advanced technology sectors – they are commonly used in data components, electric drive systems, diagnostic systems, also technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their strength 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 durability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of making nuts in the magnet and complicated shapes - recommended is casing - magnetic holder.
• Health risk related to microscopic parts of magnets can be dangerous, if swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, tiny parts of these devices can be problematic in diagnostics medical after entering the body.
• Due to expensive raw materials, their price is relatively high,

Detachment force of the magnet in optimal conditions – what it depends on?

Holding force of 0 kg is a result of laboratory testing executed under specific, ideal conditions:

• on a block made of structural steel, perfectly concentrating the magnetic field
• with a cross-section minimum 10 mm
• with an ideally smooth contact surface
• with total lack of distance (without impurities)
• during detachment in a direction vertical to the mounting surface
• in temp. approx. 20°C

Magnet lifting force in use – key factors

During everyday use, the real power depends on many variables, ranked from crucial:

• Gap (between the magnet and the plate), since even a microscopic distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet holds much less (often approx. 20-30% of nominal force).
• Base massiveness – too thin sheet causes magnetic saturation, causing part of the flux to be lost into the air.
• Plate material – low-carbon steel attracts best. Higher carbon content lower magnetic permeability and holding force.
• Surface structure – the more even the plate, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Temperature – temperature increase results in weakening of induction. Check the maximum operating temperature for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet and the plate lowers the load capacity.