SM 25x150 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

Besides their exceptional strength, neodymium magnets offer the following advantages:

• They retain full power for almost ten years – the loss is just ~1% (in theory),
• They have excellent resistance to magnetism drop when exposed to opposing magnetic fields,
• The use of an aesthetic coating of noble metals (nickel, gold, silver) causes the element to look better,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of individual creating and adapting to individual requirements,
• Significant place in electronics industry – they are commonly used in mass storage devices, electromotive mechanisms, advanced medical instruments, also multitasking production systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Cons 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 lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• When exposed to humidity, magnets usually rust. For applications 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 complex forms in magnets, we propose using a housing - magnetic mount.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these devices are able to be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

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

The force parameter is a measurement result performed under specific, ideal conditions:

• using a sheet made of high-permeability steel, acting as a ideal flux conductor
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• with an ground touching surface
• under conditions of gap-free contact (surface-to-surface)
• under vertical force vector (90-degree angle)
• at ambient temperature room level

Practical aspects of lifting capacity – factors

In practice, the actual lifting capacity is determined by a number of factors, listed from crucial:

• Distance (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) results in a drastic drop in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Metal type – not every steel reacts the same. High carbon content weaken the attraction effect.
• Plate texture – smooth surfaces ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Operating temperature – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity was measured by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as fivefold. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.