SM 25x375 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• They retain their magnetic properties for around 10 years – the loss is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the shiny finish and gold coating, they have an elegant appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• With the option for customized forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Important function in modern technologies – they find application in computer drives, electric motors, healthcare devices as well as sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to external force, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time enhances its overall strength,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to wet conditions can degrade. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Limited ability to create complex details in the magnet – the use of a external casing is recommended,
• Possible threat related to magnet particles may arise, when consumed by mistake, which is notable in the health of young users. Additionally, miniature parts from these devices have the potential to complicate medical imaging when ingested,
• Due to a complex production process, their cost is considerably higher,

Magnetic strength at its maximum – what contributes to it?

The given pulling force of the magnet means the maximum force, assessed in ideal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Lifting capacity in real conditions – factors

The lifting capacity of a magnet depends on in practice the following factors, from primary to secondary:

• Air gap between the magnet and the plate, since even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity was assessed by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.