SM 25x225 [2xM8] / N42 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (according to literature),
• Neodymium magnets are characterized by highly resistant to demagnetization caused by external field sources,
• Thanks to the metallic finish, the layer of Ni-Cu-Ni, gold, or silver gives an visually attractive appearance,
• They show high magnetic induction at the operating surface, making them more effective,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, allowing for action at temperatures reaching 230°C and above...
• Possibility of individual modeling and adapting to specific applications,
• Versatile presence in future technologies – they serve a role in magnetic memories, electric drive systems, advanced medical instruments, as well as technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets: tips and applications.

• Brittleness is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and 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 secure oxidation and corrosion.
• Due to limitations in creating threads and complicated forms in magnets, we recommend using casing - magnetic holder.
• Potential hazard to health – tiny shards of magnets are risky, if swallowed, which gains importance in the context of child health protection. Furthermore, tiny parts of these products are able to complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling force – what contributes to it?

The declared magnet strength refers to the limit force, recorded under ideal test conditions, namely:

• with the application of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• with a cross-section no less than 10 mm
• with an polished contact surface
• under conditions of gap-free contact (surface-to-surface)
• under perpendicular force vector (90-degree angle)
• in temp. approx. 20°C

Determinants of lifting force in real conditions

Real force is affected by working environment parameters, such as (from most important):

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Steel thickness – insufficiently thick sheet causes magnetic saturation, causing part of the flux to be lost to the other side.
• Steel type – mild steel gives the best results. Alloy admixtures lower magnetic permeability and holding force.
• Surface quality – the more even the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Temperature – heating the magnet causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Lifting capacity was measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet and the plate lowers the load capacity.