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

Advantages and disadvantages of rare earth magnets.

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

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (according to literature),
• They do not lose their magnetic properties even under strong external field,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to look better,
• Magnetic induction on the surface of the magnet is very high,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures reaching 230°C and above...
• Thanks to freedom in forming and the capacity to customize to specific needs,
• Versatile presence in innovative solutions – they are utilized in magnetic memories, electric motors, medical devices, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in compact constructions

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• Neodymium magnets decrease their power 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• We suggest a housing - magnetic mount, due to difficulties in creating threads inside the magnet and complex forms.
• Health risk related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child health protection. Furthermore, small components of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what affects it?

The declared magnet strength refers to the maximum value, recorded under ideal test conditions, meaning:

• on a block made of structural steel, effectively closing the magnetic flux
• with a thickness of at least 10 mm
• with a surface cleaned and smooth
• with total lack of distance (without coatings)
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

It is worth knowing that the working load will differ subject to elements below, starting with the most relevant:

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel grade – ideal substrate is high-permeability steel. Stainless steels may generate lower lifting capacity.
• Smoothness – full contact is obtained only on polished steel. Rough texture create air cushions, weakening the magnet.
• Operating temperature – neodymium magnets have a sensitivity to temperature. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, in contrast under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate lowers the holding force.