SM 32x475 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

Besides their exceptional magnetic power, neodymium magnets offer the following advantages:

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• They show high resistance to demagnetization induced by external field influence,
• In other words, due to the reflective surface of gold, the element looks attractive,
• Magnets exhibit maximum magnetic induction on the surface,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of precise shaping as well as optimizing to precise conditions,
• Universal use in innovative solutions – they are utilized in computer drives, electric drive systems, diagnostic systems, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in small systems

Problematic aspects of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a special holder, which not only secures them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• Limited possibility of making threads in the magnet and complicated forms - recommended is casing - magnet mounting.
• Potential hazard related to microscopic parts of magnets are risky, when accidentally swallowed, which is particularly important in the context of child health protection. Additionally, tiny parts of these products can be problematic in diagnostics medical when they are in the body.
• Due to complex production process, their price is relatively high,

Maximum lifting capacity of the magnet – what affects it?

The specified lifting capacity concerns the peak performance, measured under optimal environment, meaning:

• with the contact of a yoke made of special test steel, ensuring maximum field concentration
• whose transverse dimension is min. 10 mm
• characterized by even structure
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction vertical to the plane
• in temp. approx. 20°C

Determinants of lifting force in real conditions

In practice, the actual lifting capacity depends on several key aspects, presented from the most important:

• Gap between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Load vector – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is standardly many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – the best choice is high-permeability steel. Stainless steels may generate lower lifting capacity.
• Plate texture – smooth surfaces guarantee perfect abutment, which improves force. Uneven metal reduce efficiency.
• Thermal environment – temperature increase causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Lifting capacity was assessed with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under vertically applied force, in contrast under parallel forces the holding force is lower. Moreover, even a minimal clearance {between} the magnet and the plate decreases the load capacity.