SM 32x200 [2xM8] / N42 - magnetic separator

Pros and cons of neodymium magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose strength, even after approximately 10 years – the drop in lifting capacity is only ~1% (according to tests),
• They possess excellent resistance to magnetism drop as a result of external magnetic sources,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• The surface of neodymium magnets generates a intense magnetic field – this is one of their assets,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures reaching 230°C and above...
• Possibility of precise machining and adjusting to individual applications,
• Versatile presence in advanced technology sectors – they are utilized in computer drives, motor assemblies, precision medical tools, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in miniature devices

What to avoid - cons of neodymium magnets and proposals for their use:

• At very strong impacts they can crack, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as 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 advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• We recommend cover - magnetic mount, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Potential hazard resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child safety. It is also worth noting that small components of these products can be problematic in diagnostics medical when they are in the body.
• Due to complex production process, their price is higher than average,

Magnetic strength at its maximum – what it depends on?

The lifting capacity listed is a measurement result conducted under specific, ideal conditions:

• on a base made of mild steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• with an polished contact surface
• with total lack of distance (without coatings)
• for force applied at a right angle (in the magnet axis)
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

Bear in mind that the magnet holding may be lower depending on the following factors, starting with the most relevant:

• Space between surfaces – every millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically several times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Steel type – low-carbon steel gives the best results. Alloy steels lower magnetic permeability and holding force.
• Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, reducing force.
• Thermal factor – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.