SM 25x275 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even over approximately ten years – the drop in lifting capacity is only ~1% (based on measurements),
• They maintain their magnetic properties even under close interference source,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to present itself better,
• Neodymium magnets ensure maximum magnetic induction on a contact point, which increases force concentration,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the shape) even at a temperature of 230°C or more...
• Possibility of accurate modeling as well as adjusting to precise needs,
• Fundamental importance in modern technologies – they are used in data components, electric drive systems, diagnostic systems, and modern systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape as well as 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 start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complex forms.
• Potential hazard to health – tiny shards of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. Furthermore, small elements of these devices are able to be problematic in diagnostics medical after entering the body.
• With budget limitations the cost of neodymium magnets is a challenge,

Magnetic strength at its maximum – what affects it?

The load parameter shown concerns the peak performance, measured under optimal environment, specifically:

• using a base made of high-permeability steel, acting as a ideal flux conductor
• with a thickness no less than 10 mm
• characterized by lack of roughness
• with direct contact (no impurities)
• under vertical force vector (90-degree angle)
• at room temperature

Key elements affecting lifting force

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

• Air gap (betwixt the magnet and the plate), as even a tiny clearance (e.g. 0.5 mm) can cause a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Steel grade – the best choice is high-permeability steel. Cast iron may attract less.
• Surface structure – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Operating temperature – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet and the plate reduces the load capacity.