SMZR 25x200 / N52 - magnetic separator with handle

Pros as well as cons of NdFeB magnets.

Apart from their strong holding force, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• Magnets very well resist against demagnetization caused by ambient magnetic noise,
• The use of an aesthetic finish of noble metals (nickel, gold, silver) causes the element to look better,
• Magnetic induction on the working layer of the magnet is extremely intense,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Possibility of exact machining as well as adapting to individual needs,
• Huge importance in electronics industry – they find application in computer drives, motor assemblies, medical equipment, also modern systems.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• When exposed to humidity, magnets start to 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 producing nuts and complicated forms in magnets, we propose using a housing - magnetic holder.
• Health risk resulting from small fragments of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these products can complicate diagnosis medical after entering the body.
• Due to expensive raw materials, their price is relatively high,

Maximum magnetic pulling force – what affects it?

The force parameter is a result of laboratory testing performed under the following configuration:

• on a block made of structural steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• with a surface perfectly flat
• under conditions of ideal adhesion (metal-to-metal)
• for force applied at a right angle (in the magnet axis)
• at room temperature

Lifting capacity in real conditions – factors

In practice, the actual lifting capacity results from a number of factors, presented from the most important:

• Distance – the presence of any layer (rust, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds significantly lower power (often approx. 20-30% of maximum force).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Steel grade – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal environment – heating the magnet results in weakening of induction. Check the thermal limit 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 perpendicular detachment force, in contrast under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate reduces the holding force.