SMZR 32x200 / N52 - magnetic separator with handle

Pros and cons of neodymium magnets.

Apart from their superior magnetic energy, neodymium magnets have these key benefits:

• They retain full power for nearly 10 years – the drop is just ~1% (according to analyses),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• A magnet with a metallic gold surface is more attractive,
• Magnets have huge magnetic induction on the outer side,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, enabling functioning at temperatures reaching 230°C and above...
• Thanks to modularity in designing and the ability to modify to unusual requirements,
• Key role in modern industrial fields – they are used in magnetic memories, electromotive mechanisms, precision medical tools, as well as other advanced devices.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only secures them against impacts but also raises their durability
• Neodymium magnets lose 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 suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• We suggest a housing - magnetic mount, due to difficulties in creating nuts inside the magnet and complicated forms.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which gains importance in the context of child health protection. Furthermore, small elements of these devices are able to be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum lifting force for a neodymium magnet – what it depends on?

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

• on a block made of mild steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• characterized by lack of roughness
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (in the magnet axis)
• in neutral thermal conditions

Impact of factors on magnetic holding capacity in practice

Holding efficiency is influenced by working environment parameters, mainly (from priority):

• Space between magnet and steel – every millimeter of separation (caused e.g. by varnish or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is reached only during perpendicular pulling. The shear force of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Chemical composition of the base – low-carbon steel attracts best. Alloy steels lower magnetic properties and lifting capacity.
• Smoothness – full contact is possible only on polished steel. Rough texture create air cushions, weakening the magnet.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet and the plate lowers the holding force.