SMZR 25x175 / N52 - magnetic separator with handle

Strengths and weaknesses of neodymium magnets.

Besides their remarkable pulling force, neodymium magnets offer the following advantages:

• They retain magnetic properties for around ten years – the drop is just ~1% (according to analyses),
• They have excellent resistance to magnetism drop when exposed to external fields,
• In other words, due to the metallic layer of nickel, the element becomes visually attractive,
• Neodymium magnets ensure maximum magnetic induction on a small surface, which allows for strong attraction,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling action at temperatures approaching 230°C and above...
• Possibility of precise creating and optimizing to specific applications,
• Wide application in high-tech industry – they serve a role in mass storage devices, motor assemblies, precision medical tools, also modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• At very strong impacts they can break, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's 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 stability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited possibility of making threads in the magnet and complex forms - recommended is a housing - mounting mechanism.
• 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. It is also worth noting that small elements of these magnets can complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is a challenge,

Maximum holding power of the magnet – what it depends on?

The specified lifting capacity concerns the limit force, recorded under laboratory conditions, specifically:

• using a base made of low-carbon steel, serving as a magnetic yoke
• whose thickness equals approx. 10 mm
• with a surface cleaned and smooth
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

In real-world applications, the actual holding force is determined by a number of factors, listed from crucial:

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Material composition – not every steel attracts identically. Alloy additives worsen the attraction effect.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps create air cushions, reducing force.
• Thermal environment – heating the magnet results in weakening of force. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under a perpendicular pulling force, however under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.