SM 25x325 [2xM8] / N52 - magnetic separator

Pros as well as cons of neodymium magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• They show high resistance to demagnetization induced by external field influence,
• A magnet with a shiny gold surface is more attractive,
• Neodymium magnets deliver maximum magnetic induction on a their surface, which allows for strong attraction,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to flexibility in shaping and the capacity to adapt to unusual requirements,
• Versatile presence in high-tech industry – they are commonly used in mass storage devices, electromotive mechanisms, diagnostic systems, also modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which makes them useful in small systems

What to avoid - cons of neodymium magnets and ways of using them

• At strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets decrease 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 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 ability of producing nuts in the magnet and complex forms - preferred is cover - magnetic holder.
• Possible danger to health – tiny shards of magnets are risky, when accidentally swallowed, which is particularly important in the context of child health protection. Furthermore, tiny parts of these products can be problematic in diagnostics medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Breakaway strength of the magnet in ideal conditions – what affects it?

Breakaway force was determined for optimal configuration, taking into account:

• with the use of a sheet made of low-carbon steel, guaranteeing maximum field concentration
• with a cross-section no less than 10 mm
• with a surface free of scratches
• without the slightest air gap between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Determinants of practical lifting force of a magnet

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

• Air gap (between the magnet and the plate), since even a microscopic clearance (e.g. 0.5 mm) results in a drastic drop in force by up to 50% (this also applies to varnish, rust or debris).
• Loading method – catalog parameter refers to detachment vertically. When slipping, the magnet exhibits significantly lower power (typically approx. 20-30% of nominal force).
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Steel type – mild steel gives the best results. Alloy steels lower magnetic properties and holding force.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature – heating the magnet causes a temporary drop of force. Check the thermal limit for a given model.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.