SM 25x225 [2xM8] / N52 - magnetic separator

Pros and cons of neodymium magnets.

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

• They have stable power, and over nearly 10 years their attraction force decreases symbolically – ~1% (in testing),
• Magnets perfectly protect themselves against demagnetization caused by foreign field sources,
• Thanks to the metallic finish, the coating of nickel, gold-plated, or silver-plated gives an visually attractive appearance,
• They feature high magnetic induction at the operating surface, making them more effective,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to modularity in designing and the capacity to modify to unusual requirements,
• Huge importance in modern industrial fields – they are used in mass storage devices, drive modules, advanced medical instruments, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which enables their usage in compact constructions

What to avoid - cons of neodymium magnets and proposals for their use:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited possibility of creating nuts in the magnet and complicated forms - recommended is casing - magnetic holder.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these devices are able to complicate diagnosis medical in case of swallowing.
• With budget limitations the cost of neodymium magnets can be a barrier,

Detachment force of the magnet in optimal conditions – what it depends on?

The force parameter is a theoretical maximum value executed under specific, ideal conditions:

• on a block made of mild steel, perfectly concentrating the magnetic flux
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• with zero gap (no paint)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Lifting capacity in real conditions – factors

Effective lifting capacity impacted by working environment parameters, mainly (from most important):

• Distance – the presence of foreign body (rust, dirt, air) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Metal type – different alloys reacts the same. High carbon content worsen the attraction effect.
• Smoothness – full contact is obtained only on smooth steel. Any scratches and bumps create air cushions, weakening the magnet.
• Operating temperature – neodymium magnets have a sensitivity to temperature. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity was assessed by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under vertically applied force, however under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.