SM 25x300 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

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

• They retain full power for almost 10 years – the drop is just ~1% (according to analyses),
• They possess excellent resistance to magnetic field loss when exposed to external magnetic sources,
• By using a lustrous coating of nickel, the element has an proper look,
• Magnetic induction on the surface of the magnet turns out to be strong,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to flexibility in forming and the ability to modify to specific needs,
• Significant place in high-tech industry – they are used in computer drives, drive modules, medical devices, also other advanced devices.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Cons of neodymium magnets: application proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. 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 power 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 - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complex forms in magnets, we recommend using casing - magnetic mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, tiny parts of these devices can disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum lifting force for a neodymium magnet – what affects it?

Breakaway force was defined for optimal configuration, assuming:

• on a plate made of mild steel, optimally conducting the magnetic flux
• whose thickness equals approx. 10 mm
• with a surface cleaned and smooth
• under conditions of ideal adhesion (metal-to-metal)
• under axial force vector (90-degree angle)
• in stable room temperature

Practical aspects of lifting capacity – factors

During everyday use, the actual lifting capacity depends on a number of factors, listed from crucial:

• Air gap (betwixt the magnet and the plate), since even a very small distance (e.g. 0.5 mm) can cause a drastic drop in force by up to 50% (this also applies to varnish, rust or dirt).
• Load vector – highest force is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel attracts identically. High carbon content worsen the interaction with the magnet.
• Base smoothness – the more even the surface, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.