SM 32x375 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of neodymium magnets.

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

• They retain full power for almost ten years – the drop is just ~1% (in theory),
• They do not lose their magnetic properties even under close interference source,
• A magnet with a metallic gold surface has better aesthetics,
• Neodymium magnets ensure maximum magnetic induction on a small area, which allows for strong attraction,
• 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 freedom in forming and the capacity to customize to complex applications,
• Versatile presence in future technologies – they are commonly used in mass storage devices, electromotive mechanisms, advanced medical instruments, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• 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 and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding 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 immune to moisture, when using outdoors
• Limited possibility of creating threads in the magnet and complicated shapes - recommended is casing - magnetic holder.
• Potential hazard to health – tiny shards of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child safety. Additionally, tiny parts of these magnets can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Magnetic strength at its maximum – what affects it?

Breakaway force was defined for ideal contact conditions, including:

• on a block made of structural steel, optimally conducting the magnetic field
• possessing a thickness of minimum 10 mm to avoid saturation
• characterized by smoothness
• without the slightest clearance between the magnet and steel
• under axial force direction (90-degree angle)
• at room temperature

Determinants of practical lifting force of a magnet

Holding efficiency is influenced by specific conditions, such as (from priority):

• Gap (between the magnet and the metal), as even a tiny clearance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to varnish, corrosion or debris).
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is usually many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Steel type – mild steel attracts best. Alloy admixtures reduce magnetic permeability and lifting capacity.
• Surface structure – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal factor – high temperature reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the holding force.