SMZR 25x225 / N52 - magnetic separator with handle

Strengths as well as weaknesses of NdFeB magnets.

Apart from their notable magnetism, neodymium magnets have these key benefits:

• They do not lose power, even during around 10 years – the decrease in strength is only ~1% (according to tests),
• They possess excellent resistance to magnetic field loss as a result of external magnetic sources,
• Thanks to the elegant finish, the plating of Ni-Cu-Ni, gold-plated, or silver-plated gives an visually attractive appearance,
• Magnetic induction on the top side of the magnet turns out to be extremely intense,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of custom creating as well as optimizing to precise needs,
• Universal use in innovative solutions – they are commonly used in computer drives, motor assemblies, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in miniature devices

Problematic aspects of neodymium magnets and ways of using them

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• We recommend casing - magnetic mount, due to difficulties in producing threads inside the magnet and complicated shapes.
• Potential hazard related to microscopic parts of magnets are risky, if swallowed, which is particularly important in the context of child health protection. It is also worth noting that small components of these devices are able to 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

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

Information about lifting capacity is the result of a measurement for ideal contact conditions, including:

• using a sheet made of high-permeability steel, functioning as a ideal flux conductor
• whose thickness reaches at least 10 mm
• characterized by smoothness
• without any air gap between the magnet and steel
• under perpendicular force direction (90-degree angle)
• at standard ambient temperature

Practical aspects of lifting capacity – factors

In real-world applications, the actual holding force depends on many variables, presented from most significant:

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of nominal force).
• Base massiveness – too thin sheet does not close the flux, causing part of the power to be wasted to the other side.
• Chemical composition of the base – low-carbon steel attracts best. Higher carbon content lower magnetic permeability and holding force.
• Surface quality – the more even the surface, the larger the contact zone and stronger the hold. Roughness acts like micro-gaps.
• Temperature influence – high temperature reduces magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was measured using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.