MW 5x5 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They do not lose strength, even during nearly 10 years – the reduction in strength is only ~1% (based on measurements),
• They have excellent resistance to weakening of magnetic properties due to external magnetic sources,
• Thanks to the smooth finish, the plating of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• The surface of neodymium magnets generates a powerful magnetic field – this is a key feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Possibility of accurate forming and adapting to concrete needs,
• Huge importance in modern industrial fields – they serve a role in HDD drives, electric motors, medical devices, and multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (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 extremely resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of creating nuts in the magnet and complicated forms - recommended is cover - mounting mechanism.
• 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 small elements of these products can disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what it depends on?

Holding force of 0 kg is a measurement result performed under the following configuration:

• using a sheet made of low-carbon steel, functioning as a magnetic yoke
• whose thickness is min. 10 mm
• with an polished touching surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Practical lifting capacity: influencing factors

It is worth knowing that the magnet holding may be lower depending on elements below, starting with the most relevant:

• Distance – existence of foreign body (rust, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is usually several times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of generating force.
• Material type – the best choice is high-permeability steel. Cast iron may attract less.
• Plate texture – smooth surfaces ensure maximum contact, which increases force. Uneven metal reduce efficiency.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.