MW 20x5 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

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

• They retain attractive force for around 10 years – the loss is just ~1% (according to analyses),
• Magnets very well protect themselves against demagnetization caused by ambient magnetic noise,
• By applying a decorative coating of nickel, the element has an professional look,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of individual shaping as well as adjusting to defined conditions,
• Fundamental importance in high-tech industry – they are commonly used in hard drives, motor assemblies, advanced medical instruments, and technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Cons of neodymium magnets: application proposals

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets experience 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
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in realizing nuts and complicated forms in magnets, we recommend using cover - magnetic mount.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child health protection. Furthermore, small elements of these magnets can be problematic in diagnostics medical after entering the body.
• Due to neodymium price, their price is higher than average,

Maximum holding power of the magnet – what affects it?

Information about lifting capacity was defined for optimal configuration, taking into account:

• on a base made of structural steel, effectively closing the magnetic flux
• with a thickness minimum 10 mm
• with a surface perfectly flat
• with total lack of distance (without paint)
• under vertical force direction (90-degree angle)
• at conditions approx. 20°C

Determinants of practical lifting force of a magnet

In real-world applications, the actual lifting capacity is determined by many variables, listed from crucial:

• Distance – the presence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the plate is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – the best choice is pure iron steel. Hardened steels may attract less.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, reducing force.
• Thermal factor – high temperature weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.