MW 20x5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets.

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

• They retain attractive force for around ten years – the loss is just ~1% (according to analyses),
• Magnets perfectly defend themselves against loss of magnetization caused by external fields,
• Thanks to the shiny finish, the layer of nickel, gold, or silver-plated gives an visually attractive appearance,
• They show high magnetic induction at the operating surface, making them more effective,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to freedom in shaping and the capacity to customize to individual projects,
• Universal use in electronics industry – they serve a role in HDD drives, electric drive systems, diagnostic systems, as well as complex engineering applications.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Cons of neodymium magnets and ways of using them

• At strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited ability of producing nuts in the magnet and complicated shapes - preferred is a housing - magnetic holder.
• Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child health protection. It is also worth noting that small elements of these devices are able to complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Best holding force of the magnet in ideal parameters – what it depends on?

The lifting capacity listed is a measurement result conducted under the following configuration:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• whose thickness equals approx. 10 mm
• characterized by smoothness
• with zero gap (without coatings)
• for force acting at a right angle (in the magnet axis)
• in neutral thermal conditions

Practical aspects of lifting capacity – factors

Effective lifting capacity impacted by specific conditions, such as (from priority):

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Plate texture – smooth surfaces ensure maximum contact, which increases force. Uneven metal reduce efficiency.
• Thermal environment – heating the magnet causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Lifting capacity was measured by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the holding force is lower. Additionally, even a small distance {between} the magnet and the plate reduces the load capacity.