MW 20x5 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets.

Besides their remarkable field intensity, neodymium magnets offer the following advantages:

• They retain full power for almost 10 years – the drop is just ~1% (in theory),
• They feature excellent resistance to magnetism drop due to external magnetic sources,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Neodymium magnets achieve maximum magnetic induction on a their surface, which increases force concentration,
• 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 exact shaping and optimizing to complex requirements,
• Huge importance in high-tech industry – they are utilized in magnetic memories, electromotive mechanisms, advanced medical instruments, also other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets: application proposals

• At strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures 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, in case of application outdoors
• Limited possibility of producing nuts in the magnet and complicated shapes - preferred is cover - magnetic holder.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. Additionally, small components of these devices can complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what it depends on?

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

• using a plate made of high-permeability steel, serving as a circuit closing element
• possessing a thickness of at least 10 mm to avoid saturation
• with an polished touching surface
• with zero gap (no coatings)
• during pulling in a direction vertical to the plane
• at temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Real force impacted by working environment parameters, mainly (from most important):

• Clearance – existence of any layer (paint, tape, gap) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is usually many times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the attraction effect.
• Surface condition – smooth surfaces guarantee perfect abutment, which improves field saturation. Rough surfaces weaken the grip.
• Temperature – heating the magnet causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.