MW 50x20 / N38 - cylindrical magnet

Strengths and weaknesses of rare earth magnets.

Besides their remarkable pulling force, neodymium magnets offer the following advantages:

• They retain attractive force for around 10 years – the loss is just ~1% (in theory),
• Neodymium magnets are characterized by highly resistant to loss of magnetic properties caused by magnetic disturbances,
• In other words, due to the metallic finish of silver, the element gains visual value,
• Neodymium magnets generate maximum magnetic induction on a small surface, which increases force concentration,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the shape) even at a temperature of 230°C or more...
• Thanks to versatility in constructing and the capacity to adapt to client solutions,
• Versatile presence in future technologies – they find application in magnetic memories, electric motors, medical devices, also technologically advanced constructions.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At strong impacts they can crack, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of producing nuts in the magnet and complex shapes - preferred is casing - magnetic holder.
• Health risk resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these magnets can disrupt the diagnostic process medical in case of swallowing.
• Due to expensive raw materials, their price exceeds standard values,

Maximum lifting capacity of the magnet – what contributes to it?

Breakaway force was determined for ideal contact conditions, assuming:

• with the application of a yoke made of special test steel, ensuring full magnetic saturation
• whose thickness is min. 10 mm
• with a plane free of scratches
• without the slightest clearance between the magnet and steel
• under vertical force direction (90-degree angle)
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

During everyday use, the real power is determined by several key aspects, presented from crucial:

• Distance – existence of foreign body (rust, tape, gap) acts as an insulator, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Loading method – catalog parameter refers to detachment vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Metal type – different alloys reacts the same. Alloy additives weaken the interaction with the magnet.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness acts like micro-gaps.
• Temperature – heating the magnet results in weakening of induction. It is worth remembering the maximum operating temperature for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.