MW 20x5 / N38 - cylindrical magnet

Pros and cons of neodymium magnets.

Besides their immense magnetic power, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• They possess excellent resistance to magnetism drop due to external magnetic sources,
• A magnet with a metallic nickel surface looks better,
• Magnetic induction on the surface of the magnet remains strong,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to freedom in designing and the ability to adapt to specific needs,
• Key role in modern technologies – they are used in HDD drives, electric motors, diagnostic systems, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in small systems

Problematic aspects of neodymium magnets: application proposals

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets lose their force 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
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• We suggest a housing - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complex shapes.
• Possible danger related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Additionally, tiny parts of these products can be problematic in diagnostics medical after entering the body.
• With large orders the cost of neodymium magnets is economically unviable,

Maximum holding power of the magnet – what affects it?

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

• using a base made of high-permeability steel, acting as a magnetic yoke
• whose thickness reaches at least 10 mm
• with a plane free of scratches
• with total lack of distance (without impurities)
• for force acting at a right angle (in the magnet axis)
• in temp. approx. 20°C

Lifting capacity in real conditions – factors

In real-world applications, the actual holding force is determined by many variables, ranked from most significant:

• Gap (betwixt the magnet and the plate), as even a very small distance (e.g. 0.5 mm) leads to a reduction in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds significantly lower power (typically approx. 20-30% of nominal force).
• Base massiveness – insufficiently thick plate does not close the flux, causing part of the flux to be lost into the air.
• Steel type – low-carbon steel gives the best results. Alloy steels decrease magnetic properties and lifting capacity.
• Surface finish – full contact is possible only on polished steel. Rough texture create air cushions, reducing force.
• Temperature influence – hot environment reduces magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet and the plate decreases the load capacity.