MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• They do not lose power, even during approximately 10 years – the decrease in strength is only ~1% (according to tests),
• They feature excellent resistance to magnetism drop when exposed to external magnetic sources,
• A magnet with a shiny nickel surface has an effective appearance,
• Neodymium magnets ensure maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• In view of the ability of free molding and adaptation to individualized needs, NdFeB magnets can be produced in a wide range of shapes and sizes, which amplifies use scope,
• Versatile presence in high-tech industry – they serve a role in hard drives, electric motors, diagnostic systems, also modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which enables their usage in miniature devices

Disadvantages of neodymium magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets decrease 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 durability even at temperatures up to 230°C
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of producing threads in the magnet and complex shapes - preferred is cover - magnet mounting.
• Potential hazard to health – tiny shards of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child health protection. Additionally, small components of these magnets are able to be problematic in diagnostics medical after entering the body.
• Due to neodymium price, their price is relatively high,

Highest magnetic holding force – what affects it?

The lifting capacity listed is a measurement result performed under specific, ideal conditions:

• with the contact of a sheet made of low-carbon steel, ensuring maximum field concentration
• whose thickness reaches at least 10 mm
• characterized by even structure
• with total lack of distance (without paint)
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

Bear in mind that the application force will differ depending on the following factors, in order of importance:

• Clearance – the presence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is standardly many times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be adequately massive. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Plate texture – smooth surfaces guarantee perfect abutment, which improves field saturation. Rough surfaces reduce efficiency.
• Thermal environment – temperature increase results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.