MW 38x3.5 / N38 - cylindrical magnet

Strengths as well as weaknesses of neodymium magnets.

Apart from their strong magnetism, neodymium magnets have these key benefits:

• They have stable power, and over nearly 10 years their performance decreases symbolically – ~1% (according to theory),
• Magnets effectively resist against loss of magnetization caused by foreign field sources,
• Thanks to the shiny finish, the layer of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• Magnetic induction on the top side of the magnet turns out to be maximum,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Possibility of detailed shaping and adjusting to concrete conditions,
• Huge importance in high-tech industry – they are utilized in mass storage devices, drive modules, diagnostic systems, and other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets decrease 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 stability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating nuts and complex shapes in magnets, we recommend using cover - magnetic holder.
• Potential hazard resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small elements of these magnets can be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what affects it?

Magnet power was defined for optimal configuration, taking into account:

• on a block made of mild steel, effectively closing the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by even structure
• under conditions of ideal adhesion (metal-to-metal)
• for force applied at a right angle (pull-off, not shear)
• in neutral thermal conditions

Magnet lifting force in use – key factors

Holding efficiency impacted by specific conditions, mainly (from most important):

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Angle of force application – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface 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 limits the lifting capacity (the magnet "punches through" it).
• Metal type – different alloys reacts the same. Alloy additives worsen the attraction effect.
• Base smoothness – the more even the surface, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Temperature influence – hot environment weakens pulling force. Too high temperature can permanently demagnetize the magnet.

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