MW 9x3 / N38 - cylindrical magnet

Strengths and weaknesses of rare earth magnets.

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

• They retain magnetic properties for around ten years – the drop is just ~1% (according to analyses),
• Magnets effectively protect themselves against demagnetization caused by foreign field sources,
• The use of an aesthetic finish of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of custom machining and modifying to specific needs,
• Significant place in future technologies – they are utilized in magnetic memories, electric drive systems, precision medical tools, as well as complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which enables their usage in miniature devices

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated shapes.
• Possible danger to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which gains importance in the context of child health protection. Additionally, tiny parts of these products can disrupt the diagnostic process medical after entering the body.
• Due to complex production process, their price is relatively high,

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

Magnet power is the result of a measurement for optimal configuration, assuming:

• with the application of a yoke made of low-carbon steel, ensuring maximum field concentration
• possessing a massiveness of min. 10 mm to avoid saturation
• with a plane cleaned and smooth
• with direct contact (without impurities)
• for force applied at a right angle (pull-off, not shear)
• at standard ambient temperature

Practical aspects of lifting capacity – factors

During everyday use, the actual lifting capacity is determined by several key aspects, presented from most significant:

• Air gap (between the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) can cause a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Angle of force application – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the surface is typically many times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin plate does not accept the full field, causing part of the flux to be wasted to the other side.
• Chemical composition of the base – mild steel attracts best. Higher carbon content reduce magnetic properties and lifting capacity.
• Surface finish – ideal contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.