MW 40x30 / N38 - cylindrical magnet

Strengths and weaknesses of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They do not lose magnetism, even during nearly 10 years – the drop in strength is only ~1% (according to tests),
• They are extremely resistant to demagnetization induced by external field influence,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• The surface of neodymium magnets generates a intense magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to versatility in designing and the ability to adapt to unusual requirements,
• Wide application in advanced technology sectors – they serve a role in magnetic memories, electric motors, precision medical tools, also complex engineering applications.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Problematic aspects of neodymium magnets: tips and applications.

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets decrease their strength 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
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Due to limitations in producing threads and complicated shapes in magnets, we propose using cover - magnetic mount.
• Potential hazard to health – tiny shards of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, small elements of these magnets can be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what contributes to it?

Holding force of 66.35 kg is a theoretical maximum value executed under standard conditions:

• using a base made of low-carbon steel, serving as a ideal flux conductor
• with a thickness of at least 10 mm
• with a surface perfectly flat
• with total lack of distance (no coatings)
• during detachment in a direction perpendicular to the plane
• in temp. approx. 20°C

Determinants of lifting force in real conditions

Real force is affected by specific conditions, mainly (from priority):

• Clearance – the presence of any layer (paint, tape, gap) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the plate is standardly several times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of generating force.
• Chemical composition of the base – mild steel attracts best. Alloy admixtures decrease magnetic permeability and lifting capacity.
• Surface quality – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Temperature influence – hot environment reduces pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity was determined with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the lifting capacity.