BM 550x180x70 [4x M8] - magnetic beam

Strengths and weaknesses of neodymium magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They have unchanged lifting capacity, and over nearly ten years their performance decreases symbolically – ~1% (according to theory),
• Magnets very well protect themselves against demagnetization caused by external fields,
• By applying a reflective layer of silver, the element presents an elegant look,
• Magnetic induction on the working part of the magnet turns out to be very high,
• 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...
• Possibility of precise shaping as well as adjusting to individual requirements,
• Significant place in advanced technology sectors – they find application in data components, electric drive systems, diagnostic systems, also multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which allows their use in small systems

Cons of neodymium magnets: tips and applications.

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously increases its durability.
• Neodymium magnets lose their strength 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
• They oxidize in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited possibility of making nuts in the magnet and complex forms - preferred is casing - mounting mechanism.
• Health risk related to microscopic parts of magnets can be dangerous, if swallowed, which becomes key in the context of child health protection. Additionally, tiny parts of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what affects it?

Holding force of 0 kg is a result of laboratory testing performed under standard conditions:

• using a base made of low-carbon steel, serving as a ideal flux conductor
• whose thickness equals approx. 10 mm
• with an ground contact surface
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at standard ambient temperature

Determinants of practical lifting force of a magnet

Please note that the working load may be lower depending on elements below, starting with the most relevant:

• Clearance – existence of any layer (rust, dirt, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of generating force.
• Chemical composition of the base – mild steel gives the best results. Higher carbon content lower magnetic permeability and holding force.
• Base smoothness – the more even the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Thermal environment – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.