UMP 75x24 [M8+M10] GW F 200 kg - search holder

Strengths and weaknesses of rare earth magnets.

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

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (based on calculations),
• They feature excellent resistance to magnetic field loss when exposed to opposing magnetic fields,
• A magnet with a shiny nickel surface has an effective appearance,
• They show high magnetic induction at the operating surface, making them more effective,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of individual forming and optimizing to atypical conditions,
• Universal use in electronics industry – they are utilized in data components, electromotive mechanisms, precision medical tools, also technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• At very strong impacts they can crack, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose 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 durability even at temperatures up to 230°C
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• We recommend a housing - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated shapes.
• Possible danger related to microscopic parts of magnets are risky, if swallowed, which gains importance in the aspect of protecting the youngest. Additionally, small components of these devices are able to complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what affects it?

Holding force of 280 kg is a measurement result executed under the following configuration:

• using a sheet made of low-carbon steel, functioning as a ideal flux conductor
• whose thickness is min. 10 mm
• with an ground contact surface
• with zero gap (without paint)
• for force applied at a right angle (pull-off, not shear)
• in stable room temperature

Determinants of practical lifting force of a magnet

Bear in mind that the working load may be lower influenced by the following factors, in order of importance:

• Distance – the presence of foreign body (rust, dirt, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Chemical composition of the base – low-carbon steel gives the best results. Alloy admixtures lower magnetic properties and holding force.
• Smoothness – ideal contact is possible only on smooth steel. Rough texture create air cushions, weakening the magnet.
• Temperature influence – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet and the plate lowers the lifting capacity.