BM 950x180x70 [4x M8] - magnetic beam

Strengths and weaknesses of NdFeB magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They do not lose power, even during around 10 years – the decrease in lifting capacity is only ~1% (based on measurements),
• They are noted for resistance to demagnetization induced by presence of other magnetic fields,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets have very high magnetic induction on the active area,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Thanks to modularity in shaping and the capacity to customize to unusual requirements,
• Fundamental importance in high-tech industry – they find application in data components, electric motors, medical devices, and other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At very strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We suggest casing - magnetic holder, due to difficulties in producing threads inside the magnet and complicated shapes.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child safety. It is also worth noting that tiny parts of these devices can be problematic in diagnostics medical in case of swallowing.
• With mass production the cost of neodymium magnets can be a barrier,

Detachment force of the magnet in optimal conditions – what affects it?

Information about lifting capacity was defined for the most favorable conditions, including:

• with the contact of a sheet made of special test steel, ensuring maximum field concentration
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by smoothness
• with total lack of distance (no impurities)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Lifting capacity in practice – influencing factors

It is worth knowing that the magnet holding will differ depending on the following factors, starting with the most relevant:

• Air gap (betwixt the magnet and the plate), since even a very small distance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Plate thickness – insufficiently thick steel causes magnetic saturation, causing part of the flux to be lost to the other side.
• Material type – the best choice is pure iron steel. Cast iron may attract less.
• Surface quality – the more even the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and in frost they can be stronger (up to a certain limit).

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.