BM 320x180x70 [4x M8] - magnetic beam

Strengths and weaknesses of NdFeB magnets.

Apart from their consistent power, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after 10 years the performance loss is only ~1% (according to literature),
• They show high resistance to demagnetization induced by external disturbances,
• A magnet with a metallic nickel surface has an effective appearance,
• They show high magnetic induction at the operating surface, which improves attraction properties,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to modularity in shaping and the capacity to modify to individual projects,
• Wide application in electronics industry – they are used in magnetic memories, drive modules, medical equipment, and other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets and ways of using them

• They are fragile 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 advise our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited ability of producing nuts in the magnet and complicated forms - preferred is casing - magnet mounting.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. Furthermore, small elements of these devices are able to be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what contributes to it?

Information about lifting capacity was defined for ideal contact conditions, assuming:

• with the use of a sheet made of special test steel, guaranteeing full magnetic saturation
• with a cross-section of at least 10 mm
• with a plane perfectly flat
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

It is worth knowing that the working load may be lower subject to the following factors, starting with the most relevant:

• Distance (betwixt the magnet and the metal), since even a tiny clearance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, rust or debris).
• Direction of force – highest force is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick sheet does not accept the full field, causing part of the flux to be wasted to the other side.
• Steel grade – the best choice is high-permeability steel. Cast iron may attract less.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal environment – temperature increase results in weakening of induction. It is worth remembering the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.