BM 950x180x70 [4x M8] - magnetic beam

Pros and cons of neodymium magnets.

Besides their exceptional pulling force, neodymium magnets offer the following advantages:

• They do not lose magnetism, even during nearly 10 years – the drop in lifting capacity is only ~1% (according to tests),
• Magnets very well resist against loss of magnetization caused by ambient magnetic noise,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to present itself better,
• Magnetic induction on the top side of the magnet remains exceptional,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures approaching 230°C and above...
• Possibility of custom creating as well as adapting to individual needs,
• Fundamental importance in modern industrial fields – they serve a role in hard drives, drive modules, diagnostic systems, as well as multitasking production systems.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets: weaknesses and usage proposals

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only secures them against impacts but also raises their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of producing threads in the magnet and complicated shapes - preferred is cover - magnet mounting.
• Health risk to health – tiny shards of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Additionally, small elements of these devices are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum lifting capacity of the magnet – what contributes to it?

The force parameter is a result of laboratory testing executed under the following configuration:

• with the use of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• with a thickness minimum 10 mm
• with an ideally smooth touching surface
• with direct contact (without coatings)
• under perpendicular force vector (90-degree angle)
• at standard ambient temperature

Magnet lifting force in use – key factors

It is worth knowing that the magnet holding may be lower depending on the following factors, in order of importance:

• Clearance – existence of foreign body (paint, tape, gap) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Material type – ideal substrate is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Surface structure – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Temperature – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.