UMH 42x9x46 [M6] / N38 - magnetic holder with hook

Strengths as well as weaknesses of neodymium magnets.

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

• They do not lose magnetism, even over around ten years – the reduction in strength is only ~1% (theoretically),
• Magnets perfectly resist against loss of magnetization caused by foreign field sources,
• By covering with a reflective layer of silver, the element acquires an elegant look,
• The surface of neodymium magnets generates a concentrated magnetic field – this is a key feature,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures reaching 230°C and above...
• Thanks to the ability of flexible molding and customization to unique needs, neodymium magnets can be modeled in a wide range of geometric configurations, which makes them more universal,
• Significant place in high-tech industry – they are commonly used in hard drives, electromotive mechanisms, medical devices, also modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which makes them useful in miniature devices

Problematic aspects of neodymium magnets and proposals for their use:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We suggest cover - magnetic mount, due to difficulties in realizing threads inside the magnet and complicated forms.
• Health risk to health – tiny shards of magnets are risky, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small elements of these magnets can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

Breakaway strength of the magnet in ideal conditions – what it depends on?

Breakaway force is the result of a measurement for ideal contact conditions, including:

• using a plate made of low-carbon steel, serving as a magnetic yoke
• with a cross-section minimum 10 mm
• with a plane free of scratches
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at room temperature

Lifting capacity in practice – influencing factors

Please note that the application force may be lower depending on the following factors, in order of importance:

• Air gap (between the magnet and the metal), because even a very small distance (e.g. 0.5 mm) leads to a reduction in force by up to 50% (this also applies to paint, corrosion or dirt).
• Load vector – maximum parameter is available only during pulling at a 90° angle. The shear force of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Steel grade – ideal substrate is pure iron steel. Stainless steels may attract less.
• Surface finish – full contact is obtained only on polished steel. Rough texture reduce the real contact area, reducing force.
• Temperature influence – hot environment reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed using a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet and the plate reduces the load capacity.