KM HF - 22 kg - magnetic bracket

Advantages as well as disadvantages of neodymium magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• Their power is durable, and after around ten years it drops only by ~1% (theoretically),
• Magnets very well defend themselves against loss of magnetization caused by foreign field sources,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to present itself better,
• They are known for high magnetic induction at the operating surface, which increases their power,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in shaping and the capacity to customize to individual projects,
• Fundamental importance in electronics industry – they are used in HDD drives, electric motors, advanced medical instruments, as well as industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• They are fragile upon heavy 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
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of producing threads in the magnet and complicated shapes - preferred is casing - magnetic holder.
• Potential hazard resulting from small fragments of magnets are risky, in case of ingestion, which is particularly important in the context of child health protection. Furthermore, tiny parts of these products are able to be problematic in diagnostics medical when they are in the body.
• With budget limitations the cost of neodymium magnets is a challenge,

Maximum magnetic pulling force – what contributes to it?

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

• using a plate made of low-carbon steel, serving as a circuit closing element
• with a thickness no less than 10 mm
• characterized by smoothness
• with direct contact (no impurities)
• under axial application of breakaway force (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

It is worth knowing that the working load will differ influenced by elements below, starting with the most relevant:

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Angle of force application – maximum parameter is obtained 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 – for full efficiency, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Unevenness creates an air distance.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.