WM 34.5x24.3x17 / N38 - magnetic hanger

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose their even during nearly ten years – the decrease of lifting capacity is only ~1% (according to tests),
• They show superior resistance to demagnetization from external magnetic fields,
• Because of the reflective layer of gold, the component looks visually appealing,
• The outer field strength of the magnet shows remarkable magnetic properties,
• With the right combination of magnetic alloys, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• The ability for custom shaping as well as adaptation to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Wide application in new technology industries – they are utilized in computer drives, electric motors, clinical machines along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them ideal in compact constructions

Disadvantages of rare earth magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time strengthens its overall strength,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of protective material for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing complex structures directly in the magnet,
• Potential hazard due to small fragments may arise, when consumed by mistake, which is notable in the protection of children. It should also be noted that small elements from these magnets have the potential to hinder health screening when ingested,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Maximum holding power of the magnet – what it depends on?

The given strength of the magnet represents the optimal strength, assessed in ideal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet depends on in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, since even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.