UMH 25x8x45 [M5] / N38 - magnetic holder with hook

Advantages and disadvantages of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
• They show high resistance to demagnetization induced by external disturbances,
• Thanks to the metallic finish, the coating of Ni-Cu-Ni, gold, or silver-plated gives an aesthetic appearance,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in designing and the capacity to adapt to specific needs,
• Fundamental importance in modern industrial fields – they are utilized in computer drives, brushless drives, medical devices, as well as industrial machines.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At very strong impacts they can crack, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop 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 extremely resistant to heat
• They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited ability of making threads in the magnet and complicated forms - preferred is a housing - mounting mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small elements of these products can complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum magnetic pulling force – what affects it?

Magnet power was defined for ideal contact conditions, taking into account:

• on a block made of structural steel, effectively closing the magnetic field
• possessing a thickness of at least 10 mm to ensure full flux closure
• with a plane free of scratches
• with total lack of distance (without paint)
• for force acting at a right angle (in the magnet axis)
• at standard ambient temperature

Lifting capacity in practice – influencing factors

Bear in mind that the application force may be lower subject to elements below, in order of importance:

• Distance (between the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to paint, rust or dirt).
• Load vector – maximum parameter is reached only during perpendicular pulling. The force required to slide of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Steel grade – the best choice is high-permeability steel. Hardened steels may have worse magnetic properties.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Temperature influence – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under shearing force the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the load capacity.