MW 5x30 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

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

• Their magnetic field is maintained, and after approximately ten years it drops only by ~1% (theoretically),
• They show high resistance to demagnetization induced by external magnetic fields,
• By covering with a smooth coating of gold, the element has an aesthetic look,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to freedom in designing and the ability to modify to client solutions,
• Universal use in future technologies – they are used in HDD drives, electromotive mechanisms, advanced medical instruments, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in miniature devices

Cons of neodymium magnets and proposals for their use:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a special holder, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their strength 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 while using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• We suggest casing - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated shapes.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets are able to 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 increases costs of application in large quantities

Magnetic strength at its maximum – what it depends on?

The specified lifting capacity concerns the maximum value, recorded under ideal test conditions, specifically:

• using a base made of high-permeability steel, functioning as a circuit closing element
• possessing a massiveness of minimum 10 mm to avoid saturation
• with a surface cleaned and smooth
• under conditions of no distance (metal-to-metal)
• for force applied at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Magnet lifting force in use – key factors

Please note that the application force will differ subject to the following factors, starting with the most relevant:

• Gap between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Load vector – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of generating force.
• Steel grade – ideal substrate is high-permeability steel. Stainless steels may attract less.
• Surface finish – ideal contact is obtained only on smooth steel. Any scratches and bumps create air cushions, weakening the magnet.
• Temperature – temperature increase results in weakening of force. It is worth remembering the maximum operating temperature for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas 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.