MP 5x2.7/1.2x5 C / N38 - ring magnet

Strengths as well as weaknesses of NdFeB magnets.

Besides their tremendous field intensity, neodymium magnets offer the following advantages:

• They do not lose power, even during approximately 10 years – the drop in power is only ~1% (based on measurements),
• They show high resistance to demagnetization induced by external field influence,
• Thanks to the elegant finish, the layer of Ni-Cu-Ni, gold-plated, or silver-plated gives an professional appearance,
• Magnetic induction on the top side of the magnet is strong,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Due to the option of flexible forming and adaptation to unique needs, neodymium magnets can be created in a wide range of shapes and sizes, which expands the range of possible applications,
• Versatile presence in electronics industry – they serve a role in data components, motor assemblies, diagnostic systems, as well as technologically advanced constructions.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Problematic aspects of neodymium magnets and ways of using them

• At very strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. 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 during using outdoors, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture
• We suggest cover - magnetic mechanism, due to difficulties in realizing threads inside the magnet and complex shapes.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these products can disrupt the diagnostic process medical when they are in the body.
• Due to expensive raw materials, their price exceeds standard values,

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

The specified lifting capacity represents the limit force, measured under laboratory conditions, namely:

• with the application of a sheet made of special test steel, guaranteeing full magnetic saturation
• with a thickness of at least 10 mm
• with a plane free of scratches
• under conditions of no distance (metal-to-metal)
• under perpendicular force direction (90-degree angle)
• in temp. approx. 20°C

Practical lifting capacity: influencing factors

Holding efficiency is influenced by specific conditions, including (from priority):

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Angle of force application – highest force 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).
• Plate thickness – insufficiently thick steel does not close the flux, causing part of the power to be wasted into the air.
• Plate material – mild steel gives the best results. Alloy steels lower magnetic permeability and lifting capacity.
• Surface finish – full contact is obtained only on smooth steel. Rough texture create air cushions, weakening the magnet.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity was determined with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate lowers the holding force.