MP 12x8/4x3 / N38 - ring magnet

Strengths as well as weaknesses of rare earth magnets.

Apart from their superior magnetism, neodymium magnets have these key benefits:

• They do not lose strength, even over nearly ten years – the decrease in lifting capacity is only ~1% (based on measurements),
• Neodymium magnets are remarkably resistant to demagnetization caused by external magnetic fields,
• A magnet with a shiny silver surface looks better,
• The surface of neodymium magnets generates a intense magnetic field – this is a key feature,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling functioning at temperatures approaching 230°C and above...
• Possibility of detailed forming and adjusting to atypical conditions,
• Key role in modern technologies – they are used in data components, brushless drives, precision medical tools, and complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• 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.
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We suggest a housing - magnetic holder, due to difficulties in creating threads inside the magnet and complicated forms.
• Health risk to health – tiny shards of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small elements of these products can complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is a challenge,

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The force parameter is a theoretical maximum value conducted under the following configuration:

• on a block made of structural steel, optimally conducting the magnetic field
• whose thickness equals approx. 10 mm
• with a surface cleaned and smooth
• under conditions of ideal adhesion (metal-to-metal)
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

Effective lifting capacity is influenced by working environment parameters, such as (from priority):

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Load vector – highest force is available only during pulling at a 90° angle. The shear force of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the attraction effect.
• Surface condition – smooth surfaces ensure maximum contact, which increases field saturation. Rough surfaces reduce efficiency.
• Operating temperature – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate reduces the load capacity.