HH 16x5.3 [M3] / N38 - through hole magnetic holder

Strengths and weaknesses of NdFeB magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They do not lose power, even after around 10 years – the decrease in strength is only ~1% (according to tests),
• Magnets perfectly protect themselves against demagnetization caused by foreign field sources,
• In other words, due to the reflective finish of nickel, the element gains visual value,
• Magnets exhibit impressive magnetic induction on the working surface,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures approaching 230°C and above...
• Possibility of individual forming as well as optimizing to individual applications,
• Fundamental importance in future technologies – they are used in magnetic memories, drive modules, medical devices, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets and proposals for their use:

• At 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.
• Neodymium magnets lose their force 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 stability even at temperatures up to 230°C
• 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 complex forms - recommended is casing - mounting mechanism.
• Health risk to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these products are able to disrupt the diagnostic process medical after entering the body.
• Due to expensive raw materials, their price exceeds standard values,

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

Holding force of 4 kg is a result of laboratory testing executed under standard conditions:

• with the use of a sheet made of special test steel, ensuring maximum field concentration
• whose thickness equals approx. 10 mm
• with an polished contact surface
• under conditions of no distance (metal-to-metal)
• during detachment in a direction perpendicular to the mounting surface
• at standard ambient temperature

Impact of factors on magnetic holding capacity in practice

Bear in mind that the magnet holding will differ subject to elements below, in order of importance:

• Air gap (betwixt the magnet and the metal), since even a very small distance (e.g. 0.5 mm) results in a drastic drop in force by up to 50% (this also applies to paint, corrosion or dirt).
• Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel attracts best. Alloy steels reduce magnetic permeability and lifting capacity.
• Smoothness – full contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Additionally, even a slight gap {between} the magnet and the plate decreases the holding force.