NCM 30x13.5x5 / N38 - channel magnetic holder

Pros as well as cons of NdFeB magnets.

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

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• Magnets perfectly resist against demagnetization caused by foreign field sources,
• The use of an elegant layer of noble metals (nickel, gold, silver) causes the element to look better,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures approaching 230°C and above...
• Possibility of custom creating and adapting to complex conditions,
• Fundamental importance in future technologies – they find application in magnetic memories, motor assemblies, medical equipment, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which allows their use in miniature devices

Characteristics of disadvantages of neodymium magnets and proposals for their use:

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its 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 durability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• Due to limitations in creating nuts and complex forms in magnets, we recommend using cover - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets pose a threat, in case of ingestion, which gains importance in the aspect of protecting the youngest. Additionally, small components of these devices can be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

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

Magnet power is the result of a measurement for the most favorable conditions, assuming:

• with the use of a yoke made of special test steel, guaranteeing full magnetic saturation
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• without any insulating layer between the magnet and steel
• during detachment in a direction vertical to the plane
• in temp. approx. 20°C

Impact of factors on magnetic holding capacity in practice

Holding efficiency is affected by working environment parameters, mainly (from most important):

• Distance – existence of foreign body (paint, dirt, gap) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Steel thickness – too thin sheet causes magnetic saturation, causing part of the power to be lost to the other side.
• Metal type – different alloys reacts the same. High carbon content worsen the attraction effect.
• Plate texture – ground elements ensure maximum contact, which increases force. Rough surfaces reduce efficiency.
• Thermal environment – heating the magnet results in weakening of induction. It is worth remembering the maximum operating temperature for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet and the plate lowers the holding force.