UMS 20x8.6x4.5x7 / N38 - conical magnetic holder

Advantages as well as disadvantages of rare earth magnets.

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

• They have stable power, and over around 10 years their performance decreases symbolically – ~1% (according to theory),
• They are resistant to demagnetization induced by external disturbances,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets create maximum magnetic induction on a small area, which ensures high operational effectiveness,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Possibility of detailed creating and adjusting to complex needs,
• Significant place in modern industrial fields – they are commonly used in hard drives, electric drive systems, precision medical tools, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in small systems

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their power 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Due to limitations in creating nuts and complex forms in magnets, we recommend using a housing - magnetic mount.
• Health risk to health – tiny shards of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Furthermore, tiny parts of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

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

Holding force of 6 kg is a measurement result conducted under the following configuration:

• with the application of a sheet made of low-carbon steel, ensuring full magnetic saturation
• possessing a massiveness of min. 10 mm to avoid saturation
• characterized by lack of roughness
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (in the magnet axis)
• at room temperature

Practical lifting capacity: influencing factors

Effective lifting capacity impacted by working environment parameters, such as (from most important):

• Space between magnet and steel – every millimeter of separation (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Plate thickness – insufficiently thick steel does not close the flux, causing part of the flux to be wasted to the other side.
• Chemical composition of the base – low-carbon steel gives the best results. Alloy admixtures lower magnetic properties and lifting capacity.
• Surface finish – ideal contact is possible only on polished steel. Any scratches and bumps reduce the real contact area, reducing force.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity was measured using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the holding force is lower. Moreover, even a minimal clearance {between} the magnet and the plate lowers the holding force.