UMH 25x8x45 [M5] / N38 - magnetic holder with hook

Advantages and disadvantages of rare earth magnets.

Besides their tremendous magnetic power, neodymium magnets offer the following advantages:

• They have constant strength, and over around ten years their performance decreases symbolically – ~1% (in testing),
• Neodymium magnets are characterized by exceptionally resistant to demagnetization caused by external magnetic fields,
• Thanks to the shimmering finish, the layer of Ni-Cu-Ni, gold, or silver-plated gives an clean appearance,
• Magnets possess exceptionally strong magnetic induction on the outer layer,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to versatility in constructing and the ability to customize to specific needs,
• Universal use in high-tech industry – they are commonly used in computer drives, motor assemblies, medical devices, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in small dimensions, which enables their usage in compact constructions

Disadvantages of NdFeB magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets decrease their strength 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
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Due to limitations in creating nuts and complex forms in magnets, we recommend using casing - magnetic holder.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which gains importance in the context of child safety. Furthermore, small components of these magnets can be problematic in diagnostics medical in case of swallowing.
• Due to neodymium price, their price exceeds standard values,

Best holding force of the magnet in ideal parameters – what contributes to it?

Holding force of 25 kg is a theoretical maximum value conducted under the following configuration:

• on a block made of mild steel, effectively closing the magnetic field
• with a cross-section no less than 10 mm
• with an ground touching surface
• with zero gap (without coatings)
• during pulling in a direction perpendicular to the plane
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

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

• Distance – existence of foreign body (paint, tape, air) interrupts the magnetic circuit, which reduces power rapidly (even by 50% at 0.5 mm).
• Force direction – remember that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – too thin sheet does not accept the full field, causing part of the flux to be escaped into the air.
• Steel grade – ideal substrate is pure iron steel. Stainless steels may attract less.
• Plate texture – ground elements ensure maximum contact, which increases field saturation. Uneven metal weaken the grip.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

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