UMH 60x15x69 [M8] / N38 - magnetic holder with hook

Pros and cons of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They have unchanged lifting capacity, and over around ten years their performance decreases symbolically – ~1% (according to theory),
• They maintain their magnetic properties even under strong external field,
• In other words, due to the shiny layer of gold, the element gains a professional look,
• The surface of neodymium magnets generates a strong magnetic field – this is one of their assets,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, allowing for functioning at temperatures reaching 230°C and above...
• Possibility of precise forming and adjusting to complex applications,
• Fundamental importance in advanced technology sectors – they are used in hard drives, electric motors, diagnostic systems, and industrial machines.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only secures them against impacts but also raises their durability
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures 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 immune to moisture, in case of application outdoors
• Due to limitations in creating nuts and complex forms in magnets, we propose using cover - magnetic mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, in case of ingestion, which gains importance in the aspect of protecting the youngest. Additionally, small components of these products can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Detachment force of the magnet in optimal conditions – what affects it?

Breakaway force was defined for the most favorable conditions, including:

• on a block made of structural steel, perfectly concentrating the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• with an polished contact surface
• under conditions of gap-free contact (surface-to-surface)
• under axial force vector (90-degree angle)
• in temp. approx. 20°C

Determinants of lifting force in real conditions

Holding efficiency is influenced by specific conditions, such as (from priority):

• Air gap (between the magnet and the metal), because even a very small distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
• Force direction – note that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Plate thickness – too thin steel causes magnetic saturation, causing part of the flux to be wasted into the air.
• Metal type – different alloys attracts identically. High carbon content weaken the interaction with the magnet.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Heat – NdFeB sinters 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 measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the lifting capacity.