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

Strengths as well as weaknesses of NdFeB magnets.

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

• They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (based on calculations),
• They retain their magnetic properties even under external field action,
• Thanks to the shiny finish, the surface of nickel, gold-plated, or silver-plated gives an clean appearance,
• Magnets have huge magnetic induction on the working surface,
• 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 flexibility in forming and the capacity to adapt to complex applications,
• Wide application in high-tech industry – they find application in computer drives, electromotive mechanisms, medical devices, as well as technologically advanced constructions.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• 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 force 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
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest casing - magnetic holder, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. It is also worth noting that small components of these products are able to disrupt the diagnostic process medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

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

Breakaway force was defined for ideal contact conditions, taking into account:

• using a sheet made of mild steel, acting as a magnetic yoke
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• under conditions of gap-free contact (surface-to-surface)
• during pulling in a direction perpendicular to the mounting surface
• at ambient temperature room level

Practical lifting capacity: influencing factors

Bear in mind that the application force will differ depending on elements below, in order of importance:

• Clearance – existence of foreign body (rust, tape, air) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Steel thickness – too thin plate does not close the flux, causing part of the flux to be wasted to the other side.
• Steel grade – ideal substrate is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.