UMH 48x11x65 [M6] / N38 - magnetic holder with hook

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• Their strength is durable, and after around 10 years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by surrounding magnetic influence remarkably well,
• The use of a decorative nickel surface provides a smooth finish,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the design),
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Key role in advanced technical fields – they are utilized in data storage devices, electric motors, healthcare devices or even sophisticated instruments,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and enhances its overall resistance,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to humidity can degrade. Therefore, for outdoor applications, we advise waterproof types made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing complex structures directly in the magnet,
• Health risk linked to microscopic shards may arise, especially if swallowed, which is crucial in the context of child safety. It should also be noted that tiny components from these products can complicate medical imaging after being swallowed,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Optimal lifting capacity of a neodymium magnet – what affects it?

The given pulling force of the magnet means the maximum force, calculated in ideal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• with vertical force applied
• at room temperature

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, from crucial to less important:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity was assessed using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.