UMH 42x9x46 [M6] / N38 - magnetic holder with hook

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their stability, neodymium magnets are valued for these benefits:

• They retain their full power for around ten years – the loss is just ~1% (in theory),
• Their ability to resist magnetic interference from external fields is notable,
• In other words, due to the glossy nickel coating, the magnet obtains an professional appearance,
• They exhibit extremely high levels of magnetic induction near the outer area of the magnet,
• With the right combination of compounds, they reach significant thermal stability, enabling operation at or above 230°C (depending on the structure),
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which increases their application range,
• Wide application in advanced technical fields – they find application in hard drives, electric drives, medical equipment along with sophisticated instruments,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time strengthens its overall durability,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a moist environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of plastic,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Safety concern linked to microscopic shards may arise, in case of ingestion, which is crucial in the context of child safety. Additionally, small elements from these magnets may complicate medical imaging once in the system,
• Due to the price of neodymium, their cost is above average,

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

The given pulling force of the magnet means the maximum force, determined in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• 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 determined by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate reduces the holding force.