UMP 135x40 [M10+M12] GW F 600 kg / N38 - search holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (according to literature),
• They protect against demagnetization induced by surrounding electromagnetic environments remarkably well,
• The use of a polished gold surface provides a refined finish,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which increases their functional possibilities,
• Wide application in cutting-edge sectors – they are used in data storage devices, rotating machines, clinical machines and sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks while also strengthens its overall strength,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Possible threat from tiny pieces may arise, when consumed by mistake, which is significant in the protection of children. Moreover, minuscule fragments from these magnets have the potential to disrupt scanning if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Magnetic strength at its maximum – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, assessed in ideal conditions, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• at room temperature

What influences lifting capacity in practice

Practical lifting force is dependent on factors, 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) causes 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 testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.