CM PML-6 / N45 - magnetic gripper

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their immense field intensity, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after 10 years, the performance loss is only ~1% (according to literature),
• They remain magnetized despite exposure to magnetic noise,
• Because of the reflective layer of gold, the component looks visually appealing,
• They have extremely strong magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Important function in modern technologies – they find application in HDDs, electromechanical systems, healthcare devices or even technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage and additionally strengthens its overall resistance,
• They lose field intensity at extreme 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 damp environment. If exposed to rain, we recommend using encapsulated magnets, such as those made of plastic,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is difficult,
• Safety concern linked to microscopic shards may arise, when consumed by mistake, which is important in the context of child safety. It should also be noted that small elements from these magnets have the potential to disrupt scanning when ingested,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

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

The given strength of the magnet represents the optimal strength, calculated under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Key elements affecting lifting force

The lifting capacity of a magnet is influenced by in practice the following factors, ordered from most important to least 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.