CM PML-3 / N45 - magnetic gripper

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their strong power, neodymium magnets have these key benefits:

• They retain their magnetic properties for around 10 years – the drop is just ~1% (based on simulations),
• They protect against demagnetization induced by external electromagnetic environments effectively,
• Thanks to the shiny finish and silver coating, they have an aesthetic appearance,
• The outer field strength of the magnet shows advanced magnetic properties,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Thanks to the possibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Significant impact in new technology industries – they find application in computer drives, electromechanical systems, clinical machines as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and reinforces its overall robustness,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can degrade. Therefore, for outdoor applications, we suggest waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Possible threat linked to microscopic shards may arise, when consumed by mistake, which is crucial in the family environments. Furthermore, miniature parts from these assemblies can complicate medical imaging when ingested,
• Due to a complex production process, their cost is above average,

Highest magnetic holding force – what it depends on?

The given pulling force of the magnet represents the maximum force, measured in ideal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

What influences lifting capacity in practice

Practical lifting force is dependent on factors, by priority:

• Air gap between the magnet and the plate, since 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 the force acted perpendicularly, however under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.