CM PML-10 / N45 - magnetic gripper

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous strength, neodymium magnets offer the following advantages:

• They do not lose their strength nearly ten years – the loss of strength is only ~1% (theoretically),
• They show strong resistance to demagnetization from outside magnetic sources,
• Thanks to the polished finish and gold coating, they have an elegant appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• With the right combination of magnetic alloys, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• Thanks to the possibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in various configurations, which expands their functional possibilities,
• Important function in cutting-edge sectors – they serve a purpose in computer drives, rotating machines, diagnostic apparatus as well as high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which makes them ideal in miniature devices

Disadvantages of magnetic elements:

• They can break when subjected to a heavy impact. If the magnets are exposed to external force, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time enhances its overall durability,
• They lose magnetic force at extreme temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry 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, especially when used outside, we recommend using encapsulated magnets, such as those made of rubber,
• Limited ability to create threads in the magnet – the use of a external casing is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is crucial in the protection of children. Moreover, tiny components from these magnets might disrupt scanning once in the system,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, assessed in a perfect environment, that is:

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

Magnet lifting force in use – key factors

The lifting capacity of a magnet is influenced by in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, since 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 was determined using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the holding force.