CM PML-6 / N45 - magnetic gripper

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after 10 years, the decline in efficiency is only ~1% (in laboratory conditions),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• In other words, due to the shiny gold coating, the magnet obtains an professional appearance,
• They possess strong magnetic force measurable at the magnet’s surface,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to form),
• The ability for precise shaping as well as adaptation to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Key role in new technology industries – they find application in HDDs, electromechanical systems, healthcare devices as well as other advanced devices,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to mechanical hits, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall robustness,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on shape). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• They rust in a moist environment – during outdoor use, we recommend using encapsulated magnets, such as those made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing threads directly in the magnet,
• Health risk due to small fragments may arise, if ingested accidentally, which is notable in the context of child safety. Furthermore, miniature parts from these magnets have the potential to 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 strength of the magnet represents the optimal strength, assessed in the best circumstances, specifically:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

What influences lifting capacity in practice

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• Air gap between the magnet and the plate, as 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 assessed using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.