CM PML-10 / N45 - magnetic gripper

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have unchanged lifting capacity, and over more than 10 years their performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to strong external fields,
• By applying a reflective layer of nickel, the element gains a modern look,
• Magnetic induction on the surface of these magnets is very strong,
• With the right combination of magnetic alloys, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the form),
• The ability for precise shaping or adaptation to specific needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which amplifies their functionality across industries,
• Important function in advanced technical fields – they find application in hard drives, electric drives, diagnostic apparatus or even other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are fragile when subjected to a strong 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 fracture , and at the same time reinforces its overall durability,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on form). 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,
• Magnets exposed to wet conditions can degrade. Therefore, for outdoor applications, we suggest waterproof types made of coated materials,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Health risk related to magnet particles may arise, in case of ingestion, which is important in the family environments. Furthermore, miniature parts from these magnets might interfere with diagnostics if inside the body,
• Due to the price of neodymium, their cost is above average,

Optimal lifting capacity of a neodymium magnet – what affects it?

The given pulling force of the magnet corresponds to the maximum force, measured in a perfect environment, that is:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Impact of factors on magnetic holding 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, 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.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under a perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet and the plate reduces the lifting capacity.