MW 3x1 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during around 10 years – the decrease of strength is only ~1% (according to tests),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a shiny layer of silver, the element gains a sleek look,
• Magnetic induction on the surface of these magnets is impressively powerful,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which broadens their usage potential,
• Key role in modern technologies – they find application in HDDs, electromechanical systems, clinical machines as well as technologically developed systems,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to physical collisions, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally strengthens its overall durability,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent loss 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,
• They rust in a humid environment, especially when used outside, we recommend using sealed 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 not feasible,
• Health risk due to small fragments may arise, if ingested accidentally, which is notable in the context of child safety. Additionally, minuscule fragments from these devices may hinder health screening if inside the body,
• 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 lifting capacity of the magnet represents the maximum lifting force, measured in ideal conditions, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• at room temperature

What influences lifting 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, because 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 polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, however under shearing force the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.