MW 30x5 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over around ten years their performance decreases symbolically – ~1% (according to theory),
• They show strong resistance to demagnetization from external magnetic fields,
• The use of a decorative silver surface provides a smooth finish,
• The outer field strength of the magnet shows remarkable 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 geometry),
• The ability for precise shaping or adjustment to individual needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Wide application in advanced technical fields – they find application in data storage devices, electric drives, medical equipment and sophisticated instruments,
• 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 heavy impact. If the magnets are exposed to physical collisions, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time enhances its overall robustness,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can corrode. Therefore, for outdoor applications, it's best to use waterproof types made of coated materials,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing holes directly in the magnet,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is notable in the health of young users. It should also be noted that small elements from these magnets may hinder health screening once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum magnetic pulling force – what affects it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured in the best circumstances, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Key elements affecting lifting force

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) 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 with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a small distance {between} the magnet and the plate lowers the load capacity.