MW 8x1.5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• They protect against demagnetization induced by external electromagnetic environments remarkably well,
• By applying a reflective layer of nickel, the element gains a sleek look,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the design),
• With the option for fine forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Important function in advanced technical fields – they are used in computer drives, electromechanical systems, clinical machines and high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which allows for use in miniature devices

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to shocks, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time enhances its overall strength,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on height). 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Potential hazard related to magnet particles may arise, when consumed by mistake, which is important in the protection of children. Furthermore, small elements from these assemblies have the potential to disrupt scanning once in the system,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum magnetic pulling force – what affects it?

The given holding capacity of the magnet represents the highest holding force, calculated in the best circumstances, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• with vertical force applied
• at room temperature

Lifting capacity in practice – influencing factors

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

• Air gap between the magnet and the plate, as 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, whereas under shearing force the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.