MW 8x20 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over around ten years their performance decreases symbolically – ~1% (in testing),
• They show strong resistance to demagnetization from outside magnetic sources,
• By applying a reflective layer of nickel, the element gains a clean look,
• Magnetic induction on the surface of these magnets is notably high,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for accurate shaping or customization to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Key role in cutting-edge sectors – they are utilized in computer drives, rotating machines, clinical machines as well as other advanced devices,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to external force, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks and additionally increases its overall strength,
• High temperatures may significantly reduce the holding force 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 common to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is restricted,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is significant in the context of child safety. Additionally, miniature parts from these assemblies have the potential to disrupt scanning once in the system,
• Due to a complex production process, their cost is above average,

Detachment force of the magnet in optimal conditions – what it depends on?

The given lifting capacity of the magnet represents the maximum lifting force, measured under optimal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a polished side
• with zero air gap
• with vertical force applied
• at room temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is influenced by in practice key elements, from primary to secondary:

• 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 carried out on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate lowers the load capacity.