MPL 30x15x2 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They have unchanged lifting capacity, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They remain magnetized despite exposure to magnetic surroundings,
• In other words, due to the glossy nickel coating, the magnet obtains an stylish appearance,
• The outer field strength of the magnet shows advanced magnetic properties,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for fine forming and precise design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Wide application in advanced technical fields – they are utilized in computer drives, electric drives, medical equipment along with sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to physical collisions, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and additionally increases its overall robustness,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment – during outdoor use, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Possible threat linked to microscopic shards may arise, in case of ingestion, which is significant in the protection of children. Furthermore, minuscule fragments from these devices can disrupt scanning when ingested,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum holding power of the magnet – what affects it?

The given holding capacity of the magnet represents the highest holding force, measured in ideal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• in normal thermal conditions

Key elements affecting lifting force

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) 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 measured using a smooth steel plate of suitable thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.