UMP 75x24 [M8+M10] GW F 200 kg - search holder

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their tremendous field intensity, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (based on calculations),
• They are extremely resistant to demagnetization caused by external magnetic fields,
• In other words, due to the metallic silver coating, the magnet obtains an stylish appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to build),
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Important function in advanced technical fields – they serve a purpose in HDDs, electric drives, clinical machines along with high-tech tools,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and enhances its overall durability,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a moist environment – during outdoor use, we recommend using waterproof magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Potential hazard due to small fragments may arise, especially if swallowed, which is notable in the family environments. Additionally, minuscule fragments from these magnets may disrupt scanning once in the system,
• Due to the price of neodymium, their cost is considerably higher,

Maximum lifting capacity of the magnet – what it depends on?

The given pulling force of the magnet corresponds to the maximum force, assessed in ideal conditions, 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
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is affected by the following aspects, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, since 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 was determined using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under vertically applied force, in contrast under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.