UMS 25x10.5x5.5x8 / N38 - conical magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic surroundings,
• Because of the brilliant layer of nickel, the component looks high-end,
• They have very high magnetic induction on the surface of the magnet,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to form),
• With the option for tailored forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Key role in modern technologies – they are utilized in HDDs, electromechanical systems, clinical machines or even high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which allows for use in compact constructions

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to shocks, 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 reinforces its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (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 wet environment – during outdoor use, we recommend using encapsulated magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is not feasible,
• Safety concern related to magnet particles may arise, in case of ingestion, which is important in the context of child safety. Additionally, miniature parts from these products have the potential to disrupt scanning if inside the body,
• Due to expensive raw materials, their cost is above average,

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

The given lifting capacity of the magnet means the maximum lifting force, determined in a perfect environment, namely:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is conditioned 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 was measured with the use of a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet and the plate decreases the lifting capacity.