UMS 20x8.6x4.5x7 / 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 virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (according to literature),
• They show exceptional resistance to demagnetization from outside magnetic sources,
• The use of a polished silver surface provides a eye-catching finish,
• They possess intense magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and precise design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Wide application in cutting-edge sectors – they find application in computer drives, electric motors, diagnostic apparatus and technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to external force, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens its overall robustness,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a moist environment, especially when used outside, we recommend using sealed magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is not feasible,
• Possible threat related to magnet particles may arise, especially if swallowed, which is notable in the protection of children. Furthermore, tiny components from these assemblies can hinder health screening once in the system,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

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

The given pulling force of the magnet represents the maximum force, determined in the best circumstances, namely:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• in normal thermal conditions

Determinants of lifting force in real conditions

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

• Air gap between the magnet and the plate, because 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 by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet and the plate decreases the load capacity.