UMH 75x18x68 [M8] / N38 - magnetic holder with hook

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable pulling force, neodymium magnets offer the following advantages:

• They do not lose their even during nearly 10 years – the loss of lifting capacity is only ~1% (based on measurements),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a shiny layer of gold, the element gains a clean look,
• They exhibit extremely high levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for accurate shaping or customization to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Key role in modern technologies – they serve a purpose in data storage devices, electromechanical systems, healthcare devices or even high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which allows for use in compact constructions

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture while also increases its overall robustness,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• 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 internal cuts in neodymium magnets is risky,
• Potential hazard from tiny pieces may arise, when consumed by mistake, which is significant in the health of young users. It should also be noted that minuscule fragments from these devices can hinder health screening once in the system,
• Due to a complex production process, their cost is considerably higher,

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

The given pulling force of the magnet means the maximum force, determined in a perfect environment, specifically:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• with vertical force applied
• in normal thermal conditions

Determinants of practical lifting force of a magnet

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, because 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 with the use of a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the holding force.