UMT 12x20 white / N38 - board holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their strong magnetic energy, neodymium magnets have these key benefits:

• They do not lose their strength around 10 years – the decrease of lifting capacity is only ~1% (according to tests),
• They show strong resistance to demagnetization from outside magnetic sources,
• Thanks to the glossy finish and silver coating, they have an elegant appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Important function in modern technologies – they are used in hard drives, electromechanical systems, medical equipment or even other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time strengthens its overall robustness,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (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 damp environment. For outdoor use, we recommend using waterproof magnets, such as those made of plastic,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Possible threat from tiny pieces may arise, when consumed by mistake, which is crucial in the context of child safety. Additionally, tiny components from these products may complicate medical imaging if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Maximum holding power of the magnet – what it depends on?

The given strength of the magnet represents the optimal strength, measured under optimal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Key elements affecting lifting force

In practice, the holding capacity of a magnet is affected by these factors, in descending order of importance:

• 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 testing was conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.