MW 28.9x10 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (according to literature),
• They show strong resistance to demagnetization from external magnetic fields,
• By applying a bright layer of gold, the element gains a clean look,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• Thanks to their enhanced temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• With the option for tailored forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Key role in advanced technical fields – they are used in hard drives, rotating machines, medical equipment as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in tiny dimensions, which makes them ideal in compact constructions

Disadvantages of neodymium magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to mechanical hits, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall robustness,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a humid environment, especially when used outside, we recommend using encapsulated magnets, such as those made of plastic,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Health risk from tiny pieces may arise, when consumed by mistake, which is crucial in the family environments. It should also be noted that tiny components from these assemblies may complicate medical imaging if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Maximum magnetic pulling force – what contributes to it?

The given holding capacity of the magnet represents the highest holding force, calculated in the best circumstances, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• in normal thermal conditions

Determinants of practical lifting force of a magnet

Practical lifting force is dependent on elements, by priority:

• 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 measured using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.