UMH 42x9x46 [M6] / N38 - magnetic holder with hook

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent power, neodymium magnets have these key benefits:

• Their strength is durable, and after around ten years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is notable,
• Thanks to the polished finish and nickel coating, they have an visually attractive appearance,
• They possess intense magnetic force measurable at the magnet’s surface,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the structure),
• With the option for customized forming and precise design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Wide application in advanced technical fields – they serve a purpose in data storage devices, electric drives, healthcare devices and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which allows for use in miniature devices

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time reinforces its overall robustness,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (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 damp environment, especially when used outside, we recommend using waterproof magnets, such as those made of polymer,
• Limited ability to create threads in the magnet – the use of a mechanical support is recommended,
• Possible threat linked to microscopic shards may arise, in case of ingestion, which is significant in the protection of children. Additionally, miniature parts from these devices may interfere with diagnostics after being swallowed,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Breakaway strength of the magnet in ideal conditions – what it depends on?

The given strength of the magnet means the optimal strength, calculated in ideal conditions, specifically:

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

Magnet lifting force in use – key factors

The lifting capacity of a magnet depends on in practice the following factors, ordered from most important to least significant:

• 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 using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.