HH 42x8.8 [M6] / N38 - through hole magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (according to literature),
• They protect against demagnetization induced by external magnetic fields remarkably well,
• In other words, due to the shiny silver coating, the magnet obtains an aesthetic appearance,
• They have exceptional magnetic induction on the surface of the magnet,
• With the right combination of compounds, they reach significant thermal stability, enabling operation at or above 230°C (depending on the design),
• With the option for fine forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Key role in cutting-edge sectors – they serve a purpose in HDDs, rotating machines, diagnostic apparatus along with sophisticated instruments,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of magnetic elements:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time enhances its overall durability,
• Magnets lose magnetic efficiency 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,
• Magnets exposed to damp air can degrade. Therefore, for outdoor applications, we recommend waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is restricted,
• Possible threat related to magnet particles may arise, if ingested accidentally, which is crucial in the family environments. It should also be noted that tiny components from these magnets have the potential to hinder health screening if inside the body,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

Best holding force of the magnet in ideal parameters – what it depends on?

The given pulling force of the magnet means the maximum force, measured in the best circumstances, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

In practice, the holding capacity of a magnet is affected by these factors, from crucial to less important:

• Air gap between the magnet and the plate, as 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 assessed with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.