UI 17.5x5 [C310] / N38 - badge holder

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (according to literature),
• They are very resistant to demagnetization caused by external field interference,
• The use of a mirror-like nickel surface provides a refined finish,
• Magnetic induction on the surface of these magnets is impressively powerful,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• The ability for custom shaping or adaptation to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Important function in cutting-edge sectors – they serve a purpose in hard drives, electric motors, medical equipment as well as sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which makes them useful in small systems

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage and increases its overall robustness,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a wet environment. For outdoor use, we recommend using moisture-resistant magnets, such as those made of plastic,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Health risk related to magnet particles may arise, if ingested accidentally, which is important in the context of child safety. Additionally, small elements from these devices might hinder health screening when ingested,
• Due to expensive raw materials, their cost is relatively high,

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

The given holding capacity of the magnet means the highest holding force, assessed in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• under standard ambient temperature

What influences lifting capacity in practice

Practical lifting force is determined by elements, listed from the most critical to the less significant:

• 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 was assessed using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.