MP 5x2.7/1.2x5 C / N38 - ring magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They have constant strength, and over more than 10 years their attraction force decreases symbolically – ~1% (in testing),
• They are highly resistant to demagnetization caused by external magnetic sources,
• The use of a mirror-like nickel surface provides a refined finish,
• The outer field strength of the magnet shows remarkable magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for accurate shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Important function in advanced technical fields – they find application in computer drives, rotating machines, clinical machines along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which allows for use in compact constructions

Disadvantages of NdFeB magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks and additionally enhances its overall strength,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (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,
• Magnets exposed to moisture can degrade. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Safety concern linked to microscopic shards may arise, if ingested accidentally, which is notable in the family environments. Furthermore, small elements from these devices may disrupt scanning after being swallowed,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Detachment force of the magnet in optimal conditions – what contributes to it?

The given pulling force of the magnet corresponds to the maximum force, measured in the best circumstances, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

What influences lifting capacity in practice

Practical lifting force is dependent on factors, 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 testing was carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate decreases the load capacity.