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

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose their even during nearly ten years – the reduction of power is only ~1% (according to tests),
• They protect against demagnetization induced by external electromagnetic environments remarkably well,
• The use of a polished gold surface provides a eye-catching finish,
• The outer field strength of the magnet shows advanced 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 or customization to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Significant impact in cutting-edge sectors – they serve a purpose in computer drives, electric motors, medical equipment as well as sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in small dimensions, which allows for use in small systems

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to shocks, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and additionally increases its overall strength,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (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,
• They rust in a humid environment – during outdoor use, we recommend using encapsulated magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is risky,
• Safety concern from tiny pieces may arise, in case of ingestion, which is notable in the health of young users. It should also be noted that small elements from these assemblies may interfere with diagnostics when ingested,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Maximum holding power of the magnet – what affects it?

The given strength of the magnet means the optimal strength, determined in the best circumstances, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• at room temperature

What influences lifting capacity in practice

Practical lifting force is determined by factors, by priority:

• Air gap between the magnet and the plate, because 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet and the plate reduces the load capacity.