MP 12x5x2 / N38 - ring magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their full power for almost 10 years – the drop is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is among the best,
• By applying a shiny layer of silver, the element gains a modern look,
• They possess significant magnetic force measurable at the magnet’s surface,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• The ability for precise shaping or adaptation to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Significant impact in modern technologies – they find application in HDDs, electric drives, diagnostic apparatus and technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to external force, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall durability,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (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 moist environment. If exposed to rain, 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 mechanical support is recommended,
• Possible threat due to small fragments may arise, especially if swallowed, which is important in the health of young users. Additionally, minuscule fragments from these products might hinder health screening if inside the body,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The given strength of the magnet represents the optimal strength, determined under optimal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

Practical lifting force is dependent on elements, by priority:

• Air gap between the magnet and the plate, since 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 assessed by applying a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, whereas under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet and the plate reduces the load capacity.